advantages of biofuels essay

Advantages and Disadvantages of Biofuels

Biofuels have emerged as an alternative to fossil fuels in recent years due to their potential to reduce greenhouse gas emissions and promote the use of renewable energy. Their main perk is that they are produced from organic materials which replenish seasonally. These materials include plant matter such as corn, soybeans, and sugarcane, as well as animal fats and agricultural waste.

Biofuels are an alternative to fossil fuels (oil, natural gas, and coal). Fossil fuels are non-renewable and release greenhouse gases during their combustion. Compared to fossil fuels, biofuels are considered to be a more environmentally friendly and sustainable energy source due to their renewability and lower emissions of greenhouse gases during burning. But is this energy source such a positive news as it seems at the first glance?

While biofuels certainly have many potential benefits, there are also a number of challenges and trade-offs associated with their production and long-term use at larger scale. Let’s explore the pros and cons of biofuels in order to better understand their future potential as our energy source.

What are biofuels and where are they used the most?

There are several different types of biofuels: liquid biofuels such as bioethanol and biodiesel; solid biofuels like wood pellets, fuelwood, or animals waste; and biogas like landfill gas.

You may think that biofuels are used mainly in transport, but that’s not all. There is a variety of applications, including electricity generation, and heating. In the transport sector, they are often used as a substitute for gasoline and diesel fuel. For example, bioethanol, which is produced from plant matter from corn, sugarcane or rapeseed, can be blended with gasoline to create a fuel called E10, which contains 10 percent of bioethanol and 90 percent of gasoline.

Biodiesel, that is produced from animal fats or vegetable oils, can be used as a replacement for diesel fuel in heavy-duty work vehicles like trucks or buses. Biogas is used predominantly in the electricity sector. This fuel is made from the decomposition of organic matter. Biofuels are also used with success for heating buildings. During their combustion in furnaces and boilers, they produce heat just like fossil fuels do.

Biofuels are a renewable resource, so they can be replenished over time. Fossil fuels , on the other hand, are non-renewable, which means they are finite and will eventually run out. The use of biofuels can therefore help to reduce our reliance on fossil fuels and contribute to a more sustainable energy system.

What are the advantages of biofuels over fossil fuels?

The benefits of biofuels compared to fossil fuels depend on a variety of factors that need to be considered when used on a large scale. These factors are mainly taken into account under the section of disadvantages and will help you understand the complexity of the situation when it comes to finding new energy sources that would replace fossil fuels entirely.

Let’s have a look at the main advantages of biofuels over fossil fuels:

#1 Renewable fuel of biological origin

Biofuels replenish over time, whereas fossil fuels are non-renewable and will eventually run out. By being renewable, they are a type of fuel that could potentially support sustainable development by promoting the use of renewable energy and reducing our impact on the environment.

As an alternative source of energy, they also reduce our reliance on fossil fuels, minimizing or emitting negative effects that come with the use of this polluting and limited source that has been powering our economies since the industrial revolution but has also brought about increased pollution levels and emissions of greenhouse gases. Which brings us to the second advantage…

#2 Lower carbon footprint

The production and use of biofuels generates significantly less greenhouse gas emissions than the production and use of highly polluting fossil fuels.

Biofuels are considered carbon neutral because the carbon dioxide emitted when they are burned is offset by the carbon dioxide that was absorbed by the plants during photosynthesis. What does it mean? The organic material that makes biofuels is made of carbon dioxide absorbed by plants from the atmosphere as they grew. When the plant biomass is burned, it releases this absorbed carbon dioxide back into the atmosphere.

The use of biofuels can help to reduce our reliance on fossil fuels and contribute to a more sustainable energy system. However, it is important to carefully evaluate the environmental impacts of biofuels in order to ensure that they are being used in the most sustainable and responsible way possible.

#3 Improved air quality due to lower emissions

The burning of biofuels generates fewer air pollutants than the burning of fossil fuels, which can improve air quality and public health.

The burning of fossil fuels generates a variety of air pollutants, including carbon monoxide, nitrogen oxides, and particulate matter. These air pollutants can cause respiratory and cardiovascular problems, as well as damage to crops, forests, and other ecosystems.

Biofuels, on the other hand, are produced from biological materials, which are generally considered to be cleaner-burning than fossil fuels. Just consider: biodiesel is a biodegradable fuel that releases less emissions when burned. Its application in transport industry would cut a big part of the air pollution originating from this growing industry [2] .

According to studies, the levels of carbon dioxide emissions and particulate matter are reduced with biofuels, however, the nitrogen oxides are slightly higher than at fossil fuels [1] .

#4 Reduction of reliance on finite fossil fuels

By using biofuels as an alternative energy source, we can reduce our reliance on fossil fuels, which can help to reduce our impact on the environment and contribute to a more sustainable energy system that is more locally based.

This way biofuels also decrease our dependence on foreign oil, which helps to reduce our trade deficit and improve energy security on a country level.

#5 Locally sourced and good for local economy

In many cases, biofuels can be produced from locally available resources. The production, distribution, and use of biofuels can create jobs in a variety of sectors that will support the production and use of this sustainable alternative. The transition to biofuels will affect especially economic sectors of agriculture, manufacture, reprocessing, recycling, and transportation.

The development of a biofuels industry has great potential to stimulate economic development in rural areas with less job possibilities by creating new markets for crops and other agricultural products. Except providing new livelihood opportunities for local families, they could also represent a sustainable and innovative option that will contribute to rural development.

#6 Sustainable energy source and falls within a circular economy scheme

The development of new biofuels technologies can support innovation and drive economic growth in a sustainable way.

As an alternative source of energy obtained from renewable and biological material, these fuels can be produced using waste materials. This is a great news for sustainable future planning since the use of biofuels is in agreement with the development of a circular economy by closing the loop on resource use.

#7 Improved energy security for individual countries

Biological source of energy can be produced in many cases from locally available resources, which in turn decreases our reliance on imported fossil fuels that are even becoming rarer.  

Anything that is local comes with an extra benefit. It has a lower cost for the environment, as it doesn’t have to be brought over a long distance, releasing carbon dioxide emissions. But it is even more economical solution in terms of paying a cost set by international political agreements. 

The use of biofuels improves energy security of individual countries by diversifying the energy mix and reducing reliance of countries on a single energy source.

#8 Environmentally friendly energy source

When done right and well-regulated, the production of biofuels has potential to actually support local biodiversity by promoting the growth of crops that are providing support to soils and leave soils less prone to erosion.

An example of such practice could be plantation of diverse prairie grass mixtures. They are perennial. They cover the soil year-round, and support biodiversity of small soil fauna and mammals by providing nutrients. Additionally, the grass mix actually helps to offset carbon dioxide from the atmosphere. The green biomass from these grasses can be harvested regularly for the use as a biofuel.  

If biofuels are obtained from sustainable farming of reclaimed lands, their production may be much less polluting in terms of not degrading land or freshwater resources compared to fossil fuels. Restored and gently maintained land will yield enough biomass for biofuel production at lower need for synthetic substances, such as pesticides or fungicides. Higher the diversity of plants, better natural resistance to diseases and pests. This removes the need for application of chemicals and the risk of runoff and water contamination is simply lower.  

What are the disadvantages of biofuels?

There are a few potential negative effects of biofuels on the environment and economy that need to be considered when forming an opinion about their use in the future. Let’s start with one of the main arguments against the use of biofuels.

#1 Land use changes and land grabbing

The production of biofuels often leads to land use changes, such as the conversion of natural habitats to cropland. Biofuels are often produced from crops such as corn, sugarcane, and palm oil, which can be grown on a large scale. To meet the increasing demand for biofuels, farmers may convert natural habitats, such as forests and grasslands, into croplands.

Land use change leads to the loss of biodiversity, especially in many places where native ecosystems were previously untouched, as well as increased greenhouse gas emissions from the conversion of carbon-rich ecosystems.

Additionally, biofuel production can also lead to changes in land use patterns, as farmers may shift from growing food crops to biofuel crops in order to take advantage of government incentives or higher prices for biofuel crops. This can lead to food insecurity in local communities and increase in food prices.

#2 Competition for resources with food production

The production of biofuels can in some cases compete with food production in several ways.

One way is through direct competition for land, water, and other resources. For example, if crops grown for biofuels are planted on land that could be used for growing food crops. Unfortunately, in some cases, it is more advantageous for farmers to decide in favor of biofuel crops over food crops, as they sell at higher prices and some monocrops may be easier to cultivate and harvest than diverse food crops.

Additionally, using crops for biofuels can also lead to a decrease in the availability of food, as well as an increase in the cost of food.

Another way in which biofuel production can compete with food production is through the use of food crops, such as corn, as feedstocks for biofuels rather than spending resources on processing corn for human consumption. In the long term, this may lead to a decrease in food availability, nutritional quality of available foods, diversity of food crops, and possibly endanger food security. This is a serious contra argument to consider especially with climate change already shifting our ability to grow crops in certain areas.

The production of biofuels can compete with food production for land and resources, which can lead to higher food prices .

#3 Water consumption

Biofuels can require significant amounts of water for irrigation and processing, which can lead to water depletion and competition with other water uses, including even water for households, or for food production.

The amount of water used to grow biofuels varies depending on the type of biofuel, the location, and the farming practices used. However, some biofuel crops, such as corn and sugarcane, are considered to be water-intensive and their production requires large amounts of irrigation.

For example, it is estimated that growing one hectare of corn for biofuels takes between 3,000 and 5,000 cubic meters of water per year. Other biofuel crops, such as switchgrass and miscanthus, are considered to be more water-efficient and need less water for irrigation.

Additionally, the amount of water used in biofuel production is also affected by the specific farming practices used. If farmers are incentivized to plant crops that are not well suited for the location, they may end up needing more water than any other crops would.

#4 Pesticide pollution

This may sound contradictory to the advantages of biofuels mentioned earlier in this article. But we must realize that nothing in life is straightforward and applicable to all situations. Biofuel production may decrease the pesticide pollution if done sustainably and right, especially if perennial polycultures are involved.

On the other end, if previously untouched natural ecosystem is transformed into a monoculture field than there is a high chance that pesticide pollution will appear and will affect the surrounding environment. 

Some biofuel crops, such as corn and sugarcane, are considered to be high-input crops not only when it comes to water demand but even when it comes to the use of pesticides to protect them against insects, weeds, and diseases. However, other biofuel crops, such as switchgrass and miscanthus, are considered to be low-input crops and need less pesticides.

#5 Economic impacts

The development of a biofuels industry can have both positive and negative economic impacts, depending on the specific circumstances. For example, the production of biofuels can create jobs and stimulate economic development, but it can also lead to higher food prices and competition with other industries for resources.

Additionally, biofuel production can also lead to changes in land use patterns, which can displace local communities and increase the cost of land. Furthermore, biofuels can also be more expensive to produce than fossil fuels, which can make them less competitive in the market and discourage investment in the biofuel industry.

It’s worth noting that the negative effects of biofuels can be mitigated by adopting appropriate policies and regulations, such as implementing sustainable land use practices, supporting research and development of advanced biofuels, and promoting the use of biofuels in a way that doesn’t compete with food production.

#6 Higher production costs

The production of biofuels can be more expensive than the production of fossil fuels due to the costs of growing and processing the feedstocks.

The cost of biofuel production can vary depending on the type of biofuel, the location, and the specific technologies used. In general, biofuels are more expensive to produce than fossil fuels on a per-unit energy basis. This is due to the fact that biofuels are derived from renewable resources, such as crops and waste materials, which is more expensive to grow and process than fossil fuels.

However, the cost of biofuel production has been decreasing in recent years due to advancements in technology and economies of scale. Additionally, the cost of biofuels is affected by government policies and subsidies.

It’s also worth noting that the cost of fossil fuels fluctuates greatly depending on the market and political situation. Biofuels’ costs are affected by these fluctuations, so when the price of fossil fuels is high, biofuels can be more cost-competitive.

#7 Limitations in large-scale applications

The character of biofuels when they are only produced from certain feedstocks, such as specific crops, like rapeseed, or certain waste materials, means that they may be in limited supply. This factor could potentially limit the scale of biofuel production when it comes to upscaling their use.

