Alternative Fuel Sources

The twentieth century was dominated by oil. It drove the economic forces that control the world, caused wars and massive pollution since fossil fuels are major sources of greenhouse gas emissions. The 21st century is seeing a major shift towards alternative fuel sources since fossil fuels come from finite reservoirs and are not sustainable.

There are several types of alternative fuel sources. The most widely available at present are plant sources, from which we make biofuels. Ethanol is the best known type of biofuel. In the U.S. it is made mostly from corn, thanks to large subsidies given to corn farmers. This type of biofuel also attracts fierce criticism due to competition with food crops, low energy density and net energy. Some say it is even more harmful than gas itself.

Sugarcane ethanol is another popular alternative fuel source. It is very popular in Brazil where a massive program has been in place since the 1980s and most people drive flex fuel cars that can run on both ethanol and gas. The energy density of sugarcane ethanol is higher than corn ethanol but it also presents environmental problems due to the huge amounts of land it requires and emissions caused by burning, which is part of the harvesting process.

One of the promising alternatives is so-called cellulosic ethanol, which is made of non-food crops such as the bagasse of sugarcane, wood and grasses. Brazil and the U.S. lead the research while in Denmark has already made cellulosic ethanol available at a network of pumps across the country. Research is necessary to improve the energy density of cellulosic ethanol but many people agree that is a major step forward to make ethanol more sustainable.