SIOUX FALLS - Information collected 200 to 300 feet above the ground indicates the wind energy potential in South Dakota has been underestimated, according to Mike Ropp, who's overseeing the collection of data.
South Dakota has long been considered a good site for wind energy production, based on computer modeling and data collected mostly by National Weather Service anemometers, often 30 feet above the ground.
But the Wind Resource Assessment Network puts sensors on transmission towers to measure the wind at the heights where turbines would operate.
"Wind speed changes at elevation, and in the band we're looking at - 50 to 90 meters (164-295 feet) - we're finding the winds tend to be stronger than had been predicted by previous studies and a little more consistent, less gusty," said Ropp, an associate professor of electrical engineering at South Dakota State University.
"Both of those are good things from a wind power perspective."
The information from 11 WRAN tower sites is averaged into 10-minute blocks and made available on a Web site.
It's the kind of data that gets a wind developer's attention, said Dusty Johnson, chairman of the South Dakota Public Utilities Commission.
"You go from modeling data that the federal government has that is not particularly attractive to developers, and then you get the real hard data about South Dakota and particular locations," Johnson said.
"That does it. They say "We've got to get our own anemometer up in South Dakota.' As a result, they come to South Dakota, invest in some measuring equipment and after a year, in some cases two years of their own data, they really do start investing some serious dollars."
There are 34 operational wind turbines in South Dakota producing a combined 44 megawatts of electricity. The largest grouping is near Highmore, where 27 turbines operated by FPL Energy can produce up to 40 megawatts of power.
Iowa, by contrast, can produce 1,035 megawatts of wind power and Minnesota 897 megawatts, according to the U.S. Department of Energy.
A 50-megawatt wind farm could supply 15,000 homes with power for a year, Johnson said.
A study done last year for the South Dakota Energy Infrastructure Authority listed 18 possible wind energy developments in the state. Six would be 100 megawatts each, another of 140 megawatts and one of 200 megawatts near White.
The PUC recently approved the 200-megawatt White Wind Farm along the state's eastern border. Minneapolis-based Navitas Energy Inc. would spent about $300 million on the 103-turbine operation.
Ropp said the high-tower study shows another benefit for developers: the wind blows primarily out of the northwest or the south. That makes it easier for developers to design wind farms and place the turbines to make effective use of the prevailing wind, Ropp said.
But the information points out some problems, too.
At ground level, winds peak in the afternoon and gradually die off in the evening. But higher up, the peak may not come until 2 or 3 a.m.
"The reason why that's a bad thing is that tends to be the time of lowest demand on the power system," said Ropp.
Finding ways to store that electricity or use it at night - recharging electric cars, for example - might address that imbalance, he said.
It also appears that the windiest periods are March to May, a few months shy of the July-August surge in electricity demand for air conditioning and irrigation.
Developers of wind farms stand a better chance getting financing for a project if they have the kind of information the WRAN can provide, Ropp said.
WRAN sites at Fort Thompson, Leola, Crow Lake, Crandall and Summit have been operating since 2001. Gettysburg went on line in 2004, Murdo in 2005, Belle Fourche and Medicine Butte in 2006, and Faith and Martin this year.
Johnson said the PUC and the Legislature have helped wind energy development by expediting the permitting process and cost recovery period to build electric transmission lines to carry the power to other states.
"The story for South Dakota wind power the last 10 years has been, "Boy, the wind is great - if we could only harness it,"' Johnson said.
"The new story for South Dakota wind power is we're finally harnessing the wind, turning it into dollars and cents for South Dakota, turning it into green energy. The wait is over, the reality is here."
~wran
http://www.eere.energy.gov/windandhydro/windpoweringamerica
#AP-WS-08-19-07 1201EDT
