American Biogas Council finds wastewater plants could capture more energy from waste

A new nationwide survey from the American Biogas Council says U.S. wastewater facilities could do more to turn organic waste into renewable energy. The report found untapped biogas potential at plants nationwide and highlighted room to expand co-digestion, on-site power use and energy production.

Why it matters: - Wastewater plants already help manage organic waste and generate energy, but the report says many facilities could capture more biogas from existing digesters. - The findings point to more renewable power, more productive use of food waste and other organics, and less material going to landfills. - The report says the untapped opportunity could support electricity for about 1.9 million U.S. homes if the additional biogas potential is captured.

What happened: - The American Biogas Council released Anaerobic Digestion at U.S. Water Resource Recovery Facilities, a nationwide survey of U.S. wastewater facilities. - The study is the first comprehensive assessment of anaerobic digestion at wastewater facilities in more than a decade. - The 18-month effort included more than 33,000 calls and 3,271 conversations with facility managers, operators and other personnel. - The survey identified 1,213 wastewater resource recovery facilities using anaerobic digestion. - Those facilities represent about 24% of the roughly 5,000 facilities surveyed that treat at least 1 million gallons of wastewater per day.

The details: - More than 75% of facilities treating more than 30 million gallons per day use anaerobic digestion. - About 50% of facilities treating 5 million to 30 million gallons per day use digesters. - Fewer than 30% of facilities treating less than 5 million gallons per day use digesters. - The survey found 103 facilities with digesters that treat less than 1 million gallons per day. - Those smaller facilities account for nearly 9% of all wastewater facilities with digesters. - Anaerobic digestion has been part of U.S. wastewater treatment for more than a century. - The earliest facility identified by the survey began operating in New York in 1914. - About 89% of the electricity generated from biogas at wastewater resource recovery facilities is used on-site. - Wastewater facilities with anaerobic digesters capture about 100.8 billion cubic feet of biogas each year. - That volume is enough to generate electricity for about 1.1 million U.S. homes. - More than 80% of facilities use the biogas they produce for energy on-site. - 55% use the gas to generate electricity or combined heat and power. - Another 26% use it for heat. - The report identifies an additional 70 billion cubic feet of annual capture potential. - That would bring total biogas capture to nearly 172 billion cubic feet. - The larger total is enough to generate electricity for about 1.9 million homes. - 139 wastewater facilities accept outside organic material, including food waste and fats, oils and grease. - Co-digestion can allow wastewater plants to add food processing waste, post-consumer food scraps and other organics to existing digesters. - The practice can produce additional biogas and help put some of the 24 million tons of food waste landfilled each year to productive use. - The report is available to download through the American Biogas Council, along with Wastewater Fast Facts, graphs and biogas project profiles. - The American Biogas Council says its newsroom also offers additional material related to the report.

Between the lines: - The report suggests wastewater digesters are already a major source of local energy, but many plants are not capturing the full available value of their systems. - The data also shows the biggest facilities are the most likely to use anaerobic digestion, which leaves more room for adoption at mid-sized and smaller plants. - Co-digestion stands out as a practical way to increase biogas output without building entirely new treatment systems. - Patrick Serfass, executive director of the American Biogas Council, said the survey shows opportunities to expand anaerobic digestion where it makes sense and get more value from digesters already in place.

What's next: - The American Biogas Council is directing readers to the full report and related resources in its newsroom. - The findings could help wastewater operators, policymakers and project developers identify sites with room to expand digestion and biogas capture. - More facilities may look at co-digestion as a way to increase energy output and divert more organic waste from landfills.

The bottom line: - U.S. wastewater plants are already producing meaningful renewable energy, but the survey says more biogas, more co-digestion and more on-site energy use remain within reach.