Spokane County could start generating solar and hydro power at wastewater treatment facility

Spokane County has hired a consultant to figure out if it makes financial sense to operate the wastewater treatment plant less wastefully.

The Spokane County Commission last week unanimously agreed to hire McKinstry to assess the feasibility of multiple renewable energy proposals at the Spokane County Regional Water Reclamation Facility.

For $81,000, McKinstry will study whether the county would save money by adding solar panels, building a miniature hydroelectric dam and selling natural gas. Depending on how the first study goes, the county might also pay for a more thorough follow-up analysis that would cost $276,000.

Adding solar panels at the wastewater plant would be a relatively straightforward investment. The county could install enough of them to produce a megawatt of electricity on the 20-acre site and power the entire facility when the sun’s out.

Spokane County’s wastewater treatment facility already produces methane.

The county captures the methane, cleans it and uses it to run turbines that generate electricity. The turbines can power 20% of the facility’s operations, but they require significant upkeep and aren’t always running.

Selling the natural gas to Avista would mean less work for Jacobs Engineering, the private contractor that handles day-to-day operations at the plant.

If the county opts to go that route it would have to install a new pipeline to carry the gas to the utility company’s distribution system.

The miniature hydroelectric dam proposal would, like solar panels, lower the county’s electricity needs.

The county would put a turbine in its discharge pipe and harness the power of treated wastewater as it flows downhill to the Spokane River.

Ben Brattebo, the county’s water reclamation engineer, said the wastewater treatment plant discharges about 7 million gallons of water a day – a bit more than 10 Olympic swimming pools. All of that water falls about 60 feet in elevation between the county’s plant and the river.

McKinstry’s studies will determine how much the three proposals would cost up front and how much money they could save – or make – the county. Christie Hoffpauer, McKinstry’s director of business development for Inland Northwest energy projects, said federal tax credits made available through the Inflation Reduction Act could save the county 30% on the solar and natural gas proposals.

Brattebo said the projects probably couldn’t eliminate the county’s electricity needs, but they could still be worthwhile.

“This likely wouldn’t make us what would be called ‘net-zero,’ ” Brattebo said, “but it would reduce those costs.”