Grid-scale batteries: They’re not just lithium

When size and weight don't matter, lots of other battery chemistries can work.

See full article...

 

[THT]

Fires vary in kind and quality. The public quite reasonably accept ordinary fires because they're (generally) easy to exinguish. Fires which are difficult to stop or contain without specialty equipment and extended firefighter presence are different. Fires which can be stopped early with handheld or even wheeled commercial extinguishers are not the same as self-sustaining fires requiring a well-equipped fire department even to contain.

No sprinkler system can halt lithium ion battery fires. They're wonderful devices of immense value to the modern world but frequency of fire is not kind and quality of fire. Common and commonly controllable fire is different from less common, difficult to control fire.

Have some NFPA: https://afdc.energy.gov/case/3133

The public accepts all kinds of hazards without blinking an eye. Some individuals will have issues, but if there is money to be made and it makes people go, the public will accept it.

Near us, an SUV decided to run through a fence and knock out a natural gas pipeline, and the pipeline caught on fire. Residents near it were evacuated, schools and businesses near it closed, people further out were under shelter in place orders. Since it was about 20 miles of LNG pipeline, apparently the shortest run to close off the pipeline, it burned for 3 days.

And this was after they tapped it in several places to install flaring towers to hasten the burn. Nary a concern from anywhere not in the immediate area.

The good thing about battery storage is that the technologies will get better. They will have chemistries more resistant to catching on fire. They will come with fire suppression technology. It will solve itself if it is a concern. Natural gas? Well, all avenues seem to be burning it for productive or unproductive purposes, or it just leaks into the atmosphere. The public unfortunately won't get that this is infinitely worse than a battery fire.

 

[afidel]

There are large battery plants in industrial UPS applications and they don’t use 18650 cells. The small cells are used in cars because they need the energy density, and they’re leveraging the enormous consumer market for small cells. But big batteries have been around for a long long time. Phone exchanges, industrial UPS, etc. have rooms full of racks with big batteries. And big batteries have a lot of advantages - manufacturing tolerances are looser, for instance.

Sure prismatic might we'll be the best middle ground, they're being increasingly produced for auto applications so they're well up the adoption curve. My point was that things that aren't mass manufactured are inherently much more expensive.

 

[beb01]

You don't need a mountain for pumped water storage.

https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant

 

[DDopson]

From the article for the sulphur-sodium flow battery: "The batteries are packaged in 20-foot-long shipping containers that has six modules that collectively provide 1.45 megawatt-hours, Brannock said. The shipping containers are usually used in groups of four."

Doesn't seem tenable for seasonal usage for a home, unless you have a couple of acres. Scale it down to 100 kWH, maybe it is as big as 2 or 3 refrigerators? And, batteries will need to provide enough power for air conditioners where I live. Delivering a lot of power isn't a strong feature for flow batteries.

Solar+storage + V2G will pretty much do it for your house though. Get yourself about 12 to 15 kW of solar, 40 kWH of battery (likely LFP for a while), and 80 to 100 kWH in your car, you are basically set for days to weeks on end. Cloudy to rainy for several days in a row, just go charge your car and you'd be set for two or more days, repeat until it is sunny enough. Assuming the grid is out for a long time, that is.

Your bigger problem with scaling down a sulpher-sodium battery is that you need to maintain it at a blistering 300C, which is hotter than most home ovens, and the square-cube law says that the insulation required to do that doesn't scale down very well.

 

[Phenolix]

These technologies are all very interesting, but what I don't see on any of them is numbers for $/MW and $/MWhr. I'd like to think that even in the research phase, there would be an eye towards the eventual at-scale cost targets.

What you really want to look for is the levelized cost of storage (LCOS) which takes all costs, life time, and the totalt amount of power stored/delivered into account.

 

[wagnerrp]

You don't need a mountain for pumped water storage.

https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant

No, but it sure does help to at least have a nice hill. The local terrain (and bottom of the reservoir) is 250ft above Lake Michigan, with the reservoir embankment built another 120ft above that.

