More stoked for when the same is said for storage.
Solar is cool but solar that can make it through the night and a couple cloudy days is way cooler
More stoked for when the same is said for storage.
Solar is cool but solar that can make it through the night and a couple cloudy days is way cooler
> Solar is cool but solar that can make it through the night and a couple cloudy days is way cooler
The fun part is that we're still well before the point when this even matters.
Almost 60% of the US grid is still fossil fuels, with around half of that still happening during the day. Which means you can get down to ~30% fossil fuels without any storage at all because all you do is go from burning fossil fuels during the day and at night to burning fossil fuels only at night.
> at night to burning fossil fuels only at night
only natural gas plants can do this. a coal plant cannot spin up just for the night and turn back off when the sun comes up - it's incredibly inefficient and probably causes more premature wear/tear too.
Full startup and shutdown of a coal plant can take days, but throttling down to about half power during low-load periods is normal. Power plants do this every day. Late at night, load decreases and plants throttle down. Every morning, between 0600 and 0900 local time, there's "morning load take-up" as load increases.
The big issue is what's called "ramp rate" - how fast can output power be increased or decreased? This tends to be around 1% to 3% of capacity per minute. See Figure B-2 in [1], which is a detailed discussion of how to improve your coal-fired power plant's ramp rate.
Natural gas plants have much higher ramp rates, and for batteries, it's under a second. Nuclear plants can be ramped up and down, slowly, but since it's all capital cost, cutting output raises the price of the power.
[1] https://www.epri.com/research/products/3002012979
"
"Increased rates of component life consumption due to thermal fatigue, mechanical fatigue and wear caused by differential thermal expansion comprise the bulking of cycling (costs)," according to the International Energy Agency's Coal Industry Advisory Board.
"Every time a power plant is turned on and off, the boiler, steam lines, turbine and auxiliary components go through unavoidably large thermal and pressure stresses," the National Renewable Energy Laboratory (NREL) wrote in a report on cycling costs published in April 2012.
"
https://www.reuters.com/article/business/energy/to-survive-c...
Yep, I live in Finland where we are quite far ahead of the curve when it comes to renewables and nuclear. This is one large problem. When it's winter and cold and dark, solar does not help. Wind only helps when its windy.
Batteries are coming, and will solve it, but it will still take time for them to be come cheap enough.
Only once we have ~7 days of storage (~100 GWh of storage) will we be able to get rid of the last fossil plants.
Yeah the US will lag behind on this.
Other countries are better positioned. e.g. UK has really spiky wind energy. Right this second more than half the grid is wind. Which is both cool and problematic for managing the grid.
Grid scale cheap storage would dramatic help manage that chaos
Other countries are better positioned already because they don't have an administration funded by the fossil fuel lobby - but even that doesn't explain some of the decisions, like preferring to reimburse $1 billion in already paid leases rather than letting a company build wind farms on the leased area (https://edition.cnn.com/2026/03/23/climate/trump-totalenergi...).
Spain suffered a black out partially due to the lack of momentum (spinning generators).
For Europe to get rid of more fossils without putting the grid at risk we will need more storage.
I surprised we can’t, or rather don’t, make more use of tidal energy.
That and low energy density storage located at sea with the turbines.
Hmm, how much of that is base load versus the dramatic rise of natural gas plants that respond to dynamic demands? Even in daytime, I think you need storage to get rid of those, right?
I don't know why this is downvoted. Solar and wind both essentially suck at anything other than baseline throughput. That doesn't mean they're useless, it just means that solar can't be our only solution unless we have, like... 30 breakthroughs tomorrow. We otherwise need something to handle spikes, which are both common and important, as well as periods when there is extended cloud cover even for typically-dark months.
Even if we handwave all the science needed to build batteries big enough to power cities for days, I don't think it's realistic to handwave the science needed to power a city for weeks. We don't even have enough oil for that.
"Power when it is inconvenient" is pretty much the basis for a modern society.
Solar panels still work just fine when it is cloudy, just with a lower output. And usually when it is cloudy it also tends to be a bit windy, so solar and wind nicely complement each other.
Heavy clouds and zero wind, for weeks? That's a once-a-century freak event. Just build gas peaker plants if you are worried about it. You could even add carbon capture, but constructing it might emit more than it will ever capture...
> Solar panels still work just fine when it is cloudy, just with a lower output.
I assume you never tried measuring the output of a solar panel when it's cloudy. It's 10-15% of a sunny day. Closer to not working than working.
