Coordination

Ultimately, the largest single cost associated with integrating large amounts of wind power into a utility grid will occur not over seconds or hours, but on a time scale of days or longer. Better coordination of power system resources can help reduce the costs associated with this uncertainty.

Improved day-ahead wind forecasting is helping to reduce costs by better anticipating and preparing for wind power supply, thereby helping to avoid the need to fire up a system's most expensive generating plants. New analytical methods are being applied, including artificial-neural-networks technology and physical wind-flow models.

The California Independent System Operator (ISO) is so confident in the algorithms it developed for hourly and daily wind generation forecasting that it has incorporated them into the California power market. The California ISO's Participating Intermittent Resources Program allows wind farms to bid into the California electricity market without incurring the ISO's 10-minute imbalance charges—penalties for deviations between energy promised and energy delivered. Wind producers that use the California ISO's wind forecasts to schedule their energy deliveries are charged instead for their monthly net deviation. Because many of the short-term over- and under-production figures cancel out over this time, the monthly charges tend to be small.

Coordinating wind power and hydropower is another option for handling daily and monthly variation. Where hydropower stations are available, utilities are increasingly using them as a form of energy storage and to buffer fluctuations in wind generation. Hydro-rich Sweden and Norway already provide a partial backup for wind-rich Denmark and northern Germany. A somewhat similar pattern is found in the U.S. Pacific Northwest, where the Bonneville Power Administration (BPA) supplies huge amounts of electricity to California and the entire U.S. West from one of the world's premier hydropower complexes, the Federal Columbia River Power System.

BPA's Network Wind Integration Service is part of a major BPA program designed to meet growing demand in the Pacific Northwest. The Columbia River hydro system experiences significant seasonal variation, owing to the region's dry summers. By integrating significant amounts of wind power into its system, BPA hopes to conserve its hydro resources and, in the same stroke, transform wind energy into dispatchable generation capacity for peak-load periods. Wind-farm operators help finance the system by paying BPA an integration fee of $4.50/MWh.

Supergrids

The realization of wind power's potential in the United States will require bold efforts to coordinate power distribution on a continental scale. That's because our most promising area for development by far is the upper Midwest. Harnessing this energy resource will require massive new transmission facilities to carry the electricity from primarily remote areas to urban load centers. Eventually, one can envision a massive high-voltage dc (HVDC) transmission "spine" taking shape along the windy corridor stretching from the Dakotas to Texas, with branches extending east and west toward distant cities. Similar concepts are already gaining credence in Europe. For example, Dublin, Ireland-based wind farm developer Airtricity and Swiss engineering giant ABB are promoting the concept of an HVDC undersea supergrid running from Spain to the Baltic Sea. Such long-term grid connections could serve to further smooth out the fluctuating supply of wind energy, since the wind is usually blowing somewhere.

As such new technology—not only extensive HVDC but also electronic shock absorbers and battery and hydropower storage—enables large-scale integration of wind farms with utility grids, wind energy will increasingly displace fossil fuels for power generation. Part of this displacement will take place organically, as new technologies are introduced and the cost of producing wind energy continues to decline. But rising concerns over energy prices and resource security are likely to significantly accelerate the trend.

What is required is appropriate planning—on the R&D side, to continue reducing the cost of the technologies described above, and on the transmission side, to intelligently integrate these technologies into grids as new wind farms come online. Doing so will promote maximum penetration of this clean, renewable resource.