Stanford Study Shows Interconnected Wind Farms Reliable

A study by two Stanford University scientists published in the November issue of the Journal of Applied Meteorology and Climate shows that wind power can be made a reliable resource for supplying a portion of the electrical needs of the United States, and not necessarily succumb to the vagaries of the winds that power the turbines. The key lies in interconnecting the wind farms.

Cristina Archer and Mark Jacobson of Stanford say that wind-generated electricity is the fastest growing energy resource in the world, and be made more reliable. "This study implies that, if interconnected wind is used on a large scale, a third or more of its energy can be used for reliable electric power, and the remaining intermittent portion can be used for transportation, allowing wind to solve energy, climate and air pollution problems simultaneously," said Archer, lead author, in a press release from Stanford.

The study looked at 19 sites for wind farms in the Midwestern United States, and looked at the wind patterns for each of the sites. Their conclusion: As more and more wind farms become locked together in a distribution grid, the more reliable wind becomes as a source for electricity.

One supposition of the study was that the entire world’s current electrical demand of 1.8 terrawatts could theoretically be generated using a distributed grid of 890,000 wind turbines of the sort currently being manufactured, without improvements in the technology. There are currently roughly 110,000 electricity-generating wind turbines in operation today, but most of a smaller scale than Archer and Jacobson envision.

Currently, coal-fired electricity generation plants have a reliability factor of 87.5%, meaning they are capable of providing power 87.5% of the time during any one year. The average coal-fired plant generates 1,000 kilowatt-hours (KWH) of electricity, according to a report from Oak Ridge National Laboratory. The Stanford study indicates that 19 individual turbines, connected through a distribution and spaced according to wind patterns, could achieve a similar reliability pattern, while generating 222 KWH.

"The idea is that, while wind speed could be calm at a given location, it could be gusty at others. By linking these locations together we can smooth out the differences and substantially improve the overall performance," Archer said.

Archer is a consulting assistant professor in Stanford's Department of Civil and Environmental Engineering and research associate in the Department of Global Ecology at the Carnegie Institution. Jacobson is a professor of Civil and Environmental Engineering at Stanford.

Archer and Jacobson will present their findings December 13 at the annual meeting of the American Geophysical Union in San Francisco. Their talk is titled "Supplying Reliable Electricity and Reducing Transmission Requirements by Interconnecting Wind Farms."