Cornell University Search Cornell
  Home > Renewable Energy > Biofuels > What are Biofuels?

Biofuels

What are Biofuels?

Green Choices - Renewable Energy - Biofuels - What are Biofuels?Biofuels are energy sources made from living things, or the waste that living things produce. Supporters of biofuels argue that their use could significantly reduce greenhouse gas emissions; while burning the fuels produces carbon dioxide, growing the plants or biomass removes carbon diozide from the atmosphere. Detractors claim that biofuel production poses a major threat to global food systems and the natural environment.

Biofuels can come from a wide variety of sources and can be roughly divided into four categories or "generations:"

  • First generation biofuels are made from sugars, starches, oil, and animal fats that are converted into fuel using already-known processes or technologies. These fuels include biodiesel, bioalcohols, ethanol, and biogasses, like methane captured from landfill decomposition.
  • Second generation biofuels are made from non-food crops or agricultural waste, especially ligno-cellulosic biomass like switch-grass, willow, or wood chips.
  • Third generation biofuels are made from algae or other quickly growing biomass sources.
  • Fourth generation biofuels are made from specially engineered plants or biomass that may have higher energy yields or lower barriers to cellulosic breakdown or are able to be grown on non-agricultural land or bodies of water.
Biofuel Terms
Biodiesel is a renewable fuel made from seed oils (canola, sunflower, soybean, etc.), reclaimed vegetable or animal fats, or algae.

Ethanol is an alcohol made from feed stocks (such as corn), sugar cane, or cellulosic material. Ethanol is generally blended with gasoline for use in internal combustion engines.

Hard Biofuels refer to low density biomass, usually grass or wood byproducts (sawdust), that are pressed into pellets that are extremely dense and highly combustible. The pellets can be burned for electricity production or heating purposes.

Further Reading
What are Biofuels? What are Biofuels?

Vermont Sustainable Jobs Fund

2009

Opportunities and Challenges in Algae Biofuels Production Opportunities and Challenges in Algae Biofuels Production

John R. Benemann, Algae World

2008

PDF: 2.5M

A Quick Look at Fourth Generation Biofuels A Quick Look at Fourth Generation Biofuels