Depends on the cloud. Where I live I routinely get 50% generation on a "cloudy" day.
On a rainy day that drops closer to 20%.
As an aside - cloudy days avoid a problem I have with shade. In winter, at 3:30pm, the sun goes behind a tree and my production plummets to near zero. If there's cloud cover the sunlight is far more dispersed and there's no "shade".
> On a rainy day that drops closer to 20%
And you’re still able to power your entire home? What if the rain lasts for a few days, which is pretty common in many places.
No, 20% is not sufficient to power the home. I'm still attached to the grid and use grid power even solar is too low.
Worst I've had over a day in the last few months on my home solar is about 25% of my maximum daily generation. It was one day in a very rainy week here in Brisbane Australia.
I did have one rainy day back in the middle of Winter that was 16% but that will end up being literally the worst day of the year.
That's every single winter where I live in the US. We don't have a word for it like the Germans do, though, we just call it January.
The good news is: you're on a national (or semi-national) grid, and conditions like that are more unusual than they are common across the USA.
You want us to transport energy 1500 miles? Cold, dark winters cover enormous swathes of the US - inconveniently, often at similar times. So what - we're turning Florida into a solar park so the rest of the nation can use that while they're dark?
Our energy grid can't currently handle the ability to charge electric haulers locally at any scale let alone to move an entire city's worth of energy, so the solution is not to 85x the national electric grid all at once.
I used to think the people who took this "America is too incompetent to make the green transition" stance were just downplaying the tech out of some combination of ignorance and weird partisan logic.
But to give them due credit, they believed in this vision and put in the hard work to make sure it became true.
> You want us to transport energy 1500 miles?
That's literally CCP state controlled communism !! More specifically, that's what the Gansu–Zhejiang UHVDC project has as an overhead transmission line length (2,370 km in international units).
* https://www.sciencedirect.com/science/article/pii/S014206152...
* https://www.bbc.com/future/article/20241113-will-chinas-ultr...
Carbon capture makes little sense until fossil fuels have been replaced. I guess there are some Bio char technologies that might change the equation a bit, but watt for watt, you need to replace your carbon emissions first (generally speaking)
A week of low solar and low wind is a yearly or every-couple of years event that you definitely need to solve for a completely renewable grid.
Keeping coal plants around is cheap to cover that. Longer term things like producing ammonia during summer and converting it to electricity in fuel cells will allow to remove needs for fossil fuels completely.
I’d keep gas plants around, but anyway, you need to cover that case and can’t just handwave it away.
The main advantage of gas plants is that they support variability. In a world with enough battery storage to last for days that would be irrelevant. And as an insurance against rare events it is better to keep coal plants as transportation and storage of coal is vastly more resilient to interruptions.
Strictly speaking - a battery is stored potential energy
A common battery for grid level storage is pumped hydro - that is, use the peak power during the day(s) to push water from the bottom of an elevation to the top, and hold it there - bonus points if it captures water delivered from other solar processes (evaporation -> rain)
There are about 90 billion battery solutions - none of them are very efficient, cheap to manufacture, easy to manufacture/acquire materials for, and long-lasting all at the same time.
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Typical non-informed incorrect opinion.
The overwhelming majority of generation and storage is best deployed at the point of use.
Grid scale anything, is a massive inefficiency.
The only reason grid and city scale is so prevalent in public discourse is because this is the only electricity the utility is paid for, and they are very actively impeding any other solution.
In the US, there is a very large inventory of flat roof industrial buildings, in the industrial parks that are using huge amounts of electricity. Covering all of those roofs with solar (especially here in the west US) would prevent a tremendous amount of grid scale generation, and implementing storage there would eliminate a large part of the transmission line upgrades the utilities are calling for.
The biggest problem in the US isn't technical, it's the governments desire to primarily support the solutions that are best at serving utility shareholder returns, instead of the technically superior solutions.
How common is it that these industrial/commercial buildings have roof-top solar? If not common, what stops it?
It's quite common in Australia for commercial and residential.
It doesnt make economic sense to serve the entirety of daytime electricity demand from solar without batteries. Youd have to tons of fossil fuel plants that turn off during the day and then back on every night. For solar to take the next step batteries are a requirement
It's not quite as bad as that, since you don't consume fossil fuel resources when plants aren't running, but this is mostly a benefit for oil/gas plants, not coal (since the coal is likely useless without the power plant consumer anyway)
Depending on the type of power plant, it can take quite a while to spin up (or down) one of them and get them to optimal power production.
https://www.eia.gov/todayinenergy/detail.php?id=45956
If you shut down by day, it can take multiple hours for it to be able to provide full load... and multiple hours for it to shut down cleanly. During this time it is producing power at less than optimal rates and/or using the fossil fuels to keep the wheels spinning and in sync with the grid so that they don't have to go through a phase matching period.
