for utilities to pay for a service out of operating expenses than
to invest up front in a huge, expensive piece of equipment.”
DC Water, the water and wastewater utility in Washington, D.C., is taking advantage of a design-build model that
stretches well beyond the typical water system infrastructure
upgrade. In 2012, the utility signed an agreement with Pepco
Energy Services to design, build and operate a combined
heat and power plant at its Blue Plains Advanced Wastewater Treatment Plant, one of the largest advanced wastewater
treatment facilities in the world.
It is a $460-million project that doesn’t directly impact the
water or wastewater treatment infrastructure. But indirectly,
it could have long-term fnancial benefts for the utility, said
general manager George Hawkins. When it’s fully operational
in 2014, the new power plant will produce at least 14 MW of
electric power, which will supply the Blue Plains facility with 30
percent of the AWTP’s average power demand.
“The money we save from not buying power off the grid will
more than cover the cost to fnance the project,” Hawkins said.
“And over the long term, it will drive our costs down so we won’t
need to raise rates.”
The power plant is part of DC Water’s thermal hydrolysis
and anaerobic digestion project, which will use high-pressure
steam from the new power plant to turn waste from the
wastewater cleansing process into energy. That will cut the
amount of biosolids transported from the site by up to 60
tons per year, which is a substantial cost savings, while providing a hedge against increases in future power costs. The
remaining biosolids will also have greater commercial value
as fertilizer, creating a potential secondary source of revenue.
This power plant is part of DC Water’s thermal hydrolysis and anaerobic digestion project, which will use high-pressure steam to turn waste
into energy. Photo by Dennis Samson, DC Water.