It's ~$2.5B for ~20GWh, which is about the same cost as modern LiIon packs. Assembling those packs into a functional power station roughly doubles that cost, as does the operational maintenance cost of hydropower between 40yr major refurbishment cycles. Assuming the battery will just instantly stop working after its 15-20yr warranty period (it won't), that would put current battery systems at twice the cost of hydropower per storage-year at a site that had a large plateau conveniently overlooking a body of fresh water.

 

[DDopson]

Hawaii is also doing a lot with storage and trying to integrate countless individual small installations. The big deal is that without a lot of “spinning mass” keeping the grid stable is tougher, particularly when you have distributed generation and storage (e.g. houses with batteries) that isn’t centrally managed.

There’s a whole lot of research on Grid Forming Inverters that can supply reactive power and be dispatched.

There may be "research" on applying Grid Forming Inverters to home solar installations, but frequency regulation services has long been one of the core revenue sources for grid-scale battery installations. My understanding is that per MW of power capacity, batteries have 20:1 more leverage to regulate grid frequency than the passive stability provided be the inertia of a spinning turbine.

 

[Phenolix]

The article Projecting the Future Levelized Cost of Electricity Storage Technologies from 2018 has some very nice figures comparing various technologies. From the abstract:

 

[SpikeTheHobbitMage]

The Dead Sea is famously not fresh water.

The Dead Sea is part of a larger fresh water system that is vital to the region. Any significant filling would back-feed into the Jordan River, poisoning vital cropland.

 

[ThurstonBT]

The piece meets a 'tell' for fatuous poor-quality coverage of green topics -- it fails to provide cost per kilowatt hour.

 

[AngryEssay]

When size and weight don't matter, lots of other battery chemistries can work.

True. It's a whole different game if they do. The automotive sector revolution has always been just a few years away every year. But, if you don't have those requirements then you can do pretty amazing things.

 

[THT]

There may be "research" on applying Grid Forming Inverters to home solar installations, but frequency regulation services has long been one of the core revenue sources for grid-scale battery installations. My understanding is that per MW of power capacity, batteries have 20:1 more leverage to regulate grid frequency than the passive stability provided be the inertia of a spinning turbine.

Not sure I’d call it research. More like development phase or engineering validation phase at the grid level.

GETTING THE GRID TO NET ZERO Grid-forming inverters will take us to 100 percent renewable energy
“During the day, the local system operator, the Kauai Island Utility Cooperative, sometimes reaches levels of 90 percent from solar alone. But on 2 April, the 26-MW generator was running near its peak output, to compensate for the drop in solar output as the sun set. At the moment when it failed, that single generator had been supplying 60 percent of the load for the entire island, with the rest being met by a mix of smaller generators and several utility-scale solar-and-battery systems.
…
On that April day in 2023, Kauai had over 150 megawatt-hours’ worth of energy stored in batteries—and also the grid-forming inverters necessary to let those batteries respond rapidly and provide stable power to the grid. They worked exactly as intended and kept the grid going without any blackouts.”

Not gigawatt scale yet. Not sure what would the show-stopper be to scale up to gigawatt levels.

 

[Rick C.]

Other chemistries are interesting and can hopefully fill other niches more cost effectively than lithium chemistries. However, given that currently most grid storage batteries have lithium iron phosphate chemistries, the repeated assertion in the article like the one below is just coal hugger FUD.



The main exporter of lithium is Australia, a country not noted for forcing African children down lithium mines, and while the country’s politics can be quite feisty, it’s not exactly a conflict country. Oz is pretty big on iron exports as well, and phosphate is widely available and its usage in batteries is a rounding error as compared to what is used as fertiliser.

I noticed that. Two separate times within the article, the statements from the other battery chemistry guys alluded to materials coming out of regions with issues. With cheap LFP batteries, the Congonese warlords are screwed. We don’t need cobalt anymore. Or nickel. Just cheap and plentiful lithium, iron and phosphate How many lithium deposits suddenly popped up in the continental US in just the last 2-3 years? At least four sites, plus one in Canada. Together with other locations which are not China, I think we’ll be ok.

