Unlike most goods, electricity has to be consumed the moment it is produced. That is what makes “dispatchable” energy sources so vital: the source (nuclear, coal, natural gas) can produce electricity right when it’s needed to.

Not being dispatchable is a key obstacle for renewable energy sources such as solar and wind. Such “nondispatchable” sources require dispatchable sources cycling as backup generation for when the sun dips behind the clouds or the wind dies down.

Sun and wind never align themselves with human demand for electricity, which is why once everything is factored in, solar and wind are the most expensive sources for reducing energy emissions.

energy costs brookings

For solar and wind energy to approximate dispatchability, then, they need battery storage. Energy stored in batteries is dispatchable. There is of course the idea that such a thing will be workable (here it comes) within a few years.

But that’s not even remotely possible:

The total amount of electricity stored at any given moment in all the batteries out there for all purposes is countable in minutes, not months, worth of annual demand.

Elon Musk has given us a way to illustrate the challenge to store power at grid levels. The astoundingly big $5 billion Tesla battery factory under construction in Nevada, the so-called “gigafactory,” is slated to produce more than all of the world’s existing lithium battery factories combined. For battery cognoscenti, that represents a quantity of batteries each year that can store 30 billion watt-hours of electricity. A big number. But the United States consumes about 4,000,000 billion watt-hours a year.

Thus the entire annual output of the gigafactory can store about five minutes’ worth of U.S. electric demand.

So one gigafactory, at a cost of $5 billion, when it is completed, would outproduce all the world’s existing supply of lithium batteries combine.

And it could store only about five minutes’ worth of U.S. electric demand.

Not only that, but:

Storing electricity in expensive short-lived batteries is not a little more expensive but tens of thousands of times more expensive than storing gas in tanks or coal in piles adjacent to idle but readily available long-lived power plants.

But we are promised that better battery technology will continually emerge. Of course it will. But as has always been the case with batteries, newer tech is more expensive. There is, by the way, a market ready to pay up, big time, for better batteries.

New battery technological breakthroughs have opportunity costs. If people wish to use them to store solar energy for use from dusk till dawn, they have to bid away other potential users of the technology for other purposes. Which means they will be expensive.

What else?

The cost of a battery in a smartphone measured in grid terms is $1,000 per kilowatt-hour of capacity. This illustrates the problem. The target price that grid-scale storage needs to reach, according to the Department of Energy, is under $100 per kilowatt-hour — and for a system far more complex than the power unit in your phone. And even that is still too expensive for commodity storage by at least 10-fold.

Consider one more example of the scale challenge for storing electricity. Cushing, OK, is home to one of the nation’s preeminent, and numerous, tank farms to store oil.

In order to build a ‘tank’ farm to store kilowatt-hours equivalent to the energy stored at Cushing, we’d need a quantity of batteries equal to 40 years of production from 100 gigafactories. Electricity is hard to store.

Remember about the coming, $5 billion gigafactory that would outproduce the world’s existing supply of batteries. Now imagine 99 more of them. Now take this hundredfold expanse of the world’s known battery production and calculate it out for 40 years.

Presto! You have finally reached the amount of energy in the oil stored right now just in Cushing, Oklahoma.

Basically, right now and for the foreseeable future, it will be much, much, much, much cheaper to store an energy source than it is or will be to store generated electricity.