Serving the Flathead Valley & Montana since 2006. A reality based independent journal of observation & analysis. © James Conner.
What is an average home? That’s the question raised by two recent stories on electrical generation, one by the Daily InterLake’s Ryan Murray, the other by the National Journal’s Amy Harder.
Murray reported on 25 October that Stoltze Land and Lumber will sell electricity from its wood fueled generator to the Flathead Electric Cooperative for the next 20 years, a deal big enough to attract Montana Governor Steve Bullock who toured the plant last week, remarking:
“This facility makes a difference in the valley and it makes a difference in the state,” the governor said. “This will go to power 2,500 homes.”
The plant has the ability to generate 2.5 megawatts of power every year, and the sale of that power is what makes the plan workable for Stoltze. The lumber company will receive renewable energy credits as part of the deal.
Harder reported yesterday on her tour of the big Ivanpah project under construction in the California desert some 50 miles from Las Vegas. Ivanpah is a solar thermal electricity generating facility that uses heliostats (mirrors) to concentrate the sun’s heat on boilers atop a 460-foot tower (three towers when the project is completed), converting water to steam that spins the generator turbines. “The futuristic project,” Harder gushes, “will begin generating electricity by year’s end for 140,000 California homes.”
Neither Murray nor Harder defines an average home, or reports how many kilowatt hours of electricity that home uses a month. And they’re not alone in omitting that information. I couldn’t find it on Flathead Electric’s aging and not that useful website.
Murray — and/or the editor who blue-penciled his copy — also wrote, “The plant has the ability to generate 2.5 megawatts of power every year….” What does that mean? Is the plant’s nameplate rating 2.5 megawatts? Is it expected to generate an average power level of 2.5 megawatts a year? The statistic missing is kilowatt hours generated per year (divide by 1,000 to get megawatt hours per year). If we know the annual kilowatt hours generated, we can calculate how many kilowatt hours Bullock’s average home uses.
Ivanpah’s 392 megawatt nameplate rating is meaningless unless one also knows the expected capacity factor, which is basically the percent of the time the plant is actually generating at the nameplate rating. Hydrocarbon and uranium fueled baseload plants have capacity factors of 90 percent and higher, but solar, wind, and hydro do not. If Harder had done her homework, she would have learned that Ivanpah’s owners expect a capacity factor of approximately 30 percent, possibly a bit higher. My back-of-the-envelope calculations suggest the average California home of which Harder writes uses 600 kilowatt hours a month. I think that’s low, but at least it’s a starting point.
And to be fair, an average home is not easily defined. How big is it? How well insulated? Does it have electric heat? Air conditioning? How many people live in it? That information provides a basis for comparison.
But alone, that information is not enough. Reporters must learn how capacity factor differs from nameplate rating, and the how power differs from energy. It’s not rocket science.
If I were running Flathead Electric, I’d get together with the gas company and Flathead Valley Community College, and put on a free evening workshop on energy for local reporters, bloggers, and editors.
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Ivanpah gives me heartburn. I think blowing sand will coat the mirrors and dull their polish, depressing output, increasing maintenance costs, and increasing the cost per kilowatt of capacity — a cost already twice as high as for onshore wind turbines. It’s nowhere near as reliable as photovoltaic panels distributed on the roofs of 140,000 homes. It is, however, a generating model familiar to electric utility managers: a big central generating plant. That’s why they like it — and why I don’t.