As wind farms sprout like sagegrass on the prairie in spring and solar-energy installations move toward ever-larger sizes, ocean energy may be the next frontier for alternative energy generation. That frontier can be found in the heart of America’s largest city, where an array of turbines is being submerged in the New York City’s East River to tap the tidal flow. The demonstration project is riveting the attention of the ocean-energy industry.

“That’s a world-leading project,” says Roger Bedard, ocean energy leader at the Electric Power Research Institute (EPRI), Palo Alto, Calif. “It’s the first electrically connected project, the first array of turbines and it involves extensive environmental monitoring.”

The Roosevelt Island Tidal Energy project (RITE) is installing six axial-flow rotor turbines in 30 to 40 ft of water in a section of New York City’s East River about a mile long and 270 ft wide between Roosevelt Island and the Borough of Queens (ENR 1/24/05 p. 17). The turbines, each averaging 35 kW of capacity, resemble wind turbines, with fixed-pitch blades 8.2 ft long and the center line of the turbine 15 ft above the river bed. Monopiles, steel pipes 24 in. in diameter filled with rebar and concrete, anchor the turbines in the bed. Officials of Verdant Power Inc., the Arlington, Va.-based developer, claim the $8-million project is the first tidal in-stream array in the U.S.

Thomas F. Armiastead/ENR	Verdant Power Inc.
At least 6 ft of water covers Roosevelt Island turbines.

Construction began in December 2006, when a pair of turbines was installed to test materials, operation and environmental impact. Four other turbines were installed from April 25 to May 3. The “six-pack” will operate for 18 months under a preliminary permit from the Federal Energy Regulatory Commission.

Trevcon Construction Inc., Liberty Corner, N.J., delivered and installed the turbines as prime under a $1.3-million lump-sum contract, says Ron Treveloni, president. Turbines must be installed at slack tides. Divers have 25 to 40 minutes to work before the tides sweep them away. “We try to catch two tides a day,” Treveloni says. The turbine is set on the first tide and the next is used to tweak settings and cut the bungee cords that hold the blades.

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Oceaneering International Inc.’s Marine Services Division, Chesapeake, Va., is construction manager. Trey Taylor, Verdant’s president, says Oceaneering contributed “genius ideas” to the project, citing the CM’s “new engineering thinking about ways to deploy the turbines” that cut deployment costs by one-third.

Verdant’s goal is to build out to 10 MW of capacity in the Roosevelt Island channel and another field off Manhattan in a security zone beside the United Nations headquarters. Depending on the depth and the turbine size it allows, 200 to 300 more turbines could be installed, he says. Verdant’s goal is to reach an installed cost of $2,500 to $3,000 per kW.

How ocean-energy projects are developed, engineered and constructed is itself in development in this new industry where all projects so far are in pilot or demonstration phases. A few engineering and construction companies are becoming known for their experience in it, but no model for the construction team has yet emerged comparable to the engineer-procure-construct contractor for fossil-fueled powerplant construction.

Black & Veatch, Kansas City, is working with some large utilities in the U.S. on ocean energy, says Andy Baldock, technical director of renewable energy Europe, who heads the company’s global renewables team from London. “Technology providers need to prove the technology. They tend to be very involved in project development,” he says.

Few projects yet are far enough along to involve construction contractors, and the future shape of the industry remains unclear. “Once there’s been a shakeout and it’s clear who the leaders are, then I suspect most of the project development will be taken up by project development companies,” says Baldock. In a less-crowded developer field, standard contract forms will evolve.

Godfather

Some people call Roger Bedard the “godfather” of the ocean energy industry. Since starting EPRI’s ocean energy program three years ago, Bedard has shepherded state and federal agencies, electric utilities, academics and technology developers through collaborative programs to demonstrate ocean-energy conversion.

Sustainable Energy Ireland Sustainable Energy Ireland bids for market with Ocean Energy Buoy in Galway Bay.

Ocean energy has the potential to meet 10% of current U.S. electricity demand, or 400 billion MW-hours per year, Bedard says. A March 2007 EPRI status report for North America estimates the U.S. wave-energy resource alone (excluding tidal energy, such as the RITE project) equal to roughly 30,000 MW of average power. The Canadian wave-energy resource is 1,600 billion MWh per year. Bedard says a feasibility definition study of tidal in-stream energy conversion (TISEC) projects found two sites in the Bay of Fundy in Nova Scotia that together have 297 MW potential capacity, and the electricity could be sold for 4.6¢ per kWh. Province-owned Nova Scotia Power Inc., Halifax, has selected a turbine by OpenHydro Group Ltd., Dublin, Ireland, for a 1-MW, $10.8-million pilot, which it hopes to start by 2009. The province aims to obtain 20% of its power from renewable energy by 2013.

Wave-energy conversion (WEC) projects are best sited off west-facing coasts with thousands of miles of ocean between 40° and 60° north and south latitudes, says Bedard. Several WEC projects are in development between San Francisco and Southeast Alaska. TISEC resources are best in channels near a coast or estuary, such as the Golden Gate or the upper reaches of the Bay of Fundy. Bedard says he hasn’t yet studied tidal resources in the southern U.S.

North to Alaska

Some 90% of the nation’s tidal resource and 50% of its wave-energy resource is in Alaska, says Bedard, and a handful of companies are studying sites there. Ocean Renewable Power Co. LLC, Miami, Fla., is proposing a TISEC project in the Knik Arm Narrows, near Anchorage. The site’s appeal lies in its fast currents, more than six knots, and its proximity to existing submarine transmission lines. The company says it needs another $1 million to begin work.

At least eight Alaskan ocean-energy projects have FERC preliminary permits, says David Lockard, ocean-energy program manager with Alaska Energy Authority. Interest in Alaska tidal energy is growing, he says. In January, the state’s first tidal energy conference was attended by government officials, power company executives and entrepreneurs.

In March FERC issued preliminary permits for three projects in Southeast Alaska and one in the south-central part of the state. “The purpose...is to try to figure out how much power exists, and whether there would be customers in the area for this power,” explains Charles Cooper, a consultant for Oceana Energy Co., Washington, D.C., a developer.

Finding customers may be a hurdle. Alaska Electric Light & Power Co., Juneau, has said it has enough hydropower to meet local power needs for at least a decade, if not longer. But the potential base of customers for Southeast ocean-power projects is much larger than local utilities, says Chris Rose, executive director of Renewable Energy Alaska project, Anchorage. For at least a year, Alaska has studied...