(aside for coal - note that it takes more than 12 hours for a coal plant to get running from a cold start)
That's not really a problem. A spin up over a couple hours matches nicely with the slow sunset over a continent. The sun takes ~4 hours to go from a bit above the horizon in the east coast to a bit below the horizon on the west coast (solar panels make some power in twilight).
Wind also helps since wind makes more power at night, as does demand which is dramatically lower at night.
For coal, Great. Making coal economical is excellent. We should have banned it worldwide 20 years ago.
USA should explore Pumped Storage Hydropower more, it has same or better efficiency than battery storage and can use existing facilities like hydroelectric dams
Part of the pumped storage problem is "where can you do it?"
There's a good number of 'em: https://en.wikipedia.org/wiki/Category:Pumped-storage_hydroe...
https://www.ferc.gov/media/licensed-pumped-storage-projects-...
You'll see that most of them are in the Appalachian mountains and in the Sierra mountain range.
The one in Missouri is one of the interesting ones that isn't in either.
https://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_...
> The Taum Sauk pumped storage plant is a power station in the St. Francois mountain region of Missouri, United States about 90 miles (140 km) south of St. Louis near Lesterville, Missouri, in Reynolds County.
It has a hydraulic head of 860 feet and that represents the challenge - you need to find places in the US where you can get several hundred feet of elevation in a short distance.
Hypothetically, lets build one in Minnesota... Taum Sauk Mountain is the highest point in Missouri. The highest point in Minnesota is Eagle Mountain (in the boundary waters - you can't build there, pretend we can) ... the elevation to the top os 550 feet (about half what Taum Sauk provides) over 3.5 miles (Taum Sauk is just over 1 mile). ( https://maps.app.goo.gl/vHfWarwubaLvsf5z7 )
Much of the US is too flat for it to be useful.
Solar+A couple of hours of batteries is already economically viable. The storage problem that is still expensive is bridging days/weeks of insufficient sun and wind.
The US uses around 4TWh of electricity a night. A battery with that capacity, to get through the night with no generation, would cost over a trillion dollars. Of course thered still be some generation at night, but still, using a battery just to get through the night is not even close to viable
You might want to update your numbers, 1 kwh is somewhere between 50€/kwh to 75 including electronics... No economics of scale, shipping included..
That makes 300B
Eu pricing
Just by scaling up the existing technologies the full cost including installation and maintenance of a grid-scale battery in 5 years will be below 100 usd/kwh. So the price is max 400 billions or 1% of US GDP.
The war in Iraq cost a trillion dollars.
So far.
Do you imply that it was really cheap, just like solar+batteries?
You generally get more return on investment if you invest in building infrastructure in your own country rather than investing in blowing up infrastructure in a different country. So I’m implying that solar and batteries are a lot cheaper than the war in Iraq.
1 week national battery storage is totally doable. All we need to do is convince the rest of the planet to stop making GPUs, phones, computers, and EVs for the next decade, and then give us all their rocks. 78.4TWh is about $19T (all in costs) for a national battery grid for 1 week storage, could be built over ten years but would need the US to build and own double the current global output, not even considering where all the raw materials and labor comes from.
Coal is a dead end anyway.
That might work in The SouthWest of the USA, but the Northern bits dont get enough sun to get through the day, so you'll need fossil fuel plants all day night for the Winter. If they're there already its cheaper to use all day in the summer as well.
13kW on the roof and a 48kW battery. It produces on cloudy days, and battery alone can last 3-4 days with regular unmoderated use with 6 adults at home. That includes split system air-conditioners on eco mode.
It produces enough on cloudy days to still.top the batteries up to full.
I had a day recently where production topped 80kW and was exporting bulk before late afternoon grid production limiting kicked in. That's a lot of juice, and Ive basically not touched the grid in 7 months.
I don't think the winner takes all mindset can be applied in electricity generation. But I think the clever arrangement between these technologies will work:
- Solar.
- Wind.
- Nuclear.
- Pumped hydro.
- Battery.