At the same time, biofuels generally have a lower energy density per unit of mass than fossil fuels such as gasoline or diesel. This means that more biofuel is required to produce the same amount of energy as a smaller amount of fossil fuel.

The lower energy density means that transportation and storage of biofuels could be more challenging and may increase the cost of using biofuels as the main fuel source.

#8 Limited compatibility

At the moment, biofuels are not compatible with all types of vehicles and equipment. Compatibility refers to the ability of a fuel to be used in existing infrastructure and equipment without modification or damage. Biofuels are often not compatible with traditional fossil fuel infrastructure because they have different chemical and physical properties.

For example, bioethanol and biodiesel have a higher tendency to absorb moisture than fossil fuels, which can cause corrosion in fuel systems and engines. Additionally, they have a higher viscosity than fossil fuels, which can eventually lead to clogging or damage of fuel filters, injectors, and pumps. The widespread use of biofuels in daily operations requires different storage and handling equipment, engine modifications, and adapted fuel delivery systems.

This lack of compatibility is one of the reasons that biofuels have not been widely adopted as a replacement for fossil fuels. In order for biofuels to become widely used, researchers are working on developing biofuels that are more similar in properties to fossil fuels.

Are biofuels sustainable in a long-term?

Biofuels could be a sustainable energy source over the long term if they are produced and used in a responsible and well-planned manner when all the pros and cons of biofuels versus fossil fuels are considered. In the planning stage, it is important to carefully evaluate the potential impacts of different biofuel production methods and prefer practices that minimize negative environmental and economic impacts.

One of the key challenges in making the use of biofuels more sustainable over the long term is ensuring that they are sourced from feedstocks that have a low carbon footprint and are not in competition with food production . This can be achieved through the use of waste materials and non-food crops for biofuel production, as well as the adoption of sustainable practices such as minimal tillage and the use of cover crops.

It is also important to consider the full life cycle of biofuels, from production to end-use to ensure that they are used in the most sustainable and efficient manner possible. This may involve the use of advanced technologies.

Are biofuels reliable?

The reliability of biofuels as an energy source depends on a variety of factors, such as the feedstocks used, the production methods employed, and the end-use of the biofuels. In general, biofuels can be a reliable energy source if they are produced and used in a responsible and sustainable manner.

One potential challenge to the reliability of biofuels is their limited availability, as they are only produced from certain feedstocks (as mentioned in the disadvantages section). This can limit the scale of biofuel production and make it more vulnerable to disruptions such as droughts, pests, and price fluctuations.

Another challenge is the limited energy density of biofuels. This means they require more space to store the same amount of energy than fossil fuels. This can make them less practical for some applications, such as long-distance transportation.

Overall, the reliability of biofuels as an energy source will depend on the specific circumstances of their production and use.

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The potential of biofuels from first to fourth generation

Contributed equally to this work with: Philipp Cavelius, Selina Engelhart-Straub

Roles Conceptualization, Data curation, Investigation, Validation, Visualization, Writing – original draft, Writing – review & editing

Affiliation Werner Siemens-Chair of Synthetic Biotechnology, TUM School of Natural Sciences, Technical University of Munich (TUM), Garching, Germany

Roles Conceptualization, Data curation, Funding acquisition, Project administration, Supervision, Writing – original draft, Writing – review & editing

Roles Conceptualization, Data curation, Supervision, Writing – review & editing

Affiliation Chair of Technical Chemistry II, TUM School of Natural Sciences, Technical University of Munich (TUM), Garching, Germany

Roles Conceptualization, Data curation, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected] (DA); [email protected] (TB)

• Philipp Cavelius, 
• Selina Engelhart-Straub, 
• Norbert Mehlmer, 
• Johannes Lercher, 
• Dania Awad, 
• Thomas Brück

Published: March 30, 2023

• https://doi.org/10.1371/journal.pbio.3002063
• Reader Comments

The steady increase in human population and a rising standard of living heighten global demand for energy. Fossil fuels account for more than three-quarters of energy production, releasing enormous amounts of carbon dioxide (CO 2 ) that drive climate change effects as well as contributing to severe air pollution in many countries. Hence, drastic reduction of CO 2 emissions, especially from fossil fuels, is essential to tackle anthropogenic climate change. To reduce CO 2 emissions and to cope with the ever-growing demand for energy, it is essential to develop renewable energy sources, of which biofuels will form an important contribution. In this Essay, liquid biofuels from first to fourth generation are discussed in detail alongside their industrial development and policy implications, with a focus on the transport sector as a complementary solution to other environmentally friendly technologies, such as electric cars.

Citation: Cavelius P, Engelhart-Straub S, Mehlmer N, Lercher J, Awad D, Brück T (2023) The potential of biofuels from first to fourth generation. PLoS Biol 21(3): e3002063. https://doi.org/10.1371/journal.pbio.3002063

Copyright: © 2023 Cavelius et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This work was supported by the German Federal Ministry of Education and Research (BMBF) (031B0853A to NM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Abbreviations: EEA, European Environment Agency; EIC, European Innovation Council; GHG, greenhouse gas; GMO, genetically modified organism; ILUC, indirect land use change; IPCC, Intergovernmental Panel on Climate Change; IRENA, International Renewable Energy Agency; RED, Renewable Energy Directive

Introduction

For decades, global energy demand is on the rise due to economic growth and a rapidly growing world population. Additionally, the standard of living is increasing worldwide, in most cases correlating with increased energy consumption, as energy is needed in almost every aspect of our lives, including land, water, and air transport as well as in agriculture, commercial, industrial, and domestic sectors [ 1 ]. To date, fossil fuels account for around 80% of the world’s energy demand [ 2 ], despite being a major instigator for global warming, representing roughly 89% of total greenhouse gas (GHG) emissions in 2020 [ 3 ]. Additionally, fossil fuels are predicted to deplete with the steadily increasing energy demands. As petroleum demand is constantly on the rise, estimations predict a shortage by 2070 to 2080 [ 4 ]. To that end, distinct biofuel types such as liquid and biogas should be methodologically and strategically developed as a preventive measure against predicted energy shortages, all while reducing the anthropogenic climate impact and preserving the environment.

Currently, biofuels are categorized as first to fourth generation, depending on feedstock and/or biosynthetic platform (i.e., genetic engineering). In this Essay, we present comparative advantages and disadvantages among these categories, as well as fossil sources. Furthermore, the development of biofuel technologies hinges on the socioeconomic and political landscape, which can greatly benefit from policy recommendations by respective regulatory bodies. At present, the European Union has the most stringent biofuel legislation and the most ambitious climate impact goals. Hence, we focus on EU-centered development with respect to current biofuel technology platforms at various stages of industrial deployment, the legislative framework implemented in the EU, as well as policy recommendations that would accelerate academic breakthroughs toward industrial implementation. Although, our recommendations are EU-centric, many are also applicable on a global level.

The four generations of biofuels

One alternative to fossil fuels are biofuels, which originate from organic matter and therefore can be regrown and are termed renewable. Biofuels emit less GHGs and are in general more eco-friendly (non-toxic, sulfur-free, biodegradable) than their fossil fuel predecessors [ 5 ]. Biofuels contribute to the achievement of Sustainable Development Goals 7 (affordable and clean energy) and 13 (climate action) of the United Nations [ 6 ]. Global demand for biofuels is set to grow by 41 to 53 billion liters, or 28%, over 2021 to 2026 [ 7 ]. Typically, one can find four main types of biofuel discussed in the context of fermentation: biogas, bioethanol, biobutanol, and biodiesel. The physiochemical properties of these biofuels are compared to fossil-based fuels in Table 1 .

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https://doi.org/10.1371/journal.pbio.3002063.t001

Biogas formation is a fairly simple process that has been utilized for several decades. It includes four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Mixed microorganisms consortia and waste streams are combined in a sealed fermentation system in the absence of oxygen. During the biogas production process, microorganisms hydrolyze waste materials into sugars, peptides and amino acids, fatty acids, and to some part into acetate and hydrogen. Afterwards, acidogenic bacteria convert those intermediate products into organic acids, mainly constituting acetic acid. In addition, they produce carbon dioxide and hydrogen. In the third step, acetogenesis, acetate is formed from hydrogen and carbon dioxide produced in the previous stage. Lastly, methanogenesis follows, creating methane from the products of acetogenesis and acidogenesis [ 8 ]. These gases can then be transformed into hydrogen and/or electricity, or can be stored as biomethane in existing geological reservoirs [ 9 ]. Since the Ukraine crisis began, the resulting lack of fossil fuel availability in the EU has led to biogas being politically pushed as a substitute to natural gas [ 10 ].

Compared to gas (biogas/hydrogen), liquid fuels offer higher energy density and simplified transport and storage. This renders them more compatible with current engine and turbine technologies [ 11 ]. Most engines and turbines are designed and built for the use of liquid fuels, which makes liquid biofuels an easy drop-in solution without the need for modifying present engine technologies or infrastructure [ 5 , 12 ]. These gaseous fuels pose a significant safety hazard as they ignite at lower energies and are flammable over a range of concentrations, hydrogen to higher extent, requiring high level of safety procedures [ 13 ]. The low boiling point and high octane number of bioethanol allow blending with gasoline to a certain extent. The added benefits include a more complete combustion and reduced tailpipe emissions, boosting the engine performance and reducing CO 2 emissions. It is, however, inapt for blending with diesel. Diesel engines require hydrocarbons of higher chain length and low autoignition temperature. However, biodiesel, being of similar chemical constitution, can be blended with fossil-based diesel and hence constitutes a major energy-dense liquid biofuel. A third increasingly attractive biofuel is biobutanol, which holds high promise as it displays superior properties to bioethanol such as higher energy density (25% more energy than ethanol) and usually lower water content due to increased hydrophobicity. Biobutanol is less volatile and possesses less corrosive properties, making it easier and safer to use and store [ 11 , 14 – 19 ]. More importantly, it can be blended with both gasoline, fossil-based or biodiesel at any ratio without the need of new engine technologies and might even allow complete substitution of gasoline, while the use of ethanol is only possible as additive [ 11 , 18 ].

While the classification of biofuel technologies somewhat varies in the literature, products can generally be classed as first to fourth generation, depending on the type of feedstock and conversion process that was applied ( Fig 1 ) [ 5 ].

https://doi.org/10.1371/journal.pbio.3002063.g001

First-generation biofuels

Biofuels of the first generation are mainly divided into bioethanol and biodiesel. Bioethanol production of the first generation is based on microbial fermentation of edible feedstocks, rich in starch and sucrose, such as wheat, corn, and sugarcane in Europe, North America, and South America, respectively. Commercial strains include but are not limited to Saccharomyces cerevisiae , S . stipites , and S . pombe . Bioethanol production is not limited to first-generation biofuels; depending on the feedstock and production strain, bioethanol can also be categorized as second and third generation [ 32 – 35 ]. Biodiesel is mainly obtained from food-grade rapeseed, soy, or palm oil sourced from Europe, South America, and Asia, respectively. In contrast to bioethanol, it is only partially biosynthesized as its production includes chemically catalyzed steps such as transesterification of the lipids with alcohols. Enzymatic catalysis currently only exists on a lab scale [ 36 , 37 ]. Although biobutanol production is also possible by sugar fermentation from sugar cane, corn, wheat, and other food crops, it is limited by lower productivity and yields, product inhibition, and high costs [ 11 , 16 , 18 , 38 ].

During the global food demand crisis in 2007/2008, crops used for biofuel became more important to be used as food, giving rise to the “food versus fuel” debate that persists to date. Additionally, an increased demand for crops (e.g., corn) for fuel production yielded an increased market price for those foods [ 5 ]. Models predict that massive agricultural areas would be needed for fuel production and still could supply only limited amounts of fuel compared to the overall demand. It is estimated that more than two times the globally available area of arable land would needed to meet the global market demand for biodiesel when produced from rapeseed oil [ 39 ]. Furthermore, increased market values of palm oil and other biofuel cultures prompted extended deforestation of tropical rainforests for biofuel crop plantations, which releases more CO 2 than the emission saved by those biofuels. In 2008, Fargione and colleagues estimated that it would take 319 years to repay the biofuel carbon debt resulting from clearing of tropical rainforest in Brazil and subsequent conversion to soybean plantations [ 40 ].

