A Different Way Of Thinking

Staff members with the Bangor Water District pool ideas and develop ways to reduce electricity usage while also generating on-site power.
A Different Way Of Thinking
Bangor removed a pressure reducing valve in a control valve facility and replaced it with a turbine to capture energy.

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In 2006, the Bangor (Maine) Water District received a notice that electric rates were about to rise sharply. Electricity was already the district’s second biggest expenditure, and a 30 percent increase for forward capacity charges would overshoot the budget.

Management decided it was time to stop thinking like a water district. “We are a water utility, but we immediately took to learning and understanding the terms of the electric industry,” says Kathy Moriarty, general manager.

Moriarty and the 30-person staff looked at the big picture to determine where to reduce power usage and costs. As the third largest water utility in the state, Bangor pumps 4.9 mgd to its 11,000 accounts. The infrastructure includes six standpipes, four rechlorination facilities, three treatment facilities — pumping, ozone and UV — and 180 miles of pipes.

Turbine power

In 2002, under then-general manager Wayne Rogalski, the district removed a pressure reducing valve in a control valve facility and replaced it with a turbine to capture energy. When the rate increase notice arrived in 2006, the district looked at its options for generating power from that turbine. As the station was located at the bottom of a gravity-fed system, the 75 kW Cornell hydroturbine met the conditions needed to generate energy.

The turbine reduces pressure while also generating electricity continuously. The incoming flow at 135 psi is reduced to 80 psi for delivery to homes. “Somewhere in your system you need to have both a reduction in pressure and constant flow,” says Moriarty. “With more flow or a greater reduction of pressure, you can generate more electricity. We have the unique circumstance to install the turbine at the right spot.” The turbine project cost $183,000 and saves up to 12 percent in electricity costs; the district expects full payback on its investment in four to eight years.

The district maximizes the sale of energy produced by the turbine by selling power back to itself at electric wholesale rates, a process called net energy billing. “The utility meters what we produce, and then the kW hours are credited against use at all our facilities,” says Moriarty. “We generate minimum revenues of $23,000 each year.

Other savings come from enrollment in a demand response program with ISO-New England, the regional electric transmission system operator. Under that program, the district is on call to go off-grid and operate on its emergency generators during times of extreme demand on the power grid. While still awaiting its first call, the district receives monthly payments that total $14,000 to $17,000 per year.

Fine-tuning treatment

The operations staff also saves energy by constantly fine-tuning its processes for efficiency. At the Butler Ozone Water Treatment Facility, built in 1995, the district in 2011 replaced the original air compressor with an energy-efficient water-cooled unit (Atlas Copco). The project cost $69,900, and the utility received a $22,500 grant from Efficiency Maine, an independent trust dedicated to promoting the efficient and cost-effective use of energy. “Basically, the energy savings will pay for the project in less than three years,” says Moriarty. “Additionally, we expect to save $158,000 over the life of that compressor.”

At its Johnson Pump Station, built in 1958, the district plans efficiency upgrades that include new windows, insulation and pumps, all to be completed by 2016.

A new $2.5 million UV treatment facility completed in August 2013 was built with an energy-efficient design and funded in part by a State Revolving Fund loan at 1 percent interest. Because it qualified as a green project, the district received 25 percent principal forgiveness for the design costs and 5 percent principal forgiveness for construction costs.

Standpipes step up

The district also looks for savings at its six standpipes. At one site in 2009, the district replaced two steel tanks and their pumps with a 3.4-million-gallon concrete tank and a passive mixing system (Red Valve Co. / Tideflex Technologies). In summer, electric mixing costs upward of $1,200 a month; the passive system uses no power. A $26,000 Efficiency Maine grant helped fund the project.

At the 1.75-million-gallon, 110-foot-tall Thomas Hill Standpipe, built in 1897 and listed as a National Historic Landmark, a district employee found a way to save energy. The standpipe, also an AWWA-designated American Water Landmark, is open to tours several times per year. Along the standpipe’s crown were 288 incandescent light bulbs with fixtures dating back to 1916. At an employee’s suggestion, these were replaced with highly efficient LED lights that will last up to seven years and do not detract from the standpipe’s historic beauty.

Since 2006, the district has seen a 40 percent reduction in power costs, and Moriarty knows there are more opportunities for savings. “Getting your staff involved to brainstorm ideas to save costs is key to energy efficiency and cost savings,” she says. “And it’s just as important to learn about kilowatts as gallons.”  



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