We all know that conserving energy is critical. We buy energy-saving light bulbs and power down our computers when we leave the office. We resist the lure of the air conditioner on all but the hottest days. What if we could benefit even more from our natural resources and our dollars―without depleting either of them any faster?
In addition to providing a clean, sustainable source of energy, we will see long-term cost savings over the life of the facility.
The Massachusetts Water Resources Authority (MWRA) is helping residents do exactly that. As part of a regional initiative in 2007, MWRA and other state agencies in the northeastern United States have committed to obtaining 15 percent of energy from renewable sources and decreasing their overall energy use 20 percent by 2012. This year, MWRA—which generates more than 40 percent of its energy from a combination of methane, hydropower, wind and solar power—implemented a hydraulic turbine-driven generator at the Loring Road water storage facility in Weston.
MWRA supplies drinking water to 2.2 million residents and 5,500 industrial users in Boston and 44 surrounding communities. Water treated at the John J. Carroll water treatment plant travels to the Norumbega covered tank, where it is stored. Some of this water then travels to the lower-level storage facility at Loring Road. Because of the approximately 80-foot drop in elevation from Norumbega to Loring Road, excess pressure must be reduced. MWRA has been using pressure reduction valves to dissipate energy for flows of about 20 million gallons per day.
Seeing an opportunity to recover this energy in the form of electricity, MWRA approached CDM Smith to assess the feasibility of installing a hydraulic turbine-driven generator at Loring Road. CDM Smith designed the project and supplied engineering services during construction. Partially funded by the American Recovery and Reinvestment Act and the Massachusetts Clean Energy Center, the 18-month effort was completed in spring 2011 and the turbine is now operating successfully.
At Loring Road, pressurized water enters the spiral-shaped turbine through a pipeline. The velocity of the water flowing in turns a shaft, which is connected to the generator. Through this process, the pressure of the water is reduced and the energy is converted to electricity.
Now, when residents fill a glass from the kitchen sink, their water will have powered its own storage facility. By integrating these water and energy technologies, CDM Smith helped MWRA eliminate the purchase of approximately 250,000 kilowatt hours per year and also generate a surplus of 1.2 million kilowatt hours per year—enough electricity to run 110 area homes. This creates a source of revenue for MWRA, which sells this electricity to the local utility.
“This is an example of a very successful collaboration between the authority, CDM Smith, the contractor and supplier. All of the parties made a great effort to complete the work on time and within budget,” says Fred Holland, CDM Smith senior vice president.
Reviving Turbine Technologies
In the past, turbine technology was typically used in large water systems with dams. Over the years, many older turbines have been taken out of commission, due to rising fuel and maintenance costs. New, energy-efficient technologies, like Loring Road’s turbine, can operate for decades with minimal maintenance and make capturing energy on a smaller scale applicable for widespread use.
“This turbine makes power with no consumption of energy resources,” explains Richard Löf, CDM Smith principal project manager. “There are no environmental costs. Not only are you relying less on fossil fuels, but this way of generating power does not produce air emissions, noise pollution or additional traffic in the area, and uses an existing resource.”
Creating Lasting Benefits
Because energy is recovered from water flowing through existing pipelines, no surface water is affected by the project. Meanwhile, the turbine was integrated into the existing facility without constructing additional buildings or disrupting the surrounding wooded areas, where local residents hike and walk their dogs. Feedback from the community has been positive, and MWRA hopes that the success of the project will encourage more use of this technology in Massachusetts and beyond.
According to Pam Heidell, MWRA’s project manager for Loring Road, this project will have a positive impact on the environment and the bottom line. “In addition to providing a clean, sustainable source of energy, we will see long-term cost savings over the life of the facility.”