Usually solar and storage are a package deal these days for grid scale solutions. Mostly, storage is not really about providing long term storage but short term. It used to be that the sweet spot that makes the most economic sense was something like 2 or 4 hours of power (relative to the maximum output of the solar panels) but these days batteries are a lot cheaper and 8 hours or more is becoming fairly common. The point of storage is not really to cover for all the downtime when the sun doesn't shine but to give grid operators enough lead time to bring online extra generation or buy capacity on the open market and adjust their planning. Mostly a few hours is all they need to ensure the grid stays up and running through daily peak usage windows.
In aggregate, grid operators have a lot of other tools at their disposal via flexible pricing, flexible demand, and automated systems that can adapt to this to e.g. charge cars when there is a surplus of energy, turn on/off water boilers, etc. There's a lot of innovation around this topic in this space. This by the way is as much as making sure generated power doesn't go to waste than it is about ensuring there is enough power. They use batteries to time shift excess power to when they can utilize it.
Interconnected grids means that e.g. an operator in Denmark can import/export to and from the UK, Norway, Germany, etc. On a windy day they'll be exporting wind power. On a sunny day, they might add some solar to that mix. When there's no wind or sun in Denmark, they might pull in Scottish/German wind, Norwegian hydro, Swedish nuclear, etc. Batteries are being deployed all over the place at a pace that is only exceeded by the pace at which solar is being deployed. Whenever there's a surplus energy, batteries get charged up. It's very rare for all of the available generation to disappear all at the same time for long enough to drain all the batteries. And for those times of course fossil generation is still a thing as well, and will be for decades to come. There are a lot of gas based plants throughout Europe. As well as some nuclear plants of course. Singling out the EU market here but it's going to be similar elsewhere.
The point here is that there's no need to pair solar setups with days/weeks/months worth of storage. A few hours goes a long way.
Good news: batteries on are a similar exponential curve. Just a decade or so behind.
Its important to qualify that:
A decade or so behind, in the US.
If the US didn't block import of Chinese tech, we could have electrified a decade ago.
The tech available at the current moment, is even more capable of replacing petroleum based electricity.
But our government is banning Chinese tech to serve our outdated industries instead of importing it to serve the population.
As any wise country would do when faced with superior technology, we should import it with the condition of technology exchange. Chinese manufacturers should be training US workers and industrial ownership how to produce cheap, efficient, sodium batteries.
This benefits the populous immediately, and the industries are able to advance into the current century's tech.
>> As any wise country would do when faced with superior technology, we should import it with the condition of technology exchange.
Europe tried doing that. And our green technology sector promptly collapsed, because it couldn't compete with Chinese undercutting our prices. The only thing left now are wind turbines, but Chinese are making inroads there too. In the meantime, the green transition barely moved a needle when energy shock arrived in 2022 or this year. Rendering rest of our industry, especially chemical industry, uncompetitive.
>>> As any wise country would do when faced with superior technology, we should import it with the condition of technology exchange.
If it were a matter of industrial protectionism against a country which was not hostile, not authoritarian, didn't rely on slave labor, etc., then I'd agree with you. Countries have other pressing reasons besides immediate economic advantage to prevent this sort of thing.
To greatly oversimplify: Japan fought against opening their markets, as did China, out of political and social concerns for the stability of their states, far more than economic ones.
The US is far more hostile than China, also relies on slave labor, and is so increasingly authoritarian that our country's domestic & foreign policy now resembles a 3rd world dictatorship.
Doesn't matter though. The big mistake was allowing manufacturing to be exported from the US to begin with. Nearly any advanced technology we use or wish to produce is now dependent on China. They control not only the advanced manufacturing process, but also the refinement of rare earths (we can mine it but not refine it) and have cheaper labor. Not only can't we make tech without them, we can't sell it at competitive prices. Things will soon get worse as robotics and vertical integration makes Chinese products even cheaper and better quality. And we can't compete on robots because China controls that production chain too.
The smart play would be to build up our own green energy sector to gain cost savings, while investing in its manufacturing, so we can eventually compete and support ourselves (which Biden and Obama passed funding for). Trump eliminated all that when he came back, because the oil companies wanted more profits, they literally don't believe climate change is real, and they have no idea how diplomacy works. We could've had cheap battery, wind, and solar manufacturing in the US. Not anymore.
You should visit the Tibet region and ask the locals. But:
1. As a US citizen, you would probably not a get permit necessary for entering the Tibet region.
2. If you could get a permit for Tibet region and go there, you would be followed by police officers dressed in civilian clothing. The locals would be quite hesitant to speak to you.
(Source: been there long ago, seen it). China has many qualities, but freedom is not one of them.
