Bio-Mass

Biomass is organic material that can be used as fuel, either by burning or conversion to a gas or liquid. One example of biomass is wood, which people have been burning for millennia. Modern innovations come into play when we consider biomass conversion into gas and liquid fuel.

The goal of biofuel is to be carbon-neutral: the greenhouse gases that are released into the air when the fuel is burned should be completely counterbalanced by the positive effects of growing plants to produce the fuel. However, biofuel isn't advanced enough to have reached this level of sophistication yet.

Biogas

As garbage rots in landfills, it undergoes a decomposition process called anaerobic digestion. This process produces a methane-blend gas. Methane is a powerful greenhouse gas, so its escape into the atmosphere is a contributing factor in global climate change. However, this gas can be used as fuel. It has been argued that harnessing the gas for fuel is more environmentally responsible than letting it escape into the air.

Gas that comes from waste, including the methane blend found in landfills, is commonly called biogas. Landfill gas is an unsophisticated form of biogas, but there are companies that specialize in creating cleaner biogas using the same principles of decomposition.

Fermentation

Vegetable matter can also be fermented to create alcohol-based fuel. Corn-based ethanol is the most prominent example in the U.S. Similar to its cousin biodiesel (another biofuel), bioethanol can be mixed with traditional gasoline to help reduce fossil fuel use.

Criticism

In mid-2007, Nobel laureate Paul Crutzen and other chemists published an article claiming that biofuel can actually increase greenhouse gases, rather than reduce them. His article suggests that the amount of nitrous oxide created by corn-based bioethanol is so great that it could actually be contributing to global climate change, rather than combating it.

However, Cruzen has by no means put the last nail in biofuel's coffin. Some scientists have criticized his methods of measuring atmospheric nitrous oxide; others say he's miscalculated the reasons for elevated nitrous oxide levels. Regardless, even if we assume he's completely correct, his findings apply to corn-based bioethanol and rapeseed-based biodiesel. Other sources of biofuel won't necessarily produce the same results - in fact, his research indicates that cane sugar is one such alternative.

Other scientists have argued that large-scale biofuel production has negatively affected biodiversity - if we start growing more and more corn to produce bioethanol, they say, it will reduce the variety of species in a local ecosystem. Still others worry that devoting crops to fuel production will result in food shortages.

The point of this criticism is not that biofuel is a dead end, but rather that it's still in its formative stages. As the process of producing it becomes more sophisticated and we move away from first-generation biofuels, the environmental concerns these scientists address will, with luck and research, be ironed out.