Wind Energy

Transmission for wind farm in western U.S.: Lower cost, lower variability

Adding the next 11,000 megawatts (MW) of wind turbines generating capacity to the western U.S. could be done in such a way as to reduce both wholesale costs and utility system variability, according to Lawrence Willick of LS Power.

Willick, one of the speakers at the WINDPOWER 2012 session "Operation Transmission: Plugging Wind into America," said the Western Renewable Energy Zone study published in 2009 had pegged wind energy potential of the western states at 95,000 MW, well above the 14,000 MW currently installed in the region. "The question is, what’s the next step?," he added.

The CREZ Transmission Optimization Study, conducted in conjunction with the Competitive Renewable Energy Zone program in Texas, provided the technical basis for a substantial expansion of wind capacity in that state, Willick said, and a similar effort is needed in the West. He added, "What I hope to do is to provide some direction on what such a study might involve."

There are two main barriers to the development of more wind power in the region, he said–lack of transmission capacity and utility integration issues. The existing wind farm generation has been developed around the existing grid, and there’s not a lot of additional transmission capacity available. Also, "some balancing areas claim they are saturated with wind … The perception is, more wind will mean much higher integration costs," Willick said, adding, "People are looking to minimize energy, integration, and transmission costs. The way to balance those goals and get to the next increment is three words: diversity, diversity, diversity."

A video display, produced by the Midwest Independent System Operator (MISO) of wind patterns across the Upper Midwest illustrates the importance of diversifying the location of wind energy generation, he said–wind speeds follow weather systems and are constantly fluctuating, rising in some parts of the region and falling in others.

Analysis of data gathered for the National Renewable Energy Laboratory’s (NREL) 2010 Western Wind and Solar Integration Study, Willick said, makes the importance of geographic diversification very clear. The WWSIS found that when new wind energy and solar power installations were added at a variety of locations, utility system variation actually decreased below normal levels caused by changes in demand throughout the day.

Similar results, Willick said, came from looking at two scenarios for new wind power installation, one with five sites and one with 17. In both cases, the total variability was well below the variability at individual wind farm sites. Benefits of diversifying include more efficient use of transmission resources and reduced integration costs, he said, and further, the 17-site scenario could be accomplished without adding new transmission lines to those already proposed for the region.

Tom Gray, www.awea.org/blog