Why This NASA Battery May Be The Future of Energy Storage

What do you do if a satellite runs out of batteries? It’s prohibitively expensive to send a team into orbit and pop in some new AAs, and as a result many satellites use very efficient, reliable and long-lived nickel-hydrogen batteries. We’re talking about batteries that may last decades. That sounds like the sort of battery that could revolutionize grid-scale energy storage and really help out renewables back here on Earth, which is why EnerVenue is backing nickel-hydrogen batteries as the next step forward! But if batteries rugged and powerful enough for spacecraft already exist, then why haven’t we used it back here on Earth until now?

This scuba-tank-esque device is a nickel-hydrogen battery (NHB), a member of the metal-hydrogen battery family, and it could revolutionize renewable energy and grid scale storage. The unique chemistry and engineering of these batteries can allow them to retain 86% of their capacity after 30,000 cycles, or roughly 30 years, with zero maintenance to boot.¹² Better yet, these batteries are extremely temperature tolerant, able to work just fine in the temperature extremes of space.¹

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Modern designs boast 560 watts, so it’s no slouch on power either, and like other battery-based grid storage solutions we’ve examined, they scale quite easily.² All you have to do is just daisy-chain some more batteries together to suit your needs.³ But why are we only dusting off this practically ancient NASA design now? And if this battery is so great, why has it been relegated to probes and satellites so far? And where the heck did this thing even come from?

Founded as a result of space race tensions on President Kennedy’s orders, COMSAT Laboratories was tasked with exploring satellite communications for the US government. In 1970 they began experimenting with nickel-hydrogen batteries by combining the best parts of metal-hydrogen batteries and fuel cells. Precursors like nickel-cadmium power cells and hydrogen-oxygen fuel cells were already proven pieces of aerospace tech, so pushing the envelope by combining these and other pieces of tech wasn’t mad science as much as it was a logical leap forward.⁴

The result was an incredibly long-lived, energy dense and low-maintenance battery prototype, ideal for satellite-type applications. A few more successful tests and some optimization later, and the battery was passed along to COMSAT’s sister organization, INTELSAT. By 1975, the organization successfully launched the Naval Research Laboratory’s navigational satellite, the NTS-2, equipped with a nickel-hydrogen battery. And the batteries have been popular ever since, powering everything from the ISS, to the Hubble Telescope, to the Mars Rover. And the rest is history…¹⁴

…Or at least, it was, until EnerVenue saw it as a potential solution for grid scale storage issues. But if these batteries are perfect for grid scale storage, then why hasn’t anyone used these nickel-hydrogen batteries in this kind of an application until now? To explain that, let’s talk about how nickel-hydrogen batteries work, and why they might be able to do more good here on Earth.

Pros, Cons and Applications

The nickel-hydrogen battery combines the positive nickel electrode of a nickel-cadmium battery and the negative electrode, including the platinum catalyst and gas diffusion elements, of a hydrogen fuel cell.¹ The secret sauce is highly pressurized hydrogen gas. Like, very highly pressured, usually 500 to 1,500 pounds per square inch at max charge.¹ For comparison, your car’s tires should be clocking in at just 33ish PSI.

Is such an insanely high PSI necessary? Yes, chemically and mechanically — The high PSI can significantly increase the energy density of the battery, which indirectly improves the energy efficiency by allowing the batteries to store more energy for a given volume. Without going too deep into the chemistry, higher pressure means more hydrogen gas, and more hydrogen gas means a higher propensity for the reaction to occur. The pressure also makes the hydrogen more mobile and available, which results in better stats for the battery.

The electrode is also a porous structure, so a higher pressure of the battery means the electrolyte can also better “squeeze” into the pores of the electrode to react. This is desirable because when it comes to new battery tech, density is often the name of the game. We want to be able to store the most amount of energy in the least space possible.⁵⁶⁷

So, by highly pressurizing the hydrogen we make the battery denser, both physically and energetically. Still, I don’t know if I’d want something so highly pressurized in my car or phone… not that a battery the size and shape of a scuba tank could fit in my phone, but ‘y’know.

