Energy Efficiency is as Easy as Smart Budget Planning

Greeley treatment plant uses smart budget planning to replace aging equipment and drive down energy costs by 37 percent.
Energy Efficiency is as Easy as Smart Budget Planning
Tom Dingeman, left, Water Pollution Control Facility manager, explains the costs and benefits of the 500 kW solar array with Neil Kolwey, CIEC program.

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The City of Greeley (Colorado) Water Pollution Control Facility has reduced its total energy consumption by 37 percent since 2011, achieving annual energy cost savings of $190,000.

Under the leadership of Tom Dingeman, plant manager, the efficiency improvements were achieved mainly by leveraging the facility’s five-year capital-budgeting plan to replace aging equipment.

The main energy efficiency projects were the replacement of the aeration system blowers with high-speed turbo blowers, installation of a new biosolids dewatering system and replacement of aging facility lighting with LED lamps.

Better blowers

To replace the existing centrifugal blowers, Greeley chose six 300 hp turbo blowers from Aerzen USA. The new blowers are 27 percent more efficient and save an estimated $100,000 per year on electricity. The $790,000 project cost about 20 percent more than if Greeley had chosen new centrifugal blowers, but Xcel Energy, the local electric utility, provided a $121,000 rebate that offset most of the cost difference.

The new biosolids dewatering system saves an additional $69,000 in annual energy costs. The Aldec G3 centrifuge (Alfa Laval Ashbrook Simon-Hartley) has an innovative design that improves throughput and allows for lower horsepower motors. The main motor for the new centrifuge is rated at 100 hp with a 50 hp back-drive motor. It replaced an old centrifuge with 250 hp and 75 hp motors.

All told, the new centrifuge is 45 percent more energy efficient than its predecessor. The initial cost of the new system was about the same as for a less energy efficient alternative.

Efficient lighting

On the lighting front, the city replaced its outdoor pole-mounted lighting (metal halide and some high-pressure sodium lamps) and wall-mounted outdoor metal halide lamps with LEDs. The LED lighting saves $7,000 per year, and the longer-life LED lamps also reduce the cost of changing lamps, especially for the pole-mounted fixtures.

Additional energy efficiency projects in the past five years include:

  • Replacement of 10 pump variable-frequency drives with new and more efficient units.
  • Upgrades to heating and air conditioning equipment.
  • Installation of an energy data management system that allows Dingeman and his staff to monitor the plant’s electricity consumption on a daily basis.

Dingeman also championed the installation of a 500 kW solar energy project, which saves $7,500 per year, in return for an initial investment of $10,000.

Taking the challenge

In December 2011, the Greeley plant joined the Colorado Industrial Energy Challenge (CIEC), a voluntary program managed by the Southwest Energy Efficiency Project. The plant set a goal of 20 percent energy savings from 2011 to 2016.

In May 2015, Jeff Ackerman, director of the Colorado Energy Office, presented Greeley an Excellence in Energy Efficiency Award on behalf of the CIEC program for outstanding energy efficiency achievements and for exceeding its energy goal two years early. According to Dingeman, substantial energy efficiency improvements do not happen on their own: “Each organization needs a champion to spearhead the effort,” says Dingeman.

The Greeley plant uses a capital-budgeting process, or master plan, that is reviewed and updated every five years. Dingeman says some of his success comes through taking full advantage of the budget process. When he plans process upgrades or equipment replacements, he compares the life cycle costs of the alternative technologies or equipment, including maintenance and energy costs. That typically enables him to choose the most energy efficient and environmentally sound technology.

“If we don’t do these kinds of improvements, our operating budget keeps going up,” says Dingeman. He advises against waiting for something to break before looking into replacing it. “It is always better to be proactive than reactive.”

About the authors

Neil Kolwey is a senior associate with the Southwest Energy Efficiency Project (SWEEP) and Colorado Industrial Energy Challenge program manager. Frederica Kolwey is a SWEEP intern.



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