Biofuels and synthetic fuels
Biofuels and synthetic fuels represent alternative energy sources derived from renewable materials, aimed at reducing dependence on fossil fuels and mitigating climate change. Biofuels, such as ethanol, biodiesel, and biogas, are produced from organic matter, including crops and waste, while synthetic fuels, like syngas and synfuels, are created through chemical processes involving coal or biomass. These fuels can serve multiple purposes, notably as substitutes for gasoline and diesel in transportation, as well as sources for electricity generation and heating.
Historically, biofuels have been utilized for thousands of years, with significant advancements occurring during the Industrial Revolution and continuing into modern times. Recent global concerns over climate change and energy security have propelled interest and investment in this field, particularly in countries like the United States. Despite challenges such as fluctuating petroleum prices and technological hurdles, the biofuel sector is projected to grow, with increasing demand expected through 2028.
The industry not only holds potential for environmental benefits—such as reduced greenhouse gas emissions—but also for economic opportunities, as it creates jobs across research, engineering, and production. As advancements continue, biofuels and synthetic fuels may play a crucial role in shaping a more sustainable energy future.
Biofuels and synthetic fuels
Summary
The study of biofuels and synthetic fuels is an interdisciplinary science that focuses on development of clean, renewable fuels that can be used as alternatives to fossil fuels. Biofuels include ethanol, biodiesel, methane, biogas, and hydrogen. Synthetic fuels include syngas and synfuel. These fuels can be used as gasoline and diesel substitutes for transportation. They are also suitable as fuels for electric generators to produce electricity, and as fuels to heat houses, which in fact is their traditional use. Both governmental agencies and private companies have invested heavily in research in this area of applied science.
Definition and Basic Principles
The science of biofuels and synthetic fuels deals with the development of renewable energy sources, alternatives to nonrenewable fossil fuels such as petroleum. Biofuels are fuels generated from organisms or by organisms. Living organisms can be used to generate a number of biofuels, including ethanolbioethanolbiodiesel, biomass, butanol, biohydrogen, methane, and biogas. Synthetic fuelssynfuel and syngasare a class of fuels derived from coal or biomass. Synthetic fuels are produced by a combination of chemical and physical means that convert carbon from coal or biomass into liquid or gaseous fuels.
Around the world, concerns about global climate change due to the emission of greenhouse gases from human use of fossil fuels, as well as concerns over energy security, have ignited interest in biofuels and synthetic fuels. A large-scale biofuel and synthetic fuel industry has developed in many countries, including the United States. A number of companies in the United States have conducted research and development projects on synthetic fuels with the intent to begin commercial production of synthetic fuels. Although biofuels and synthetic fuels still require long-term scientific, economic, and political investments, these alternatives to fossil fuels is expected to mitigate global warming, protect the global climate, and to reduce US reliance on foreign oil.
Background and History
People have been using biofuels such as wood or dried manure to heat their houses for thousands of years. The use of biogas was mentioned in Chinese literature more than 2,000 years ago. The first biogas plant was built in a leper colony in Bombay, British India Mumbai, India in the middle of the nineteenth century. In Europe, the first apparatus for biogas production was built in Exeter, England, in 1895. Biogas from this digester was used to fuel street lamps. Rudolf Diesel, the inventor of the diesel engine, used biofuelpeanut oilfor his engine during the World Exhibition in Paris in 1900. The version of the Model T Ford built by Henry Ford in 1908 ran on pure ethanol. In the 1920's, 25 percent of the fuels used for automobiles in the United States were biofuels rather than petroleum-based fuels. In the 1940's, biofuels were replaced by inexpensive petroleum-based fuels.
Gasification of wood and coal for production of syngas has been done since the nineteenth century. Syngas was used mainly for lighting purposes. During World War II, because of shortages of petroleum, internal combustion engines were modified to run on syngas and automobiles in the United States and the United Kingdom were powered by syngas. The United Kingdom continued to use syngas until the discovery in the 1960's of oil and natural gas in the North Sea.
The process of converting coal into synthetic liquid fuel, known as the Fischer-Tropsch process, was developed in Germany at the Kaiser Wilhelm Institute by Franz Fischer and Hans Tropsch in 1923. This process was used by Nazi Germany during World War II to produce synthetic fuels for aviation.
During the 1970's oil embargo, research on biofuels and synthetic fuels resumed in the United States and Europe. However, as petroleum prices fell in the 1980's, interest in alternative fuels diminished. In the twenty-first century, concerns about global warming and increasing oil prices reignited interest in biofuels and synthetic fuels. Though some vehicles were converted to run on biofuels, the vast majority of vehicles continued to utilize petroleum-based fuel.
How It Works
Biofuels and synthetic fuels are energy sources. People have been using firewood to heat houses since prehistorical time. During the Industrial Revolution, firewood was used in steam engines. In a steam engine, heat from burning wood is used to boil water; the steam produced pushes pistons, which turn the wheels of the machinery.
