The Opportunities for and Benefits of Combined Heat and Power at Wastewater Treatment Facilities

The U.S. Environmental Protection Agency's (EPA's) Combined Heat and Power (CHP) Partnership has encouraged the integration of CHP into wastewater treatment plant designs since 2005. In 2007, the CHP Partnership completed a market analysis titled, “Opportunities for and Benefits of Combined Heat and Power at Wastewater Treatment Facilities (WWTF).” The report's target audience was the stakeholders to developing CHP at a WWTF, such as the local facilities, municipal utilities, developers, financiers, and energy supply companies (ESCO). The report objective was to develop engineering rules of thumb, quantify market potential, and identify short-term opportunities for increasing the deployment of biogas-fueled renewable CHP at WWTFs in the United States.The report yielded two key findings. First, in general, each 4.5 MGD [0.197 m3/s] of influent flow at a WWTF that employs CHP can be utilized to produce approximately:100 kilowatts (kW) of electricity to offset purchased electricity or sell to the grid.12.5 million British thermal units (MMBtus) per day [153 kW] of thermal energy that can be used as heat for an anaerobic digester and/or for space heating loads.Second, if all WWTFs in the U.S. with anaerobic digesters and influent flow rates greater than 5 million gallons per day (MGD) [0.219 m3/s] installed CHP systems, approximately 340 Megawatts (MW) of clean electric capacity could be generated, offsetting 2.3 million metric tons of carbon dioxide emissions annually (these reductions are equivalent to removing the annual emissions of approximately 430,000 cars).The report substantially advanced the Partnership's work in the wastewater treatment sector by establishing an overall technical potential estimate, and presenting a strong case for CHP at WWTFs. Since the report was first published, the Partnership has found that there is interest in investigating CHP applications at facilities between 1 and 5 MGD. There is also an interest better understanding the economic opportunities for CHP applications. In tandem, there is an interest in the challenges to successful project development including how systems can benefit from federal and state clean energy policies and incentives.The CHP Partnership's goal is to complete a comprehensive update of the 2007 report that reflects these technical and economic drivers. The report will include real world examples of CHP installations to highlight the market drivers, benefits, barriers, and lessons learned from them. The report findings will be of interest to the various stakeholders in the CHP WWTF industry at WWTF, local utilities and government, and project developers and intends the report to be completed by the fall of 2010.