First-generation fuels refer to biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology'
The more common first generation biofuels are listed below.
Vegetable oil
Vegetable oil used as a fuel is produced using the same methods as vegetable oil used for consumption. The quality of the oil may be a lot lower for fuel use. Vegetable oil can be used in many older diesel engines (equipped with indirect injection systems), but only in the warmest climates. Usually it is turned into biodiesel instead. No engine manufacturer explicitly allows any use of vegetable oil in their engines.
Biodiesel
Biodiesel is the most common biofuel in Europe. It is produced from any oil or fat using transesterification to get a liquid similar to mineral diesel. It can be used in any diesel engine and can be mixed with mineral diesel in any percentage. In some countries manufacturers cover many of their diesel engines under warranty for 100% biodiesel use, although Volkswagen Germany, for example, asks drivers to make a telephone check with the VW environmental services department before switching to 100% biodiesel (see biodiesel use). Many people have run thousands of miles on biodiesel without problem, and many studies have been made on 100% biodiesel. In many European countries, 5% biodiesel blend is widely used and is available at thousands of gas stations.
Because more than 80% of all commercial trucks and city buses run on diesel gas, "the nascent U.S. market for biodiesel is growing at a staggering rate—from 25 million gallons per year in 2004 to 78 million gallons by the beginning of 2005. By the end of 2006 biodiesel production was estimated to increase fourfold to more than 1 billion gallons," energy expert Will Thurmond writes in an article for the July-August 2007 issue of THE FUTURIST magazine.
Ethanol
Ethanol is the most common biofuel worldwide. It is an alcohol fuel. It can be produced from wheat, corn and sugar cane and many other biomass stocks. The production methods used are fermentation of the sugars, distillation and drying. Ethanol can be used in the petrol engine as a replacement to gasoline; it can be mixed with gasoline to any percentage, see common ethanol fuel mixtures for information on ethanol. However, until the recent introduction of new engines, cars would need to have their engines modified in order to run with 100% alcohol.
Butanol
Butanol is often claimed as a direct replacement for gasoline. It is not in wide spread production at this time, and engine manufacturers have not made statements about its use[verification needed]. While on paper (and a few lab tests) it appears that butanol has sufficiently similar characteristics with gasoline such that it should work without problem in any gasoline engine, no widespread experience exists. Butanol is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. Butanol will produce more energy and allegedly can be burned "straight" in existing gasoline engines (without modification to the engine or car) , and is less corrosive and less water soluble than ethanol, and can be distributed via existing infrastructures.
Methanol
Methanol, which is now produced from natural gas, can also be produced from biomass — although this is not economically viable at present. The methanol economy is an interesting alternative to the hydrogen economy.
Alcohols
Biologically produced alcohols, most commonly ethanol and less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through fermentation.
BioGas
Biogas is produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can also be used as a biofuel.
Biogas contains methane and can be recovered in industrial anaerobic digesters and mechanical biological treatment systems. Landfill gas is a less clean form of biogas which is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere it is a potent greenhouse gas.
Oils and gases can be produced from various biological wastes:
- Thermal depolymerization of waste can extract methane and other oils similar to petroleum.
- GreenFuel Technologies Corporation developed a patented bioreactor system that uses nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, biogas and a dry fuel comparable to coal.
Solid Biofuels Examples include wood, charcoal, and dried excrement.
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