Regulating Wind Power's Variability

Tuesday, June 17, 2008 - 7:00pm

As the Texas’ electric grid operator prepares to add power lines for carrying future wind-generated energy, Dr. Surya Santoso is developing improved methods for determining the extent to which power from a wind farm can displace a conventional power plant, and how best to regulate varying wind power.

As Texas’ electric grid operator prepares to add power lines for carrying future wind-generated energy, an electrical engineer at The University of Texas at Austin is developing improved methods for determining the extent to which power from a wind farm can displace a conventional power plant, and how best to regulate varying wind power.

“The cost of wind energy has become competitive with that of energy from fossil fuels because of technology improvements,” said Assistant Professor Surya Santoso. “Unfortunately, electric power generated from wind energy is intermittent and variable. That means we need to have better measurements of wind power plants’ output as we integrate wind energy into existing power systems. We also need to develop a way of managing wind power so it can be more readily called upon when needed.”

Texas has outstripped California since 2006 as the leading national producer of wind power, with most of the state’s renewable energy goal by 2025 focused on wind power. To help meet this goal, the state’s Electric Reliability Council of Texas is expected to add about 1,500 megawatts of new wind generation this year alone. In late September, Texas also awarded four offshore tracts along the Gulf Coast for wind power projects with a generating capacity of 1,150 megawatts.

Santoso is developing two strategies to manage and overcome the intermittent and variable behavior of wind power. With a two-year, $200,000 grant from the National Science Foundation, he and his students are developing computational methods to measure the actual capacity contribution of wind farms. This will allow system planners to calculate how much a wind farm can contribute to meeting expected power needs.

Santoso’s lab is also using the funding to establish the technical requirements of energy storage systems that would serve as temporary ”batteries” for releasing stored wind energy at optimal times.

“Having a proper energy storage system would allow you to harness free wind when it’s available, but release that energy at the time of your choosing with a desired power profile,” Santoso said. He noted that a wind energy storage system would also increase wind farms’ overall capacity contribution and reduce the likelihood of overloading transmission power lines that must carry energy from different power sources.

According to the American Wind Energy Association, Texas has more than three times the installed wind power capacity of any other U.S. state. And Texas continues to add capacity at a breakneck pace, installing more wind power in 2008 than any country except China and the U.S.

West Texas has considerable room to expand wind power, a necessity if the U.S. expects to approach some of the more ambitious goals put forth by wind advocates, such as achieving 20 percent of the nation's power generation from wind by 2030.

Whether or not this lofty goal can ever be reached, the good news, reports Webber, is that Texas has ample room to expand wind power—offshore. While the coastal areas of other U.S. states extend three miles offshore, Texas (and Florida along the Gulf of Mexico) extends three marine leagues offshore, or about nine miles, under its original terms of statehood. So in addition to having a lot of wind in the Gulf, Texas has exceptional room to place turbines. Offshore wind farms could generate power during the peak energy days of summer, when the West Texas winds breezes tend to die down.

Research on wind power takes place in several departments at the Cockrell School of Engineering. One important resource is the Laboratory for Advanced Studies in Electric Power and Integration of Renewable Energy Systems under the leadership of Surya Santoso, an assistant professor in the Department of Electrical and Computer Engineering.

Santoso works on making wind farms more efficient at generating electricity. As an offshoot of that research, he develops models that simulate wind farms and wind power plants so researchers can predict their performance in the field. The model development is funded by the National Renewable Energy Laboratory of the Department of Energy.

Students from around the world come to the university to work in Santoso's group, yet many alumni are finding post-graduate employment right in Texas—a natural result, given the size of the state's wind market. These alumni could become a valuable commodity. Just as, in the 20th century, Texas exported scientific and engineering expertise to petroleum markets around the world, the state could soon be training and exporting scientific and engineering expertise for wind energy.

Santoso believes Texas will continue to be a major force in wind power for a long time to come, but to solidify its position, the state should continue to invest in research. He would like to see greater investment in energy generation methods to make power from renewable sources less intermittent, and hence more reliable and economic. New technologies, such as mass storage capacities for intermittent energy resources, are critical areas for research and development. And Santoso would like to see policy and regulation that incentivizes further use of renewable energy.

These research initiatives will in the end have huge beneficial societal impacts in emissions, energy security and trade deficit reduction, says Santoso.