Biofuels

Biofuels are defined as solid, liquid, or gas fuel derived from recently dead biological material. This distinguishes it from fossil fuels, which are derived from long dead biological material. Biofuel can be theoretically produced from any biological or carbon source, though the most common by far is photosynthetic plants. Many different plants and plant-derived materials are used for biofuel manufacture. Biofuels are used globally, most commonly to power vehicles and cooking stoves. Biofuel industries are expanding in Europe, Asia and the United States.

Biofuels offer the possibility of producing energy without a net increase of carbon into the atmosphere because the plants used in to produce the fuel have removed carbon dioxide from the atmosphere, unlike fossil fuels which return carbon which was stored beneath the surface for millions of years into the air. Biofuel is therefore more nearly carbon neutral and less likely to increase atmospheric concentrations of greenhouse gases. The use of biofuels also reduces dependence on petroleum and enhances our energy security.

There are two common strategies of producing biofuels. One is to grow crops high in either sugar, such as, sugar cane, sugar beet, and sweet sorghum or starches, like corn, and then use yeast fermentation to produce ethyl alcohol or ethanol. The second is to grow plants that contain high amounts of vegetable oil, such as oil palm, soybean, algae, or jatropha. When these oils are heated, their viscosity is reduced, and they can be burned directly in a diesel engine, or the oils can be chemically processed to produce fuels such as biodiesel. Wood and its byproducts can also be converted into biofuels such as woodgas, methanol or ethanol fuel. It is also possible to make cellulosic ethanol from non-edible plant parts, but this can be difficult to accomplish economically.

Biofuels are discussed as having significant roles in a variety of international issues, including: mitigation of carbon emissions levels and oil prices, the food and fuel debate, deforestation and soil erosion, impact on water resources, and energy balance and efficiency.

First generation biofuels refer to biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology. The basic feedstocks for the production of first generation biofuels are often seeds or grains such as wheat, which yields starch that is fermented into bioethanol, or sunflower seeds, which are pressed to yield vegetable oil that can be used in biodiesel. Some examples are: vegetable oil used as fuel, biodiesel, bioalcohols or ethanol, and biogas.

Supporters of biofuels claim that a more viable solution is to increase political and industrial support for second generation biofuels from non food crops, including cellulosic biofuels. Second generation biofuel production processes can use a variety of non food crops. These include waste biomass, the stalks of wheat, corn, wood, and special-energy-or-biomass crops.

Algae fuel, also called oilgae or third generation biofuel, is biofuel from algae. Algae are low-input and high-yield organisms. The output is 30 times more energy per acre than land than feedstocks to produce biofuels and algae fuel is biodegradable.

A fourth generation biofuel is based on the conversion of vegoil and biodiesel into gasoline.

To read our chapter that covers all of our renewable energy sources, please visit our clean renewable energy page.