Nor are civil rights, or civil litigation for that matter.
I don't think the poster you're responding to is writing in good faith; they're either an agent of an authoritarian power, or blind to the difference of being one.
People in China can say anything the government approves of, but they can't say "long live freedom and democracy," unless they want to be executed.
Neither, I suspect, will Chinese AI models make any statement in sympathy with personal freedom, democracy, or human rights; it would come at the expense of the people who paid to train those models, and that can't be allowed.
Fun fact: there are huge government-sponsored posters proclaiming Freedom (自由) and Democracy (民主) through China, because they're two of the official twelve Core Socialist Values.
https://en.wikipedia.org/wiki/Core_Socialist_Values
That is a fun fact.
I guess freedom means different things to different people. Do people in China just roll their eyes at that?
And are we perfectly free in America? No. But we can say whatever we want about the government or the corporations, provided we're nonviolent. And we're not commanded how many children we can or can't have, or what religion to practice or not, or forced to show loyalty to a political party.
Plus we can smoke weed, buy guns, vote the bums out every four years, and most importantly make money without having to pay off some party official.
>> The US is far more hostile than China, also relies on slave labor, and is so increasingly authoritarian that our country's domestic & foreign policy now resembles a 3rd world dictatorship.
As a child of immigrants from the Soviet Union, and also as someone who knows people still resident in authoritarian dictatorships: This is patently ridiculous. Everything else in your post is a spray of nonsensical policy points and predictions. You led off with the tell. Frankly, it makes everything you say afterward sound like what an authoritarian enemy government would want people in the US to think about their own country.
What you wrote in your first sentence is either (a) wildly misinformed (like, you have no idea what life is like in an authoritarian country with actual slave labor, which is an insult to the people who do currently live there), or (b) intentionally nefarious (like, you work for such a country, in a capacity to minimize the distinction between their system of autocracy and the United States' democracy). If it's (a), study at least a little bit of the history of mass murder in the 20th Century. If (b), well, we live in a free country so you can spew whatever garbage you want. Interestingly, we have not been overtaken by any of the dictatorships that have sprung up in Eurasia over the past hundred years, and I don't think we will be soon.
All fine and dandy until your grid goes mysteriously offline the day after China moves on taiwan.
Call me paranoid. I have a couple of inverters here that are grid connected and I made sure everything that allowed outside connectivity in the box mysteriously stopped working. A little bit of RF knowledge goes a long way with stuff like that. It was interesting to see how many ways it tried to do this. Fortunately it kept working even without connectivity. Configuring the things is a pain though, the display and buttons are clearly not meant to be used that way but it does work.
That's not paranoid.
Paranoid is me testing the plates I bought off amazon for lead, and throwing away the bathtub mat which smelled like petroleum waste. I'm fairly convinced that the goal of that ruthless dictatorship is to poison, degrade and infiltrate every single household abroad in every way possible. A fast attack might be to bring as many devices offline as possible, but the slow attack is simply to lower people's intelligence by hardware or software methods (e.g. TikTok, Qwen... or, let's say, not notifying anyone for a few months that a new SARS virus had escaped a lab). Everything that comes out of communist China is warfare, even if it looks like a plush toy.
> But our government is banning Chinese tech to serve our outdated industries instead of importing it to serve the population.
It protects American companies who operate in the green energy generation and storage arena from Chinese competition.
No, it protects fossil fuel energy companies from having to retool and change.
It does that too, but it would be unbalanced to not also recognize it protects green energy companies in America from Chinese competition.
Not only does Chinese competition get blocked, but governments are incentivizing green energy. For instance, just recently it was reported that Tesla’s $10B solar factory could get 35 years of tax breaks in Texas (Oil Capital!!!)
https://electrek.co/2026/10/23/tesla-solar-factory-texas-35-...
Sorry, which country in the world burns the most coal? https://worldpopulationreview.com/country-rankings/coal-cons...
Honestly, it's not even doing that. Thing that would really push the US ahead would be the tax breaks we had until a couple years ago.
> protects American companies who operate in the green energy generation
Wont someone think of the big beautiful clean coal companies
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Diurnal storage is solved by batteries. Longer term storage will very likely be solved. For several days, cheaper batteries (perhaps with lower specific power). For longer periods, either thermal storage or e-fuels.
My guess is seasonal will be handled with flow batteries. A big tank and cheap-ish electrolyte, with the expense being in the electrodes sized for whatever max power is required. Tanks good for multiple cubic meters worth of liquid storage aren't exactly difficult to find, nor to place in a garden.