For all this talk of density, nickel-hydrogen batteries are still only about ∼140 Wh/kg, so they aren’t as energy dense as lithium ion batteries at around 260 Wh/kg.³ That’s precisely why lithium ion is starting to edge nickel-hydrogen batteries out of aerospace.⁸ That’s okay, though, because stationary storage applications have space to spare and don’t care a whole lot about energy density. There’s a lot of other benefits to these batteries, too. Lithium ion is temperature-sensitive and ideally likes room temperature ranges. Nickel-hydrogen on the other hand can handle the temperature extremes of Mars and space, so it will have no problem with the hottest and coldest temperatures on our planet.⁹¹⁰ Like some of the other grid-scale tech we’ve seen, this doesn’t require a heating or cooling system like lithium io does, which in turn could offer additional savings.¹¹ You build out a system in the middle of the desert and not have to worry about any maintenance or heating issues.

You also don’t have to worry about thermal runaway like with lithium ion batteries.¹²¹³¹⁴ Hydrogen is still flammable and reactive. I mean, look at the sun — this stuff has to be handled responsibly. However, it’s lighter than air and dissipates quickly into non-flammable concentrations when it escapes confinement, and hydrogen fires produce a lot less ambient heat than comparable hydrocarbon fires. Industrial designs can help direct hydrogen up and away in the case of an unexpected release.^{15 16 17} That’s not to diminish the fire concern, but safely managing hydrogen is absolutely possible.

The other big safety concern is the high pressurization of the hydrogen gas. Though it sounds like these batteries could explode like the scuba tank in the climax of “Jaws,” that isn’t the case. In testing, EnerVenue deliberately perforated their batteries with nails and even a variety of firearms. They observed no explosion, no fire, and no materials were ejected from the battery — not even the bullets! Also, during these tests the surface temperature of the cell topped out at a reasonable 44 C (or 112 F), and both the pressure and voltage dissipated as soon as the battery was perforated. So no explosion, the hydrogen dipped out safely, and neither the heat nor the electricity could start a fire.¹⁸ That’s a solid safety report card! This is backed up by a 2017 test from NASA, showing that even in the event of a “hypervelocity impact,” NASA’s nickel-hydrogen batteries didn’t “catastrophically rupture” or experience an “unusual thermal event.”¹⁹

While we’re on the subject of how rugged and forgiving the nickel-hydrogen chemistry is, I should also mention that there’s no dendrite formation with this chemical formula. Dendrites are tiny, spiky, metal structures that accumulate on a battery’s anode during charging. Repeated charge cycles can cause the dendrites to grow, eventually causing short circuits that can lead to fires or other battery failures. As a result, they’re a major limiting factor when it comes to the lifespan of batteries, especially the ever popular lithium-ion batteries, but they don’t form in nickel-hydrogen batteries.That’s a big part of the reason why NASA and EnerVenue call these batteries low maintenance or virtually “maintenance-free.”

Low maintenance is a big deal, because their aforementioned pressurization requires a hermetic seal. In other words, cracking one open for some quick repairs just isn’t an option.¹⁴ And because most of the chemicals in there are hydrogen and water, they’re relatively non-toxic too.¹¹ Always nice when we’re trying to be more environmentally friendly.

The simplicity of the chemical reaction and lack of moving parts also means that this battery is pretty easy to manufacture. EnerVenue claims their version only requires about 20 unique components.²⁰ Hydrogen is famously the most abundant element in the whole dang universe,²¹ and nickel is fairly abundant on all major continents. This eases the supply chain and costs issues of nickel-hydrogen batteries compared to other new battery technologies.²²

That said, the price of nickel surged 250% in 2022. It was only for a couple days, but still it forced an unexpected halt to trading, and it could happen again despite nickel’s abundance.²⁰ However, EnerVenue’s batteries can last 30,000 cycles, or about 30 years of daily use, and a long-lived battery means less batteries that get thrown away or need to be recycled.²¹² Plus, when the time comes, EnerVenue claims their battery is almost 100% recyclable.²³

A lot of the cost of solar plants come from maintenance, up to a third, so the “set it and forget” nature of NHBs are expected to be a huge operational cost saver for renewable energy storage facilities.²¹ Which is good, because as you might’ve guessed by now, all these great features come at a price, a very high price.

