The environmental theory behind the use of biofuels is that they exist on a short-term carbon cycle. Plants take in CO2 from the atmosphere to grow, then their carbon structures are burned to release energy. By burning the organic matter, carbon is released back into the atmosphere. This carbon is then absorbed by other plants, closing the loop. Petroleum based fuels pull carbon out of the ground and release it into the atmosphere, making more of a line.
Biofuels can be divided into three types:
- Ethanol--Fuels derived from plant sugars
- Biodiesel and Vegetable Oil--Fuels composed of fats and oils
- Biomass--Unprocessed plants
The future of biofuels depends largely on new technology. Research in how to produce cellulosic ethanol (ethanol from waste biomass, i.e.: cornstalks) shows promise to separate the food and fuel markets. Another development in the production of biodiesel is extracting oil from algae. Algae produces a high amount of energy in the form of oil per energy input so if large-scale algae farms can be created without covering too many lakes and wetlands, it is a promising source of fuel.
Ethanol, or ethyl alcohol, is made by fermenting plant sugars and distilling the alcohol. Normally, ethanol intended for use as fuel is produced from corn, wheat and barley. Ethanol is frequently blended with petroleum-based gasoline to lower emissions and increase engine performance. Vehicles manufactured since 1970 should have no problem with a 10% ethanol blend (E10). Recently, car manufacturers have been producing “flexfuel” vehicles, which they market as guaranteed to handle up to 85% ethanol fuel blends (E85). The increased use of ethanol is thought to have contributed to a worldwide increase in food prices. An alternative to food-based ethanol is cellulosic ethanol, a process still in development that would extract sugars from organic matter (i.e.: corn stalks, wood processing waste, switchgrasss). Cellulosic ethanol has been produced in labs, but nobody has yet figured out how to mass-produce it in a cost effective manner.
Waste Vegetable Oil is what runs our bus. Pure vegetable oil is purchased by restaurants to fry things like french fries in. After they use it, it usually goes in a dumpster behind the restaurant where, with permission from the owner, it may be collected for free. Using waste vegetable oil as fuel is one way to recycle the grease (other uses for waste vegetable oil include dog food and cosmetics). In order to use WVO as a fuel, the bits of food must be filtered out, then the oil is heated (usually by the coolant in the engine) in order to be less viscous. WVO conversion kits are available to convert the fuel systems of diesel engines to run WVO.
As the use of biodiesel and WVO conversions on diesel cars, trucks and busses become more popular, restaurants have started selling their waste vegetable oil; what was once a waste product is now a commodity. In some parts of the country, cities, companies or cooperatives have contracts with local businesses to collect their waste grease and use it to produce fuel. Filtered vegetable oil can be used as the feedstock for biodiesel as well as a fuel on its own.
The last form of biofuel is biomass. Biomass is any type of plant matter that is used to make electricity, heat or to power a machine. Putting a log on a fire is a form of using biomass as fuel. This can be done on a larger scale by burning farm waste to make electricity. Biomass is not a likely solution for transportation, as the energy-per-unit-volume of most plants is too low to be practical.