 |
- Over 150 anaerobic digesters are operating on farms in the U.S. (www.epa.gov/agstar), primarily at dairies and some hog farms. Farm digesters reduce odors associated with manure, as well as pathogens. In addition to generating electricity, heat from gas engines is captured and utilized in farm operations. Many farms also are accepting food waste streams from area generators, which provides a revenue stream and boosts biogas production.
- More than 1,500 municipal wastewater treatment plants have anaerobic digesters to process the solids stream. Increasingly, these treatment plants are capturing the biogas to offset electricity and natural gas use, savings that go directly to the cities’ bottom line. A handful of facilities are being designed in the U.S. to process organics such as food waste and yard trimmings from the municipal solid waste stream. In September, construction of the first facility got underway in Oshkosh, Wisconsin.
- Methane is a highly potent greenhouse gas, with a global warming potential 72 times higher than carbon dioxide over a 20-year period because of its relatively short residence time in the atmosphere (12 years). Increasing the capture and use of methane-rich biogas via anaerobic digestion now could help reduce U.S. greenhouse gas emissions significantly in the near term.
- The methane in renewable biogas could displace as much as 10-15 percent of current fossil natural gas use by 2025-2035.
- Most biogas that is captured and used in the United States today is from landfills. However, decomposition conditions are suboptimal, resulting in lower quality biogas with increased contaminants and much of the methane still escapes from landfills. AD enables cost effective and environmentally sustainable diversion of organics from landfills, resulting in higher, faster rates of biogas production and substantially lower emissions.
- AD can be a beneficial partner to composting since the digestate requires minimal curing to form a stable compost, or can be combined with woody waste for accelerated composting.
- As a renewable energy source, biogas has the advantage over wind and solar energy since it is generated continuously and can be used as base load power. In addition, biogas can be used directly for thermal energy or upgraded and compressed for vehicle fuel.
- The California Air Resources Board has certified that renewable biogas used as a transportation fuel has the lowest life cycle carbon emissions of any biofuel available today.
- Biogas can be cleaned and refined to pipeline quality gas, known as biomethane, for distribution in the existing natural gas pipeline system. Several large natural gas and electric companies have contracts to purchase biomethane from AD facilities.
- In livestock operations, processing manure through an anaerobic digester to produce biogas also produces higher value fertilizer and bedding material, provides odor control and pathogen destruction, and reduces nutrient run-off potential.
- In urban settings, organic waste diversion facilities and anaerobic digesters can and must be operated successfully in densely populated areas. In addition to producing biogas, these systems can produce high value compost material and soil amendments.
- In Germany, a carbon tax, carbon cap and trade system, and a renewable energy feed-in tariff have created the incentives for the biogas industry to flourish, creating tens of thousands of jobs in the biomass energy industry. Germany now has more than 5,000 biogas production plants of various sizes in both rural and urban areas.
|
|
|
|
