If you are a politician in a blue area, the big thing these days is to make the pledge that you will put your state or city on the fast track to getting 100% of its electricity from the "renewables." Here in New York, trendy progressive Cynthia Nixon (challenging Governor Cuomo in a primary for Governor) has issued the call for getting 100% of electricity from renewables by 2050. Even trendier Congressional candidate Alexandria Ocasio-Cortez wants the same 100% from renewables without specifying a date. Out in California, a bill advancing through the legislature calls for 100% of electricity from "renewables" by 2045.
But has anyone stopped for a moment to ask how this would work or how much it would cost? Of course there is the Manhattan Contrarian -- for example in "How Much Do Climate Crusaders Plan To Increase Your Price Of Electricity?" in August 2016; or "How Self-Delusional Can We Be On The Cost Of Electricity From 'Renewables'?" in February 2018. Yes, mine are basically back-of-the-envelope calculations. Not that there's anything inherently wrong with a back-of-the-envelope calculation on this subject. The truth is that you can get pretty good rough estimates from easily available sources of how much back-up you need to fill in for the intermittent "renewables," and you can multiply that by cost-per-kWh figures for batteries, and thus, using no more than pencil and paper, get useful estimates of impact on electricity costs. Those impacts, by the way, are not small.
But how about looking for a study that's a little fancier and more sophisticated, maybe from some certified academic source? If you have the idea that this is a calculation that nobody in academia really wants to do, you would not be very wrong. But a reporter named James Temple from the MIT Technology Review is just out (July 27) with a piece -- relying on a 2016 report from researchers at MIT and the Argonne National Lab and on recent work from a Boston-based think tank called the Clean Air Task Force -- that analyzes the situation in California and comes up with some rather specific cost implications. These will take your breath away.
To begin, you need to address the question: how much storage do you need to buy for California to get to an 80% renewable, or 100% renewable, system? Assume that you buy enough windmills and solar panels to provide an amount of electricity that is, in the aggregate, equal to what California consumes in a year. But unfortunately, this system will not provide the electricity when you need it. At noon on a windy day in the summer, it might provide five or ten times what you need, and on a calm night it will provide nothing. So you just need to buy enough batteries to store the excess power when it is produced, and to release it when it is needed. How much could that be? Three days' worth? Five? Maybe a weeks' worth?
It turns out to be far worse than that. Unfortunately, the inputs from wind and sun in California turn out to vary not just intra-day or week, but seasonally. There is hugely more wind and sun available in the Spring and early Summer than in the Fall and Winter. You actually need something like a two and a half months' worth of battery storage, to be charged up in March through August and then drawn down from September to February. Here is a chart of the seasonality of California's wind and solar generation that the Clean Air Task Force put together using data from the California ISO:
Do a little arithmetic with this chart, and you will find that the average monthly generation is 2,400,000 MWH; but to deliver that amount equally per month throughout the year without any other source of backup, you will need to have 6,200,000 MWH in storage at the end of August in order to carry yourself through February.
So how much storage would California need to get to an 80% or 100% renewable system?
The Clean Air Task Force, a Boston-based energy policy think tank, recently found that reaching the 80 percent mark for renewables in California would mean massive amounts of surplus generation during the summer months, requiring 9.6 million megawatt-hours of energy storage. Achieving 100 percent would require 36.3 million.
Current prices for big battery packs are running around $200 per kWh. (A December 2017 piece at Clean Technica titled "Batteries Keep On Getting Cheaper!" gives a current average price of $209/kWh, and predicts a 2025 price of more like $100/kWh. You can believe that if you want.) At $200/kWh, the 9.6 million MWH of storage will run California about $1.9 trillion (with a T); The 36.3 million MWH for a 100% system will be $7.2 trillion. Cut those numbers in half if you believe the battery price will go down to $100/kWh. For comparison, the annual state budget of California is running at about $200 billion (with a B).
Temple of the MIT Technology Review then translates these numbers into a cost per unit of electricity:
Building the level of renewable generation and storage necessary to reach the state’s goals would drive up costs exponentially, from $49 per megawatt-hour of generation at 50 percent to $1,612 at 100 percent.
He doesn't give backup for his calculation, and it looks rather low to me. But assume it is right. $1,612 per MWH is $1.612 per kWh. That's just for the storage system. Presumably you need at least another $.10 per kWh for the generators (windmills and solar panels) and the delivery system. Given that the average cost of electricity to consumers in the U.S. is currently about ten cents per kWh, we are talking about multiplying that cost by around a factor of 17! (And that's assuming that you can actually buy that much battery capacity, and that all those batteries would actually work at scale to keep the entire state of California running for months on end.)
Temple concludes by quoting Jesse Jenkins of the Clean Air Task Force:
“The risk,” Jenkins says, “is we drive up the cost of deep decarbonization in the power sector to the point where the public decides it’s simply unaffordable to continue toward zero carbon.”