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Saving Energy at 24/7 Wastewater Treatment Plant

July 29, 2010 - 4:11pm

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In the city of Longview, Texas, the wastewater treatment facility uses more electricity than any other public building. Making investments to permanently cut energy costs at the plant is important for this East Texas city of approximately 77,000. 

"Our city has felt the effects of the recession. Several companies have laid 100-200 folks off and many are still waiting to be hired back," said Shawn Raney, a safety specialist with the Longview city government. "The improvements will help local taxpayers by reducing the amount of electricity the wastewater facility needs to operate."

City officials were able to fund a new co-generation power plant and energy efficiency upgrades at the facility through a $781,900 Energy Efficiency and Conservation Block Grant (EECBG) from the U.S. Department of Energy via the Recovery Act. The city also provided approximately $300,000 in matching funds.

Creating energy from wastewater byproducts

Wastewater treatment facilities use bacteria to break down solid waste. Methane gas is a natural by-product of this process, and most wastewater plants flare off the gas, producing CO2 emissions and wasting potential energy in the process.

To capture these emissions and reduce energy usage, the city turned to Electrical Energy Inc., a Longview-based engineering firm, to construct a co-generation power plant within the wastewater treatment facility. The plant will capture the methane gas by-product produced by the treatment process and convert it to electricity to help run the plant.

"The methane gasses produced by the wastewater treatment plant are 25 times more harmful than regular CO2 emissions," said Raney. "The co-generation plant gives us the opportunity to prevent these emissions from entering the atmosphere and to turn them into energy."

The co-generation power project, scheduled to be completed by the end of September, is projected to reduce greenhouse gas emissions by 712,999 lbs per year and save 16,571 kWh of electricity per year.

For every kW of peak demand the facility reduces, Longview's utility provider AEP-SWEPCO will provide the city a rebate of $150. City officials plan to cooperate with AEP-SWEPCO to closely monitor the wastewater plant's electricity use once all the renovations are completed. In addition, meters will be installed to calculate accurate energy efficiency and green house gas reductions.

High-efficiency blowers help

The city also contracted with KSA Engineers, another Longview engineering firm, to replace two existing blowers at the plant with high efficiency blowers.

Blowers at the wastewater plant are housed in a single room and are used to push air into aeration bases where the bacteria are kept alive.

According to Raney, at least three blowers have to be on at all times while the plant is operating and the blower room uses more electricity than any other building. Raney expects the two high efficiency blowers to significantly reduce the amount of electricity needed to run the blowers.

"These improvements are good short term investments with long-term benefits for the community."

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