 

[real mikeb_60]

From the article for the sulphur-sodium flow battery: "The batteries are packaged in 20-foot-long shipping containers that has six modules that collectively provide 1.45 megawatt-hours, Brannock said. The shipping containers are usually used in groups of four."

Doesn't seem tenable for seasonal usage for a home, unless you have a couple of acres. Scale it down to 100 kWH, maybe it is as big as 2 or 3 refrigerators? And, batteries will need to provide enough power for air conditioners where I live. Delivering a lot of power isn't a strong feature for flow batteries.

Solar+storage + V2G will pretty much do it for your house though. Get yourself about 12 to 15 kW of solar, 40 kWH of battery (likely LFP for a while), and 80 to 100 kWH in your car, you are basically set for days to weeks on end. Cloudy to rainy for several days in a row, just go charge your car and you'd be set for two or more days, repeat until it is sunny enough. Assuming the grid is out for a long time, that is.

To be fair, the article was talking about grid-scale storage, not residential on a grand scale. Residential (usually with solar) storage currently uses some flavor of Li-based battery; LFP is fairly common in recent installations.

Your last paragraph illustrates "grand scale" for me. I have 3.5 kw of solar on my roof. Perhaps double that might fit if I use all reasonably available space. I probably can spare space in a side yard for 2-3 standard Powerwall modules or something similar - perhaps as much as 30 kwh but closer to 20 is more likely. I would not be able to interconnect with that much of either solar or storage, though, because interconnection is limited to 110% of recent (usually the past 3 years) of usage, and the solar I have now (without storage, but with Net Metering 1.0 that expires in 2030) covers 80-90% most years. V2G would be interesting if I could find a (edit: affordable for me) EV that does it (other than the Leaf); so far, not many, and an expensive option for the few that do. Granted, that's for only the 2 of us in a decently (but not up to current code) insulated small (by current standards, under 2000 sq ft) suburban house with a recent (about 5 years ago; gas heat and "Gold" rated a/c) HVAC system, gas cooking, and gas water heat.

I see numbers like you quoted, though, and see a retail system cost, installed, in the $100Ks in California especially if that includes the EV with V2G (the EV being around $100K all by itself); my simple little system (before tax credit) was about $14K. Your system seems to be scoped for a large rural property designed for off-the-grid operation most of the time. My own utility would refuse to allow that property to interconnect with their system, except under some kind of commercial distributed-generation tariff based on unlimited utility dispatchability of the production. I just don't see a more commonly-sized suburban or urban property needing that much power.

 

[DDopson]

I'd very much like to know how long term storage of hydrogen works.

Because it doesn't.

Hydrogen for cars is extremely stupid. I'm skeptical even for airplanes. But for electricity, it's paradoxically the cheapest path to zero emissions, a path that's currently blocked behind it being incrementally cheaper to pollute for that last few percent of residual unmet demand.

See my prior post near the top of page 2 for a description of the https://model.energy/ simulation that I've been using to model grid mix.

Hydrogen energy storage is currently too expensive to compete with burning natural gas, which explains why there zero of it in our current grid mix, but were we to enact a $50/tCO2 carbon tax, it would be economically efficient to use a mix of hydrogen infrastructure and gas peakers, and were we to demand a zero emissions grid, the solution including hydrogen infrastructure is only +10% more expensive than the lowest-cost polluting solution, versus it being +30% more expensive to sufficiently over-provision solar, wind, and batteries without utilizing any hydrogen storage.

That hydrogen storage can save money may seem paradoxical, given how horribly expensive it is to generate a MWhr of electricity from stored hydrogen that took as many as four MWhrs to produce. And the electrolyzers, compressors, and hydrogen turbines are all capex intensive.

