Guest Post by Willis Eschenbach

I’ve been reading some folks’ claims about how batteries are the key to a bright green renewable future. Of course, we wouldn’t need batteries if we didn’t try to depend on unreliable, intermittent sources like solar and wind, but let’s set that question aside for the moment.

A number of ways of storing energy exist that allow us to generate electricity as needed. Batteries, pumped water storage, compressed air, electro-mechanical flywheel systems, electro-chemical “flow batteries”, all are in use in various locations. And there are “intermittent flow” systems, which although they are not storage, allow for greater generation at certain times … including Niagara Falls, where the flow over the falls is reduced at night so more power can be generated when it’s not masquerading as a tourist attraction. Not storage … but pretty cool nonetheless …

Figure 1. Niagara Falls, minus the water.

Setting Niagara aside, I thought I’d look at how much energy storage exists in the world. Here’s a list of all of the world’s energy storage systems, by type.

Figure 2. Global energy storage systems, with capacity in terawatt-hours.

I love science because I am constantly surprised. In this case, the surprises are how much bigger pumped hydro storage is than all the others. The sum of all other systems is about a twentieth of the pumped hydro storage.

The next surprise was where lithium ion batteries, the Tesla Powerwall style of batteries, fall on the list … second from the bottom.

Being curious, I thought I’d look at just the US storage systems. Figure 3 shows that result.

Figure 3. As in Figure 2, but for US energy storage systems, with capacity in terawatt-hours.

The US pretty much mirrors the rest of the planet. Mainly pumped hydro, not much lithium ion batteries.

Now that looks all impressive … but is it really? So I thought I’d compare the electrical energy storage shown in the figures above with the amount of electricity consumed in one single day. I started by looking at the globe as a whole in Figure 4.

Figure 4. Global energy storage system compared to global daily electricity consumption.

Hmmm … doesn’t look at that impressive compared to even one measly day’s electricity usage. For example, all of the lithium ion “Tesla-style” batteries in service would only supply the global electricity demand for … wait for it … two-hundredths of one second.

And once again, I looked at the corresponding US data as well, as shown below in Figure 5.

Figure 5. As in Figure 4, but for US energy storage system compared to US daily electricity consumption.

Proponents of solar and wind power will be glad to know that lithium ion batteries can power the US for about 50% longer than the global average … which is to say, they hold about three-hundredths of one second’s storage for the US, rather than two-hundredths of a second for the world.

Now, looking at this, you’d be tempted to think, wow, we could do it all with pumped hydro energy storage. But pumped hydro has some huge disadvantages:

• To do it you need the proper geographical setup, with hills, a water source, and a place to dam up a valley to make a storage lake.

• Such sites exist, but they are few and far between. And a number of countries have no such sites.

• Often, such sites have roads, towns, or other immovable things of value located where the proposed storage lake would go.

• Even if there are no towns or roads in the proposed location, in California, as in many other locations, it’s basically impossible to put in any new dams, because feelings. The ever-so-green liberals, the ones insisting on intermittent energy sources that require backup, don’t want us to drown some worms and make some squirrels and cute bunnies move to the next valley over to create the backup they demand—that would be krool to nature.

• Good sites are often very far from where the power is needed. You can put a conventional power plant, or even a Tesla-style battery, next to a city where the power need exists … but you generally can’t do that with pumped hydro. So you end up with very large transmission costs and transmission losses.

• Pumped hydro is not all that efficient. You only get back about 70%-80% of the energy that you put in …

• The best sites are far too often already in use.

Subject to those constraints, pumped hydro storage is the best of our to-date bad choices. Some new ones will probably be created, but likely few and far between.

So that’s the current state of play in the world of storing energy to generate electricity. Short version? We are a long, long way from batteries or other storage systems being able to hold and deliver enough energy to do anything larger than balance out short-term fluctuations in energy supply versus demand.

My best to all,


Post Scriptum: As always, in the spirit of avoiding misunderstandings, I ask everyone to quote the exact words that you are discussing. That way we can all be clear on exactly what and who you are responding to.

via Watts Up With That?

2021 June 15