Biomass is part of the carbon cycle. Carbon from the atmosphere is converted into biological matter by photosynthesis. On death or combustion the carbon goes back into the atmosphere as carbon dioxide. This happens over a relatively short timescale and plant matter used as a fuel can be constantly replaced by planting for new growth. Therefore a reasonably stable level of atmospheric carbon results from its use as a fuel.

Biomass is a renewable fuel and is called a carbon neutral fuel.  When biomass is used for energy production it is widely considered carbon neutral, or a net reducer of greenhouse gasses because of the offset of methane that would have otherwise entered the atmosphere. The carbon in biomass material, which makes up approximately fifty percent of its dry-matter content, is already part of the atmospheric carbon cycle. Biomass absorbs carbon dioxide from the atmosphere during its growing lifetime. After its life, the carbon in biomass recycles to the atmosphere as a mixture of carbon dioxide and methane, depending on the ultimate fate of the biomass material. Methane converts to carbon dioxide in the atmosphere, completing the cycle. In contrast to biomass carbon, the carbon in fossil fuels is locked away in geological storage forever, unless extracted. The use of fossil fuels removes carbon from long-term storage, and adds it to the stock of carbon in the atmospheric cycle.

The existing commercial biomass power generating industry in the United States, which consists of nearly 2,000megawatts of operating capacity actively supplying power to the grid, produces almost one percent of the U.S. electricity supply. This level of biomass power generation avoids approximately 11 million tons per year of carbon dioxide emissions from fossil fuel combustion. It also avoids approximately two million tons per year of methane emissions from the biomass residues that, in the absence of energy production, would otherwise be disposed of by burial in landfills, in disposal piles, or by the plowing under of agricultural residues, by spreading, and by open burning. The avoided methane emissions associated with biomass energy production have a greenhouse warming potential that is more than 20 times greater than that of the avoided fossil fuel carbon dioxide emissions. Biomass power production is at least five times more effective in reducing greenhouse gas emissions than any other renewable energy technology.

For a list and definitions of our renewable energy sources, please visit our clean renewable energy page.