Tapping the Energy of the Tides

Computer model of Verdant Power's underwater turbines. (Courtesy Verdant Power)

(coming in it hits this shore pretty heavy, going out it hits the Newington shore pretty heavy, it is a dramatic roar)

Jack Pare, a retired aerospace systems engineer, points to the water under the General Sullivan and Little Bay Bridge in Dover.

He says the tides here in the Piscataqua River move quickly –almost nine feet per second at its maximum.

(nat Sound )

Pare says engineers know how to capture that free flowing energy – and it would be a completely renewable source of power for the state.

1289 Jack – 1:05 It’s just one of many things you have to do if you want to save the planet or otherwise cut down on our carbon emissions, there’s no single magic bullet, this is one pellet of that shotgun to be able to take the top off global warming.

Some state representatives believe it’s an idea worth pursuing.

State legislators passed a bill that establishes a commission to study tidal power generation here under the bridge.

Representative Tom Fargo of Dover, the bill’s sponsor, says unlike wind power, the benefit of tidal power is its reliability.

1:20 the tide will flow until the earth rotates no more, it’s available, we know when it’s coming, we know from day to day and even hour to hour how much energy you’re going to be able to get from it, it’s very predictable.

And water is more than 800 times denser than air – making it much more powerful.

But almost all the various technologies used to capture tidal power are expensive and experimental.

Only one company so far is producing it in the United States.

A little known start-up called Verdant Power has six underwater turbines, resembling windmills, in the East River in New York.

So far, Verdant Power founder Trey Taylor says the turbines power the lights in a supermarket and a parking garage on Roosevelt Island.

9:20 but also inside that garage there are electric vehicles, there’s hybrid electric buses, but also there’s little electric vehicles that go up and down Roosevelt Island, something a little bit bigger than golf carts, and those are all being plugged into our tidal power which I think is a pretty cool story in and of itself.

But Taylor has much bigger hopes.

He foresees a time when 300 of these underwater turbines will power about 8,000 homes in New York.

But Jack Pare points out the turbine technology that works well in New York’s East River may not be appropriate for the Piscataqua.

1290 1:18 we have deep water fishing, we have harbor seals, we have stripers and lobster, none of which are present on that other site. So there’s a little bit more to be careful of.

Two companies currently hold federal preliminary permits to study the feasibility of tidal power in the Piscataqua.

Underwater Electric Kite's hydrokinetic turbine. (Courtesy Underwater Electric Kite Company)

Philip Vauthier is President of one of them – the Underwater Electric Kite Company based in Annapolis Maryland.

He says his turbine technology won’t turn fish into fillets.

6:21 we put a screen in front of the turbine to protect the fish to reach that point 6:29// 7:25 absolutely no problem with them, anything bigger than three quarters of an inch is safe it will be deflected

Vauthier says smaller fish would be able to glide through unharmed.

He predicts his 2.4 million dollar project could produce 40 megawatts or enough to power about 36-thousand New Hampshire homes.

The other company that holds a permit - New Hampshire Tidal Energy Company –owned by Oceana Energy - is predicting a much larger power output along three stretches of the river.

Charles Cooper is a technical advisor for the project.

22:44 I’d be surprised if it reached more than 100 megawatts at the most and that would be very optimistic, that’s not trivial in that it certainly can supply a number of end uses bit it’s not going to be the baseload for the region.

Cooper says Oceana’s prototype looks like a large wheel about the size of a Ferris Wheel, with an open center that allows large marine animals to swim through.

But he adds their technology won’t work everywhere.

7:14 this is not really deep water in the Piscataqua, so if Oceana’s technology turned out to work best in very large sized unit that might be 60 to 80 feet in diameter, they wouldn’t be appropriate for the Piscataqua site.

In that case, Oceana would likely use another company’s technology at its sites.

Both companies say there are a lot of challenges and unknowns surrounding tidal energy in the Piscataqua.

But the permits give them three years to study the sites.

What they learn will also help the state decide if tidal power is worth pursuing.

For NHPR News, I’m Amy Quinton.