But the alternative to that hydrogen infrastructure, which spends 12% of all capex satisfying the last 3.3% of residual unmet demand (in the model from my prior post), is to spend three times as much building out additional renewables capacity that will be curtailed >95% of the time (in addition to doubling the solution's battery capacity). That overbuilding isn't all that expensive in the big picture, but it's extremely expensive per additional MWhr satisfied. Or alternatively, you could continue using gas turbines, but then pay even more money to sequester the CO2, which is non-economical unless that gets a lot cheaper (turning on the model's CO2 sequestration settings is the same as disabling natural gas). Or a nuclear plant is of a similar cost per MWhr as carbon sequestration, but then you have to pay that higher rate on all of your power, not just the last 3.3%.

I can't tell you when it will make sense to deploy hydrogen infrastructure because that's closer to a political question than to a technical or economic one. As long as CO2 emissions are untaxed, it's cheaper for that last few percent of generation to pollute that to invest in long-term storage. For hydrogen to win in an unsubsidized market, I need to do something aggressive like dividing the model's electrolyzer capex by 4, compressor capex by 2, and making hydrogen turbines free under the assumption that we can burn it in the existing gas peakers. Most gas turbines do support up to 20% hydrogen in their fuel mix, so if electrolyzers really did get a lot cheaper, it's at least conceivable that green hydrogen could outcompete the cost of natural gas and be included in the fuel mix, which even though that's only 20%, it's a huge deal because it allows the hydrogen infrastructure to begin bootstrapping on a "learning curve", and the existence of an affordable large-scale green hydrogen market creates a bigger market for fuel cell development to enter and outcompete the turbines.

 

[DDopson]

What you really want to look for is the levelized cost of storage (LCOS) which takes all costs, life time, and the totalt amount of power stored/delivered into account.

Yes, if anyone published credible LCoS numbers for these technologies. Are you aware of any? That wiki link merely defines the term. Lazard definitely doesn't cover them. I've had to spitball my own guesses based on DoD reports and academic papers at least half a decade old. The companies cited in the article don't seem to share any pricing info beyond "20% cheaper than the previous model". Perhaps it's in one of the $7000 industry reports, but I haven't found much online.

 

[DDopson]

The article Projecting the Future Levelized Cost of Electricity Storage Technologies from 2018 has some very nice figures comparing various technologies. From the abstract:

View attachment 90861

That was an interesting read. They seem pretty bullish on Vanadium-flow batteries as a potential competitor to Lithium-ion. Pumped hydro slowly being outcompeted by battery technologies as time advances makes sense to me. The conclusions regarding hydrogen and flywheels seem pretty obvious, although I'm not sure there's enough of a gap in the "faster than batteries" segment for flywheels to find a lasting market.

 

[melbourne_mat]

Investor in Redflow here.

Redflow was placed in voluntary administration in Australia on August 23, 2024. (The US equivalent is probably chapter 11 bankruptcy?) https://redflow.com/asx-announcements

As a fellow Australian it was sad to hear this. Hopefully the technology will be bought but I'd guess that's a haircut for you. Perhaps by a company headquartered in the US to take advantage of the Inflation Reduction Act.

 

[cwolf]

Not really, to give a sense of perspective Iron flow batteries might only achieve 30Wh/L, a small fraction of the 210Wh/L of LFP but a standard olympic swimming pool is about 4M Liters so in a relatively small structure you can store 120MWh. The site of a small coal power plant near me that was recently cleared was 62 acres, you could fit 200 pools on that site or 24GWh of Iron flow battery. The power plant was only 250MW when it was operating meaning in the same footprint you can store about 100 hours of what the old plant could output. So land use is not going to be the limiting cost factor at grid scale.

Edit
I missed I decimal place, it's 24GWh, not 2.4, makes it even less of an issue

If you are using these for storage from solar generation is there any reason you couldn't just put the batteries under elevated solar panels and not need any additional land?

And is there any reason, where if you were needing to install someplace where footprint needed to be kept to a minimum that you couldn't just build up instead of out and stack batteries vertically?

