Cities along the East Coast may one day power their homes using electricity generated from turbines resembling underwater wind farms that capture the Gulf Stream’s energy.

That’s a future David Duquette, CEO of Massachusetts-based Littoral Power Systems, says he has in mind when testing a new renewable energy technology designed to power cities with slow-moving ocean currents.

“There’s tremendous promise in harvesting power from the ocean,” Duquette told Bloomberg Environment. In saltwater, which is many times more dense than air, the relatively small devices can create “a tremendous amount of power,” he said.

Twelve firms and universities, including Littoral Power Systems, are receiving $25 million in recently announced Energy Department funding to test a new generation of technology that can harness the power of tides, waves, and river and ocean currents to generate renewable energy that can one day feed into electric power grids.

Known as hydrokinetic energy, the power of currents, waves and tides is a largely untapped source of carbon-free electricity in the U.S. The Energy Department estimates that hydrokinetic energy has the technical potential to supply the U.S. with more than 40 percent of its electricity.

The companies developing hydrokinetic energy technology are doing so as coal fades as a source of electricity in the U.S. and as the demand for renewables to cut climate pollution rises globally.

The Energy Department didn’t respond to Bloomberg Environment’s requests for comment.

Undersecretary of Energy Mark Menezes said in a Jan. 8 statement that power generated by currents, waves and tides will help secure domestic energy supplies and is part of the agency’s “all of the above” energy strategy.

Technology in Its Infancy

Although a few projects have been built around the world, including a high-profile tidal project in New York City’s East River, hydrokinetic energy is still in its infancy. It isn’t yet widely used commercially to produce electricity in the U.S.

In a few years, that could change.

“Within 10 years, you’ll start to see substantial development projects being put in place. It will look a lot like wind looked in its earlier years,” said Reenst Lesemann, CEO of Virginia-based Columbia Power Technologies Inc., a hydrokinetic energy technology company receiving Energy Department funding to develop a low-power wave energy converter.

Current and tidal energy technology are as far along today as wind power was in the late 1990s, but the development of wave energy technology is comparable to where wind was in 1985—still about a decade from maturity, Robert Thresher, a researcher at the National Renewable Energy Laboratory, said.

Tidal and current energy are both maturing and stand on the shoulders of wind energy because they borrow a lot of blade, foundation and other design elements from wind farms, Thresher said.

“I consider them to be underwater wind turbines,” he said.

Hydrokinetic energy has a handful of champions in Congress. In 2017, Sen. Ron Wyden (D-Ore.) introduced legislation promoting hydrokinetic research and development. Those provisions were included in the Senate’s broader energy bill sponsored by Sen. Lisa Murkowski (R-Alaska), which gained little traction in the last Congress.

“Capturing the energy found in ocean waves, tides and currents right off the Oregon coast means producing more clean energy and more clean energy jobs,” Wyden said in a 2017 statement. “Marine energy has the potential to provide a nearly inexhaustible source of homegrown renewable electricity to power American homes and businesses while addressing the very real challenge of climate change.”

Wyden plans to reintroduce his legislation sometime this year, spokeswoman Nicole L’Esperance said.

Unknown Risks

Underwater turbines may have an impact on marine life that isn’t well understood, Thresher said.

“We don’t really know what the risks are,” he said. “Environmental concerns are pretty strong for this type of device.”

Marine animals could collide with hydrokinetic energy power plants, Thresher said. And the plants would generate underwater noise, create potentially harmful electromagnetic fields, and change the flow of water in in certain areas.

“If you put enough of these devices in, you change the volume-of-flow rate locally for a tidal flow,” Thresher said.

John Rogers, a senior energy analyst at the Union of Concerned Scientists, said that while it’s exciting to see such technologies draw more attention, the potential challenges need to be understood.

“Any time you place a foreign object in the ocean and secure it to the seabed, you’re going to be disturbing things to some extent,” Rogers said. “That can matter for fish, whales, other marine mammals, plants, birds.”

‘White Meat’ of Hydrokinetic

Of the various technologies under development, Duquette said wave energy is the major focus of the Energy Department’s research funding, which was announced Jan. 8.

Technology that harnesses the power of waves to generate electricity has proven difficult to scale up enough to connect to a power grid, said Stefan Siegel, director of fluid dynamics at Colorado-based Atargis Energy Corp., which received Energy Department funding to test a wave energy converter technology.

“Wave energy is far behind in terms of being cost-efficient,” Siegel said. “There are working devices out there, but they don’t produce much power, and the power they do produce is very expensive.”

Atargis is using about $3.5 million Energy Department funding to test a converter that uses a “wave terminator” and hydrofoil blades to generate electricity more efficiently in coastal waters about 120 feet deep, Siegel said.

At full scale, the company envisions the wave converters built in arrays off coastlines, potentially generating hundreds of megawatts of electricity. If the tests are successful, the technology become commercially available within a decade, Siegel said.

Another wave energy project that received $1.3 million in Energy Department funding was announced Jan. 14 by the University of Hawaii-Manoa. Researchers there are testing ways to generate power by forcing water through the center of a submerged doughnut-shaped disk.

“Our calculations suggest that this can be a power-generation methodology that produces encouragingly low-cost electricity,” said Patrick Cross, a Hawaii Natural Energy Institute researcher and project lead, said in a statement.