Light From a Pipe

Portland’s experiment in generating energy from the city’s tap water system

by Sam Dean

Portland, Oregon has a municipal water system a lot like any other in the country. A bunch of big, four-and-a-half foot wide steel pipes contain water flowing down from a reservoir system in the nearby mountains, and those eventually feed into smaller and smaller chunks of pipe, which eventually lead to your home. There are some valves and grates along the way, but it’s pretty straightforward stuff.

But one chunk of pipe, inserted into one of the city’s four-and-a-half-foot wide water mains, is different. It’s called a Lucid Pipe, it’s painted bright blue, and it feeds electricity drawn from all that water back into the grid. Four whirling turbines along the inner bore of the pipe spin as the city water flows by, cranking the generators that poke out towards the surface along the length of the tube. A small amount of the generated electricity powers computers housed alongside each generator, and those computers can control the speed of the turbines and collect data on the flow rate and chemical composition of the water rushing past — data that Water Department techs can then download over the Lucid Pipe’s wireless network.

The Lucid Pipe, hovering in 3D-render space (credit: Studio 2a)

This is all pretty cool. Generating power from the manmade underground rivers we’ve already built into our cities seems like a supremely elegant eco-urbanist plan, the kind of thing a nerdy kid from the ‘90s might assume would be happening by 2015, integrated into the renewable-energized City of Tomorrow (Portland!).

In other words, it’s one of those inventions that seems obvious once it exists. But the elegance of the Lucid Pipe idea, the neatness of the energy-conservation circle, obscures the century-long flow of hydroelectric thinking that needed to be reversed before it could come into being. Because most hydropower comes from dams — structures that almost completely stop water from moving — but the Lucid Pipe is part of a system, the municipal water pipe network, whose only purpose is to transport water at pressure over long distances, to people’s homes.

So how does it work?

Simpler Times — Moulin Dussart in Belgium (credit: Daniel Dussart)

Well, first lets get back to the basics. For as long as there have been rivers, people have thought of ways to put them to work. Little waterwheels pulled power from waterfalls and streams to turn millstones (or whatever), then the first phase of textile factories used water turbines to run their vast looms, redirecting the river’s flow through matrices of pulleys and drive belts.

Things get complicated — The Laxey Wheel on the Isle of Man, built in 1854 to pump water from deep mineshafts

Soon after that, the advent of electricity meant that any factory, or any home, could draw on the power of the river from hundreds of miles away, as turbines housed inside dams were used to crank electric generators, whose power was zipped into the grid.

Each advance in hydropower has been more efficient at making rivers work for us, but energy is a zero-sum game. A megawatt of electricity generated is a megawatt of energy sucked from the river. To pull the maximum power from its flow, you have to stop the water, pile it up behind a dam, point it past the turbines and then let it out as a trickle on the other side.

The Colorado River brought to a standstill behind the Hoover Dam

That works great, if all you want to do is make electricity. But massively enervating the river destroys the native ecosystem, which in turn messes with the ecosystem of the surrounding landscape and the ocean at its mouth, which, in turn, makes some people think that there might be a different way to do things.

Which is where the Lucid Pipe got its unlikely start, as the researchers who eventually created Lucid Energy tried to figure out how to slurp up power from a river in Indiana while still leaving it wild.

The problem with standard hydroelectric turbines is that, like the dams that house them, they present an almost entirely solid obstacle to the water flowing through — not a great format for minimal impact on a river. So the original Lucid team started out working with a kind of helical turbine that had been developed in the ‘90s. Josh Thomas, Lucid’s engineering program manager (and Lucid’s longest-serving employee), said these turbines looked like “hydrofoils wrapped around the surface of a cylinder, like strands of DNA.”

A chain of horizontal helical turbines waiting to be installed in Maine (credit: Squaresol)

Compared to the solid-wall dam turbines, there isn’t much material in the helical turbine to block the water’s flow. And instead of being turned by the brute head-on impact of the water, they used the power of lift — the same principle that makes windmills turn and planes fly — to spin and generate electricity as water flowed past the blades.

These turbines worked great in theory, but in practice, in the burbling, variable, debris-filled world of a real river, Lucid found that they couldn’t quite cut it as reliable sources of energy. So the team tried taking a page from the classic hydropower handbook and built a little sluice that routed some of the water through a boxy, square-edged pipe, the kind you’d find at old-timey goldmine museums.