 

[afidel]

If you are using these for storage from solar generation is there any reason you couldn't just put the batteries under elevated solar panels and not need any additional land?

And is there any reason, where if you were needing to install someplace where footprint needed to be kept to a minimum that you couldn't just build up instead of out and stack batteries vertically?

Sure, you could put both on the same footprint, but you generally wouldn't. Labor is such an expensive part of the project that it's better to put the solar panels on standard ground mounts and build and install the batteries separately. I was actually thinking about this and yes you'd build up, 20m tanks like are used for storing jet fuel or gasoline in tank farms would probably be the best storage solution since there's already a large industrial base for those and crews who know how to assemble them. My example was mostly to illustrate that ground costs would be a miniscule portion of the cost even with the least dense flow batteries.

 

[numerobis]

StorEn Technologies of Greenville, SC is developing a vanadium flow battery system that can address home residential as well as industrial and larger-scale projects. Vanadium flow batteries can be discharged 100% over and over without losing their capabilities, and they have an estimated lifespan of 25 years or more. Also the electrolyte can be recycled into new batteries and doesn't suffer from the costs required to recycle LiON batteries.

Vanadium is more expensive than cobalt. Using it to try to save on cost is ... dubious.

 

[numerobis]

That was an interesting read. They seem pretty bullish on Vanadium-flow batteries as a potential competitor to Lithium-ion. Pumped hydro slowly being outcompeted by battery technologies as time advances makes sense to me. The conclusions regarding hydrogen and flywheels seem pretty obvious, although I'm not sure there's enough of a gap in the "faster than batteries" segment for flywheels to find a lasting market.

Keep in mind that 2018 is six years ago.

Also, batteries have far faster response time than flywheels. If you want to buy a dedicated device that will respond multiple times per day, then maybe you'd choose a flywheel. That's going to be a dead market though; anywhere you might be tempted to use spinning metal, you're going to have installed large batteries nearby anyway. So just use the batteries that already exist to also provide the extremely fast response you need, rather than buying a separate device.

 

[afidel]

Vanadium is more expensive than cobalt. Using it to try to save on cost is ... dubious.

I read 6.3kg per kWh and knew it was DoA, way too much of a relatively expensive material.

 

[leonwid]

Hydrogen for cars is extremely stupid. I'm skeptical even for airplanes. But for electricity, it's paradoxically the cheapest path to zero emissions, a path that's currently blocked behind it being incrementally cheaper to pollute for that last few percent of residual unmet demand.

See my prior post near the top of page 2 for a description of the https://model.energy/ simulation that I've been using to model grid mix.

Hydrogen energy storage is currently too expensive to compete with burning natural gas, which explains why there zero of it in our current grid mix, but were we to enact a $50/tCO2 carbon tax, it would be economically efficient to use a mix of hydrogen infrastructure and gas peakers, and were we to demand a zero emissions grid, the solution including hydrogen infrastructure is only +10% more expensive than the lowest-cost polluting solution, versus it being +30% more expensive to sufficiently over-provision solar, wind, and batteries without utilizing any hydrogen storage.

That hydrogen storage can save money may seem paradoxical, given how horribly expensive it is to generate a MWhr of electricity from stored hydrogen that took as many as four MWhrs to produce. And the electrolyzers, compressors, and hydrogen turbines are all capex intensive.

But the alternative to that hydrogen infrastructure, which spends 12% of all capex satisfying the last 3.3% of residual unmet demand (in the model from my prior post), is to spend three times as much building out additional renewables capacity that will be curtailed >95% of the time (in addition to doubling the solution's battery capacity). That overbuilding isn't all that expensive in the big picture, but it's extremely expensive per additional MWhr satisfied. Or alternatively, you could continue using gas turbines, but then pay even more money to sequester the CO2, which is non-economical unless that gets a lot cheaper (turning on the model's CO2 sequestration settings is the same as disabling natural gas). Or a nuclear plant is of a similar cost per MWhr as carbon sequestration, but then you have to pay that higher rate on all of your power, not just the last 3.3%.