Second-generation biofuels

As a result of the issues of the first generation, second-generation biofuels were developed, utilizing lignocellulosic biomass from agricultural and woodland residues as well as other waste streams (for example, from food industry like wheat bran, animal fats, or wastes of cooking and frying oil). Other non-food plants like the drought-resistant shrub or tree Jatropha curcas , which can also be grown in wastelands, might yet be a different promising source for second-generation biofuels [ 41 ]. Hence, second-generation biofuels circumvent the need for agricultural land use change and do not compete with food resources. However, often second-generation waste streams represent more complex feedstocks than sugarcane or palm oil, potentially containing compounds able to reduce fermentation efficiency, such as lignin. Therefore, application of additional pretreatment steps are common, increasing process time and costs [ 5 , 42 , 43 ].

For the most part, biofuels of the first and in the vast majority of the second generation are commercially produced, around 4% and 96% in 2019, respectively [ 44 ]. One example is the commercially available sunliquid from Clariant, which is a cellulosic ethanol from currently underutilized agricultural residues, such as straw. The first commercial ethanol plant in Romania started production in 2022, with plans to convert 250,000 tons of locally sourced agricultural residues to 50,000 tons of ethanol per year. After enzyme production, which hydrolyses cellulose and hemicellulose to sugar monomers, optimized microorganisms are used in fermentation to produce ethanol. These microorganisms can utilize various carbon sources like glucose and xylose, ensuring higher yields and enabling high efficiency and flexibility in waste valorization as more building blocks of waste streams can be converted to product [ 45 ]. Alongside ethanol producers, the production of second-generation biodiesel is possible from microbial lipids produced by organisms, such as Cutaneotrichosporon oleaginosus , a yeast capable of producing up to 90% (w/w) lipids per biomass in a fermentation process, which can be grown on residue streams (e.g., wheat bran hydrolysate medium) [ 46 – 49 ]. Second-generation biodiesel can also be sourced from waste oils via catalytic cracking and hydrogenation. Drawbacks of this process include incomplete conversion and coke formation, which leads to the deactivation of the catalyst. [ 50 , 51 ]. Biobutanol production on lignocellulose biomass and other waste streams is most commonly based on Clostridia fermentation, as it is one of the oldest and best-established fermentative processes for butanol production. Many Clostridia are natural butanol producers and possess the ability to metabolize a variety of different substrates. However, similar to its first-generation predecessor, the process is limited by low butanol titers and product inhibition [ 11 , 16 , 18 , 38 ]. Typically, butanol is produced via ABE fermentation, which results in solvents in ratio of 3 parts acetone, 6 parts butanol, and 1 part ethanol, and butanol refinement is not an energetically favorable solution. Other drawbacks also include cell toxicity at low concentration [ 52 , 53 ]. To that end, cell-free isobutanol biosynthesis using a designed artificial metabolic pathway has been developed [ 54 ]. At present, this approach remains costly for commercialization.

Various carbonaceous compounds can be transformed to syngas by gasification. Commonly, it is a gaseous waste stream from industrial processes such as steel manufacture, in which fossil fuels are burned in the process. Syngas is a mixture mainly consisting of carbon monoxide (CO), CO 2 , and hydrogen. It can be derived from biomass, including lignocellulosic compounds, coal, animal or municipal solid waste, and industrial CO-rich gases. This gas can be metabolized by strictly anaerobic, methanogenic archaea as well as by acetogenic bacterial genera such as Acetobacterium or Clostridium , often used in syntrophic fermentations. The process is mostly focused on biosynthesis of organic acids and alcohol compounds such as acetate, ethanol, and butanol [ 55 – 57 ]. Advantages of syngas fermentation compared to other second-generation approaches are high feedstock flexibility as well as high rates of energy and carbon capture. Complicated pretreatments of second-generation feedstocks can be replaced with gasification, using all components of the biomass, including lignin and other recalcitrant compounds [ 58 ]. LanzaTech developed a process converting feedstocks including industrial waste streams to fuel and chemicals utilizing bacteria. They estimate a total product capacity of 600,000 metric tons as well as 1,000,000 metric tons of captured carbon per year, for all their plants combined [ 59 ]. Since 2022, a demonstration plant in Japan has turned municipal solid waste to ethanol, with a production target of 20 tons of ethanol per day [ 60 ].

More than half of the biologically stored carbon is bound in marine biomass, especially macroalgae and seagrass. Detached seagrass material is seasonally washed on beaches and shore lines; due to low biological degradation and herbivore consumption, an excess of it accumulates as waste. Estimations of up to 40 million tons of dry seagrass biomass, which can be used for biofuel production, are given. Through enzymatic hydrolysis, the carbohydrate content of the seagrass can be used in a fermentation medium for microorganisms, additionally offering low nitrogen and phosphorus content, which is typically required for lipid production [ 61 ].

Despite the highly favorable ability to valorize waste streams, second-generation biofuels by themselves will not be sufficient to supply energy for the current worldwide demand. As is the case for food crops with first-generation biofuels, biomass used in these processes is available in limited amounts. Therefore, second-generation biofuels must be combined with other technologies to ensure sufficient provision of fuels. This prompted research on third-generation biofuels. However, scientific estimations predict second-generation biofuels could supply up to 30% of the world’s transportation energy [ 5 ].

Third-generation biofuels

Third-generation biofuels are mainly derived from microalgae and cyanobacteria biomass, which can be used to naturally generate alcohols and lipids to transform into biodiesel or any other high energy fuel product. Algae exhibit 2- to 4-fold higher photosynthesis rates than terrestrial plants, resulting in faster biomass formation [ 62 ]. Algae do not require arable land or fresh water for cultivation. Many cultures can be grown using waste water, brackish or salt water, which is cost efficient and circumvents competition with agricultural activity [ 63 , 64 ]. Most importantly, efficient algae cultivation requires a direct CO 2 supply, which can be derived from industrial emitters or by atmospheric carbon capture. In conventional cultivation systems, around 70% of supplied CO 2 is used for photosynthesis and therefore biomass production [ 65 ]. Hence, algae biofuels potentially could have a negative carbon footprint as they directly bind the GHG in their biomass. One of the most prominent third-generation processes is the production of biodiesel or other energy density biofuels, such as biokerosene, using oleaginous microalgae [ 66 , 67 ].

One of the most economically critical and versatile operations in algal biofuel production is algae cultivation. Algal bioreactors ( Fig 2 ) are independent of location and climate, therefore can be operated almost irrespective of these factors. For low price, high volume products, such as biofuels, algae are commonly cultivated in open ponds. Open pond reactors are significantly cheaper in their construction and operation but have drawbacks like high loss of water through evaporation and lack of temperature control, which lowers biomass productivity. The alternative, preferred for high price, low volume products, such as cosmetic ingredients, is a closed photobioreactor, where process parameters can be precisely controlled, which often leads to higher productivity [ 63 , 68 ]. These bioreactors also enable a three-dimensional mode of cultivation, significantly increasing the productivity per area. In contrast to second-generation biofuels, the third-generation processes completely decouple biofuel production from the need for agricultural land. Additionally, algal-based oil production is likely greater than that in higher plants, as lipids mainly accumulate in specific parts of the plant (e.g., in rape seeds), while in algae, each cell can contain high amount of lipids, making the process more mass efficient. One bottleneck in production is harvesting, as the low size and density of the microalgal cells combined with the sensitivity of the cells to changes in pH render it challenging. [ 66 ]. Furthermore, downstream processing for algal biofuels is commonly more energy intensive than other biofuel productions [ 63 , 69 ]. Araújo and colleagues mapped 447 algae and cyanobacteria Spirulina production units in 2021 in the EU [ 70 ]. Most of these companies directed their biomass to the production of food, feed, and related uses; commercial application of biofuels only had a very small share. Further technological developments in upscaling and reduction of production costs are necessary for commercialization.

This image showcases the open algae cultivation systems located at Technical University of Munich, Ottobrunn.

https://doi.org/10.1371/journal.pbio.3002063.g002

Fourth-generation biofuels

The latest biofuel generation, termed fourth-generation biofuels, encompasses the use of genetic engineering to increase desired traits of organisms used in biofuel production. This applies to a variety of traits from utilizing multiple types of sugars (e.g., pentoses and hexoses), to higher lipid synthesis or increased photosynthesis and carbon fixation. For model organisms, such as Escherichia coli and Saccharomyces cerevisiae , a wide variety of tools for genetically engineering the regulation of endogenous pathways or inserting new pathways are reported. Unfortunately, for most native producers of biofuels, the genetic engineering toolbox is far more limited.

Currently, two different approaches have been adopted: engineering of pathways in native producers (optimizing growth rates, utilization of different carbon sources, directing the metabolic flux toward biofuel production and increased production titers) and reconstruction of pathways identified in natural producers in more genetically accessible model organisms. A wide variety of microorganisms can be used as heterologous hosts for the production of biofuels, including bacteria, yeast, and algae. Their metabolic versatility enables the use of various substrates to produce a wide range of biofuels. For example, butanol pathway genes from Clostridia were introduced into E . coli , Pseudomonas putida , and Bacillus subtilis strains [ 14 , 16 , 19 ]. While the introduction of heterologous genes is well established, a major challenge is the disruption of competing metabolic fluxes. Another obstacle for high product titers can be toxicity of large amounts of product on the cell. To enable increased accumulation of biofuels, the cellular stress response can be modified through genetic engineering, for example, with cell membrane modifications. Through the overexpression of certain membrane transporters, biofuel molecules can be secreted into the medium thereby circumventing accumulation as well as toxicity while simultaneously simplifying product recovery. In E . coli , membrane transporters have been used successfully to excrete n-alkanes, such as n-octane [ 71 , 72 ]. However, the overexpression of transporters is challenging as it modifies the membrane composition, creating a metabolic burden as well as potentially overloading the cellular import and export, thereby disabling the cells ability to regulate its internal environment/homeostasis [ 71 ].

Genetically modified algae can offer higher product yields and a variety of other improvements compared to wild-type algae. In order to enhance photosynthetic efficiency, the antennae systems of algae capable of absorbing a broader range of the light spectrum could be transferred to more suitable production organisms [ 44 , 73 ]. With respect to genetic engineering, CRIPSR/Cas9 is a frequently used tool, as it offers a simple design with efficient transfection and targeted gene disruption [ 74 ].

In fourth-generation biofuel processes that focus on genetically optimized cyanobacteria, the production of ethanol, as well as other fuel products such as butanol, isobutanol, and modified fatty acids have been realized successfully [ 75 , 76 ]. While 1-butanol production reached titers of 300 mg/L, bioethanol titers of up to 5.5 g/L were reported [ 77 – 79 ].

For the efficient optimization of native producers, systems biology can offer many insights. The availability of whole-genome sequences is essential, as this information allows for the annotation of genes to their respective function and reconstruction of the innate metabolic pathways, which can subsequently be modified. Recent advances have been made in the field of genome sequencing allowing for a more rapid and cost-efficient collection of data [ 19 ], while the gene expression patterns in different growth environments can be analyzed by transcriptomics and protein products identified by proteomics.

With genetic engineering tools, the quantity and quality of biofuels can be controlled and increased but will need political acceptance and support to be widely adopted [ 5 ]. There is a controversial debate around genetic engineering in agriculture and medicine, especially in Europe; therefore, similar concerns can be anticipated surrounding the use in biofuel production. A European-based study came to the conclusion that genetically engineered algae for biofuel production would be accepted by the majority of consumers, when the safety of the systems can be guaranteed [ 80 ]. However, with proper containment methods and carefully selected locations, such risks could be drastically minimized. Therefore, closed production systems with high security standards are expected to be built [ 80 ]. Additional biocontainment methods can be directly based on genetic changes inside the production cells such as auxotrophies or kill switches, significantly decreasing the risk of genetically modified organism (GMO) escape [ 44 , 81 ].

