With Novel Tidal Tech, ResHydro Heads To Scotland

First Minister Alex Salmond has lured a U.S. tidal power company to Scotland to develop its technology. Like a lot of startups in the marine power sector, ResHydro has its own novel way of generating power that appears to need a good deal of work before it might be put to use.

A cash grant and the promise of working in the hotbed of marine power development convinced the company, which will apparently retain its business office in New York, to set up shop in Glasgow.

reshydro tidal power

The Hydrofoil Cascade Resonator (image via ResHydro)

“The SMART: SCOTLAND award, coupled with our partnership with the University of Strathclyde, positions ResHydro in the most vital marine power industry market,” ResHydro’s CEO, Samuel Lewinter, said in a statement released by the government. “We are pleased to have the opportunity to open our Scottish subsidiary where we will have access to significant technical expertise and where market conditions will contribute to the most expeditious commercialisation of our technology.”

Salmond is in the U.S. as part of a government-sponsored promotion called Scotland Week 2013. He is a fierce proponent of renewable energy, pushing his country toward matching 100 percent of its electricity consumption with the clean stuff by 2020.

The cash going to ResHydro – £100,000 – is from a program intended to fund early stage proof of concept research and development for small to medium sized companies. Early stage does seem to fit the bill for ResHydro, which had yet to appear on our marine energy radar. But that’s not too surprising, with both wave and tidal power crawling with small startups chasing a big idea. Within tidal power there are designs that use vertical-axis turbines, horizontal-axis turbines, the venturi effect, tidal kites … even one based on the Archimedes Screw, according to the EMEC.

ResHydro’s technology is in a broad category of tidal power called oscillating hydrofoil. This sort of device is typically envisioned with a hydrofoil attached to an arm that rises and falls as the tidal stream exerts force and causes a pressure difference on the foil. The Newcastle company Engineering Business was developing such a device in the mid-2000s – called “Stingray” – but appears to have abandoned it since being acquired in 2008 by the Dutch shipbuilding group IHC Merwede (there’s not a peep about the device on the company website).

There appears to be a twist to the ResHydro system, however; as pictured on the company website, its foils would be positioned vertically, and would move “translationally and rotationally,” the company says, as the tidal flow (or river current) runs through the device. This induces a phenomenon known as “flutter,” a sort of self-sustaining vibration that yields energy continuously, regardless of water velocity, via hydraulic pump.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.