(top, photo) Thinkstock; (bottom, graph) Kempton et al, PNAS Early Edition (2010)

Blowin' in the wind. Electricity output from individual turbine farms can vary greatly (colored lines), but linking them up along whole coastlines can smooth out total power production (thick black line).

East Coast Winds Would Support a Stable Power Grid

Individual wind turbines and even whole wind farms remain at the mercy of local weather for how much electricity they can generate. But researchers have confirmed that linking up such farms along the entire U.S. East Coast could provide a surprisingly consistent source of power. In fact, such a setup could someday replace much of the region's existing generating capacity, which is based on coal, natural gas, nuclear reactors, and oil.

In terms of potential, wind-energy resources are tremendous. One estimate puts it at nearly five times as much as the world's entire existing electricity demand. And for environmentalists and anticarbon advocates, wind offers an energy source that does not require drilling, mining, or enriched uranium—and its carbon footprint is essentially zero.

But wind is erratic. A region might get gale-force winds one day and dead calm the next. To balance things out, engineers have proposed linking up wind farms to take advantage of wind variability across a wider area. But until now, no one had ever quantified whether meteorological conditions would justify such a linkup.

In the new study, energy policy analyst and electrical engineer Willett Kempton of the University of Delaware, Newark, and colleagues did just that. "Instead of just looking at the statistics of connecting turbines," he says, "we also decided to look at the meteorology." First the researchers chose a region known for its relatively constant winds. They compiled 5 years of wind data from 11 offshore weather-monitoring stations buoyed along 2500 kilometers of the East Coast. They estimated how much power offshore wind farms could produce if they had been placed at the same locations as the monitoring stations—which would be the case under current wind-farm configurations. Then they calculated the combined power output of the farms if they were all connected into a single grid.

As the team reports online today in the Proceedings of the National Academy of Sciences, at no time during the 5-year span of the study did the winds die down completely along the hypothetical grid. That means it would have been possible for the hypothetical offshore wind-power grid to generate electricity continuously for all of that time. Moreover, Kempton explains, linking the wind farms showed "a tremendous amount of smoothing" of power output. Farms located, say, in the Northeast might be operating at full tilt under gale-force winds, while the southeastern portion of the grid languishes under sunny skies and tepid breezes. As the wind data showed, he added, the quick swings between high- and low-power generation periods that are characteristic of individual wind farms slowed down dramatically within the simulated grid, taking days instead of hours or even minutes. By creating a wind-power grid, he says, "you can make a rapidly changing and unsteady source of power a slowly changing and stable one."

This is the first time a study has demonstrated that offshore East Coast wind energy can provide "a relatively reliable supply of smooth power," says environmental engineer Mark Jacobson of Stanford University in California. The findings are "important," he says, because the wind resources of the region are "tremendous and could theoretically supply all U.S. electric power demand."

The findings are "amazing," agrees Cristina Archer, a specialist in wind energy meteorology at California State University, Chico. Kempton's team shows "that an uninterrupted power supply from winds along the most populated and most energy-demanding coastal area in the country, and perhaps in the world, is possible."

Posted in Earth, Technology