One alternative to targeted genetic engineering is random mutagenesis, which can be described as accelerated evolution. Microorganisms and products generated by this approach are not subjected to GMO regulations. Furthermore, this technique can be performed with little knowledge about the production organism and production pathway. Random mutagenesis can be achieved by a variety of methods such as UV light, chemical agents, or fast neutron irradiation. For the first time, the latter was applied on C . oleaginosus , resulting in mutants with elevated lipid titers suitable for biodiesel applications. It is noteworthy that biodiesel from prominent oleaginous yeast platforms, such as Yarrowia lipolytica , C . oleaginosus , Rhodosporidium toruloides , and Lipomyces starkeyi , are compliant with international biodiesel standards, including US ASTM D6751 and EU standard EN 14214 [ 82 , 83 ].

A new, more experimental approach to fourth-generation biofuels is the production of electrobiofuels. These are based on the approach to establish new-to-nature hybrid systems, which are able to use renewable electricity and carbon sources directly for the production of commodity chemicals and biofuels, thereby enabling the conversion of solar energy into storable liquid fuel. Such a process could combine the higher photon efficiency of modern photovoltaic systems (compared to photosynthesis) with the sustainability of biofuel production, increasing overall process effectiveness [ 84 ].

Economics of biofuels in transportation

Apart from reducing GHG emissions and air pollution, biofuel industries can contribute to energy security on a local and national scale, as it is not reliant on local reservoirs of fossil oil. Additionally, the creation of new employment and economic growth, especially in rural locations, should positively impact the social environment as well. However, to fully exploit all the positive traits of biofuels, further research and investments are necessary, as the production of biofuels requires more processing steps compared with the conventional methods of drilling into the ground to obtain crude oil, followed by refining. Therefore, at present, biofuels commonly exceed fossil fuel production costs. Furthermore, raw materials for biofuel production do not compare to crude oil in energy density, requiring far greater amounts of biomass for the same energy output compared to fossil sources. The infrastructure required for the sector of biofuel production has to be extensively developed as well. One example is the primary energy needed to run the process, which should be obtained through sustainable operations. Candidates for that include solar and wind energy among others. Thus, by reducing the overall production cost and increasing process efficiency, biofuels could become more competitive to fossil fuels. Furthermore, by-products of biofuel production should be efficiently utilized in a circular economy, which could increase cost efficiency of such processes.

Transportation is one of the most socioeconomically sensitive sectors for the use of liquid biofuels ( Fig 3 ). It contributes about 17% of global CO 2 emissions [ 85 , 86 ], and so far, sustainable solutions are not fully developed. Due to their limitations, current technologies for biofuels are not likely to completely replace fossil fuels in their entirety but can offer new routes for waste stream valorization in a circular economy and contribute significantly to minimize our dependency on fossil fuels one step at a time. A complementary approach to this goal is electric cars, which have zero tailpipe emissions, although CO 2 emissions are associated with the production of the car and the source of the electricity. Essential in electric vehicle batteries are metals like lithium, cobalt, nickel, and manganese. The demand for these metals is surging, while at the same time toxic waste electronics are accumulating all over the world. Traditional recycling/extraction methods require high temperatures and strong acids. This is a high energy process involving toxic chemicals. One alternative is bioleaching or biomining, which employs microbes such as Acidithiobacillus ferrooxidans that can bind and recover metals, bypassing the need for high temperatures and toxic chemicals [ 87 – 90 ]. This emerging technology offers an eco-friendly approach to recycling but still requires extensive research and development. Additionally, a new infrastructure must be put into place, supporting millions of electric cars at the same time. To that point, a combination of synthetic and biofuels in synergy with electric cars might be an optimal solution for the years to come, partially substituting fossil fuels, thereby drastically reducing CO 2 output of transportation.

The transport sector, specifically, results in 17% of emissions. Adapted from Ritchie and colleagues (2020), Carbon Leadership Forum 2020 [ 85 , 86 ].

https://doi.org/10.1371/journal.pbio.3002063.g003

EU policy recommendations

In order to promote the use of clean and sustainable energy at the industrial, retail, and consumer level, a cohesive framework of policies is imperative. The European Commission and European Environment Agency (EEA) have cooperated with the International Renewable Energy Agency (IRENA) and the Intergovernmental Panel on Climate Change (IPCC) in leading the efforts for clean energy transition through a number of directives and legislations since the 1990s [ 91 – 94 ]. These efforts manifest as a commitment by EU countries to lower GHG emissions and increase the use of renewable energy. Most notable is the Renewable Energy Directive (RED), which came into force in 2009. Through this directive, EU countries set targets for renewable energy consumption, including a subtarget mandating 10% of energy used in transport to be produced from renewables. It is noteworthy that the deployment of renewable energy has continuously grown, exceeding 22% in 2020 [ 92 ]. The legislation also mandates GHG reduction targets for fuel suppliers, requiring a reduction in GHG intensity of the fuel mix by 6% in 2020 [ 92 ]. In 2018, the commission revised the legislative proposal and the European Parliament and the EU Council proposed amendments as RED II. Therewith, the EU aims to increase the share of renewable energy to 32% and in transport to at least 14%, including a minimum share of 3.5% of advanced biofuels (second- and third-generation biofuels). The latter streamlines waste residues, such as agricultural waste (e.g., straw), and also encompasses renewable electricity in road and rail transport [ 95 ].

At present, the industrial biofuel production is dominated by first- and second-generation processes, respectively. Nevertheless, RED II and indirect land use change (ILUC) proposals have initiated the gradual shift toward second- and third-generation processes, which are associated with significant changes in feedstock supply and logistics, as well as technology deployment (e.g., market penetration of advanced biofuels). ILUC qualifies first-generation biofuels based on the unintended consequences of releasing carbon emissions as a result of land use changes [ 96 , 97 ]. While technical process development for third- and fourth-generation biofuels is advancing rapidly in academic and start-up settings, large-scale industrial implementation remains lagging. This indicates a profound gap in transferring technologies from a pilot scale (TRL 5) to an industrial scale (TRL 8). To that end, clear and implementable criteria remain to be addressed by legislators for industrial technology transition toward advanced biofuels with a notable climate impact. Table 2 summarizes our policy recommendations aimed at advancing biofuels implementation as well as their respective expected results and acting entity.

https://doi.org/10.1371/journal.pbio.3002063.t002

First and foremost, legislators need to create stable policies and regulatory frameworks based on measurable cradle-to-cradle sustainability performance indicators. In the past, one of the greatest barriers for industry to adopt new biofuel technologies, at least in the EU, was the constantly changing regulatory and provisions framework, which ultimately led to waves of market and company consolidation for first-generation fuels such as crop-based biodiesel, corn and sugar beet-based bioethanol, and, more recently, corn-based biogas products. Therefore, it is of the utmost importance that policy makers provide clearly formulated, long-term stable policies, provisions, and regulatory frameworks to allow industrial transition to advanced biofuel technologies with clear climate impact.

With respect to sustainability, measurable criteria can be categorized as agriculture biomass, forest biomass with respect to biodiversity, and carbon stocks and emissions. Biofuel ILUC factors could be included in the biannual reports of fuel suppliers and EU countries. Accordingly, biofuel produced from palm oil and soy should carry a high ILUC factor and phasing out these feedstocks could be achieved by encouraging the diversification of feedstock. Reports estimate that 130,000 to 210,000 hectares of deforestation, which has detrimental effect on biodiversity and soil quality, could be avoided by limiting the demand of EU countries for palm oil biofuels [ 98 ]. Land requirement and fresh water use, carbon trading, and carbon offsets should also be factored in upcoming legislations. The criteria should also include GHG emissions that take the levels of methane, nitric oxides, and sulfur oxides into account in addition to levels of CO 2 . Legislation criteria should also take into consideration end-use performance, whereby industry sector, energy efficiency, and socioeconomic impact could represent qualifying measures. Risk determination and possible exceptions could be evaluated for specific industries, such as security and electricity. With respect to energy efficiency, it should be considered that distinct biofuels differ in their output. For example, ethanol yields 25% more energy than that invested in its production, while biodiesel yields 93% more [ 99 ]. To that end, performance-based renewable energy policies are needed. Finally, a reliable system that verifies compliance and reporting is eminent to putting these proposals into practice. In that respect, a mass balance system that observes the global carbon inventory and defines optimal distribution of energy profiles (first to fourth generation) and mixtures (e.g., E10 petrol/ethanol) to ensure minimal climate impact is in order. This system could integrate a range of parameters, including flexible distribution channels, demand management, storage, and price signals in real time [ 97 , 100 ]. Independent auditing services could further ensure compliance, which could also be extended to trading partners of the EU countries at a later stage.

As the implementation of industrial biofuel production sites are associated with immense capital investments, it is crucial to shed light on the financial aspect linked to these policies, primarily, multilevel incentives schemes, investment risk reduction, and infrastructure and logistics. On an EU level, specific funding mechanisms such as European Innovation Council (EIC) pathfinder, EIC Transition, and EIC Accelerator that aim to enable and accelerate the scaling trajectory of new technologies toward market entry already exist. While this is an initial step toward implementing new biofuel technologies, these measures do not translate into national actions and legislation on a member state level, which impedes the regional mobilization of capital, leading to a slow uptake and implementation of new technologies. Hence, a significant step toward rapid technology adoption and implementation would be the regional implementation of funding and capital mobilization as already practiced on the EU level.

An integral element in promoting advanced biofuels could be incentivizing biofuel processes that show favorable sets of sustainability parameters and end-use performance by a higher cost of CO 2 certificates, which realistically should be in the order of 500 to 1,000 Euros/ton CO 2 . Consolidated long-term measures would also provide companies and investors with valuable tools to calculate return of investment and hence de-risk decision-making for iterative technology transition. To enable more efficient technology transfer from academia toward industrial technology deployment, additional factors need to be considered. To that end, academic projects should receive sequential, stage-gated extended funding periods of 4 to 8 years that commonly go beyond a single governmental administration period. This would allow ideas to be developed toward a proof of concept stage, where they can be translated to spin-outs or industry partners. Governments should incentivize start-up formation derived from academic units using focused funding measures, such as the EXIST funding program in Germany [ 101 ]. As technology development from proof of concept (TRL 2 to 4) in academic settings to pilot plant level often requires time periods exceeding 5 to 7 years, synergistic midterm private funding resources also have to be mobilized. To that end, technology familiarity, better understanding of time frames for solid technology development, and proper risk assessment are essential for private capital investors. In order to motivate private capital in the EU to accept development risks and extended time frames for return of investment in biofuel start-up companies, governments could implement tax write-offs for spent risk capital. This legislatively guided de-risking of capital investment into new technologies is already implemented in the United States of America and the United Kingdom, as well as in other, less compliance-driven, financial markets. Hence, the EU has to rapidly implement such legislative tax reliefs to secure innovation on the biofuels and other innovation and sustainability-driven sectors for added economic value and a vibrant job sector.

Capital is also short at the infrastructure and logistics level. Investments are required to construct dedicated pilot plants that allow industrial scale validation and optimization of new technologies, independent of any large-scale industrial partner. In that respect, multiple regionally decentralized pilot plants could provide dedicated instrumental parks that house state of the art fermentation and downstream processing equipment. In the case of gas fermentation, these parks could be associated with significant security measures and demand special regulatory approval and regular inspection. Accordingly, construction and operation by large national research organizations, such as Fraunhofer institutions in Germany, or private–public partnerships is recommended. Governmentally driven funding actions that enable access and use of these pilot plant facilities by innovators in the biofuels sector could further accelerate industrial deployment and market entry. In parallel to technology market readiness, the implementation of biofuels in industrial processes requires a secured feedstock supply.

