The negative aspects of biomass energy are similar to those associated with the use of fossil fuels for generating electricity, with the exception that biomass fuels are renewable energy sources. Burning of biomass fuels causes concerns about emissions and water use. Biomass fuels are less efficient and require more land.
Biomass energy uses fuel from plant and animal sources. These sources include waste such as wood chips, sewage, manure and rotted trees but also include crops grown specifically for biomass conversion. While people have used wood for centuries as a source of heat, biomass energy uses this fuel source to power engines or electrical generating plants. However, creating the fuel source is often expensive, even when it consumes waste products.
While biomass energy helps to reduce carbon dioxide emissions, it increases other greenhouse gases, including methane. From an environmental standpoint, emissions from a biomass plant are just as harmful as those from fossil fuels. Use of waste from animals and humans also creates undesirable odors.
Because biomass energy produces methane gas, it requires more land than other types of energy production in order to protect those living near the plant. If the demand for additional biomass exceeds the waste products available, there is the potential for farmers to convert from food crops to biomass crops, which reduces the availability of food. The demand also has the potential to place further demands on already stressed forests.