Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass.  Biofuels help meet transportation fuel needs. Biofuels can be used in cars, trucks, buses, airplanes, and trains.

The most common types of biofuels are biodiesel, ethanol and methanol.

• Biodiesel is made by combining alcohol, like methanol with vegetable oil, animal fat, or recycled cooking greases.  As an additive to gasoline (typically 20%), biodiesel has successfully reduced vehicle emissions. In its pure form, it can be used in diesel engines.
   
• Ethanol  (CH3CH2OH) is made by fermenting any biomass high in carbohydrates (starches, sugars, or celluloses). So, ethanol is an alcohol, the same as in beer and wine.  Just to let you know that the ethanol used as a fuel is modified to make it undrinkable.
  
  Ethanol is mostly used as blending agent with gasoline to increase octane and cut down carbon monoxide and other smog-causing emissions.  A new class of vehicles that can run on a mixture of gasoline and up to 85% ethanol are commercially available.
  
  Ethanol made from cellulosic biomass materials instead of traditional feedstocks (starch crops) is called bioethanol.
   
• Hydrogen (H2) is the simplest and lightest fuel. Hydrogen is in a gaseous state at atmospheric pressure and ambient temperatures. Hydrogen may contain low levels of carbon monoxide and carbon dioxide, depending on the source.
   
• Methanol (CH3OH) also known as wood alcohol, is produced from biomass. Biomass is converted to methanol through gasification.
   
• Methane (CH4) is a greenhouse gas that remains in the atmosphere for approximately 9-15 years. Methane is over 20 times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period and is emitted from a variety of natural and human-influenced sources. Human-influenced sources include landfills, natural gas and petroleum systems, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial process.

  Methane is also a primary constituent of natural gas and an important energy source. As a result, efforts to prevent or utilize methane emissions can provide significant energy, economic and environmental benefits. In the United States, many companies are working with EPA in voluntary efforts to reduce emissions by implementing cost-effective management methods and technologies.