Perhaps unsurprisingly for technology designed for spy satellites and deep space probes, nickel-hydrogen batteries are very expensive devices. The cost is so intense, it’s the main reason we haven’t used the tech on earth very much. It’s been a financial limiting factor, not a technological one. Despite possible cost savings from the lack of maintenance, the commonality of nickel, and other features, these batteries prominently feature pricey platinum or palladium.²⁰ If you’ve ever been unfortunate enough to have your catalytic converter stolen, you’re probably all too familiar with how expensive these metals are. We don’t have to give up on these incredible batteries yet, though because EnerVenue believes it’s found a way to make nickel-hydrogen not just cheaper, but even cost competitive with the market-dominating lithium ion batteries.²⁴

Future Implications

The company is attacking the cost issue on two fronts. Firstly, it’s using the economy of scale and mass production to bring down the price. Now, don’t get me wrong, these are still expensive batteries, but with a one-million square foot “gigafactory” putting together tons of them, they’ll no longer be the bespoke-custom-design kind of expensive.²⁵ That factory is almost ready, by the way. It’ll be complete and enter phase one of production in the first quarter of 2024.¹⁴²⁵

On top of this, EnerVenue has already signed 805 megawatt-hours worth of firm orders. Not many in the battery space can boast similar success stories before they’re even open for production, but then again, nickel-hydrogen batteries are a proven piece of tech that’s been around for years. ²⁰ So it’s not a risky bet if the price is right.

As we so often find on this channel, mass production and standardization really tempers some of the most expensive parts of the design and machining process. Will mass production alone make nickel-hydrogen batteries cost-competitive with lithium batteries? No, but lithium doesn’t scale up very well, and these guys do. In theory, this will make nickel-hydrogen batteries cost competitive in large, grid-scale circumstances, which is exactly where we need them most.²⁶

But assembly lines and standardization can only get you so far when the components themselves are expensive. Hydrogen, though abundant, has to be separated from other components before it can be used. There’s variety of ways to do this, but the least expensive methods are also the least environmentally friendly.²⁷ And there’s still the problem of very pricey platinum or palladium being a key component in these batteries.²⁸

At the time of writing, platinum clocks in at around $1,000 per ounce,²⁹ and palladium at over $1,300 per ounce.³⁰ For large scale projects like, oh, maybe a grid scale storage plant, we’re gonna need A LOT of these precious metals. EnerVenue has been working on this pain point as well, and it’s replaced the platinum anode inside a NHB with something else. What? We don’t know for sure, but there are some good clues. That information is proprietary, but it was developed by Stanford materials science professor Yi Cui, a prolific researcher in the sustainability space.

EnerVenue claims that Cui’s design is compatible with mass production, is cheaper than platinum, works better, and makes the battery generally easier to produce. And EnerVenue’s tech was successfully commercially deployed in 2022.¹¹ Research from Stanford, some of which professor Cui was involved in,³¹ has demonstrated that replacing a nickel-hydrogen battery’s platinum catalyst with a bifunctional nickel-molybdenum-cobalt alloy catalyst could reduce the cost to just $83 per kWh.³ The United States Department of Energy (DOE) has a target of $100 kWh for grid storage, so this achieves that milestone. Is this the new catalyst that Enervenue is using? Again, we don’t know for sure, but it at least proves that cheaper alternative catalysts, like the kind Enervenue claims to be using, are not theoretical or just hype. That said, I can’t help but remain a little skeptical about this development until we know exactly what Professor Cui’s mystery material is, and its effectiveness and cost has been verified.²⁰

So, are our energy storage problems solved? Maybe. There’s still plenty of known-unknowns — like whether developers can successfully hook up these funky batteries to form large-scale storage plants as EnerVenue claims. Similarly, utility companies are often change-averse, and for good reason. As long as the power is flowing, their customers are happy, but anything that threatens that state of order could lead to big trouble.

Are these companies ready to adopt something so out of the ordinary (even a long proven piece of space technology)? It remains to be seen, but if these batteries work as advertised and the utilities do adopt them, then the biggest albatross around the neck of renewables could disappear. A cheap, durable, long-lasting, cost competitive way to store (and easily “un-store”) mass amounts of renewable energy? That’s the dream, and thanks to EnerVenue, it might be closer than we think.