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Dec. 8, 2022

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Upgrades to Clark Public Utilities’ gas-powered plant to boost flexibility, lower emissions, costs

River Road Generating Plant $10.6 million upgrades to allow fluctuating output to meet demand

By , Columbian staff writer
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4 Photos
Clark Public Utilities' River Road Generating Plant burns natural gas to make about 225 megawatts of electricity, using a turbine similar to those used on jet engines in airplanes.
Clark Public Utilities' River Road Generating Plant burns natural gas to make about 225 megawatts of electricity, using a turbine similar to those used on jet engines in airplanes. (The Columbian files) Photo Gallery

Clark Public Utilities’ River Road Generating Plant has been a controversial place. Its billowing clouds of steam and carbon emissions stick out in a region powered largely by hydropower. Now it is on its way to becoming less of a dominating force and more of a backup option.

Until now, the utility has been required to run River Road at full capacity, or shut it down and replace the entirety of what it would produce with other energy resources.

With that maximum energy production comes high operating costs and emissions, all of which soon will be reduced.

The utility’s board of commissioners last month approved $10.6 million in upgrades for the natural gas-fired electric turbine plant, which will allow the resource to be powered down to low generation levels or powered up to meet customers’ peak energy demands. Rather than having to power down the plant for an entire month when other resources are plentiful and cheaper, the utility would be able to make that judgment daily.

“This is a very significant investment for us — probably one of the biggest at the plant itself,” said Dameon Pesanti, media specialist at the utility.

“At the end of the day, our customers are not going to experience any changes,” he added. The utility will offer the same reliability, Pesanti explained, but power managers will be better able to integrate renewable energy like wind and solar into the daily mix of power resources.

“It’s tremendous for us as a company in meeting our state mandates ahead of schedule,” Pesanti added. “But it is also great for our customers because it’s an opportunity for us to reduce our energy resource expenses during a time of market volatility.”

Constant change

The demand for energy changes during the year and even during the day. It spikes during hot spells and cold snaps and decreases overnight.

The energy produced by renewable resources varies as well. Solar power is unavailable after dark. Wind energy depends on the weather. And hydropower fluctuates seasonally, peaking during the spring runoff and winter rains.

The River Road plant has been in use for 25 years and is considered a base load resource for the region. That means the utility is required to either deliver a maximum of its power to the electricity grid or to buy electricity to replace it.

This isn’t always economical. Last week, for instance, Steve Andersen, power manager at Clark Public Utilities, noticed it would be more economical for the plant to ramp down its power a couple of days because of an increase in hydropower.

“Right now, we don’t have the capability to bring it down during short periods of time,” he said.

Dan Bedbury, director of energy resources at the utility, likened the current procedure to always driving your car at 60 mph, without being able to speed up or slow down.

Last month, the utility secured approval from the Bonneville Power Administration, the federal power marketing agency, to deliver less energy from the plant in the future. It also allows the plant to be run as a flexible energy resource that can be turned down when renewable resources are available.

“It reduces costs and it reduces carbon emissions,” said Andersen.

The plant currently generates 225 megawatts on average annually and is expected to produce 102 megawatts on average annually by 2030. By that year, natural gas generation will provide 15 percent of Clark’s power, compared with 34 percent now. Hydropower will then increase from 51 percent to 66 percent.

With the passage of the Clean Energy Transformation Act by the Legislature in May 2019, Clark Public Utilities has to cut its carbon emissions. By 2025, it must not sell coal-produced electricity. By 2030, it must be greenhouse gas neutral, meaning 80 percent of the utility’s load must be from renewables and nonemitting resources. The remaining 20 percent can be emitting, but must be offset with renewable energy credits and other alternatives. By 2045, the utility must sell 100 percent clean energy.

The utility plans to not just reach these goals but to exceed them and to do so before the pending deadlines. The hope is also to keep the energy reliable and at-cost for consumers.

The upgrades will cost $10.6 million but the utility expects to save $3.2 million every year, so the project is expected to pay for itself in 3½ years. The utility also expects to reduce the plant’s operating costs by $21.5 million to $26.5 million over 10 years.

“As an at-cost utility, these savings contribute to rate stability by helping to offset anticipated increases in other operating costs,” Pesanti said.

Autotune software was installed at the plant in 2020, which keeps the plant constantly operating at its most efficient state and producing the least amount of air emissions possible. This was a foundational step for the plant to become a flexible resource. Previously, adjustments were made manually twice a year. Hardware upgrades will be made in May 2024.

The upgrades will allow the plant’s output to fluctuate between 90 and 270 megawatts per hour.

“That enables us to adapt to fluctuation in customer demand and also to integrate less predictable renewable energy resources if they become available,” said Pesanti.

By 2045, the plant will have to close to meet the state’s emissions targets for utilities. That would bring it near the end of its estimated lifespan anyway. Until then, the region will begin to lessen its dependence on River Road and electricity generated from natural gas.

The goal for the plant is to run at a low level most of the time but to be available for use when peak demand stresses the energy grid. So, when water conditions are very low and not creating as much hydropower or when blustery conditions have folks turning up their heaters, the plant will be able to increase its production to meet those demand levels.

The plant’s carbon emissions are expected to be reduced by nearly half by 2030.

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