Wind and solar power get the lion’s share of attention in the realm of green energy. But Monday marked a milestone for another renewable energy source, tidal power, with the nation’s first-ever application to build a tidal power plant licensed to transmit energy onto the nation’s electrical grid.
“We are extremely excited about the submission of this license application,” Ron Smith, CEO of Verdant Power said in a statement. “It represents the culmination of nearly a decade of work undertaken by Verdant Power and a variety of project stakeholders to add tidal power to the US clean energy mix.”
The company's three-bladed underwater turbines work a lot like a submerged version of a wind power plant to capture the power generated by tides, the cyclical rushing of water toward shore or back toward the ocean. But to deploy such a system, the company had to conduct extensive research to show its system does not harm fish or other aquatic life.
To do that, Verdant Power from 2006-2008 deployed six full-size turbines in the East River, delivering energy to New York City businesses. Partial funding for the design and testing of a new composite turbine blade was contributed by the US Department of Energy. Research support came from the National Renewable Energy Laboratory in Golden, Colorado, Sandia National Laboratories in New Mexico, and the University of Minnesota.
"It's a big step and a great milestone for the US and the offshore-energy industry," says John Miller, executive director of the New England Marine Renewable Energy Center at the University of Massachusetts, Dartmouth. "Verdant certainly has had to carry more of their share of the load. They've been the groundbreaker for this. They've conducted a tremendous number of costly studies in order to show no harmful impacts on fish."
Interest in offshore wave and tidal power is intense – if regional. The world's most developed market is off the shore of Scotland, where large demonstration projects have shown the possibility of providing as much as 20 percent of the United Kingdom's energy needs. Canada, as well, has been pushing demonstration projects around the Bay of Fundy, famed for its dramatic tides.
In the US, by contrast, a few demonstration projects on both coasts have pushed ahead with just a dollop of public funding. Most has come from the pockets of entrepreneurs and their backers, with the DOE recently offering $50 million to help push the projects to completion, Dr. Miller says.
Tidal power is not a huge resource – but it is significant, Miller says. Each year the US uses about 4,000 Tera-watt (TW) hours of electricity. Offshore wind holds the potential to provide about 1,000 TW hours, he says, and wave power about 260 TW hours – about equal to all the electricity hydro-electric dams produce today.
Tidal power, Miller says, holds the potential for about 110 TW hours. (With a large nuclear power plant producing roughly 1,000 megawatts of power, the figure for tidal power’s potential represents the annual output of 12 or so such large nuclear plants.)
"Tidal may not be the biggest, but because it's so close to land it can be a lot cheaper to develop than wind power and wave power that may be a lot farther offshore," he says. "The other thing about it is that it's incredibly predictable for centuries.”