Golly. Gosh. Gee whiz. Did you know you can’t just plug in wind and solar capacity to replace coal and nukes? Clean in, dirty out?
Of course, readers of this blog and POWER magazine understand the problem of renewable intermittency. Solar and wind MWs don’t equal coal, nuclear, or gas MWs. It’s been a topic for discussion, debate, and analysis for decades.
But suddenly the Washington Post and green energy reporter Chris Mooney have discovered the dirty little secret of wind and sun: it takes natural gas –gasp! — a fossil fuel to make wind and solar practical on a large scale today. The headline on the story last week tells all: “Turns out wind and solar have a secret friend: Natural gas.”
Citing a recent paper by the National Bureau of Economic Research, Mooney reports breathlessly, “Because of the particular nature of clean energy sources like solar and wind, you can’t simply add them to the grid in large volumes and think that’s the end of the story. Rather, because these sources of electricity generation are ‘intermittent’ — solar fluctuates with weather and the daily cycle, wind fluctuates with the wind — there has to be some means of continuing to provide electricity even when they go dark. And the more renewables you have, the bigger this problem can be.”
Welcome to the real world of electricity supply.
The intermittency answer today, because electricity storage at a large scale, other than pumped hydro, is still a pipe dream, is natural gas. We already knew that, right?
The poster child of gas backup for solar (not so with politically incorrect hydro and geothermal, which can be dispatched to follow load) is the massive, troubled Invanpah solar thermal project in the California desert. The idea behind the 377-MW, $2.2 billion project, occupying 3,500 acres – which has $1.6 billion in DOE money, some $500 million in federal tax breaks, and the backing of PG&E, Google, and BrightSource Energy (in which Google is a large investor) – was to use the sun to make steam to turn a turbine.
In a blog posting last April, I suggested that Ivanpah could be the plant that killed solar thermal. Its costs were excessive, given the low price of natural gas generation. I quoted MIT’s Technology Review, “When it first came online in late 2013, the massive Ivanpah concentrated solar power plant in the California Desert looked like the possible future of renewable energy. Now its troubles underline the challenges facing concentrated solar power.”
Earlier this month, the conservative Heritage Foundation’s The Daily Signal took on the Ivanpah project as an example of how California consumers are being bilked by regulators allowing the use of natural gas at the plant to support excessive electric rates aimed at rewarding solar energy. The point of the article is that the project really isn’t a solar plant, but a hybrid solar-gas plant that’s not in line with California’s stated (and stupid, in my view) methane antipathy.
At Ivanpah, concentrated solar beams hit a target where water is turned to steam, to generate electricity. The Mojave Desert is hot during the day, but often quite cold at night, so Ivanpah must use natural gas to raise steam to follow load in the morning.
The Heritage article notes, “The electricity is not entirely solar produced, yet it is sold at the higher prices regulators allow for solar power, a benefit worth millions of dollars per year to Ivanpah’s owners.
“Ivanpah is abetted in this mischaracterization by the California Energy Commission, whose strained interpretation of the rules allows Ivanpah to ignore gas used to heat the water, unless the ‘generator breaker is closed.’ This means that none of the gas burned at night to reheat the water is counted toward the caps placed by government on natural gas use in generating power.
“Those caps require natural gas to be responsible for less than 5 percent of the overall generation of power, with 95 percent coming from solar. In reality, the California Energy Commission’s own data show Ivanpah’s gas use is responsible for closer to 30 percent of its output than it is to 5 percent.”
The Washington Post article on the need for natural gas backup for wind and solar naively cited one of the NBER researchers that “that the findings are something that decision-makers hoping to add more clean energy to the grid will have to take into account.” Duh. It’s the bite of intermittency and nothing new at all.