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Energy-efficiency reaps rewards for sewer utility ratepayers

Summary

King County will protect regional water quality while reducing energy consumption at the South Treatment Plant in Renton thanks in part to a generous grant from Puget Sound Energy.

Story

King County will protect regional water quality while reducing energy consumption at the South Treatment Plant in Renton thanks in part to a generous grant from Puget Sound Energy.

“Increasing our energy production and efficiency is a top priority, and today, we’re pleased to celebrate the completion of a project that represents another small but meaningful step toward making the Wastewater Treatment Division a carbon-neutral utility,” said Deputy King County Executive Fred Jarrett.  

The PSE grant will help cover the cost to install new two energy-efficient agitation air blowers that pump air into wastewater so beneficial bacteria can more efficiently break down and treat pollutants.

The new equipment replaces three multi-stage agitation air blowers that were noisy, hot, and costly to operate and maintain. King County estimates the new blowers will save $55,000 in annual energy costs and reduce South Treatment Plant’s energy consumption by 782,268 kilowatt-hours (kWh) per year, which is the equivalent of powering 45 homes.

Since 2007, PSE has generously awarded King County’s Wastewater Treatment Division more than $1 million in conservation grant funding to pursue innovative energy efficiency solutions in its facility operation.

The blower replacement project also benefits from a $668,215 loan at a 1 percent interest rate from the Washington State Public Works Board.

In total over the past six years, King County WTD energy efficiency projects brought in $10.3 million in grants and $4.3 million in low-interest loans and bonds, which will ultimately save WTD ratepayers about $1.4 million each year in energy costs.

The wastewater treatment process is energy intensive, and WTD is the largest user of electricity in all of King County government. The division’s annual energy bill is nearly 14 percent of its operational budget, totaling more than $17 million a year.

The efficiencies fall in line with the ongoing strategic efforts King County is taking to decrease energy consumption in all County facilities by 20 percent by 2020 while putting greater emphasis on using or generating renewable energy.

King Couty’s Wastewater Treatment Division is already converting byproducts of the treatment process into resources – namely digester gas, excess heat, biosolids and reclaimed water. The division scrubs digester gas from the treatment process and uses it in several ways – for energy on site, to sell to Puget Sound Energy, or for powering large pumps and recycling the heat from the pumps.

For more information about WTD’s energy program, please visit the website.