Solar viable option to supply power to wastewater plant

Constructing a solar array to produce power alongside the city’s new wastewater treatment plant could offset some of cost of operating the plant, according to a solar feasibility study.

OnSite Energy this fall completed the study for the city examining the potential for a solar array at the plant. The study found that by installing a roughly 2-acre solar array on the city’s property adjacent to the plant that could provide annually 32% of the power needed to operate the new plant.

Construction on a new wastewater plant is set to begin in 2020 and be operational by fall of 2021 (see related story).

The city’s Climate Action Plan adopted last year calls for a strategy to offset energy use and emissions from the new wastewater plant by installing a solar array system.

Public Works Director Craig Workman said the idea for investigating a solar array came from the city’s Climate Action Plan with the main goal of the plan to reduce carbon emissions throughout the city.

“The wastewater plant is one of the largest energy users in the city,” Workman said.

The city received a grant from the Department of Environmental Quality to partially pay for the $20,000 study.

OnSite Energy is a solar design and installation business based in Bozeman and Missoula.

The assessment found that by constructing a solar array the city could generate an annual production of 636,500 kilowatt hour. The electricity generated would go directly into the city’s sewer plant.

The estimated cost to install the array is about $880,000. The study says that the city would make a return on its investment in about 27 years.

The estimated savings over 25-year lifespan of the system would be $957,000, according to the study.

“We wouldn’t be selling the electricity,” Workman said. “We’d simply be using it at the site.”

Workman said that technology improvements in the future could allow for the costs of installing the solar array to be reduced while the return on investment goes up.

Workman said the city recognizes that the power the it purchases now from Flathead Electric Co-op because it’s hydropower is nearly carbon-neutral. However, if the city can produce some of its own power that could down the road free up some of the power from FEC for other users on the grid.

“My goal is to use this project as a platform to support Flathead Electric’s sustainable energy initiatives as opposed to detracting from them,” he said.

Council discussed the solar study during a work session earlier this month.

Councilor Richard Hildner said the Climate Action Plan looks at a region-wide approach to energy usage.

“The electricity we use is already green, but if we produce green energy here then other places regionally have less reliance on coal or other sources,” he said.

The solar feasibility study notes that there would need to be further study of the site including engineering work to produce the design for the solar array before a project could move forward. The city would also have to formulate a plan for project funding.