Brown researchers claim hydrofoil has 'secret sauce' for shallow tidal power

A research group at Brown University in the US is working on a shallow water tidal power device, a hydrofoil of sorts, that it claims it has a ‘special sauce’ to overcome problems associated with shallow water devices.

By K.Steiner-Dicks on Jun 4, 2014

Led by Shreyas Mandre, assistant professor of engineering, the group is developing a hydrofoil — a water wing — as a means to harvest tidal energy. And unlike other tidal energy technologies, the wing is a shallow water specialist.

That “secret sauce” that Mandre and the team have created is a computer algorithm that monitors and controls the fine motion of the wing for maximum efficiency.

“It tries a certain stroke and measures the power output. Then it tries a neighboring stroke and measures the power from that. If the new stroke works better, it moves to that stroke,” Mandre said. “The tidal currents are constantly changing, so this lets us search constantly to find the best movement.”

Mandre and his colleagues have been testing their design using a small prototype about 16 inches wide. In a water flow created in the lab, they have shown that their device gathers power as much as two to four times more efficiently than existing hydrokinetic systems. And those data come from the relatively slow flow speeds achievable in the lab. The team expects their efficiency to increase in faster flows outside the lab, said a Brown University news report.

With support from the Advanced Research Projects Agency-Energy (ARPA-E), the group has designed a small prototype has been testing in the lab to prove the concept. Late last month, they presented their preliminary results at the ARPA-E Energy Innovation Summit in Washington, D.C., and at The Bicameral Task Force on Climate Change, organized by Sen. Sheldon Whitehouse (D-R.I.) and Rep. Henry Waxman (D-Calif.).

“We were very encouraged by the response we received,” Mandre said. “We’re looking forward to getting to work on the next phase of the project.”

The group’s work grew partly out of a recent study commissioned by the Department of Energy to identify the best locations for harvesting tidal energy. The study found that many ideal locations are in shallow bays and inlets, often 10 meters in depth or less.

“We’re confident about how our lab results will scale with size,” Mandre said. “The next step is to demonstrate that with a larger device in a tidal test site.”

The group has arranged a partnership with a testing facility near Little Bay in New Hampshire. They’re now seeking federal funding and industry partnerships to build their new prototype and push the project forward.