Contrary to Nordic countries that are the forefront of advanced biofuel processes development, most industrialized countries in the EU with a high population density do not have sufficient land or biomass availability for large-scale biofuel production [ 100 ]. Hence, the location and feedstock supply require strategic positioning. Two routes for biofuels production are viable in the EU: a large production plant located in a region with abundant, long-term feedstock/biomass supply or secured trade routes; or a network of smaller, decentralized production facilities. In the latter case, a farm-integrated production facility with secured access to local residue streams can be envisioned. To optimize the economics of the production facilities, its location should be leveraged with maximal carbon credits in order to meet fuel market prices. To make an informed decision on the location and mode of production, a global carbon inventory map would be extremely beneficial. While we have a good overview of regional carbon emissions, there is little information on correlative carbon storage, which is mostly limited to terrestrial biomass. To that end, other carbon storage mechanisms should be considered, such as existing geological carbon (CO 2 ) capture activities and marine biomass. Considering that 68% of the world population is projected to live in urban areas by 2050, it is sensible to consider urban waste streams, such as sewage sludge and food waste, as yet underutilized biomass feedstocks for biofuel production processes [ 102 ]. More generally, a map of the carbon flux resolved on a country-specific level would enable a more informed decision on the selection of process feedstock (biomass residues/CO 2 ) and trading partners that could secure operation of large-scale production facilities for third- and fourth-generation biofuels. Currently, the major trading partners of the EU are Argentina, Brazil, USA, Indonesia, and Malaysia [ 97 ]. These trading practices do not ensure level field sustainability over the long term. To that end, future trading legislation should consider balanced trade between the global North and global South to ensure long-term beneficial socioeconomic impact on the stability and sustainability of feedstock and biofuel production.

Conclusions

In this Essay, we laid out the reasoning for biofuel production as immediate and long-term measures to limit and eliminate energy and mobility-related GHG emissions. In that regard, biofuels will not be the only solution but an essential building block in a network with other physical (i.e., wind power, photovoltaic systems [ 103 – 105 ]) and chemical technologies (i.e., Sabatier process, Power to X [ 106 , 107 ]) that together can provide carbon neutral or even carbon negative energy and mobility solutions. In regard to transportation, biofuels should act in synergy with other technologies, such as electrified vehicles. In addition to biofuel manufacturing, similar processes could also be implemented in other applications. Here, algal and yeast oil can be transformed into building materials such as carbon fibers and cement additives. Via these routes, atmospheric CO 2 can be absorbed from the environment and stored for very long periods of time. Such technologies could complement materials derived from fossil fuels or that generate large amounts of CO 2 during the manufacturing process (e.g., steel, aluminum and concrete) [ 108 ].

We are convinced that, in the last decades, mankind has been generally too hesitant to adopt climate-centered technologies, which has put the world on a perilous pathway toward catastrophic climate change [ 109 – 111 ]. The destructive outcomes of this scenario have been documented in the scientific literature and are subject to numerous high level reports [ 112 – 117 ].

As time for action is already overdue, it is essential to act now by implementing the tools and technologies we have at hand at the present time. It is our opinion, that the only path to enable climate effective energy security and mobility is to deploy available technologies at a global scale right now. The global implementation of large-scale production infrastructure for sustainable (bio)technologies to kick-start production of renewable energy carriers and sustainable commodities is imperative in this timely development scenario. Once production with a base process has commenced, these processes can be iteratively refined or modulated at scale to evolve toward the next technology generation. This approach demands close, long-term academic and industry partnerships.

This fundamental transition toward sustainable bio-based technologies will require long-sighted, fact-driven legislative guidance and immense capital investments across the private and governmental sectors. However, it will be the only route to limit climate change effects and provide a livelihood for future societies.

With respect to governments, this means that neither ideology nor demagogically driven decision-making will protect any society from the effects of climate change. There are just no simple answers to complex, global problems. What is needed are global governmental alliances that make technocratically oriented long-sighted decisions, aiming for definitively set climate-centered outcomes even if the communication of the measures that have to be taken may not be popular on first sight.

Even outside the scientific communities, people are ready to accept change of the status quo in order to curb climate change effects and transition to a sustainable society. The question remains if the global political elites are ready to communicate and implement this change. Time is running out to maintain the global ecosystems as we know it.

Acknowledgments

The authors dedicate this manuscript to Dr. Christian Patermann (former EU Program Director Biotechnology, Agriculture, and Food) and Dr. Günther von Au (Chairman of the Board of Directors of Clariant AG), each being outstanding political and industrial visionaries, influencers, and decision-makers in the field of sustainable (bio)technologies and the bioeconomy, respectively.

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Advantages and Disadvantages of Biofuels

Have you ever wondered if there are different ways to power cars, buses, or even airplanes besides using gasoline? Well, there are! One important alternative energy source is biofuel. But what exactly is biofuel, and why is it special? Let’s take a closer look!

Page Contents

What are Biofuels?

Biofuels  are a type of fuel made from plants or other organic materials, which are often called  biomass . Instead of digging deep underground to find  fossil fuels  like oil, which takes millions of years to form, we can grow plants like corn, sugarcane, or soybeans to create biofuels. This means biofuels are a type of  renewable energy , which means we can keep making more as long as we keep growing the plants. These fuels are also known as  alternative fuels  because they are a different choice from using fossil fuels, which are running out and can harm our environment.

Types of Biofuels

Biofuels  are generally grouped into three main types:  ethanol ,  biodiesel , and  advanced biofuels . Each type uses different materials and processes to create fuel that we can use as an alternative to fossil fuels.

Ethanol  is one of the most common types of biofuels . You might have heard about it being mixed with regular gasoline to make cars run more cleanly. But what exactly is  ethanol biofuel , and how is it made?

Ethanol is made from  feedstock , which are the raw materials used to produce energy. In this case, the feedstock is usually  corn ,  sugarcane , or other crops rich in sugars. The process of making ethanol involves  fermentation , which is the same process used to make bread rise or to make yogurt. During fermentation, tiny organisms called yeast eat the sugars in the plants and produce ethanol. This ethanol can then be mixed with gasoline to help reduce the pollution that cars produce.

Ethanol is often called a  first-generation biofuel  because it is made from crops we also grow for food. While it helps reduce harmful gases, some people worry that using food crops for fuel might lead to food shortages.

The next type of biofuel is  biodiesel .  Biodiesel production  is a bit different from ethanol. Instead of using sugary crops, biodiesel is made from oils. These oils can come from  vegetable oil ,  animal fats , or even leftover cooking oil from restaurants!

To make biodiesel, a process called  transesterification  is used. It’s a big word, but the idea is pretty simple. The oil is mixed with a chemical to change it into a form that engines can burn. After this process, the biodiesel can be used in trucks, buses, and even some cars.

Biodiesel is great because it produces less harmful emissions than regular diesel fuel. Plus, using waste oils, like cooking oil, means we can recycle something that would otherwise be thrown away!

Advanced Biofuels

Advanced biofuels , sometimes called  second-generation biofuels , are newer and made in ways that solve some of the problems with using food crops for fuel. These biofuels use materials like  lignocellulosic biomass , which includes parts of plants we don’t usually eat, such as wood chips, grasses, or the tough stalks of corn plants. This means we’re not using our food to make fuel, and we’re using parts of the plant that might have gone to waste.

Some advanced biofuels are also made from  algae biofuel . Algae, which are tiny green plants that grow in water, can produce oil that can be turned into biofuel. This is really exciting because algae grow very fast and don’t need the same space or soil that food crops need.

Another type of advanced biofuel is  biogas , which is produced from things like animal manure, plant scraps, or even food waste. The process of making biogas is called anaerobic digestion, where microorganisms break down the waste in an environment without oxygen, creating a gas that can be used for cooking or heating.

Advanced biofuels are important because they are more  sustainable – they use materials that wouldn’t normally be used, and they help reduce waste.

Advantages of Biofuels

Now that we know what  biofuels are and the different types that exist, let’s look into why biofuels are considered so beneficial for our environment and economy. There are many reasons why people believe biofuels could be an important part of our future energy solution. Let’s explore some of the key benefits  of using biofuels.

Emission Reduction and Cleaner Air

One of the biggest advantages of biofuels is their ability to help the environment by reducing harmful emissions. When we use  fossil fuels , they release a lot of  greenhouse gases like carbon dioxide (CO₂) into the air, which makes the Earth warmer – a problem called global warming. Biofuels, on the other hand, produce fewer greenhouse gases compared to fossil fuels. This means they have a smaller carbon footprint .

Biofuels can be close to  carbon neutral . This means that the amount of carbon dioxide released when they are burned is balanced by the amount of CO₂ that plants absorb from the air while they grow. By using biofuels, we can help improve  air quality  and reduce pollution, which is better for both the planet and our health!

Renewable and Sustainable Energy

Unlike fossil fuels, which take millions of years to form and can eventually run out, biofuels are  renewable . This means we can keep making them as long as we keep growing the plants used to produce them. Biofuels are part of a type of energy known as  sustainable energy —energy that can be maintained without harming future generations. Because they are made from crops like corn, soybeans, or algae, biofuels can be continually renewed every growing season.

This makes biofuels an important part of the transition to  renewable energy , which includes other sources like wind and solar power. It’s all about finding ways to use energy that won’t run out and doesn’t damage the Earth.

Energy Security and Independence

Another great benefit of biofuels is their role in  energy security . Today, many countries rely on oil from other places, which can be risky. If something happens to interrupt the supply of oil, it could lead to big problems. Biofuels help countries become more  energy independent  because they can be produced locally. This means less dependence on other nations for energy and a more stable supply that’s not affected by global politics or oil shortages.

By using biofuels, countries can make sure they have enough energy to power vehicles, machines, and industries without worrying about running out of oil. This is important for making sure that everyday life, like driving to school or heating our homes, continues without interruption.

Economic Opportunities and Agricultural Development

Biofuels also provide a lot of opportunities for farmers and rural communities. To produce biofuels, we need a lot of crops, which can be great for the  rural economy . Farmers can grow  energy crops  like corn, sugarcane, or soybeans specifically for biofuel production, which creates new jobs and helps people earn a living.

This can lead to significant  agricultural development  because growing biofuel crops means farmers can have a stable income. It also helps small towns and farming communities grow stronger because more jobs are created, not just on the farms but also in biofuel production facilities and transportation.

Carbon Offset and Reduced Environmental Impact

Biofuels can also help offset the carbon emissions from other activities. When people talk about  carbon offset , they mean that one action (like growing plants for biofuels) can help reduce or “balance out” the negative effects of other activities (like using fossil fuels). Since plants absorb CO₂ as they grow, they can help to offset the emissions produced when we burn biofuels for energy.

By using biofuels, we also help to reduce the  environmental impact  of our energy use. For example, using leftover cooking oil to produce biodiesel keeps it from being thrown away and polluting the environment. This kind of recycling helps make our energy sources cleaner and better for the Earth.

Disadvantages of Biofuels

While biofuels offer many advantages, like helping the environment and providing renewable energy, they also come with some challenges and limitations. It’s important to understand both sides of the story so we can make better choices about how to use energy. Let’s take a look at the  disadvantages of biofuels  and some of the problems that come with using them.

Land Use and Deforestation

One of the biggest challenges of biofuels is related to  land use . To produce biofuels, we need to grow a lot of crops, like corn or sugarcane, which requires large areas of  arable land  (land suitable for growing crops). This can lead to  deforestation , which is when forests are cut down to make room for more farmland. This is harmful because forests are home to many animals and plants and are very important for absorbing carbon dioxide.

When forests are destroyed, it can actually increase  greenhouse emissions , which contributes to global warming – the opposite of what we want when using biofuels. Plus, when forests are cleared, it affects biodiversity and harms the environment.

Food vs. Fuel Debate

Another important issue with biofuels is the  food vs. fuel debate . Since biofuels are made from crops like corn, soybeans, and sugarcane, using these crops for fuel means there is less available for food. This creates  competition for arable land  because farmers have to decide whether to grow crops for food or for fuel.

When a lot of crops are used for biofuel production, it can cause  food scarcity , which means there might not be enough food for people or animals. This could make food prices go up, which can be especially tough for people in poorer communities. The idea that we might be using valuable farmland to grow fuel instead of feeding people is one of the main criticisms of biofuels.

Water Consumption and Fertilizer Impact

Producing biofuels also requires a lot of water, which is another challenge.  Water consumption  is a major issue, especially in places that already have water shortages. Growing crops like corn or sugarcane for biofuels means using large amounts of water for irrigation, which can put extra stress on local water supplies.

