Utility scale energy storage has a long way to go to make renewables possible

What follows comes from my book When Trucks Stop Running: Energy and the Future of Transportation , which is also where you’ll find the references backing up what I’ve written below.

I often get letters from people about energy breakthroughs in biofuels, solar, electric trucks, and so on. This post is about the “record breaking amount of battery storage add in 2018” (go here to read the article).

To enhance your own evaluation of the constant barrage of happy news in the media, here’s why I didn’t get excited or cheered up and go back to thinking the future was bound to be bright and shiny.

First, let’s go over the four possible ways to store electrical energy. We don’t need to store much now, because we still have natural gas, which kicks in to balance solar and wind power (but not coal and nuclear, which are damaged by trying to do this), and for much of the year provides 66% of electricity generation (along with coal), because wind and solar are so seasonal.

So if the grid is to be 100% renewable someday, which it has to be since the 66% of power coming from fossil fuels now to generate electricity is finite, then utility scale energy storage is essential Let’s look at what it would take each of the four methods to store just one day of U.S. electricity generation, 11.12 Terawatt Hours (TwH).

The only commercial way to store electricity is pumped hydro storage (PHS), which can store 2% of America’s electricity generation today. But we’ve run out of places to put new dams. Only two have been built since 1995. There are only 43 PHS dams now, and we’d need 7800 more to store one day of U.S. electricity.

The only other commercially proven way to store electricity is compressed air energy storage (CAES). But we only have one small 110 MW plant in Alabama. This is because they must be located above rare geological salt domes 1650-4250 feet underground that only exist in 3 gulf states and a small part of Utah, and they use quite a bit of fossil fuels to compress the air.

Then there’s Concentrated Solar Power with Thermal Energy storage (TES). But these plants only contribute 0.06% of our electricity and most don’t have any TES. The billion dollar Crescent Dunes plant is one of the few that does have TES. We’d need 8,265 more of them to store one day of electricity.

So that leaves batteries. As I mentioned above, the March 2019 article “US Energy Storage Broke Records in 2018, but the Best Is Yet to Come” gushes about the record deployments of energy storage batteries in 2018 and the expectations that even more will arrive in 2019 and thereafter.

But don’t get too excited. The total storage capability of the 2018 batteries was only 777 Megawatt Hours or 0.000777 Terawatt hours (TwH). Every day the United States generates 11.12 TwH, so to store one day of electricity generation would require 14,311 times more batteries than the ones installed in 2018.

On top of that, because wind and solar are so extremely seasonal, and there’s no national grid or ever likely to be one, on average a region would need to store at least 42 days of electricity to make it through long periods when the wind isn’t blowing and the sun isn’t shining. That’s 600,000 times more batteries than installed in 2018.

There are three possible candidates for utility-scale energy storage: NaS (sodium–sulfur), advanced lead–acid (PbA), and lithium-ion. As with advanced auto batteries, there are challenges:

  • Storing energy in a battery is no free lunch. Energy is lost due to heat and other inefficiencies. Roundtrip efficiency defines how much energy is lost in a “round trip” between the time the battery is charged and then discharged. Batteries lose 10–40 % of the energy generated due to roundtrip efficiency losses, so to produce 11 TWh would require generation of between 12.1 and 15.4 TWh to make up for losses (depending on the battery technology used).
  • Lead–acid batteries take five times as long to recharge as to discharge.
  • Battery lifespan is reduced if charged or discharged beyond optimal range.
  • Li-ion are more expensive than PbA or NaS, can be charged and discharged only a discrete number of times, can fail or lose capacity if overheated, and the cost of preventing overheating is expensive. Lithium does not grow on trees. The amount of lithium needed for utility-scale storage is likely to deplete known resources (Vazquez et al. 2010).

Using data from the Department of Energy energy storage handbook, I calculated that the cost of NaS batteries capable of storing 24 hours of electricity generation in the United States came to $40.77 trillion dollars, covered 923 square miles, and weighed in at a husky 450 million tons.

Sodium Sulfur (NaS) Battery Cost Calculation: NaS Battery 100 MW. Total Plant Cost (TPC) $316,796,550. Energy Capacity @ rated depth-of-discharge 86.4 MWh. Size: 200,000 square feet. Weight: 7000,000 lbs, Battery replacement 15 years (DOE/EPRI p. 245). 128,700 NaS batteries needed for 1 day of storage = 11.12 TWh/0.0000864 TWh. $40.77 trillion dollars every 15 years = 128,700 NaS * $316,796,550 TPC. 923 square miles = 200,000 square feet * 128,700 NaS batteries. 450 million short tons = 7,000,000 lbs * 128,700 batteries/2000 lbs.

Using similar logic and data from DOE/EPRI, Li-ion batteries would cost $11.9 trillion dollars, take up 345 square miles, and weigh 74 million tons. Lead– acid (advanced) would cost $8.3 trillion dollars, take up 217.5 square miles, and weigh 15.8 million tons. These calculations exclude the round- trip losses. It is even more expensive if you take round-trip efficiency into account. NaS batteries have a round-trip efficiency of 75%. That means the U.S. would need to increase generation capacity by 33% (1/0.75−1). So it’s not just the cost that is prohibitive, we would need an insane amount of wind and solar to charge these goliath battery storage farms.

These batteries are so large that most of them will literally run out of the materials needed even if all of that mineral only was devoted to energy storage batteries. Barnhart looked at how much material and energy it would take to make batteries that could store up to 12 hours of average daily world power demand, 25.3 TWh. Eighteen months of worldwide primary energy production would be needed to mine and manufacture these batteries, and material production limits were reached for many minerals even when energy storage devices got all of the world’s production (with zinc, sodium, and sulfur being the exceptions). Annual production by mass would have to double for lead, triple for lithium, and go up by a factor of 10 or more for cobalt and vanadium, driving up prices. The best to worst in terms of material availability are CAES, NaS, ZnBr, PbA, PHS, Li-ion, and VRB

And these batteries aren’t cheap. Assuming a constant per-energy-unit battery price of $209/kWh, the system costs vary from $380/kWh to $895/kWh. So 777,000 kwh worth of these batteries cost from $295 million to $695 million dollars (Fu, R., et al. 2018. 2018 U.S. Utility-Scale PhotovoltaicsPlus-Energy Storage System Costs Benchmark. National Renwable Energy Laboratory).

Yet we need over 14,000 times more battery power to store just one day of U.S. electricity generation, 600,000 times more for 6 weeks of storage.

Alice Friedemann   www.energyskeptic.com  author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report

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2 Responses to Utility scale energy storage has a long way to go to make renewables possible

  1. Mark says:

    Thanks for highlighting the issues still to be resolved.

    I followed the solar link to your CSP post from back in 2015 that highlighted the less than stellar performance of CSP. It a tad unfortunate that the capacity factors still suck for the technology in the winter months.


  2. NJF says:

    I can tolerate the bad ideas, the misplaced idealism proposed by the “tech break though” media and their armchair science reporting.

    But what drives me insane is that you NEVER see anyone out there (besides basically some WordPress blogs like this one) saying that it is NOT a certainty that we can outfox this.

    I have discussed with my friends – engineers, PhD scientists, etc. – about the contents of this blog. Their wishful thinking gets in the way of absorbing any of the arguments I make. They have already decided they are not amenable to having their minds changed. Too much feel good crap being pumped out every day has clouded their reasoning.

    And these are extremely scientifically literate people.

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