Past The Theoretical: Fulfilling Offshore Wind Energy’s Vast Potential

NAW Staff
Written by Bjorn Carey
on September 18, 2012 No Comments
Categories : New & Noteworthy

10417_offshore_wind_turbines Past The Theoretical: Fulfilling Offshore Wind Energy's Vast Potential There are enough offshore wind resources along the U.S. East Coast to meet the electricity demands of at least one-third of the country, but in order to fulfill that potential, the projects will be have to be sited in the right locations, finds a new study conducted by Stanford University researchers.

The report could act as a guide for wind energy developers looking to site projects in the most rewarding locations, according to Mark Z. Jacobson, professor of civil and environmental engineering at Stanford and director of the research.

The scientists paid special attention to the Maine-to-Virginia corridor – as the historical lack of strong hurricanes in the region makes it a favorable site for offshore wind turbines – and found that turbines placed in that zone could satisfy the peak-time power needs of these states for three seasons of the year, with summer being the only exception.

‘We knew there was a lot of wind out there, but this is the first actual quantification of the total resource and the time of day that the resource peaks," Jacobson explains. ‘This provides practical information to wind farm developers about the best areas to place turbines.’

Some breezes are better than others: Wind energy that peaks during times of high electricity demand is more valuable and can offset fossil-fuel generation that runs for only a few hours a day.

The researchers used a weather model to generate five years of hourly wind speeds at 90 meters above the sea surface – the standard height of offshore wind turbines. (The projection was validated against real data from offshore buoys and towers.)

The team inserted about 140,000 5 MW wind turbines into their computer model, at various ocean depths and distances from the shore, from Florida to Maine. After factoring in standard transmission losses and turbine array inefficiencies, the U.S. East Coast offshore winds were found to produce between 965 TWh and 1,372 TWh of electricity annually – enough to satisfy the electricity demands of one-third of the U.S., or the entire East Coast.

A critical factor in achieving this potential is the time of day that the electricity is delivered, the scientists note.

‘People mistakenly think that wind energy is not useful because output from most land-based turbines peaks in the late evening or early morning, when electricity demand is low,’ explains Mike Dvorak, a recent graduate of Stanford's Atmosphere/Energy Ph.D. program and a member of the research team. ‘The real value of offshore wind energy is that it often peaks when we need the most electricity – during the middle of the day.’

Tapping this vast resource would not come at the expense of ocean views, nor would it seriously impact wildlife or recreational and commercial water use, the researchers say. Many of the turbines would be sited so far offshore that they would not be seen. In fact, the analysis assumed the use of only one-third of available shallow-water locations out to water depths of 30 meters, and two-thirds of the remaining sites out to water depths of 200 meters.

Jacobson recognizes that the country would not convert completely to wind energy. In fact, it would not be wise to have more than 40% or 50% of electricity production tied up in any one energy source, he notes.

Ideal locations
Jacobson says the study should serve as a guide for developers looking to site offshore wind farms in the most rewarding locations. For example, there is a substantial amount of peak-time wind energy near the East Coast's largest population centers.

‘This study enables the planning and development of very large wind farms offshore of New York City or Boston," he says. "Connecting the power to the grid would be technically as easy as laying a cable in the sand and hooking it directly into the grid without the need to build often controversial transmission lines on the land.’

Both Jacobson and Dvorak acknowledge that it could take years before developers begin to tap this resource to the extent that it is needed. Although wind energy currently costs more than natural gas – and offshore wind turbine installation currently costs two to three times more than onshore wind turbine installation – both the short- and long-term economics of offshore wind power make it attractive, they say.

For instance, in the near term, offshore wind farm construction would create jobs in states that do not currently have a large energy industry, and it would further wean consumers off fossil fuels, the researchers note. In the longer term, a greater shift to wind energy would offset pollution, and thereby reduce the associated health and environmental costs, they add.

However, the biggest benefit could come in price stability, Jacobson notes.

‘But the real advantage of wind versus natural gas or coal is that, even though there's a higher cost now for offshore wind, it results in price stability,’ he says. ‘There's zero fuel costs once they're in the water. Coal and gas are depletable resources, so their cost will inevitably go up over time. The cost of wind energy will remain stable, and the wind resource is infinite.’

Bjorn Carey is science information officer at Stanford News Service. He can be reached at bccarey@stanford.edu.

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