In addition to water, biofuel crops often need fertilizers and pesticides to grow well. The use of these chemicals can have a negative impact on the environment. Fertilizers can run off into rivers and lakes, causing pollution and harming aquatic life. This shows that while biofuels are more renewable than fossil fuels, they can still cause significant environmental damage if not managed properly.

Lower Energy Efficiency

Another disadvantage of biofuels is that they have  lower energy efficiency  compared to fossil fuels. The amount of energy you get from burning biofuels, known as  energy yield , is generally less than the energy you get from fossil fuels like gasoline or diesel. This means that we need to use more biofuel to get the same amount of energy, which can make it less efficient.

Not only do biofuels produce less energy, but the process of growing crops, transporting them, and converting them into fuel also takes energy. Sometimes, the amount of energy used in production can be almost as much as the energy produced by the biofuel itself, which makes it less efficient overall.

Production Costs and Economic Feasibility

The  production costs  of biofuels can also be quite high. Growing, harvesting, and processing the crops used to make biofuels require a lot of work and money. This makes the  economic feasibility  of biofuels a challenge. For example, farmers need to spend money on seeds, water, fertilizers, and equipment, and then there are costs involved in turning these crops into usable fuel.

Compared to fossil fuels, biofuels are often more expensive to produce. This makes them less competitive in the market, especially when the price of oil is low. Governments sometimes need to give financial support to make biofuel production worthwhile, which can be a burden on the economy.

Environmental Impact of Biofuels

Now that we’ve explored the  advantages  and  disadvantages  of biofuels, it’s important to talk about how biofuels affect the environment. Biofuels can have both positive and negative impacts on ecosystems and our climate. Let’s take a closer look at these  environmental impacts .

Positive Environmental Impacts

Emissions reduction and carbon footprint.

One of the most important benefits of biofuels is that they help reduce harmful emissions. Burning  fossil fuels  releases a lot of  greenhouse gases like carbon dioxide (CO₂) into the atmosphere, which causes the Earth to warm up – a problem known as global warming. Biofuels , on the other hand, produce fewer greenhouse gases when they are burned. This means that using biofuels can help lower the overall  carbon footprint  of our energy use.

Biofuels are also part of the  carbon cycle . The plants used to make biofuels absorb CO₂ from the air as they grow, a process called  carbon sequestration . This helps balance out some of the carbon emissions that happen when the biofuels are burned, making them closer to  carbon neutral  compared to fossil fuels.

Supporting Soil Health and Water Resources

In some cases, growing biofuel crops can help improve  soil health . Plants like switchgrass, which are sometimes used for biofuel, can help prevent soil erosion and keep the soil healthy by adding nutrients back into it. This is especially true if farmers practice careful crop rotation and don’t overuse the land.

Also, using  biogas , which is made from things like manure and food scraps, helps recycle waste that would otherwise go into landfills. By using waste materials to make energy, we reduce the amount of waste that ends up in the environment and help improve the health of water resources by reducing pollution.

Negative Environmental Impacts

Habitat loss and biodiversity impact.

Although biofuels can help the climate by reducing emissions, they also pose challenges for  biodiversity . Growing large amounts of crops for biofuels can lead to  habitat loss . To grow energy crops like corn or sugarcane, farmers sometimes clear forests, grasslands, or wetlands. This destruction of natural areas can hurt the  ecosystem impact , reducing habitats for animals and plants and threatening the survival of many species.

When natural habitats are destroyed, many creatures lose their homes, and this can have a ripple effect across the entire ecosystem. This is why some people are concerned about how sustainable biofuels are when it comes to protecting nature’s diversity.

Impact on Water Resources

Growing biofuel crops can use a lot of water, which is another negative impact on the environment. Large amounts of water are needed to irrigate crops like corn and sugarcane, especially in dry regions. This high  water resource impact  can put pressure on local water supplies, which can be a problem for both people and wildlife. If too much water is used for growing biofuel crops, it can lead to water shortages in nearby areas.

Air Pollutants and Soil Degradation

While biofuels produce fewer greenhouse gases than fossil fuels, they can still release  air pollutants  when burned. These pollutants might not be as harmful as those from fossil fuels, but they still contribute to air quality problems, especially if biofuels are not used properly.

Using chemical fertilizers and pesticides to grow biofuel crops can also have a negative impact on the environment. These chemicals can run off into rivers and lakes, causing pollution. This runoff can harm fish and other aquatic animals, and it can also lead to  soil degradation , where the quality of the soil gets worse over time, making it harder to grow healthy crops.

Biofuels and Energy Security

Did you know that biofuels can help make our country safer and more independent when it comes to energy? Biofuels are more than just a cleaner way to power our cars and machines – they also play an important role in our nation’s energy security . Let’s learn about how biofuels help reduce our reliance on fossil fuels from other countries and why this is so important.

Energy Independence and Reduced Reliance on Fossil Fuels

One of the biggest reasons why biofuels are helpful is because they can reduce our need for  imported fossil fuels  like oil and gas. Today, many countries depend on importing fossil fuels from faraway places, which can be risky. What if there is a problem in those countries, or what if the prices go way up? Depending too much on other countries for energy can lead to problems. This is where  biofuels  come in.

Biofuels, such as  ethanol  and  biodiesel , are made right here from plants like corn, soybeans, or even algae. This kind of  local production  means that we can create our own energy without having to buy as much from other countries. When we make energy here at home, it helps us become more  energy independent , meaning we are less affected by changes in other countries and more able to make our own energy decisions.

Enhancing National Security with Biofuels

When a country produces more of its own energy, it becomes more secure. This is what we call  national security . If we are not reliant on imported oil from places that might have political problems or conflicts, our country is safer. We can avoid energy shortages and make sure we always have enough fuel for our vehicles, businesses, and homes. This is especially important in times of crisis when having enough energy can help a country stay strong and stable.

Using  domestic energy , like biofuels, helps a country maintain its own  strategic reserves – the backup supply of energy that is saved in case of an emergency. With biofuels being produced locally, we can make sure there is enough fuel available to keep everything running smoothly, even if there are problems in other parts of the world.

Energy Diversification – Having Many Energy Options

Another way biofuels help with  energy security  is by promoting  energy diversification . This means that instead of relying on just one or two types of energy, like oil or natural gas, we use different sources, including  renewable energy  like wind, solar, and biofuels. Having many different ways to produce energy makes us stronger because if there is a problem with one source, we have other options to rely on.

For example, if oil prices suddenly go up or if there is an oil shortage, we can use more biofuel to make up for it. By using  fossil fuel alternatives  like biofuels, we have a more flexible energy system. This kind of  energy diversity  is very important for making sure that there are always enough resources to meet our energy needs.

Local Jobs and Economic Benefits

Producing biofuels also helps our economy. Since biofuels are made from crops like corn or soybeans, this means more work for farmers and workers in biofuel production facilities. By encouraging  local biofuel production , we not only make our energy supply stronger but also create new jobs and support the people in our communities.

Having local energy production means that we keep more money within our country rather than spending it on buying oil from other countries. This is important for the economy and helps everyone have a better standard of living.

Comparison with Fossil Fuels

We have learned a lot about  biofuels and the benefits and challenges they bring. But how do they compare with the energy sources we use most often today – fossil fuels ? In this section, we will explore the differences between biofuels and fossil fuels to see how they measure up in terms of energy, environmental impact, availability, and long-term sustainability. This comparison will help us understand why biofuels might be a good choice for our future.

Energy Content and Efficiency

One of the key differences between  biofuels  and  fossil fuels  is their  energy density . Energy density is how much energy you get from a certain amount of fuel.  Fossil fuels  like  petroleum  and  coal  have very high energy density, meaning they can produce a lot of energy from a small amount of material. This makes them very efficient and powerful, which is why they are used so much for cars, airplanes, and electricity generation.

On the other hand,  biofuels  generally have lower  energy density  compared to fossil fuels. This means you need more biofuel to get the same amount of energy that you would from a smaller amount of oil or coal. This can make  biofuel efficiency  lower in comparison, and it’s one reason why fossil fuels are still commonly used, especially in places where a lot of energy is needed.

Environmental Impact – Carbon Emissions and Pollution

When it comes to  environmental impact , biofuels have some big advantages over fossil fuels.  Fossil fuels , when burned, release large amounts of  carbon dioxide (CO₂)  into the atmosphere. This CO₂ is a  greenhouse gas  that traps heat and contributes to  global warming . Fossil fuels have been releasing CO₂ for millions of years, which is why they are considered  nonrenewable – once they are gone, they are gone for good.

Biofuels , however, come from renewable sources like plants. As plants grow, they absorb CO₂ from the air. So, when we burn biofuels, they release CO₂, but the CO₂ was already taken from the atmosphere while the plant was growing. This makes biofuels much closer to  carbon neutral  compared to fossil fuels. Biofuels help reduce the amount of extra CO₂ being released, which can lead to a smaller carbon footprint and better air quality.

However, producing biofuels also has some negative impacts. Growing the crops requires water and sometimes fertilizers, which can lead to pollution. Still, when we compare the  carbon emissions  from both types of fuel, biofuels are generally better for the environment.

Availability and Extraction

Another big difference is how we get these fuels.  Fossil fuels  like oil and coal must be extracted from the ground. This  extraction process  can be very harmful to the environment. Mining coal can destroy landscapes, and drilling for oil can lead to spills that harm oceans and wildlife.

Biofuels , on the other hand, come from  renewable  sources like crops that can be grown every year. Since we can grow plants again and again, biofuels are much more sustainable in the long term. Instead of extracting a resource that takes millions of years to form, we can grow new biofuel crops in just a few months.

But, it’s not all easy – biofuel production  requires a lot of land and water. This means that biofuels are not completely without their own challenges. If too much land is used for growing energy crops, it could take away land needed for food, which could lead to problems.

Long-term Sustainability

The main difference between  biofuels  and  fossil fuels  is their  sustainability outlook .  Fossil fuels  are  nonrenewable , meaning that once we use them, they can’t be replaced. We are using fossil fuels faster than the Earth can create them, which means eventually, they will run out. This makes fossil fuels a limited resource that we can’t rely on forever.

Biofuels , on the other hand, are part of a  renewable energy  solution. As long as we manage land properly and use smart farming techniques, we can keep growing plants to produce biofuels. This makes biofuels a  fossil fuel alternative  that can help us move toward a future where our energy doesn’t run out.

Economic Impacts of Biofuel Production

Biofuels do not just affect the environment – they also have a big impact on the economy, especially in rural areas where most of the energy crops are grown. Let’s explore how biofuel production  can influence  local economies , from creating new jobs to supporting agriculture and bringing investments into farming communities.

Job Creation and Rural Employment

One of the biggest  economic benefits of biofuel  production is the creation of jobs. Biofuels are made from crops like corn, soybeans, and sugarcane, and these crops need to be grown, harvested, and processed. All these steps involve people, which means more  job opportunities  for many communities. Farmers grow the energy crops, workers help process them into fuel, and truck drivers transport them to where they are needed.

This leads to more jobs in  rural areas , which is very important. In many farming communities, there aren’t always a lot of job options. But with  biofuel production , there is an increased demand for farmworkers, technicians, drivers, and plant workers. This can help strengthen  rural development  by providing steady work and keeping people employed in the local area. By boosting  rural employment , biofuels can make a big difference for families living in farming regions.

Boosting Agriculture and Crop Pricing

Biofuel production  also helps farmers by increasing the demand for their crops. Farmers who grow corn, soybeans, or sugarcane can sell their crops for use as both food and fuel, which can be very good for their income. The more demand there is for these crops, the better the  crop pricing  can be, which helps farmers make a good living. Biofuels also provide farmers with another market for their crops, which is a kind of safety net. If food prices go down, farmers can still make money by selling their crops for energy.

Governments also sometimes give  farming subsidies – special payments to help farmers grow biofuel crops. These subsidies make it easier for farmers to grow energy crops and help make  biofuel production  more profitable. This encourages farmers to invest in growing the kinds of crops that are needed for making biofuels, which further supports the  agricultural influence  of biofuel production.