Biofuels and synthetic fuels such as ethanol, biodiesel, butanol, biohydrogen, and synthetic oil can be used in internal combustion engines, in which the combustion of fuel expands gases that move pistons or turbine blades. Other biofuelsmethane, biogas, or syngasare used in electric generators. Burning of these fuels in electric generators rotates a coil of wire in a magnetic field, which induces electric currentelectricityin the wire.
Hydrogen is used in fuel cells. Fuel cells generate electricity through a chemical reaction between molecular hydrogen (H2) and oxygen (O2). Ethanol, the most common biofuel, is produced by yeast fermentation of sugars derived from sugarcane, corn starch, or grain. Ethanol is separated from its fermentation broth by distillation. In the United States, most ethanol is produced from corn starch. Ethanol can also be produced from cellulose, found in the inedible parts of corn plants and other crops. Because using the waste from the production of food crops is better for the environment than growing more crops so that some can be used for fuel, the US government and various private companies have invested significant money into improving the methods of producing cellulosic ethanol, but as of 2016, distilling ethanol from cellulose remained more difficult and costly than distilling it from corn starch or sugarcane. Biodiesel, another commonly used biofuel, is made mainly by transesterification of plant vegetative oils such as soybean, canola, or rapeseed oil. Biodiesel may also be produced from waste cooking oils, restaurant grease, soap stocks, animal fats, and even from algae. Methane and biogas are produced by metabolism of microorganisms. Methane is produced by microorganisms called Archaea and is an integral part of their metabolism. Biogas produces by a mixture of bacteria and archaea.
Industrial production of biofuels is achieved mainly in bioreactors or fermenters of some hundreds gallons in volume. Bioreactors or fermenters are closed systems that are made of an array of tanks or tubes in which biofuel-producing microorganisms are cultivated and monitored under controlled conditions.
Syngas is produced by the process of gasification in gasifiers, which burn wood, coal, or charcoal. Syngas can be used in modified internal combustion engines. Synfuel can be generated from syngas through Fischer-Tropsch conversion or through methanol to gasoline conversion process.
Applications and Products
Transportation
Biofuels are mainly used in transportation as gasoline and diesel substitutes. As of the early twenty-first century, two biofuels—ethanol and biodiesel—were being used in vehicles. In 2005, the US Congress passed an energy bill that required that ethanol sold in the United States for transportation be mixed with gasoline. The US Department of Energy (DOE) reports that by 2014, 95 percent of gasoline sold in the United States had up to a 10 percent ethanol content. The federal government allowed the ethanol content to be raised from 10 to 15 percent in some gasoline, which can be used in cars produced after the year 2000. Most cars in Brazil can use an 85 percent/15 percent ethanol-gasoline mix (E85 blend). These cars must have a modified engine known as a flex engine. In the United States, only a small fraction of all cars have a flex engine.
Biodiesel performs similarly to diesel and is used in unmodified diesel engines of trucks, tractors, and other vehicles and is better for the environment. Biodiesel is often blended with petroleum diesel in ratios of two, five, or 20 percent. According to the DOE, the most common blend is B20, or 20 percent biodiesel to 80 percent diesel fuel in the United States. Biodiesel can be used as a pure fuel (100 percent or B100), but pure fuel is a solvent that degrades the rubber hoses and gaskets of engines and cannot be used in winter because it thickens in cold temperatures. The energy content of biodiesel is less than that of diesel. In general, biodiesel is not used as widely as ethanol, and its users are mainly governmental and state bodies such as the US Postal Service; the US Departments of Defense, Energy, and Agriculture; national parks; school districts; transit authorities; public utilities; and waste-management facilities. Several companies across the United States (such as recycling companies) use biodiesel because of tax incentives.
Hydrogen power ran the rockets of the National Aeronautics and Space Administration for many years. A growing number of automobile manufactures around the world are making prototype hydrogen-powered vehicles. These vehicles emit only water, no greenhouse gases, from their tailpipes. These automobiles are powered by electricity generated in the fuel cell through a chemical reaction between H2 and O2. Hydrogen vehicles offer quiet operation, rapid acceleration, and low maintenance costs because of fewer moving parts. During peak time, when electricity is expensive, fuel-cell hydrogen automobiles could provide power for homes and offices. Hydrogen for these applications is obtained mainly from natural gas (methane and propane), through steam reforming or by water electrolysis. Many problems need to be overcome before hydrogen-powered vehicles become widely used and readily available. Nonetheless, auto manufacturers began introducing fuel-cell production vehicles in 2014 and 2015.
Methane was used as a fuel for vehicles for a number of years. Several Volvo automobile models with Bi-Fuel engines were made to run on compressed methane with gasoline as a backup. Biogas can also be used, like methane, to power motor vehicles.
Airlines have also begun to use biofuels to power their planes. In 2015, United began using a biofuel blend for its flights from Los Angeles, and in 2016 Lufthansa and JetBlue made agreements with biofuel companies. JetBlue, in particular, vowed to use biofuel for about 20 percent of its fuel needs, which was the largest commitment any airline had made at that time. Numerous airlines committed to converting roughly 10 percent of their overall fuel usage to biofuel by 2030 as part of an effort to become carbon neutral by 2050.
