lickering whenever the stadium powers up for a big game.
Because variability is inherent in wind, Kempton says utilities use the same equipment to accommodate fluctuations in power levels introduced by the small volume of wind generation currently feeding into the grid.
"If you have 20 percent wind, that's fine, no problem. We'll just ramp the generators up and down as the wind fluctuates." So it works — up to a point.
"It keeps the managers busy; it's not that they let the fluctuations go out and let your lights bulbs flicker, but it adds maybe 5 percent to the cost of wind power to do that management."
However, "If you want to run 50 percent or 80 percent of your electricity from wind, then that fluctuation becomes more problematic." This calls for either massive power storage systems to warehouse energy for a rainy (or not so rainy) day, or major investments for more gas-fired generators.
Kempton believes that wind farms up and down the coast, under the power of local weather conditions, could perform the same load balancing function for one another that gas turbines provide onshore.
He and his co-authors Dana Veron and Felipe Pimenta from University of Delaware and Stony Brook University associate professor Brian Colle tracked coastal winds over five years using hour-by-hour data from 11 offshore weather buoys and meteorological stations.
Then they put together a computer simulation that substituted wind farms for weather stations and included the proposed interlinking cable. They generated data simulating five years' worth of power feeds from the hypothetical wind farms.
While the researchers found that output from individual wind farms varied widely over time, the power output of the network as a whole held steady. Fluctuations, when they did occur, were gradual, but at no time during the study period did power output on the simulated grid drop to zero.
Other wind energy researchers see potential in other U.S. coastal areas. For example, Stanford's Mike Dvorak and Mark Jacobsen looked at the California coast and determined that despite deep water close to shore creating headaches for placing turbines, offshore wind conceivably could meet up to 83 percent of the state's electricity demand.
Kempton says the reliability of the North America's coastal wind resource is a happy accident of geography. A similar exercise using data from Great Britain's coastal areas suggested considerably less promising results.
Researchers on the British study observed "large power swings in a 12-hour period" during the height of winter, when the region faces its highest demand for power. From that experience, lead researcher James Oswald of Coventry University suggested that "distributed generation would not help much" in the case of the British Isles, "since most of the region experienced the same wind conditions."
By contrast, according to Kempton, from the Bermuda High to the Nor'easter, "there is almost always a pressure gradient somewhere and cyclonic events move along the [Atlantic] coast. There are a few times of low power throughout, but they are not due to any one particular weather pattern."
An energy superhighway
Kempton calls his proposed cable interconnect the Atlantic Transmission Grid, although he imagines it as an "energy superhighway." It would shuttle power between wind farms spanning 1,500 miles (2,500 kilometers) of coastline, eventually sending that power to shore wherever it is needed.
"We have a uniform grid, in a sense, already. Everything in the Eastern Interconnection is all connected together. But this would make one line that would enable us to move a lot of power north and south."
Kempton estimates the transmission system would add less than 15 percent to the capital cost of offshore wind generation and says the figure is "in line with the market cost of leveling wind via existing generation."
There are also other start-up issues that will raise the price, including a provision in the federal Merchant Marine Act of 1920 that requires the ships used to build the offshore portions to be U.S.-built and U.S.-citi