Economic Incentives and Investment Opportunities

The production of biofuels is often supported by  economic incentives . This means that governments might offer support or rewards to encourage companies to produce biofuels. These incentives can help make biofuels cheaper to produce, which means more companies are willing to invest in this kind of energy. This leads to more  investment opportunities  in local communities, especially in building processing plants, creating storage facilities, and developing better ways to grow energy crops.

These investments can help create new industries in rural areas, where  economic opportunities  might have been limited before. This not only helps the people directly involved in biofuel production but also boosts local businesses like stores, restaurants, and other services that benefit from a growing community.

Challenges for Local Economies

While there are many benefits, there can also be challenges for local economies. With more farmers growing crops for fuel, there is sometimes less land available for food crops, which can lead to higher food prices. This is known as the  food vs. fuel  problem. Also, the increased demand for certain crops can make the prices go up, which might be good for farmers but harder for people who need to buy food.

Another challenge is that  biofuel policy  and prices can change based on the  energy market . If fossil fuel prices drop, then biofuels might become less profitable, which can make it harder for farmers and workers who rely on biofuel production. This makes it important for there to be a good balance between energy crops and food production.

Future Prospects and Innovations in Biofuels

Biofuels are an important part of our journey toward cleaner energy, but they are not perfect. There are still challenges that need to be solved, like the need for more land and water, and how to make biofuels as efficient as fossil fuels. But don’t worry – technological innovations  are helping to improve biofuels every day! Let’s explore some exciting  emerging technologies  and the future of  biofuel technology .

Third-Generation Biofuels and Algae Technology

One of the most promising innovations in biofuel is the use of  third-generation biofuels , which involve using  algae  to produce fuel. Algae are tiny green plants that can grow in water, and they can be turned into biofuels in a way that is much more efficient than using crops like corn or sugarcane.

Algae technology  is exciting because algae grow very quickly and do not need good farmland to thrive. They can grow in places like ponds, lakes, or even saltwater. This means we can use land that isn’t needed for growing food. Algae also have a high oil content, which makes them perfect for making  biodiesel . Scientists are researching how to grow and harvest algae better so we can make algae biofuels cheaper and easier.

Using algae for biofuels could solve some of the problems we face with first- and second-generation biofuels, like competition for farmland and water use. If algae biofuels become widely used, they could be a game-changer for  sustainable energy .

Synthetic Biology and Biotechnology

Another exciting development in the world of biofuels is the use of  synthetic biology  and  biotechnology . Scientists are working to improve how we make biofuels by changing the genetics of plants and microorganisms so they can create more fuel, grow faster, or even grow in harsher conditions.

By using biotechnology, scientists are developing special types of  energy crops  that are more resistant to pests or need less water. They are also working on bacteria and other organisms that can turn plant material into fuel more efficiently. These  efficiency improvements  could make the biofuel production process faster and use fewer resources, making biofuels a more attractive alternative to fossil fuels.

Sustainable Production and the Renewable Energy Roadmap

As biofuel technology continues to improve, the goal is to make  sustainable production  even better. Researchers are looking for ways to use waste products like leftover food, wood chips, or even garbage to produce biofuels. This helps in two ways—it reduces waste that might otherwise end up in a landfill, and it creates clean energy.

This type of production is part of the larger  renewable energy roadmap  that scientists and governments are working on to make energy cleaner and more accessible to everyone. By finding ways to use waste or grow special crops just for energy, biofuels can help reduce our reliance on fossil fuels while keeping the environment healthy.

Efficiency Improvements and Energy Trends

One area of focus for making biofuels more viable is  improving efficiency . Right now, biofuels do not produce as much energy as fossil fuels, which means more fuel is needed to get the same amount of power. Scientists are researching how to make biofuels with higher  energy density , which would make them better for powering vehicles and machines.

In addition, new  energy trends  include combining biofuel technology with other types of renewable energy, like solar and wind power , to create energy systems that are both reliable and green. By using different types of energy together, we can ensure that there is always enough power, even when the sun isn’t shining or the wind isn’t blowing.

FAQs on the Advantages and Disadvantages of Biofuel

What are the main advantages of biofuels compared to fossil fuels.

Biofuels offer several advantages over fossil fuels. They are renewable, produce fewer greenhouse gases during combustion, and contribute to energy security by reducing dependence on imported oil. Additionally, biofuels can be produced from waste products, making them a more sustainable option.

Are biofuels environmentally friendly?

Yes, but with considerations. Biofuels are often considered more environmentally friendly because they emit fewer greenhouse gases compared to fossil fuels. However, their production can lead to deforestation, water usage concerns, and land competition, which may harm biodiversity.

How do biofuels contribute to reducing greenhouse gas emissions?

Biofuels can help reduce greenhouse gas emissions because they produce lower levels of carbon dioxide during combustion. The carbon emitted is partially offset by the CO2 absorbed during the growth of biofuel crops, potentially creating a closed carbon cycle.

What are the economic benefits of using biofuels?

The economic benefits include job creation in agriculture and biofuel production sectors, as well as the stimulation of rural economies. Additionally, biofuels can reduce dependency on imported petroleum, thereby improving energy security and price stability.

What are the disadvantages of biofuels regarding food supply?

One disadvantage is the competition for resources. Crops used for biofuel production, such as corn and sugarcane, can compete with food crops for land and water, potentially leading to increased food prices and food scarcity in some regions.

How does the use of biofuels impact land use and biodiversity?

Biofuel production can lead to significant land use changes, such as deforestation and habitat destruction, which negatively impact biodiversity. The conversion of natural ecosystems into farmland for biofuel crops can threaten native species and lead to loss of habitats.

Are there concerns about water usage in biofuel production?

Yes, biofuel production can be water-intensive, especially in regions with limited water resources. Growing feedstock like corn or sugarcane often requires large amounts of water, which can lead to strain on local water supplies and potential conflicts over resource allocation.

What are the challenges of biofuel production in terms of energy efficiency?

Biofuels can sometimes have lower energy returns compared to fossil fuels. The energy required to grow, harvest, and process biofuel crops can reduce the net energy gain. This efficiency challenge makes certain biofuels less practical without technological improvements in production methods.

References and Sources

Wikipedia – Biofuel

US EPA – Economics of Biofuels

Environment – Biofuels Pros and Cons

Home — Essay Samples — Environment — Resource Management — The Benefits of Biofuels for the Environment

The Benefits of Biofuels for The Environment

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Benefits and perspectives on the use of biofuels

Juan‐luis ramos, miguel valdivia, francisco garcía‐lorente.

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For correspondence. E‐mail [email protected] ; Tel. +34 954 937 111.

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Received 2016 Feb 17; Accepted 2016 Feb 19; Collection date 2016 Jul.

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Short abstract

The current primary obstacle to biofuels is the current low price of fossil fuels, and the primary incentive to 2G biofuels is the growing world population and need to increase food suplies. Both of these will be increasingly subject to political, regulatory and legislative changes that will be positive for 2G biofuels.

Petrol prices between December 2015 and January 2016 have been at their lowest in years. These more affordable gasoline prices encourage less efficient car‐based transportation and longer trips, which is, in turn, expected to lead to increased carbon dioxide emissions and increased greenhouse gas levels in the atmosphere. Terrestrial transport can represent up to 20% of all C emissions to the atmosphere ( www.eea.europa.eu ). In addition to emissions from terrestrial vehicles, about 2% of all human carbon dioxide emissions are the result of aircraft emissions – many of which represent vacation trips. The relationship between tourism, as a global industry, and energy use is often neglected (Becken, 2002 ). This is despite the fact that if tourism continues to grow at currently predicted rates, it will lead to considerable increases in aircraft emissions by 2050. At present, the Natural Resources Defense Council indicates that it is estimated that air travel emits more than 650 million metric tonnes of carbon dioxide annually – equivalent to the pollution from 136 million cars, making the increased use of sustainable biofuels critical for reducing its carbon footprint (Martínez, 2014 ).

Kyoto Protocols and the most recent Paris Protocols are calling for the use of clean, green and renewable transportation fuels to replace gasoline, diesel and jet fuel (United Nations, 2016 ). Biofuels for motor vehicles are considered a potential alternative for carbon emission savings because biofuels are produced through processes that significantly reduce net emissions (Fargioni et al ., 2008 ). A number of biofuel programmes have been implemented in the United States and the European Union with the aim of not only reducing emissions but also reducing the importation of fossil fuels and enhancing the security of fuel supply at a national level. Despite of these efforts, current estimates indicate that only about 1% of the energy used globally can be traced back to a biofuel source; therefore, there exists great opportunities to increase the use of renewable liquid fuels (Hill et al ., 2006 ).

First‐ and second‐generation ethanol

Currently, bioethanol is the most common biofuel. Almost 99% of it is produced from corn grain (and other cereals) and it is referred to as ‘first generation’ (1G) bioethanol. In the United States, ethanol production rates are in the range of 14–15 billion gallons per year at corn dry mills; these mills produce not only ethanol but also corn oil and dry distillers’ grains (DDG) – a product that is used as animal feed (Mosier and Ileleji, 2014 ). It is estimated that the ethanol produced in the United States serves to replace about 500 million barrels of petroleum annually. Europe currently produces about 2.5 billion gallons of ethanol per year at around 70 ethanol production plants (Voegele, 2013 ). In Brazil, which is the second largest producer and user of ethanol, about 6.2 billion gallons of ethanol were produced in 2014 from sugarcane, and this ethanol also belongs in the 1G category (Barros, 2014 ).

Although 1G bioethanol is recognized as a renewable energy source, its production is not free from controversy, as it has been the subject of a wide range of societal and political debates. Questions about costs, security of energy supply, greenhouse gas emissions, sustainability of production systems, impact on food production and on biodiversity are some of the many issues which have been raised regarding this source of energy.

Hill et al . ( 2006 ) proposed that for a biofuel to be a viable gasoline alternative, it should provide a net energy gain, have environmental benefits, be economically competitive and be produced in large amounts without reducing food supplies. It is clear that 1G bioethanol does not fulfil all these requirements, although many process modifications have been made in the last years to improve sustainability. Continuous improvements to 1G bioethanol technology have led to savings of around 3.7 pounds of CO 2 per every gallon of ethanol produced in standard 1G plants – savings that are achieved through the capture and liquefaction of CO 2 during fermentation. Although volatility of corn grain and ethanol is high, a number of studies suggest that every $1 spent to produce ethanol through input feedstock yields $1.83 in finished products, that is, alcohol, corn oil, CO 2 and DDG, which guarantees ethanol's economic viability.

In an attempt to address the food versus fuel controversy, the biofuel industry has searched for new, alternative feedstock sources for biofuel production. This approach is necessary for other reasons, namely because it has been calculated that even if all the US corn was used to produce biofuels, this would only satisfy 12% of the demand for gasoline (Hill et al ., 2006 ). The use of non‐food sources, such as corn stover, wheat straw, woody biomass or organic matter from municipal solid waste (MSW), for ethanol production is known as ‘Second‐generation’ (2G) bioethanol. 2G ethanol has been considered to be a promising alternative to 1G ethanol. These 2G biofuels are considered to be more energy efficient than conventional fossil fuels and are more environmentally friendly as well. While the number of 1G facilities worldwide is not increasing (Voegele, 2013 ), many initiatives have been put in place to increase 2G plants. Several companies have recently announced the opening of commercial cellulosic ethanol facilities, namely INEOS‐bio, POET‐DSM, Dupont and Abengoa, although a number of hurdles have been encountered that have delayed launch dates and prevented steady production rates, such that they are running at a small fraction of their nameplate capacity. The US cellulosic ethanol capacity at the end of 2015 was estimated at 86 million gallons; however, only 1.6 million gallons were registered. In retrospect, this may not be fully unexpected given the novelty of this incipient industrial process. The United States has put in place a number of initiatives to promote 2G biofuels. At the federal level, the Renewable Fuel Standard (RFS2) mandates increasing the volume of biofuels to be blended into gasoline and diesel, while providing a premium price for biofuel based on a credit system known as ‘RINs’ (for more information on the current status of the RFS2 can be found at ‘EPA cuts US biofuels quota through 2016’). At the state level, California's Low Carbon Fuel Standard (LCFS) mandates additional amounts of low carbon fuels to be blended into petroleum products above and beyond the RFS2. The LCFS also has credits attached to each gallon of biofuel, for which their monetary value is determined based on the carbon intensity of the fuel.