Electricity Generation
Biogas and methane are mainly used to generate electricity in electric generators. In the 1985 film Mad Max Beyond Thunderdome, starring Mel Gibson, a futuristic city ran on methane generated by pig manure. While the use of methane has not reached this stage, methane is a very good alternative fuel that has a number of advantages over biofuels produced by microorganisms. First, it is easy to make and can be generated locally, eliminating the need for an extensive distribution channel. Second, the use of methane as a fuel is a very attractive way to reduce wastes such as manure, wastewater, or municipal and industrial wastes. In farms, manure is fed into digesters (bioreactors), where microorganisms metabolize it into methane. Landfill gas facilities in the United States also generate electricity using methane. San Francisco , for example, extended its recycling program to include conversion of dog waste into methane to produce electricity and to heat homes. With a dog population of more than 100,000, this initiative could generate a significant amount of fuel and reduce waste at the same time.
Heat Generation. Some examples of biomass being used as an alternative energy source include the burning of wood or agricultural residues to heat homes. This is a very inefficient use of energy, because typically only 5 to 15 percent of the biomass energy is actually used. Burning biomass also produces harmful indoor air pollutants such as carbon monoxide. On the positive side, biomass is an inexpensive resource whose primary cost is the labor to collect it. Biomass supplies about 8 percent of the energy consumed worldwide, according to a 2014 report by research firm Worldwatch Institute. Biomass is the number-one source of energy in developing countries; in some countries, it provides more than 90 percent of the energy used.
In many countries, millions of small farmers maintain a simple digester for biogas production to generate heat energy. For instance, according to the Global Methane Initiative, by 2010, nearly 40 million household digesters were being used in China, mainly for cooking and lighting.
Careers and Course Work
The alternative fuels industry is growing, and research in the area of biofuels and synthetic fuels is increasing. Growth in these areas is likely to produce many jobs. The basic courses for students interested in a career in biofuels and synthetic fuels are microbiology, plant biology, organic chemistry, biochemistry, agriculture, bioprocess engineering, and chemical engineering. Many educational institutions are offering courses in biofuels and synthetic fuels, although actual degrees or concentrations in these disciplines are still rare. Several community colleges offer associate degrees and certificate programs that prepare students to work in the biofuel and synthetic fuel industry. Some universities offer undergraduate courses in biofuels and synthetic fuels or concentrations in these areas. Almost all these programs are interdisciplinary. Graduates of these programs will have the knowledge and internship experience to enter directly into the biofuel and synthetic fuel workforce. Advanced degrees such as a master's degree or doctorate are necessary to obtain top positions in academia and industry related to biofuels and synthetic fuels. Some universities such as Colorado State University offer graduate programs in biofuels.
Careers in the fields of biofuels and synthetic fuels can take different paths. Ethanol, biodiesel, or biogas industries are the biggest employers. The available jobs are in sales, consulting, research, engineering, and installation and maintenance. People who are interested in research in biofuels and synthetic fuels can find jobs in governmental laboratories and in universities. In academic settings, fuel professionals may share their time between research and teaching.
Social Context and Future Prospects
The field of biofuels and synthetic fuels expanded greatly between 2000 and 2012. Demands for biofuels and synthetic fuels were driven by environmental, social, and economic factors and governmental support for alternative fuels.
The use of biofuels and synthetic fuels reduces the US dependence on foreign oil and helps mitigate the impact of increases in the price of oil, which reached a record $140 per barrel in 2008. The production and use of biofuels and synthetic fuels reduces the need for oil and thus helps keep the price of oil lower. Many experts believe that biofuels and synthetic fuels may one day replace oil.
Pollution from oil use affects public health and contributes to global climate change because of the release of carbon dioxide. Using biofuels and synthetic fuels as an energy source generates fewer pollutants and little or no carbon dioxide.
The biofuel and synthetic fuel industry in the United States was affected by the economic crisis in 2008 and 2009. Several ethanol plants were closed, some plants were forced to work below capacity, and other companies filed for Chapter 11 bankruptcy protection. Such events led to layoffs and hiring freezes. Nevertheless, overall, the industry was growing and saw a return to profitability in the second half of 2009. One segment of the biofuel and synthetic fuel industry, the biogas industry, was not affected by recession at all. More than 8,900 new biogas plants were built worldwide in 2009. Research and development efforts in biofuels and synthetic fuels actually increased during the economic crisis. However, the falling price of petroleum and the boom in shale gas in North America in the mid-2010s posed challenges to the future of biofuels and synthetic fuels, at least in the short term. Nonetheless, biofuel production continued to increase slightly throughout the late 2010s and into the early 2020s. According to the Energy Information Agency, biofuel demand in the United States will expand by 10 million gallons from 2023-2028. In 2028, expected biofuel consumption was expected to reach 52 million gallons. Renewable diesel and ethanol was forecasted to provide almost 70% of this increase.
In 2024, the U.S. Department of Energy and the Environmental Protection Agency invested $9.4 million to spark the development of advanced biofuels. The funds were earmarked for partnership efforts seeking to improve performance, reduce costs, and add scale to production. The program was aimed at organizations such as domestic businesses, academia, and non-profit organizations.
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