Micro-hydroelectric power may be the next big climate solution

Inside a pump house in rural Mount Vernon, in Washington state's Skagit Valley, a group of Advanced Placement environmental science students from the local high school filed in, carrying notepads and clipboards.

Project engineer Sam Shipp, who now works for the nearby Port of Everett, led the group to a room full of big pumps and water pipes.

“This is one of our pump stations,” he said. “We're running about 600 miles of pipe, which is a lot of pipe. And we're servicing right around 88,000 people.”

He explained how heavy all that water is. Pressure builds up as it flows downhill from a 6 million-gallon tank outside — and has to go somewhere.

Until recently, the excess pressure went to a valve and was released as heat. But in 2021, Skagit Public Utility District partnered with a company called InPipe Energy and purchased a special unit that spins the excess power into electricity.

“So right now what we do is we run the water through the blue pipe. And it goes in there and we have a special — it’s a singer valve — and that goes into the turbine.”

New tech based on old ideas

Shipp later demonstrates how it gradually ramps up after ignition, starting smoothly and increasing to a speed and frequency that matches the pressure needed in the turbine. We hear a pop as it starts.

“Now it’s running,” Shipp said. “We’re generating power.”

He said it generates enough electricity to power 14 homes, which Skagit PUD sells back to the power utility for about $12,000 dollars a year.

The students are full of questions. They want to know: is this risky? Was it controversial? How much did it cost and how soon will it pay for itself?

Their curiosity is driven, in part, by the fact that the utility is about to install a second micro-hydro unit, that will generate twice as much power, right next to their school. Some of the power will offset Mount Vernon High’s electricity bill; the rest will power new chargers for electric vehicles on site.

Their teacher asks how it will fit in with intermittent sources of renewable power, like wind and solar.

“That's probably one of the best things about this,” Shipp responded. “As long as the people in Mount Vernon are using their water, we're generating power. So this runs all the time. It’s also very predictable,” he said.

He said the concept is no different from an old-fashioned water wheel…and the technology is so simple that it took only about three days to install. The permitting was the hard part, it took several months.

Still, Shipp told the class, he doesn’t see a downside.

He said the costs of the project were mostly covered by government grants for clean energy projects. And the utility expects to earn back the remaining $100,000 they invested in less than a decade.

The project has been highlighted by Washington Governor Jay Inslee as a successful clean energy investment, made possible by the Climate Commitment Act .

After the tour, even the most skeptical students seemed to agree.

Samuel Solano, a member of the high school debate team, said he went in concerned this might be risky because it’s so new.

“Now that I know a little more, I feel like, there is no risk,” he said. “The cost is very...it's there. But it's more beneficial. So, its benefits outweigh its risk.”

His teacher, Rebecca Krueger, said she’s excited about the possibility of plugging her car into the new EV chargers at school. But even more than that, she said with all the controversy that tends to surround big hydropower projects , it’s good to see an application that appears to do no harm.

“It’s fantastic that it’s energy that’s just being wasted for heat to be put to use, without all other costs,” she said. “It's great that we can use hydro in a way that's not harmful to salmon and our communities.”

Just starting to take off

So why has it taken so long to get more small hydro projects like this one up and running?

Brian Polagye, a mechanical engineering professor at the University of Washington who specializes in water power, said micro-hydro is still a niche idea. And as with any new technology, there’s a bit of a chicken and egg problem to get it to take off. That perception of risk is diminished as costs come down

“As you start to demonstrate that it's not creating risk, then you see the technology become more mainstream,” Polagye said.

He said these new forms of energy generally start small, and grow from there. Think about the first time you saw a solar panel – it was probably tiny and localized, he said – maybe it was on a solar-powered pocket calculator?

“That was an early application. Now, we see solar everywhere, at larger scale, and the move from that to residential to utility scale, and so there's always this progression with technologies,” Polagye said.

Gregg Semler, the CEO of InPipe Energy, told KNKX his company has done a lot to make this technology more attractive, especially to water utilities, which are inherently conservative.

“We weren’t the first ones to have the idea. We were the first ones to create a solution,” Semler said. He said all their turbines are installed in a bypass unit, with integrated software and sensors that make it safe and reliable.

“We've tried to make it as easy as purchasing a valve. And so we've really simplified the technology, so that water people can really understand the solution, they can see that other people are doing the exact same thing. It's not a one-off, it's a standardized approach.”

One of the company’s current goals is to get at least one InPipe unit up and running in every state. They now have projects running in Washington, Oregon and California, and the first unit in Colorado is coming online this month.

Semler said he sees endless potential for this kind of renewable energy: not just with public water utilities, but anywhere there’s a water pipe with a pressure valve. Think power-hungry industries, like data server farms, that use water for cooling. Or developing countries or war zones, where new water infrastructure is just being built or re-built.

All that aside, Polyagye said the next InPipe unit that Skagit PUD is putting in at Mt. Vernon High School, is a great use case. It will bring renewable energy infrastructure to a rural area that otherwise probably wouldn’t get it for a long time. He said the more people see it working or hear about it, the more momentum for this kind of solution will grow.

The utility said the new unit will be installed this fall and should be on line, generating electricity, by January.