The production of 2G bioethanol usually requires three major steps: a physicochemical pre‐treatment, an enzymatic breakdown of biomass into its constituent sugars and fermentation (Taherzadeh and Karimi, 2007 ; Álvarez et al ., 2016 ). At present, the main hurdles in 2G ethanol seem to arise from mechanical issues in the handling of materials and the efficient operation of the pre‐treatment units. Pre‐treatment is required to make the polysaccharides (cellulose and hemicellulose) in lignocellulosic material accessible. The process depends upon cellulases and hemicellulases that convert complex sugars into simple sugars, which can then be fermented (Taherzadeh and Karimi, 2007 ). Although a number of studies point to the use of ionic liquids as a new potential pre‐treatment (Uppungundla et al ., 2014 ; Ding et al ., 2016 ), their current prices make them non‐competitive at the industrial scale. Because of this, dilute acid or caustic treatments followed by steam treatments are the most commonly used.

It is well known that in nature a number of fungi secrete a set of enzymes that allow them to grow by metabolizing lignocellulosic residues (Wackett, 2011 ; Zhou et al ., 2015 ). The use of fungi to produce enzymatic cocktails has been iteratively improved and a series of recombinant strains to produce these cocktails are available. The ultimate goal of using these cocktails on biomass is to enable the release > 80% of the sugars present in celluloses and hemicelluloses as monosaccharides. 2G enzymatic cocktails have been commercialized by Novozymes, Genencor and Abengoa Biotec, among others. Enzyme manufacturing for 2G has been achieved in 400 m 3 fermenters – a process that has been shown to be safe, efficient and profitable, yielding 100 g of protein per kg of cocktail (Abengoa's own source). In tandem, enzyme efficiency has been increased by a factor of 10 by Abengoa.

Fermentation of sugars released from corn stover, sugarcane and other agricultural residues requires specialized yeasts able to simultaneously ferment glucose and xylose (Heer and Sauer, 2008 ). The yeasts used in 2G fermentation are genetically modified to convert more than 96% of glucose and more than 90% of xylose into ethanol with overall fermentation yields >90% of the theoretical maximum – results that demonstrate how far this part of the process has come.

Despite these gains, at present 2G biofuels are not cost‐competitive versus 1G biofuels (Somerville et al ., 2010 ). Investment in the construction of the 2G plants, feedstock prices and operational costs associated with enzymatic hydrolysis comprise a large fraction of the costs of producing 2G biofuels.

Thus, the reduction of capital costs is a key factor for 2G ethanol affordability – one that will require a very significant ‘learning curve’. Costs associated with setting up 2G plants will likely only diminish after several plants have been built; however, even if high subsidies favour the construction of several full‐size plants in the next few years, the lessons learned will likely not significantly reduce the costs of 2G biofuels for years (Abengoa's own source). Therefore, it is expected that even in 10 years’ time, 2G biofuels may still be more costly than 1G biofuels.

The second key point to address before 2G bioethanol can become economically feasible is the reduction of operational costs – an issue that has been cited in several recent techno‐economic studies (Macrelli et al ., 2012 ; Gnasounou and Dauriat, 2010 ). Most of these costs rest in the raw material used to feed the process, as well as in the cost of enzymes for enzymatic hydrolysis. Feedstock prices are governed by supply and demand market forces, as well as supply chain logistics (Somerville et al ., 2010 ). Although biofuel developers have been willing to pay for corn stover and other residues, farmers have been cautious about removing stover and straw from their fields because it is known that they help to fertilize the land and protect it against weather changes. Farmers are also unsure of the long‐term stability of 2G biofuels and are cautious of devoting specific resources towards collecting residues or developing a supply chain when there may be no further cellulosic biofuel plants built. At present, 2G plants pay above what they expected for feedstock and may need to actively participate in the creation of more affordable supply chains. This means recruiting interested farmers, developing the right machinery for residue collection, hiring people to collect and deliver the feedstock, and then, developing safe ways of storing and handling it. These problems have been well known for years, but are proving to be very challenging. To address this, the industry is currently evaluating various alternatives to the existing feedstock supply chain. One example of this is the use of an intermediate storage or processing at depot (Lamers et al ., 2015 ) – an approach that successfully reduced the risk of raw material availability shortfalls. Despite this success, further supply chain innovations are needed to impact the cost‐competitiveness of 2G bioethanol. An early estimation of the price of corn stover delivered to the ethanol plant gate was in the range of $25–50/tonne. DuPont, who has done significant work in feedstock supply chain development, estimated for 2015 a cost of $55/tonne, although prices as high as $75/tonne have been quoted. In Europe, agricultural residues may be purchased at a cost below $50/tonne.

While enzyme costs in 1G ethanol are not significant to the total alcohol production cost, in 2G technology the enzyme cost can be in the range of 15% of total ethanol operation costs. Thus, current efforts in the 2G enzyme technology are directed towards enhancing the efficiency of enzyme production and enhancing the activity of these enzymes. At present, Abengoa's 2G enzymatic cocktail costs are estimated at around 0.4–0.5 US$/gallon ethanol.

Other feedstocks

Although most 2G bioethanol production efforts have been focused on the use of corn stover and sugar cane straw, other agricultural residues like wheat straw, sorghum straw, woody biomass and sugarcane bagasse are also being considered. They were predicted to have stable prices and could provide options for long‐term fixed price off‐takes (Somerville et al ., 2010 ). Other less conventional agricultural residues also have promise. For example, Corbin et al . ( 2015 ) published in Bioresource Technology that up to 400 l of bioethanol could be produced through the fermentation of 1 tonne of grape marc (the leftover skins, stalks and seeds from winemaking). Other potential biomass starting materials for 2G bioethanol production are vegetables that, either at the place of production or at market, are removed from the supply chain and are not sold to the public. New approaches to deal with the set of different potential feedstocks and the use of more than one feedstock at the same time deserve more study.

Forest wood resources are some of the highest potential non‐food biofuel feedstocks in terms of availability, and this availability has started to attract global attention. Felipe Benjumea, former President of Abengoa, foresaw the benefits of harnessing fast‐growing trees because they provide perennial renewable feedstocks, which would not compete with foods and could be more sustainably harvested. Along this line of thinking, researchers at several institutions have shown the outstanding diversity and adaptability that make trees a global renewable resource of fibre for ethanol production (Myburg et al ., 2014 ). Of various forest woods, willow trees have demonstrated a higher potential for use in biofuel production, because they produce large quantities of accessible sugar, are fast‐growing and can tolerate harsh environmental conditions, such as windy slopes and poor soils. Researchers at Imperial College London, in collaboration with Rothamsted Research, explored why growing willow trees at an angle improved their biofuel yields. The researchers found that growing the willow trees at a 45° angle resulted in plants producing up to five times more sugar than plants grown normally (Brereton et al ., 2015 ). This increase was found to correlate with substantial xylem tissue remodelling involved in wood fermentation, but the molecular basis of why and how this happen remains unexplored.

As in the 2G process with herbaceous residues, the main hurdle in the use of woody biomass for 2G biofuels resides in the price of wood and supply chain costs. In addition, enzyme costs are expected to be higher than with herbaceous straw wastes due to the intricate bonds of lignins and polysaccharides in woody mass (Álvarez et al ., 2016 ), and because the hydrolysis of woody biomass leads to the production of a number of chemicals (i.e. acetic acid and aromatic compounds) that act as feedback inhibitors of the enzymes (Reviewed by Álvarez et al ., 2016 ) or interfere with the fermentation of sugars (Heer and Sauer, 2008 ).

It is estimated that advanced biofuels from MSWs and other residues could replace 16% of fuel used by the U.S. transportation sector by 2030. A study by Kalago et al . ( 2007 ) stressed the importance of ensuring that MSWs are sustainably sourced, and that if they are, their use could reduce related greenhouse gas emissions savings by 65%, even when taking into account all possible indirect emissions. The organic fraction of MSW is around 61% in the United States and, according to the EPA, if the 164 million tonnes that are currently diverted to landfills in the United States were converted to bioethanol, about 7.5 billion gallons of ethanol would be produced from biowaste, representing savings of around 250 million barrels of petrol.

Ethanol, isobutanol and n‐butanol blends in gasoline: symbiont biofuels

In 1944, Charles Kettering identified ethanol as a blending agent and estimated an optimal blend to be 30% ethanol in gasoline (Kettering, 1944 ). In the United States, by law, ethanol can be blended with gasoline up to a 10%. This gasoline is known as E10 – fuel that requires no major technological adjustments to existing infrastructure or vehicle motors. Higher blends (i.e. 15% ethanol in gasoline) require small modifications to vehicles and derogation of hydrocarbon emissions limits. Adding 10% ethanol in gasoline reduces the emission of fine particulate matter by 36%, and by as much as 65% in cars with large displacement volumes. Benzene is often identified as the most important toxic and carcinogenic compound found in car exhaust, and E10 gasoline emitted 25% less benzene (Niven, 2005 ).

The blending of gasoline with medium chain alcohols such as butanol has been authorized by the American Society for Testing and Materials. Two of the butanol isomers, isobutanol and n ‐butanol, are considered useful biofuels (Coons, 2012 ). Currently, debates within the biofuel field are positioning butanol a better fuel component than ethanol. Those who support butanol point to three key benefits: (i) butanol has a higher fuel density; (ii) it can be added to gasoline at a higher blend ratio of 1.6:1 (i.e. E10 is equivalent to B16); and (iii) it is highly compatible with existing petroleum distribution systems (Green, 2011 ), including fuel pumps. However, butanol has also some disadvantages in comparison to ethanol:butanol has a lower octane rating, a lower heat of evaporation and a significantly lower Reid vapour pressure (RVP) (Wu et al ., 2014 ).

Current biological production of butanol is very limited; only one company (Gevo, Luverne, MN, USA) has reported the bioproduction of isobutanol, with a total yield of 50 000 gallons in 2014. n ‐butanol and isobutanol can also be produced from lignocellulosic materials (Ding et al ., 2016 ) and from corn grain (Green, 2011 ). A detailed techno‐economic analysis of cellulosic isobutanol, n ‐butanol and ethanol has been carried out by Tao et al . ( 2014 ); they concluded that the relative energy returned on investment for each biofuel is isobutanol < ethanol < n ‐butanol. It has been proposed that butanol and ethanol can be blended together to make a better fuel blending agent (Elfasakhany, 2015 ). A combined alcohol blend of about 18% ethanol and 12% butanol can maintain the original Blendstock for Oxygenated Blending RVP, but would lack optimal latent heat of evaporation (Brandon and Ezike, 2015 ; Elfasakhany, 2015 ).

Conclusions and further perspectives

The value of biofuels goes beyond their use as transportation fuels, and attention should be given to the economic and environmental benefits of the co‐products of biofuels. Both 1G and 2G biofuel industries serve to significantly reduce greenhouse gas emissions and our reliance on crude oil, encouraging energy diversity, while promoting the creation of a large number of rural jobs. Today, with the blending limit in the United States set at 10% and gasoline prices going down, corn ethanol producers have relatively little incentive to partner with cellulosic‐based fuel companies as they regard next‐generation ethanol as a market competitor that would only displace their existing corn ethanol. Presently, the long‐term success of 2G ethanol requires financial incentives and supportive regulations, which are instrumental for driving the commercial production and adoption of advanced biofuels.

In looking towards 2030, there is great potential for the production of biofuels from non‐edible plant materials and MSW residues. In addition to ethanol, the production of other chemicals, such as butanol farnesene and several carboxylic acids (Eggleston and Lima, 2015 ; Ding et al ., 2016 ; Ramos et al ., 2016 ), from non‐food feedstocks hold great potential for increasing the value and usefulness of biofuels.

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