It wouldn’t make sense to send Wyoming’s potentially abundant wind power to California if Wyoming produced wind power at times when California had plenty of its own. But scientists looking at wind sites in the two states say that’s not the case; they say the states have complementary wind resources, and connecting them – as has been proposed – could help smooth the flow of renewable energy onto the California grid.
The principle at work here is wind diversity. If a grid relies on wind power from a limited region, generation can swing dramatically from day to night, seasonally or as weather systems pass. This can be hell for grid operators, and costly. Widening the geographical sources of wind power can theoretically help overcome some of these issues, mitigating the essential problem with wind power: its intermittent nature.
In their new study [PDF], researchers at the University of Wyoming’s Wind Energy Resource Center looked at five locations in Southeastern Wyoming where wind power is either already generated or is planned (more on that in a bit), and at three California sites – Tehachapi Pass, San Gorgonio Pass and Altamont Pass – where wind is already well developed.
What they found was there was little correlation between the wind power density of the sites in Wyoming and the sites in California. They found, too, that monthly average wind power densities tended to vary quite a bit between the two states – Wyoming sites showed peak production in the late fall and winter (and lower in the summer), while California sites peaked in the summer and fell off in the winter.
The researchers then dove in deeper and found that by matching the power output of specific California and Wyoming sites, it could be possible to ensure the Golden State has plenty of renewable power – including its own solar power – when most needed, between 6 a.m. and 10 p.m. Looking at a particular day (Aug. 9, 2012), the researchers found:
As expected from sites with good diversity, the Wyoming wind would continue to produce even as the wind assets in California are dropping. In fact, this example shows that the combination of Wyoming wind and California solar makes up for the drop in California wind during the day in this instance. Equally important is that production from Wyoming wind remains significant as the solar resource drops later in the day.
What it all adds up to, the researchers said, were three specific real-world benefits from linking Wyoming wind to California’s grid: reduced big swings in renewable output, thus making grid integration easier; savings of around $100 million a year from needing less fossil-fuel power to fill in renewable gaps; and, as mentioned, availability of power for the California grid when most needed.
As it happens, there are plans unfolding to make this California-Wyoming magic happen – but it’s going to be a long, uncertain haul. The Obama administration is supporting the building of the giant Chokecherry and Sierra Madre Wind project south of Rawlins, Wyo., which could see up to 1,000 turbines putting out 2,000 to 3,000 megawatts of electricity. Wyoming has no need for the power; the thinking is to send it west.
In October, when the U.S. Department of Interior declared the Wyoming site suitable for development, the company behind the project made no bones about what it hoped to do with the power. “The Record of Decision milestone moves us closer to having bulk supplies of clean, cost-effective electricity available to serve nearly 1 million U.S. homes – and in a timeframe well ahead of the RPS targets set by California and other Western states,” said Bill Miller, Power Company of Wyoming president and CEO.
But California has refined its RPS to make it more difficult for projects from out of state to gain regulatory approval. The state might have needed big projects from surrounding Western states in the early years of its RPS, but in the last few years it has approved dozens of projects within its own borders. “The pipeline of projects seeking future approval is robust,” Gov. Jerry Brown’s renewable energy advisor told Western grid players in 2011, in a letter [PDF] that essentially warned out-of-state developers that California might not be needing their power.
And even if California did want Wyoming’s wind power, there would be the challenge of getting it there. TransWest Express, a corporate cousin of Power Company of Wyoming, is aiming to build the “extra-high-voltage direct-current electric transmission system” that would connect the Wyoming site to the Desert Southwest. The Obama administration is strongly backing that project, but it’s a huge undertaking, a 725-mile line, still making its way through the regulatory thickets itself.