WIND ON THE WIRES

You Do Have to Know Which Way the Wind Blows on the Grid – Study
Peter Behr, October 30, 2009 (NY Times)

"How and when the fickle winds blow are increasingly critical issues for operators of the nation's electricity grid, concludes a new 10-year assessment of regional outlooks for renewable energy…The questions already matter to the energy companies, funds and speculators that trade more than $500 billion in over-the-counter electricity contracts annually.

"The North American Electric Reliability Corp. released [The 2009 Long-Term Reliability Assessment]…its annual assessment of the long-term vulnerabilities of its eight regional grid organizations and asked them to consider a scenario with 15 percent of electricity output coming from renewable generation -- primarily wind…Meeting [that target] by 2018 would require more than 95,000 megawatts of new wind and solar generating capacity, or nearly one-quarter of all power plant capacity, NERC said…[potentially presenting significant] operational challenges…{It stressed] the need for more transmission lines, both to maximize the potential for wind and solar generation and to reduce threats to the transmission grid from overloaded lines….Texas, one center of wind power production, will require 660 miles of high-voltage alternating and direct current lines, including a direct DC link from Western wind centers to Houston…Wind generation in the Great Plains -- the other wind hub -- grew by 50 percent between June 2008 and this past June, and could grow to 32,100 megawatts in 2017, meeting 42 percent of electric power requirements…"

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"…[A]long with the familiar warnings about transmission shortages, NERC's report also gives a hard push to the need to improve wind and weather forecasting…[though] the rapid growth of wind power has not [yet] created any general reliability or power line congestion problems…But wind power is projected to grow rapidly…

"…[G]rid operators are developing more sophisticated forecasting models…[thanks to] commercial innovations…Genscape's Enva marketing intelligence group and WSI Corp. announced a new analytical tool that will provide seven-day hourly wind forecasts, updated throughout the day…[using] several thousand sensors…deployed around the country, which read the power flows on high-voltage transmission lines leading away from wind farms and other generator sites…This enables [Enva] to combine wind data, hourly changes in power line congestion, and spot wholesale electricity prices at "nodes" or transmission line hubs where traders and utilities buy and sell electricity. The forecasting systems are being offered in Texas and the Great Plains-Midwest regions…[Enva's] forecasting tool is designed to predict how changes in wind production could cause prices to separate between two nodes…The rapid growth of wind power in both regions is producing dramatic spreads in wholesale power prices in Texas and the Midwest, and transmission line congestion is the key element…"

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"On Feb. 24 this year, at 9:30 a.m., for example, wind generation west of Minnesota's Twin Cities was so plentiful relative to demand that wind farms were paying more than $10 an hour to utilities to take their electricity. Wind generators can afford to sell at a small loss because they make $19 a megawatt-hour from a federal production tax credit. But congested power lines prevented the excess wind from moving through northeastern Iowa toward population centers in the Midwest, where prices jumped above $40 a megawatt-hour in that hour…Understanding -- and accurately predicting -- how wind shifts affect prices is a central issue to the future stability of the grid, and not just the profit goals of traders…

"Coal-fired power plants cannot be ramped up and down efficiently or effectively by the hour or the day to match swings in wind generation. So grid managers may have to choose which kind of power is crucial to keeping the grid operating safely. As wind power expands, so will natural gas-fired generation, NERC predicts, and that could make electricity markets more vulnerable to the volatility of gas prices, or compel utilities to invest in gas pipelines or storage…"