Hydroturbine system in source water pipe generates substantial electricity while serving the function of a pressure-reducing valve.
The Portland (Oregon) Water Bureau is using a different kind of hydropower to generate electricity, tapping the energy of water flowing through its pipes. Online since January 2015, four 50 kW hydrogenerators make enough electricity to power up to 150 homes for a year.
The bureau installed a turbine system from Lucid Energy, also of Portland, as part of a $150 million upgrade to its system. The 200 kW LucidPipe Power System will generate an average of 1,100 MWh per year.
Bill Kelly, Lucid president and CEO, says the four turbines are installed across 50 feet of a 42-inch gravity-fed pipe that delivers 57 mgd from a new reservoir. “We were willing to finance it and take on the operation and maintenance, and we negotiated with Portland General Electric to buy the energy,” he says.
Each turbine has five blades with a stainless steel shaft inside the pipe. The power components (Siemens) are outside the pipe. The minimum flow requirements are 20 cfs at 40 psi. Each turbine reduces head pressure by just 1 to 5 psi. That allows them to be installed in series four diameters apart.
For the water utility, the turbine system serves the same function as a pressure-reducing valve. “It operates upstream of the valve to take that energy they’re otherwise burning off through the valve and turning a turbine to produce electricity,” says Kelly. The utility also benefits from sensors in the turbine system that continuously monitor pressure and other metrics.
First of its kind
The Western Municipal Water District in Riverside, California, has also installed a LucidPipe system, but the Portland project is the first in-pipe hydropower installation to have a 20-year power purchase agreement, according to Kelly. In that time, it will generate about $2.5 million worth of renewable energy to pay for development, installation and operations.
“We welcomed the opportunity to explore the innovative use of a pipe delivering water to create hydroelectric power as well,” says David Shaff, Portland Water Bureau administrator.
“Water and energy are closely linked. The LucidPipe system enables us to contribute to generating electricity for our community in a clean, low-cost and renewable way.”
The entire project was funded by Harbourton Alternative Energy and cost the city nothing. All the electricity is sold to the local utility, Portland General Electric, at 8 cents per kWh, with a 4 percent annual escalation. Profits are shared by Harbourton and the Portland Water Bureau.
After 20 years, the utility will have the right to own the system, which has a life expectancy of 40 years. At that time, the bureau could continue to sell the electricity or use it to power its own equipment.
“Water agencies are very interested in what we’re doing,” says Kelly. “They don’t have a lot of capital. They’re just trying to keep their infrastructure functional. That’s why we’ve had to innovate on the business model. There is a lot of private capital available that water agencies haven’t tapped.
“Water agencies need to figure out how to monetize their single biggest asset, which is their pipes. We see LucidPipe as a tool they can use to work with large energy companies that have the know-how and also good balance sheets. Everybody wants to be greener and cleaner, but how do you afford it?”
Proving the technology
Lucid is not the first company to develop such small hydroturbine products. Its in-pipe comes from an effort by three scientists to develop an efficient turbine to place in a river or stream.
“What they found is that it’s very difficult to predict the flow of water in a river or stream,” Kelly says.
“The head of our engineering group got the insight that if you took the turbine and put it inside a pipe, you’d be able to control the conditions, predict the energy output and do it without any environmental impact. It’s not weather-dependent. It’s a very predictable source of low-cost electricity.”
Lucid took the idea to Northwest Pipe of Vancouver, Washington, about five years ago. The two developed LucidPipe, which has systems for pipes 24 inches and up. “The challenge when you’re introducing a new product is that it’s hard to find people who want to be the first,” Kelly says. “Now we have two installations in the United States and are overwhelmed with the interest from around the world. In the future, we believe this will become a standard way that people manage water infrastructure.”
Why not more?
The company is working on turbines for use in small distribution pipes that could power local monitoring systems and distributed sensor networks. “Water agencies could have early warning systems about what is happening inside their infrastructure and get real-time information about the quality of the water, where the water is going,” Kelly says. “We can help home in on where water is being lost so they can attack that problem directly.”
The LucidPipe products meet NSF/ANSI Standard 61 for use in potable water systems and are suitable for wastewater utilities and other large water users, such as industrial facilities and farm irrigation systems. “The potential for the technology, I think, is quite large,” Kelly says. “There’s going to be an enormous investment in water infrastructure over the next 20 years, and using a system like this will enable water agencies to be more efficient about how they manage their pipelines.”