Clean biomass energy does have great environmental potential. For example, combustion of biomass releases almost no sulfur, the pollutant that causes acid rain. This combustion does release carbon dioxide, the major global warming pollutant, but an equal amount of carbon dioxide (CO2) was absorbed during the growth of the trees or crops that are burned. So biomass energy is "carbon neutral" as the CO2 is recycled, minimizing the impact on global climate change.
One type of biomass energy is methane gas or “biogas” produced by decomposing waste. Methane is produced when waste decomposes at landfills, sewage treatment plants, and farms. This gas can be collected, processed, and used as fuel. When this natural decomposition process is enhanced using new technologies, such as methane digesters for manure or advanced gasification techniques for other wastes, the process becomes more efficient and clean. In this way, biogas projects avoid the use of fossil fuel and avoid the release of methane, a powerful greenhouse gas.