DC Water picks Pepco Energy for CHP plant

By Anna Austin | March 07, 2012

The largest advanced waste water treatment facility in the world is installing a combined-heat-and-power (CHP) facility and has hired Pepco Energy Services to design, build and operate it.

DC Water’s 153-acre Blue Plains Advanced Wastewater Treatment Plant serves approximately 725 square miles of Washington D.C., Maryland and Virginia, and has a capacity of 370 million gallons per day. The CHP plant will run on biogas generated from the anaerobic digestion of water cleansing process waste, and a thermal hydrolysis process will use high-pressure steam from the plant to increase the rate of biogas production and neutralize contaminants in waste streams.

DC Water broke ground on the anaerobic digestion and thermal hydrolysis projects in May 2011. The CHP component is slated for construction in August, and will produce at least 14 MW of power, enough to supply the facility with nearly 30 percent of its average power demand and supply more than 8,000 homes.

The plant will also include three Solar Mercury 50 low nitrogen oxide gas turbines, digester gas cleaning and compression equipment, heat recovery steam generators, duct burners, a backup boiler, and electrical equipment needed to operate in parallel with the utility grid and ancillary systems.

Overall, the CHP facility will reduce DC Water's greenhouse gas emissions by approximately 40 percent, as well as reduce the risk of increased disposal costs and provide a hedge against increases in future power costs, according to Pepco.

DC Water and Pepco have signed a 15-year, $89 million on-site operations and maintenance services contract, and the overall project is valued at approximately $170 million. It should be completed in December 2014.