A&M engineer floats plan to harness offshore wind power

By Jeannie Kever
Houston Chronicle

Wind farms blanket the western half of Texas, turbine blades spinning across the Panhandle and Permian Basin, making the state the nation’s leader in generating electricity from wind.

But for most of the country, the greatest potential for wind energy lies offshore. Developers are pushing ahead with projects on the East Coast and elsewhere despite environmental concerns about fishing habitats, migratory bird paths and even the seaside views valued by tourists and coastal residents alike.

This activity is largely driven by requirements for utilities to include a certain percentage of electricity from renewable sources. Beyond the environment, permitting and other concerns, investors also struggle with the high cost of offshore wind developments.

Now research by an engineer at Texas A&M University at Galveston aims to make the turbines less expensive and allow them to be moved farther from shore, reducing complaints about visual blight.

“Wind energy profits are razor thin,” said Bert Sweetman, associate professor of maritime systems engineering at A&M-Galveston. “Cost has to be a bigger issue than when you’re building an oil platform.”

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Although his work is still based on mathematical models, he said he’s confident it will result in savings.

Sweetman estimated that various design possibilities would cut the amount of steel required by 30 percent.

Like other offshore wind turbine designs, these would be tethered to the seabed. A cable to carry the current generated would also run to the sea floor and on to an onshore power station.

Wind energy is well established in Texas, accounting for 13 percent of generating capacity in 2012, the Electric Reliability Council of Texas reports. Most of that comes from turbines in West Texas, although there are two coastal wind farms, both in Kenedy County south of Corpus Christi.

Andy Lubershare, senior analyst with IHS Emerging Energy Research, said many states don’t have Texas’ “phenomenal wind onshore.”

Densely populated areas in some states, especially in the Northeast, make building wind farms inland even more difficult.

“Offshore might have an advantage in New England and the Mid-Atlantic,” he said, and that area is expected to be the first where offshore wind developments come online.

Still, it’s expensive. Although Europe has a number of commercial offshore wind developments in operation, none have begun in the U.S. and several projects under development in New England face challenges.

Chris Long, manager of offshore wind and siting policy for the American Wind Energy Association, said offshore winds tend to blow when energy demand is greatest.

“On that hot summer afternoon, the temperature differential between land and sea creates the sea breeze,” he said. “Just as everyone is cranking up their air conditioning, that’s one of the times the sea breeze is greatest.”

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Offshore wind developments also could create economic opportunity, similar to offshore oil drilling, Long said, citing engineering and design, project management, fabrication, marine services and supply companies.

The U.S. Energy Department has tried to jumpstart offshore wind projects by funding demonstration projects along the Atlantic Coast, the Great Lakes and the Gulf of Mexico, including a grant to an Austin company to install three 6-megawatt wind turbines in state waters near Port Isabel.

The Interior Department has begun leasing offshore blocks and assessing wind resources to speed development, Lubershare said. Even so, he said, finding the right location and getting permits can take as long as seven years.

Sweetman spent a decade working for Mobil Oil before joining the A&M faculty, “back when deep water was 3,000 feet.”

Companies now drill at twice that depth and more.

Sweetman’s research interests include floating production concepts and software tools for engineering applications, and he helped develop the American Petroleum Institute’s guidelines for floating production.

He approached the current project, supported by a $313,000 grant from the National Science Foundation, as a mathematical puzzle, looking at various combinations of wind and wave patterns, wave heights and other variables, including the impact that a lighter base would have on the turbines’ efficiency in harvesting energy from the wind.

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Using a computer model to predict how much electricity a floating turbine will generate, as well as how it would react to wind and waves in the ocean, he and his team — A&M doctoral graduate Lei Wang and students Shu Dai, Ju Gao and Blake Wilder — have compared various designs.

The ability to move the wind turbines farther from shore would avoid public controversy while still taking advantage of the population density close to the coast.

“Ten miles offshore, you’re in the middle of nowhere,” Sweetman said. “But 10 miles offshore, you’re close to (the electricity) market.”

Floating oil production platforms and floating wind turbines are made from similar materials, he said. But there are stark differences as well.

“They’re much, much smaller,” he said of the wind turbines. “They are much cheaper. They’re unmanned. Safety’s less important, because the consequences of failure are lower.”

And in a commercial-scale offshore wind farm, “there are a lot more of them.”

Technical challenges, from building to installing the turbines, account for much of the cost, Lubershare said.

“The major issue with offshore wind, as with any energy resource, is cost,” he said. “Based on costs we’re seeing in Europe, it’s a more expensive energy resource than many others.”

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But as more U.S. states require utilities to include electricity generated from renewable sources in their portfolios, wind energy has become part of the mix.

The question, he said, is whether the cost will drop enough for wind energy to compete successfully with other energy sources.

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