Renewable Energy at Deer Island
Massachusetts Water Resources Authority

The MWRA’s Deer Island Wastewater Treatment Plant treats an average of 360 million gallons of wastewater each day from 43 communities in greater Boston and is one of the largest electricity users in the Northeast.

Deer Island currently self-generates 23% of its electricity needs and more than half of the Island’s energy demand is provided by on-site, renewable generation:

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Wind turbines at Deer Island (larger image)

• In November 2009, two 190-foot, wind turbines (600 kW each) went on-line at Deer Island. The wind turbines generate over 2 million kW hours per year for an annual estimated savings of $230,000. The $4 million project was funded in part by a $400,000 grant from the Massachusetts Technology Collaborative. Plans are underway for three more wind turbines at Deer Island.

• A 100-kW roof-mounted solar photovoltaic system was installed on the Residual/Odor Control Building at Deer Island in early 2008.  All power generated is being utilized on-site. The $870,000 solar photovoltaic project was funded by a $310,000 CREB loan and a grant of $560,000 from the Division of Energy Resources. The solar installation will be qualified as a Massachusetts Renewable Portfolio Standards Program (RPS) renewable generation unit and MWRA can sell the Renewable Energy Certificates for solar as it currently does for digester gas.

• A 180-kW roof-mounted solar photovoltaic system was installed on the Administration/Warehouse roof in fall 2009. This $1.2 million design/build project was partially funded through the American Recovery and Reinvestment Act.
  

• Another 456 kW in solar panels will be installed soon both on the ground under the existing wind turbines and on two more roof tops. The $1.1 million project was procured through a Solar Power Purchase Agreement, is a financial arrangement in which a third-party developer designs, procures, installs, owns, operates and maintains the system and the host customer provides the site and purchases the electricity. The installation cost is funded through the American Recovery and Reinvestment Act.
  

• Since 2002, energy is recovered by the flow of treated wastewater as it drops from the plant into the outfall tunnel shaft through two one-megawatt hydroelectric generators that produce over 5 million kW hours of electricity, avoiding approximately $500,000 in energy costs annually.
  

• The methane generated from the sludge digestion process (“digester gas”) is collected and used in Deer Island’s on-site power plant to create steam that supplies hot water and heat for the facility. The steam is also run through a steam turbine generator that produces electricity. This co-generation facility saves MWRA approximately $15 million in annual fuel oil costs.
  

• Digester gas-derived electricity generated by the steam turbine qualifies as a renewable (“green”) source of energy under the Massachusetts RPS Program. This program prescribes that a minimum amount of power that is supplied into the Massachusetts market be derived from renewable energy sources. Deer Island is awarded certificates for each megawatt-hour of green electricity produced. Suppliers that do not meet the minimum requirement through their own sources can purchase certificates from generators such as Deer Island through an open bid process, generating $1 million in revenues for MWRA in FY2008.
  

• Deer Island electricity has been purchased competitively since 2001. Energy market conditions are characterized by their volatility, and MWRA has sought to balance the ability to respond to changing conditions with maintaining a measure of budgetary predictability.
  
  
• Electrical upgrades are ongoing at the two pump stations to replace the variable frequency drives that power the eighteen 1,250 horsepower motors with more energy efficient technology. Work at the South System Pump Station was completed in August 2007, resulting in an annual reduction of electricity purchases of $130,000 plus a rebate of $209,000.
  
  
• Through NStar, Deer Island recently completed the second phase of a multi-phase lighting improvement program aimed at replacing existing lamps and ballasts with high performance fluorescent reduced wattage fixtures, integrated day lighting, occupancy controls, and replacement of “Exit” signs with LED technology. 

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Updated June 29, 2010