Secretary Richard K. Sullivan Jr.
Secretary, Executive Office of Energy and Environmental Affairs
Executive Office of Energy and Environmental Affairs
The Massachusetts Water Resources Authority’s (MWRA) Deer Island Wastewater Treatment Plant has played a huge part in helping to clean up Boston Harbor, but I’d also like to recognize it as one of Massachusetts’ great renewable energy and energy efficiency achievements. Just this last May, Deer Island was awarded the Energy Leadership Award by the United States Environmental Protection Agency (EPA). Using renewable energy and energy efficiency measures, the plant treats an average of 350 million gallons of wastewater each day and removes human, household, business and industrial pollutants from 43 communities in Greater Boston.
Today more than half of the plant’s energy demand is provided by on-site, renewable generation.
I took a tour of the plant this summer and learned it is one of the largest electricity users in the Northeast, which is why the MWRA sought energy efficient alternatives. The plant energy demand is 18 megawatts and the electric bill around $16 million annually. The plant now self-generates 22 percent of its electricity needs with ground and roof-top solar photovoltaic systems, wind turbines, hydro-electric generators that capture water as it drops from the plant into the outfall tunnel shaft, and digester gas-derived electricity generated through steam. The island’s renewable energy now saves MWRA $4 million a year, or 25 percent.
Two 600 kilowatt wind turbines were installed on Deer Island in November 2009. They currently generate over 2 million kilowatt hours (kwh) per year and save around $200,000 annually. A third 100 kilowatt prototype wind turbine was installed this spring by Massachusetts-based FloDesign. It is the first full-scale wind turbine the company has produced. Its newfangled turbine design is supposed to generate 30 percent more electricity at lower wind speeds than convention wind turbines.
The plant recovers energy as the flow of treated wastewater drops from the plant into the outfall tunnel shaft through two 1-megawatt hydroelectric generators. These generators produce over 6 million kWh of electricity per year and save over $600,000 in electricity costs.
Of the 350 million gallons of sewage the plants treats daily, the island’s anerobic digesters are able to use the methane from the sludge as fuel, saving about $15 million a year. While it also generates energy, the sludge is pelletized to become fertilizer at the MWRA’s Nut Island plant in Quincy, is given to cities and towns served by the Authority, and sold to turf farms.
MWRA is also in the midst of a multi-phased lighting project (it’s currently 80 percent complete) that involves changing out motion sensors, exit signs, ballasts, and lamps. They also had an energy assessment done by NSTAR and as a result put 75 percent of the lighting on the island on automatic shut off, which saves about $1.5 million annually.
It’s a premiere example of how integrated clean energy solutions are taking us closer to our goals to cut greenhouse gas emissions, energy use and energy costs.