I can't tell you when it will make sense to deploy hydrogen infrastructure because that's closer to a political question than to a technical or economic one. As long as CO2 emissions are untaxed, it's cheaper for that last few percent of generation to pollute that to invest in long-term storage. For hydrogen to win in an unsubsidized market, I need to do something aggressive like dividing the model's electrolyzer capex by 4, compressor capex by 2, and making hydrogen turbines free under the assumption that we can burn it in the existing gas peakers. Most gas turbines do support up to 20% hydrogen in their fuel mix, so if electrolyzers really did get a lot cheaper, it's at least conceivable that green hydrogen could outcompete the cost of natural gas and be included in the fuel mix, which even though that's only 20%, it's a huge deal because it allows the hydrogen infrastructure to begin bootstrapping on a "learning curve", and the existence of an affordable large-scale green hydrogen market creates a bigger market for fuel cell development to enter and outcompete the turbines.

Would it be possible to convert abundant green energy not in hydrogen, but in methane? Use carbon-capture to create the methane, and after burning sequester the CO2. The process is more complex, but methane is a lot easier to handle and more energy dense.

 

[sjl]

Investor in Redflow here.

Redflow was placed in voluntary administration in Australia on August 23, 2024. (The US equivalent is probably chapter 11 bankruptcy?) https://redflow.com/asx-announcements

Former investor in Redflow here, and somebody who had one of their batteries in his home.

I love the idea of the tech. It makes a lot of sense to me. But zinc bromide has a bunch of issues; the biggest being dendrite formation when the zinc gets plated on its electrode. My battery died after only two or three years - manifesting as progressively worse discharging rates (it's supposed to be able to do 3 kW all the way down to empty; mine was only managing 800 watts towards the end); failure to come back from maintenance unless prodded (Redflow's solution to dendrite formation was to do a maintenance cycle every three days: fully discharge the battery, then scrub the electrodes to clear them of any remaining material); and eventually, complete failure to come back from maintenance, even when prodded.

Redflow offered me a replacement battery, or a buyback for what they were paid for it by the installer: $AU6600 (which gives you an idea of the cost for their 10 kWh unit, although I don't know if they're making any profit on that). I took the buyback. Then there was a battle to get them to remove the dead battery, which they eventually got done... one month before they went into administration. (I definitely dodged a bullet there. For what it's worth, the installer went bankrupt some time ago; it looks like mismanagement, basically - so Redflow was the only place I could go to get any sort of warranty satisfaction.)

They have a lot of work to do to convince me that they've solved the problems. My view of the company isn't helped by their commentary on the warranty issues being very light on detail, and what detail they did share not matching up with what I saw with my unit. If the upper management goes, I think there's a chance; but if they stick around, I doubt the tech will fly. Which would be disappointing, IMO, but that's where I see Redflow as being at.

 

[sjl]

My understanding is that per MW of power capacity, batteries have 20:1 more leverage to regulate grid frequency than the passive stability provided be the inertia of a spinning turbine.

Just look at the Hornsdale Power Reserve. It's been incredibly profitable in its provision of grid stability services (ie: artificial inertia), being able to respond extremely quickly to frequency fluctuations while other generators spin up to take over the load.

There's definitely room for batteries to take on that role; lithium ion in particular is extremely good at providing that burst of power for long enough to allow other batteries (or other energy sources) to come onstream and take over.

 

[dio82]

Vanadium is more expensive than cobalt. Using it to try to save on cost is ... dubious.

There isn't even any Cobalt in LiFePO4 battery chemistry. This chemistry can scale to arbitrary size without any problems. There are zero resource bottlenecks. Merely manufacturing bottlenecks.

 

[bjn]

I read 6.3kg per kWh and knew it was DoA, way too much of a relatively expensive material.

Surely that’s the solutions used to store the charge not the amount of vanadium?

