Big Wind Near Big Dam Get US OK

President Obama last Tuesday promised more approvals for large-scale renewable energy projects on public lands, and by Friday his Interior secretary, Sally Jewell, delivered with a big wind project not far from the legendary Hoover Dam.

Jewell gave her backing to a BP Wind Energy plan to put up to 243 turbines on nearly 40,000 acres of federal lands in Mohave County, Ariz. The site is about an hour’s drive southeast of Las Vegas – and just 20 miles from Hoover Dam, long one of America’s biggest non-fossil-fuel-burning energy producers. The wind farm could have an installed capacity of 500 megawatts, depending on the transmission line it connects to, which would be about a quarter of Hoover’s original 2,080 nameplate capacity.

mohave county wind farm

The planned wind farm is about 20 miles southeast of Hoover Dam (image via Wikimedia Commons)

Not that it’s a competition, but it is interesting to compare these two projects as energy generators. If the wind farm indeed comes in at 500 MW and operates at a 30 percent capacity factor – a not overly ambitious target – it would produce 1.3 terawatt-hours of electricity per year, equal to all the electricity used in a year by about 116,000 total U.S. households, based on the U.S. average annual consumption of 11,280 kilowatt-hours per household.

This would be one-third of Hoover’s longtime average of 4.2 TWh, but that figure only begins to tell the Hoover Dam power production story.

Hoover has produced as much as much as 10.3 TWh (1984) and as little as 2.6 TWh (1956) as precipitation in the Rocky Mountains and Colorado River Basin has risen and fallen over the years, according to the dam’s managers. The trend in recent years – years marked by drought – has been toward declining power production capacity.

Since those peak years of the early 1980s, Hoover has never run at capacity, according to a 2012 Washington Post report on the drought’s impact. And it’s a problem that could get much worse. Hoover loses “between 5 and 6 megawatts of capacity” for every foot the water drops in Lake Mead. The dam’s operators are investing in new, more efficient turbine technology to try to make up for the losses, but the long-term ability of Hoover to pump out power is certainly in doubt.

That could make the new wind power generation not just a nice addition to the Southwest’s power sourcing (about half of Hoover’s power goes to Southern California, with the other half more or less split between Arizona and Nevada), but a necessity to make up for what’s vanishing from Hoover. But there are detractors. The desert conservation group Basin and Range Watch, in posting about the approval, said this of BP:  “The same company that soaked tens of thousands of birds in oil in the Gulf will now find another way to reduce our avian populations.”

The feds claim, however, that in the several-year process that brought this project to the point where it stands now:

The company agreed to undertake significant mitigation efforts to minimize impacts to wildlife and other resources, including reducing the project’s footprint by about 20 percent from the original proposal. The smaller footprint will protect golden eagle habitat and reduce visual and noise impacts to the Lake Mead National Recreational Area. In particular, today’s decision bars the installation of turbines within designated sensitive areas to avoid golden eagle nesting locations, as well as provides for a 1.2-mile buffer zone to protect the nests. Additionally, no turbine will be closer than a quarter-mile to private property.

When might work on the Mohave Count Wind Farm begin? Once BP gets power purchase agreements lined up.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.