City hasnt given up on DifGEN

March 5, 2011
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The revolutionary, high-tech gadget the city of Grand Rapids bought last summer to help cut expenses for the water system and make the city more energy efficient so far hasn’t panned out as planned. But city officials haven’t thrown in the towel, as testing of the new DifGEN continues at the Coldbrook Pumping Station.

The DifGEN was developed by Zeropex, a Norwegian company with a U.S. division based in Birmingham. The device combines a valve, which maintains water pressure at the station, with a generator that captures the electricity the pumping station uses. After seizing the electricity from the pumping action, the DifGEN is supposed to distribute that energy throughout the Monroe Avenue facility at no increase in operational costs. The apparatus reportedly replaces pressure chokes, closes the energy loop and reduces a facility’s carbon footprint. Being able to control water pressure and produce electricity at the same time is a first for the water-utility industry.

Grand Rapids was the first U.S. city to purchase a DifGEN last summer for $150,000. City Water System Manager Joellen Thompson said in August that her department expected to recoup the cost in five to six years; the device has been projected to save Coldbrook about $30,000 annually in electricity charges. A year’s electric bill at Coldbrook runs approximately $240,000.

The DifGEN, which Zeropex said has an operational life of at least 30 years, should cut that yearly bill by roughly 12 percent and allow the pumping station to create its own energy for internal use. But the original installation last fall didn’t go as planned, and since then the device’s output hasn’t met its promise.

“This is a transfer of new technology, and it takes time to implement it,” said Haris Alibasic, part of the city’s executive office who oversees energy usage, in an e-mail to the Business Journal. “There was a structural design issue in the initial installation that required modifications to the layout in order to accept their product with respect to our existing conditions.”

Alibasic said the installation of the DifGEN is an ongoing process. The device was tested recently and more tests are planned. “Even though there were improvements, the product still has to meet certain performance metrics in order to provide better output,” he said of the test conducted Feb. 15. “Zeropex and their consultants will work on further refining the output within our system.”

Zeropex U.S. Vice President of Sales and Marketing Sven Anden said the device is widely used in Europe and has a higher efficiency rating in capturing energy than either solar and wind systems. He said the DifGEN is from 71 percent to 75 percent efficient.

The city has set a goal of operating on 100 percent renewable energy by the year 2020.

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