 

[Factorial]

How are paper batteries doing these days?

I’d imagine that the performance is so so. But they can probably be made cheap, and hopefully without any metals in the anode or cathode. Then you can burn them once they’ve reached their end of life to get energy out of that, and the CO2 released is not “new”.

 

[David Woodward]

Just look at the Hornsdale Power Reserve. It's been incredibly profitable in its provision of grid stability services (ie: artificial inertia), being able to respond extremely quickly to frequency fluctuations while other generators spin up to take over the load.

There's definitely room for batteries to take on that role; lithium ion in particular is extremely good at providing that burst of power for long enough to allow other batteries (or other energy sources) to come onstream and take over.

There are also synchronous condensers for grid stabilisation. They are like an electric motor with no shaft. A few have been installed in South Australia recently. SA being a good test bed for renewable energy grids, with variable renewable energy “generation provided at least 70% of its total generation during half of the year in 2023”**, and renewables reaching 100% at times.

**
https://reneweconomy.com.au/south-a...e-boundaries-of-renewable-energy-integration/
https://en.wikipedia.org/wiki/Synchronous_condenser
https://www.energymagazine.com.au/sa-synchronous-condensers-installed/

 

[paulfdietz]

Vanadium is more expensive than cobalt. Using it to try to save on cost is ... dubious.

Annual world production of vanadium is only about 100,000 tons. It's mostly secondary production, so the production rate is not very elastic, not responsive to increases in price. And much of the production is from fossil fuel residues, like ash from combustion of petroleum and coal.

(USGS Mineral Commodity Summaries are a very interesting and comprehensive source for information of this kind.)

https://www.usgs.gov/centers/nation...n-center/commodity-statistics-and-information
https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-vanadium.pdf

 

[David Woodward]

StorEn Technologies of Greenville, SC is developing a vanadium flow battery system that can address home residential as well as industrial and larger-scale projects. Vanadium flow batteries can be discharged 100% over and over without losing their capabilities, and they have an estimated lifespan of 25 years or more. Also the electrolyte can be recycled into new batteries and doesn't suffer from the costs required to recycle LiON batteries.

Sumitomo MW/MWh scale vanadium flow batteries have been installed for over 20 years. There are other suppliers as well, it is a mature tech. Given the other comments in the thread, and given that the tech has been around this long and hasn’t taken off; I’m not sure vanadium flow has a huge future.

 

[paulfdietz]

Would it be possible to convert abundant green energy not in hydrogen, but in methane? Use carbon-capture to create the methane, and after burning sequester the CO2. The process is more complex, but methane is a lot easier to handle and more energy dense.

Direct air capture of CO2 would be too expensive, I think. If you are going to sequester the CO2, you might as well use that as the source of CO2 for manufacture of the carbon-carrying e-fuel. And you wouldn't make methane, you'd make methanol. This requires a bit more carbon per unit of stored energy but can be made with similar efficiency as methane, and is storable in cheap tanks as a liquid.

This sort of scheme has been looked at. The best approach appears to involve the following. When the hydrogen (one of the feedstocks for methanol synthesis) is created by electrolysis, also store the oxygen byproduct. The methanol is later burned by oxyfuel combustion in a CO2 turbine system (Allam cycle, although properly speaking the Allam cycle has an integrated air separation plant to get the oxygen; that is not needed here.) The CO2 is saved for later methanol synthesis.

So, this scheme involves storing three things: CO2, oxygen, and methanol. The first two are stored by liquefaction (and in the case of CO2, modest pressurization); the methanol is stored in above ground tanks. Overall, it may be competitive with hydrogen stored in surface pressure tanks. However, there's an efficiency hit, and I suspect it may not be competitive with artificial geothermal.

The mention of CO2 capture from combustion does raise the possibility of CO2 capture and sequestration from burning of natural gas. This has the problem of methane leakage, but it would enable current very cheap natural gas to continue to be used without CO2 emission.

