Grid-Scale Storage of Renewable Energy: The Impossible Dream

According to a study conducted by "Energy Matters," a group started by Euan Mearns, entitled Grid-Scale Storage of Renewable Energy: The Impossible Dream, available online at, providing firm power from wind and solar for a year in conditions with variability for the year 2016 in England and Scotland, would require about 390 watt-hours of storage per average watt of installed capacity, or about 70 watt-hours per peak watt. Total energy consumption in Britain, in electricity equivalents, for 2015, was 1610.75 TWe-hours. Solar and wind provided about 40 TWe-hours electricity (and nothing for transport or any of the non-electric uses for industry, commerce, domestic...). The rest was provided by coal, oil, gas, nuclear, hydro, which have capacity factors of about 90%. So total average electricity-equivalent capacity was 1755 GWe. Using Mearns's 390 Wh/W factor, 680,518 GWe-hours of storage would be necessary to provide 1755 GWe firm power in an all-electric all-renewable energy system, with 2016 variablilty, in England and Scotland.

The Big South Australian Battery has a capacity of 0.129 GWe-hr. The 2019 price for a Tesla PowerWall-2 battery is $0.578 per watt hour. At that price, it cost $74,562,000. Maybe Tesla gave South Australia a volume discount. At 0.129 Gwe-hr each 5,275,334 of them could have assured an all-electric all-renewable British energy system with firm power if the yearly variation were as in 2016. At an estimated cost of $50 million for the BSAB, the cost would be "only" $393,339 BILLION! And lithium batteries only last five years or so. So the cost would be about $78,668 billion, every year for storage alone! British GDP for 2016 was $2,619 billion. So Britain would need "only" 30.04 times their 2016 GDP, every year, for batteries alone! Using heat pumps for space heating and moderate-temperature industrial processes, electricity for transportation, etc., would result in lower requirements -- but still too much to contemplate realistically.

In a similar study entitled Geophysical constraints on the reliability of solar and wind power in the United States, Shaner et al used 36 years of geophysical data for all of North America, with one hour resolution. Their conclusion was that storage capacity of 400-800 watt hours per average watt (Wh/W) of wind and solar capacity would be required for firm (99.97% available) power.

Norman Rogers reached a similar conclusion in Is 100 Percent Renewable Energy Possible? Using data from Texas, he calculated that storage capacity of 400 Wh/W is needed.

I made a rough calculation and concluded that an all-nuclear mostly-electric US energy economy, using heat pumps instead of resistance for space heating and some medium temperature industrial processes (food, plastics), direct reactor-core heat for industrial processes up to 1000 degrees Fahrenheit, electricity for higher-temperature processes (steel), and making liquid hydrocarbon fuels for ships, airplanes, heavy construction, and farming, would require average capacity of 1,700 GWe. So an eventual American economy that succeeded in making that transition would have about the same requirements, and would need five million or so of those big batteries -- maybe somewhat fewer because of our different climate conditions. US 2016 GDP was $18,570 billion. We would be spending about at least 3.95 times total 2016 GDP (using Mearn's estimate) or maybe 8.1 times total 2016 GDP (using the estimate from Shaner et al) for batteries alone, every year! Without nuclear, and therefore without direct reactor-core heat for industrual processes, more would be needed.

How much storage will be needed when we have another eruption like Tambor, which gave us 1816, the "year without a summer?"

Over-reliance on wind and solar is starting to look not only prohibitively expensive, but positively dangerous!