Biomass refers to living and recently dead biological material. It can be used as an energy source directly, such as by burning, or to produce a biofuel, such as ethanol. Biomass accounts for 4% of world wide energy production, much of this in developing countries which burn wood, charcoal and other materials for cooking and heat. However, a lot of research is going into biomass-based energy, especially in the area of biofuel for transportation.

Biomass is a renewable resource since crops can be planted again and again. It is also thought to be carbon neutral since the carbon released during energy conversion is absorbed by new plant growth. In practice, biomass is not truly carbon neutral, since energy is required to grow crops and convert them in to fuel, though it is generally an improvement over fossil fuels. However, recent studies indicate that the advantages of reduced carbon emissions of crops such as rapeseed and corn may be more than offset by increased nitrous oxide emissions which has a much higher greenhouse effect [Source: EnviroStats].

There are other negative impacts of using biomass for energy. One is that some biomass sources, such as corn, are also major food sources. This can potentially lead to food shortages. Another issue is deforestation to create cropland. It is often the case that the biomass crop absorbs less carbon than the forest it displaced, causing a net increase in carbon dioxide.

Energy from biomass waste is an interesting prospect. Converting municipal solid waste, farm waste and other biodegradable waste streams to energy could reduce global warming as well as reduce pollution and waste stream management problems. Landfill sites generate gases such as methane. Capturing this methane and using it as a fuel source can also reduce emissions of greenhouse gases. Waste may not meet all of our energy requirements, but not utilizing this energy source has a negative impact. The University of New Hampshire is the first university in the country to use landfill gas a primary energy source [Source: Earth911].

Biofuel sources range from simple vegetable oil to bio-engineered algae. The primary focus has been to replace gasoline and diesel in transportation. While corn-based ethanol has had a lot of support in the US, it also carries a lot of negatives [see Energy Roundup]. Biodiesel has a lot of potential [see Green Myth-Busting], but diesel engines are not common for standard cars in the US (though could be a benefit to trucking). Butanol, which is claimed to be a direct gasoline replacement, is another potential biofuel that has received some high profile investment lately [see Green Wombat]. In the meantime, companies like LS9 and Amyris Biotechnologies are trying to engineer bacteria which can produce a gasoline substitute from biomass sources [see Greenstock].

It seems to me that our energy future will come at least in part from biomass.