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If the weather report says it's supposed to be sunny and breezy tomorrow, do you trust that forecast enough to plan a picnic?
But what if the efficiency and reliability of the region's electricity grid was at risk?
The growing number of Midwestern wind farms has raised the stakes for weather forecasts. Operators of the power grid need to estimate wind-turbine output in the hours and days ahead to avoid wasteful generation by other plants. But improving wind predictions would require investments in new technologies at a time of constrained budgets.
"If grid operators have more confidence in our weather forecasts, they'll be able to avoid burning excessive fossil fuels," says Melinda Marquis, a renewable energy program manager with the National Oceanic and Atmospheric Administration (NOAA), which runs the National Weather Service.
NOAA recently partnered with the U.S. Department of Energy on the Wind Forecast Improvement Project, an attempt to measure the economic benefit of improved forecasting for the energy industry.
Earlier research suggests better forecasts could save the industry $1 billion to $4 billion annually, according to a paper Marquis coauthored in the September issue of the Bulletin of American Meteorological Society.
The two agencies recently deployed more than a dozen new wind detection instruments across 300 square miles of the Upper Midwest, including parts of Minnesota, Iowa, Wisconsin, Nebraska, Missouri, and most of North and South Dakota. NOAA is also making a next-generation weather modeling service available to its research partners, which include St. Paul forecasting firm WindLogics.
"We're determining how much does that stuff help improve the wind power forecast?" says WindLogics CEO Mark Ahlstrom.
The new technology isn't cheap -- a single radar installation can cost $1 million. The results of this study will help determine whether there's a business case for improvements nationwide.
A constant balancing act
Maintaining a power grid is a balancing act, as operators try to align the amount of electricity generated with the amount used. There's always a cushion, but generating too much electricity is wasteful, expensive and can overload transmission lines. Too little and operators must fire up other generators.
Wind's variability complicates the process. Grid operators, such as MISO (formerly the Midwest Independent Transmission System Operators), are used to dealing with variability in electricity use, which is fairly predictable based on time of day and temperature. But predicting wind generation requires a whole new set of data.
WindLogics has been developing wind forecasting models for more than two decades. The company was founded in St. Paul in 1989 by supercomputer architects who teamed up with meteorologists to work on government projects.
As the wind energy industry grew, so did its need for better forecasting data. About a decade ago, WindLogics decided to shift its focus from government to business customers. Today, it's one of several private firms that supplies tailored forecasts to the industry.
WindLogics uses supercomputers to combine forecasts from the National Weather Service and others. The aggregated forecast is run through computer models containing information about wind farms.
The results: a wind power generation forecast that's more than 85 percent accurate for the day ahead and nearly 95 percent accurate for the next hour. The system uses historical data and artificial intelligence to improve accuracy over time.
"They're down in the range where they're very valuable when you are trying to operate the grid, even though they are not perfect," says Ahlstrom.
MISO, which manages the grid for the Upper Midwest, started purchasing wind forecasts from a German company in 2008, says Mike McMullen, MISO's St. Paul regional director. Before then, there just wasn't enough wind power to affect generation decisions.
With nearly 10,000 megawatts of wind capacity in MISO's territory, it's now critical to plan around the wind. At its 24-hour control center in St. Paul, McMullen's team works facing a 30-foot-wide video board that displays, among other things, a chart of recent and forecasted wind generation for a 72-hour period.
"We use that to look ahead so we know what other generation to take offline or put online," says McMullen.
Every five minutes, MISO operators can "redispatch," or adjust the flow of electricity on the grid. Its computers can remotely turn generation up or down at certain plants and re-route electricity to transmission lines where it is needed.
The more accurate wind forecasts become, the more comfortable grid operators will be in taking other generation offline. They'll never be perfect, says Ahlstrom, but even incremental improvements should result in savings.
WindLogics received a $1.2 million Energy Department grant last year to work with NOAA on the project. Another forecasting firm also received a grant for a similar study in Texas.
"If we can prove that investing in these better weather models and weather data actually saves money on incorporating renewables, then that becomes a good justification for improving the whole weather system," says Ahlstrom. And those improvements could then benefit a whole range of industries, such as aviation and agriculture.
They might even help keep you dry during your next picnic.
Dan Haugen is a Minneapolis freelance writer. He wrote this article for Midwest Energy News, a service of Fresh Energy, a St. Paul nonprofit that advocates for clean energy such as wind and solar.