 

[paulfdietz]

The article Projecting the Future Levelized Cost of Electricity Storage Technologies from 2018 has some very nice figures comparing various technologies. From the abstract:

View attachment 90861

Recent X/Twitter post from one of the authors of that study, with an animated version of the diagram:

https://x.com/iain_staffell/status/1722544993179504965
Li-ion batteries and hydrogen are squeezing out the competitors there (CAES, PHES, vanadium flow, flywheels.)

Note the author explicitly states they only include technologies with demonstrated cost improvement trends; otherwise, this would become an exercise in competing optimistic numbers from salesmen. So it's very possible a new technology will come along and demonstrate better costs that these.

DDopson: he links to a pdf of a book they have on this subject. I haven't read it, but maybe you'd find it interesting?

 

[David Woodward]

Well, just about the entire Basin and Range Province has suitable geography for pumped storage. The White Pine Pumped Storage project I linked before is to be located there, near Ely, Nevada.

This area is under crustal extension, estimated to have been roughly 100% since the start of extension. This causes faults that drop valleys and raise ridges ("horst and graben" geography). Almost anywhere is suitable for locating pumped storage.

I agree Li-ion price drops are placing pumped hydro projects in jeopardy. It's not clear the White Pine project will go forward now, given market realities.

There is an Australian National University study which has identified “616,000 potentially feasible Greenfield PHES sites with storage potential of about 23 million Gigawatt-hours”. Most are closed loop, off river. Combined with HVDC transmission, a lot of the world has potential.

Pumped hydro has the benefit of long term storage, overnight or longer.
https://re100.eng.anu.edu.au/pumped_hydro_atlas/

 

[David Woodward]

No mention of Form Energy's iron air batteries?

Their factory with a 500 megawatt production capacity is beginning production, and they just received a $150 million grant to scale up to 20 gigawatts of batteries per year by 2027.

https://formenergy.com/department-o...he-buildout-of-west-virginia-battery-factory/

I hope they do work out commercially; but, 35% round trip efficiency, and they need a water supply. Response time is (from memory) around 10 seconds; which is worse than pumped hydro, and means they can’t directly take part in some grid stability services, although their design includes Li-ion batteries as a buffer.

 

[David Woodward]

Pumped hydro energy storage is like 90% of the current global energy storage market. But its drawbacks are that it takes up a lot of space and needs mountains. California already has a few significant mountain reservoirs, but it needs those for municipalities and agriculture.

In Watt/hours, no doubt, but an argument has been made that BESS systems are catching up in Wattage.

“An often cited statement (I read this most recently in Prof. Mark Jacobson's book 'No Miracles Needed') is that PHES makes up 97% of installed grid storage. This was true just a few years ago in a MW sense but has been quickly outdated by exponential mathematics:

In 2020 17.6GW BESS vs 159.5GW PHES (90% PHES)
In 2021 27.3GW BESS vs 165.0GW PHES (86% PHES)
In 2022 44.9GW BESS vs 175.0GW PHES (80% PHES)
In 2023 89.2GW BESS vs 185.5GW PHES (68% PHES)
In 2024e 156.6GW BESS vs 196.6GW PHES (56% PHES)
In 2025e, the balance tips forever.”
https://www.linkedin.com/posts/mlkubik_energystorage-batteries-activity-7195671484004974593-nijT/

 

[raxx7]

There are also synchronous condensers for grid stabilisation. They are like an electric motor with no shaft. A few have been installed in South Australia recently. SA being a good test bed for renewable energy grids, with variable renewable energy “generation provided at least 70% of its total generation during half of the year in 2023”**, and renewables reaching 100% at times.

**
https://reneweconomy.com.au/south-a...e-boundaries-of-renewable-energy-integration/
https://en.wikipedia.org/wiki/Synchronous_condenser
https://www.energymagazine.com.au/sa-synchronous-condensers-installed/

Trivia about synchronous condensers:
In theory we could repurpose the generators of decommissioned power plants as synchronous condensers.