Harnessing Water Power

Mohawk Valley Water Authority uses hydroturbines to cut electric bills and generate income, while plant upgrades keep things running efficiently.
Harnessing Water Power
The microturbine at the Deerfield reservoir.

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Decades ago, the Mohawk Valley Water Authority (MVWA) used throttling valves in the drinking water transmission system to prevent excessive pressure down the line.

Seeing an opportunity to capture the power of water pressure and flow for electricity, MVWA installed two hydroturbines and a microturbine that provide revenue and savings that total $95,000 a year. The utility has also optimized its treatment plant to be more energy efficient, use less chemicals and produce less sludge.

MVWA, in Utica, N.Y., serves 130,000 people in 18 municipalities. The service area in the foothills of the Adirondack Mountains has elevations that vary by up to 800 feet. Most of the 23 pressure zones have their own pump stations and water storage. The 373-square-mile Hinckley watershed, which provides the water supply, is mostly within Adirondack Park. MVWA has rights to withdraw up to 48.5 mgd from the 25-billion-gallon Hinckley Reservoir, owned by the New York State Canal Corporation. The utility’s 30 storage tanks hold 60 million gallons.

MVWA’s water treatment plant (32 mgd capacity, 20 mgd average) uses conventional coagulation, clarification and filtration. Following U.S. EPA requirements for disinfection byproducts, the authority installed granular activated carbon (GAC) filter media in its four filter beds and is pilot-testing in-situ carbon regeneration methods.

MVWA has a staff of 90 and an in-house EPA-certified lab that does contract work for other area utilities. The annual budget for treatment and distribution is $21 million.

Generating Power

While designing a new treatment plant in 1992, MVWA knew that microturbines were a logical addition. “When we throttled to relieve water pressure, we were wasting energy,” says Dick Goodney, P.E., director of engineering. “It made sense as part of the treatment plant to provide some type of energy recovery mechanism, and hydroturbines were the best option.”

Two Byron Jackson hydroturbines (Flowserve) now provide 450 kW of capacity. An upstream turbine in the treatment plant basement controls the raw water flow and pressures into the chemical contact basins. The downstream turbine is several miles from the plant on the finished water line that runs to the distribution system. MVWA earns $80,000 in revenue annually from these two units by selling hydroturbine power to the local utility, National Grid.

More Power

Seeing the success of the hydroturbines, and understanding local topography, utility staff contracted with the Wendel Duchscherer engineering company to study the feasibility of microturbines to capture more energy. The New York State Energy Research and Development Authority (NYSERDA) provided a $5,000 grant for this $10,000 research study.

The study identified several locations with potential for smaller in-line turbines, including the Deerfield Reservoir storage tank. A 25 kW turbine (Cornell Pump Co.) is now installed at the tank’s control building and is coupled to a centrifugal pump (Goulds). The microturbine energy powers the standby open reservoir’s water recirculation system, which pumps 2 mgd. By using the microturbine instead of grid power, MVWA saves $15,000 annually, for a payback of less than five years.

In another initiative to enhance efficiency, MVWA has upgraded its treatment plant. Using funds from a National Grid incentive program, the utility last year replaced old fluorescent lighting with LEDs in 40,000 square feet of administration and process areas. Since the older lights were often slow to turn on, staff members often left them on even when spaces were unoccupied. The LEDs respond quickly and are only turned on when needed. Projected payback is five years.

To retain heat in the entire plant, MVWA replaced an old vinyl roof with an 18,000-square-foot single-membrane synthetic (EPDM) roof and added more insulation to meet state codes for R-value. Now, the facility costs less to heat and is more comfortable for employees.

Research partially funded by NYSERDA is underway to evaluate a more efficient HVAC system for the maintenance facility. The 20,000-square-foot building now uses a 30-year-old gas-fired boiler. Study results are due in early 2014, and the changeover is planned for 2015.

Reducing Residuals

MVWA also looked for ways to save on chemicals, reducing costs and limiting water treatment plant sludge production. Over the years, the utility has been optimizing processes to minimize chemicals used for coagulation (alum) and pH adjustment (lime and soda ash). MVWA continuously tests incoming water and adjusts chemical dosages.

“We want to minimize chemical use because everything we add to the water eventually comes out in backwash sludge,” Goodney says. “By adding fewer solids in the form of chemicals, we have less sludge to handle.

“What’s most important for us is performance. We have to provide reliable water into our system. But looking at sustainability and energy efficiency, most of the time, they complement the performance improvements. When we can get a better, more efficient workplace that’s sustainable, it just makes sense.”



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