This was the first time that anyone had tried using this type of turbine in an enclosed environment, with all the weird turbulence problems that come up in the process, but it worked like a charm — it had minimal impact on the river, and generated enough power to be useful to a small consumer, like a remote research station or a little cabin.

The only problem left was one of basic geometry: their helical turbine fit in a rectangular pipe. That might sound a little weird, but look at a strand of DNA from the side, and you’ll see that the outer edge of the double helix describes a rectangle. With their proof-of-concept data in hand, Lucid Energy had already approached the biggest water pipe manufacturer in North America, the Vancouver-based Northwest Pipe, to see if they’d be interested in working together to mass-produce their system. Northwest was into it, but only if Lucid could figure out a way to circle that square and fit the turbine into a normal pipe.

The spherical solution (Credit: Cathy Cheney/Portland Business Journal, Courtesy of Lucid Energy)

Thomas, the longtime employee, says that there really isn’t a good way to wrap a helix into a ball (and even thinking about it can make your head hurt), so the design team went for a more hands-on approach. They took the blades, already curved for lift like an airplane’s wings, tilted them at a slight angle, and bent them to form the outline of a sphere. Then they just attached that whole blade-ball to a couple of hubs and tried it out in a pipe.

And it worked! The earlier helical system had had all kinds of problems with turbulence — it could get so bad at high spinning speeds that the blades would start audibly bending under the pressure. The round turbine, on the other hand, “not only was very smooth operating,” says Thomas, “but it was more efficient.” That kickstarted development, Lucid picked up a grant from the Department of Energy, and the partnership with Northwest was sealed. Once Portland expressed interest, Lucid picked up and moved there, too — with the added bonus of being closer to the manufacturing mothership.

The Portland system, installed (Credit: Jamie Newton)

Now, the Lucid Pipe is churning along under the pavement at Portland’s SE 147th Ave and Powell Boulevard. It’s supposed to generate an average of 1,100 megawatt-hours per year, enough to power 150 homes, while only skimming 1–5 PSI off the water pressure. Most water agencies promise to deliver 40 to 60 PSI to customers’ taps, and many have excess pressure in the system, so Lucid Pipe’s take is just a little dip in the stream.

Lucid Energy CEO Gregg Semler says that the company is working on new projects in California and Arizona, and has been talking with water bureaus in other cities in the region to install the Lucid Pipe.

The company’s focusing on the West thanks to the laws of nature and geography. Thermodynamics dictate that skimming electricity from water you’re already pumping (with electricity) is going to be a net loss, so the system only makes energy sense in situations where the water is flowing downhill. The West has a lot more mountains than the East (let alone the Midwest), so that’s where Lucid’s looking for its first wave of customers.

A chunk of Lucid Pipe on its way to the Portland site (Credit: Sherri Kaven)

Even in Wichita, though, Semler believes there’s hope for municipal-scale Lucid Pipes. Mountains make the job easier, but many water systems use a workaround to put gravity to work as much as possible: At night, when electricity from the grid is cheaper, cities pump water up to higher-altitude reservoirs nearby, or even to water tanks on the roofs of big apartment buildings. Then during the day, when electricity is pricier, they let gravity do the rest on demand. As long as the gravity feed from that hilltop reservoir or rooftop tank is supplying more pressure than necessary, the Lucid Pipe could still help recoup the cost of the pumping power from the night before.

But Semler says that the company is already looking beyond the big-bore Lucid Pipe market: “we’re definitely going down in size.” Circling back to Lucid’s original purpose, when it was just a couple researchers trying out helical turbines in a river in Indiana, the company is working on making Lucid Pipes small enough to power a network of little sensors across the nation’s water infrastructure. “You could put a little turbine ahead of your water meter,” he says, “so you could be constantly monitoring the quality of water, powered by a battery that can run forever.”

And when the power cuts out (unless you rely on a pump to run your faucets), your little Lucid could still be whirring away, generating enough juice to light a bulb or charge a phone. Sipping energy from the tame water running into our homes might not be quite as epic as damming whole rivers and extracting their power, but it sure seems like the future.