Biomass as a fuel refers to plants, animal wastes and other fuels of a biological origin. Since reserves of biomass can be readily replenished with organic growth, they are considered to be a renewable fuel. Energy produced with biomass is called bioenergy.  [1]

Some biomass fuels, such as wood, have been used throught history. Others, such as modern automotive biofuels, are results of highly sophisticated scientific research. The combined share of biomass derived fuels in global primary energy consumption is 10.6 %, higher than any other renewable energy source. Moreover, there is widespread use of firewood that takes place outside of statistics, especially in developing countries. [2]

Biomass is a versatile source of energy and nearly any kind of fuel can be replaced or supplemented with a biofuel: coal with wood, natural gas with biogas, gasoline with ethanol, diesel with biodiesel and so on.

Unlike fossil fuels, however, biomass is carbon-neutral and does not contribute to climate change as long as the biomass consumed is replaced by new growth. This is because the growth of biomass relies on absorption of carbon dioxide from the atmosphere. Since identical amounts are absorbed and released in this cycle, the result is carbon neutrality.

Wood, straw and some other kinds of biomass can be used directly to fire power plants that resemble, in principle, normal fossil fuel fired power plants. Sometimes they are also mixed with fossil fuels.

For use in vehicles, biomass can be converted to liquid biofuels. The liquid biofuel in greatest production is ethanol, which is usually made by fermenting and distilling cereals or sugar. Other processes are under investigation. Ethanol can be mixed with gasoline for use in regular cars.

The second most common liquid biofuel is biodiesel, which is made primarily from oily plants such as the soybean or oil palm. Correctly blended, biodiesel is completely interchangeable with regular diesel in most engines.

Some biofuels are produced from the wastes of some industrial process or consumers. For instance, in the paper industry toxic black liquor is nowadays routinely burned in power plants to harmless end products. Another example is turning waste cooking fat from restaurant deep-frying into biodiesel. Such practices offer the double benefit of generating renewable energy and solving a waste problem.

One distinctive promise of biofuels is that, combined with the emerging technology of carbon capture and storage, the use of biofuels may be capable of perpetually removing carbon dioxide from the atmosphere. Biofuel crops could remove carbon dioxide from the air as they grow, and energy facilities would capture the carbon dioxide given off as biofuels are burned to generate power. Thus the use of biomass could not only reduce our greenhouse gas emissions but also actually mend some of the damage already caused.

Footnotes

[1] "Biofuel" in Encyclopædia Britannica. Encyclopædia Britannica, 2009.

[2] IEA: Renewables in Global Energy Supply. IEA/OECD, 2007.