WERF pegs biogas energy barriers at wastewater treatment plants

By Anna Simet | September 07, 2012

The Water Environment Research Foundation has released a report identifying the barriers to biogas use for energy at wastewater treatment facilities (WWTF), and it indicates that inadequate payback and lack of available capital remain the dominant hindrances.

Only about 8 percent of the 43 percent of plants that employ anaerobic digestion generate electric or thermal energy using biogas, the report points out, so the potential to expand wastewater-derived renewable energy is significant. The U.S. EPA Combined Heat & Power Partnership estimates it has the potential to supply an additional 3 million megawatt-hours per year of power, to be used onsite at wastewater treatment facilities or plugged into the electric grid.

The main impetus of WERF’s report was to determine why more WWTF that use anaerobic digestion—43 percent of existing plants—don’t generate energy from biogas, and to ask facility managers who are successfully doing it how they have done so.

According to the report’s executive summary, inadequate payback and lack of available capital remain the dominant barriers to recovering power through anaerobic digestion with combined-heat-and-power (CHP) production. “The largest, most widespread barriers are economic, related to higher priority demands on limited capital resources or to perceptions that the economics do not justify the investment,” it says, listing possible solutions as being better whole-life cost and benefit estimation methods, and legislation to assist in financing CHP projects.

Other main barriers fall into the categories of regulatory policy factors and human decision-making factors. A surprisingly high percentage of survey and focus group respondents from smaller-capacity (5-10 million-gallon-per-day) facilities have found means to justify biogas use projects, according to the report, while the midsized plants (10-25 mgd) identified inadequate gas production as a barrier. Enhancement of gas production, such as co-digestion with food waste, can help overcome this barrier, the report says.

It also states that government policy, such as a state renewable portfolio standard providing renewable energy credits, could add more incentive for WWTFs to install CHP technologies.

The 156-page document is free to members, and can be downloaded here.