Then again, I'm basing this opinion on a recent-ish video from NightHawkInLight: https://www.youtube.com/watch?v=eq7fR9ISuCw
Flow batteries might be ok for a week or so, but their market window has been shrinking as Li-ion has gotten cheaper.
The technology I'm most excited about is ultra low capex thermal, as being done by Standard Thermal. Capital cost per unit of energy storage capacity as low as $0.10/kWh(th), so it can work with seasonal storage and just a few tens of charge/discharge cycles over its lifespan.
Standard Thermal has raised $11M and is building in Germany, where they say they can deliver 365/7/24 solar resistive heat (400 C or perhaps 600 C) for half the cost of heat from burning natural gas there.
Flow batteries keep coming up again and again, but they just don't work well in practice. The power density of electrodes is too low to be practical, and this is a fundamental problem.
A regular 18650 cell has about 0.1 square meters of electrode surface. And you have thousands of these cells in a car battery, resulting in literal football fields of electrode area.
Wood burning heat is perfect compliment to solar in remote areas.
Agreed, e-fuels seem to be far and ahead the front-runner.
We can get to 95% using just short term storage. I suspect that most jurisdictions will just say "95% is good enough" rather than paying for ridiculously expensive long term storage.
We've got the nat gas capability already; keeping it around for the 5% is quite inexpensive, making the massive investment in long term storage for marginal benefit hard to justify.
OTOH, while the premium for e-fuels seems excessive, if you're only running that nat gas plant 2 days a year that premium is not so scary.
> Agreed, e-fuels seem to be far and ahead the front-runner.
For covering Dunkelflauten? Yes.
For seasonal storage with a prolonged discharge (so, low power/storage capacity ratio)? I think thermal storage wins there.
Sure, thermal is great where it's possible. But there aren't that many places where district heating is viable.
I'm not talking about district heating. I'm talking about high temperature storage for conversion back to electricity. Round trip efficiency could be around 40%, better than green hydrogen burned in combined cycle plants.
Standard Thermal's website's front page only covers heat delivery; did you mean to link to somewhere else?
Those are 2 very different use cases.
Thermal is low rate extraction. It's 1 cycle per year, but the extraction is performed over months so is low rate.
Electricity long term storage is high rate extraction. It's only used a few times a year, but when it is used it needs to cover roughly 100% of the entire grid's needs. I doubt thermal storage is suitable for high rate extraction, but I'd love to be wrong.
Edit: rereading your parent comment you seem to think thermal is suitable for a different use case? Could you elaborate further? When is "prolonged discharge" useful?
That's what they're focusing on to start with, but the temperature is high enough to drive heat engines to make power. There's more on the concept at the seed company's (Orca Sciences) web site and at Austin Vernon's blog.
https://www.orcasciences.com/articles/standard-thermal
https://austinvernon.substack.com/p/building-ultra-cheap-ene...
They talk about temperature up to ~600 C, which I believe is limited by the desire to use cheap steal (much hotter and creep becomes a problem). This is also perhaps not coincidentally about the temperature of steam from a coal fired boiler, so one of the eventual goals is to repower retired coal fired power plants with this storage providing the heat instead of coal combustion.
You're right this is not good for something needed "a few times a year" for relatively short periods, for example to cover Dunkelflauten. Combustion of an e-fuel is better for that. But it's well suited to seasonal storage of solar energy, as that would be extracted over months, more or less continuously. The resistive heaters should also be much cheaper per W than electrolyzers.
> But it's well suited to seasonal storage of solar energy, as that would be extracted over months, more or less continuously.
But what is that useful for? During almost all of those months it would be a lot cheaper to use renewables & short term storage. And it's not fast enough for the few days it's not beaten by something cheaper.
It's useful for storing cheap solar energy for use in winter. Sizing the solar collectors for winter would require them to be much larger. Basically, this lets 2.5 W of solar in summer deliver 1 W of solar in winter. For a high latitude where the change in insolation is higher than that, this is superior. In Hamburg, for example, insolation varies by more than a factor of 10 from July to December.
Put another way: if you oversize the solar to be adequate in winter, you have enormous amounts of surplus solar in summer. So why not store it?
> So why not store it?
Because 0.10 $/kWh(th) / 0.4 kWh(e)/kWh(th) is expensive.
That's the capex for storage capacity. It's amortized over the number of charge/discharge cycles. Divide by 20 or more. It's amazingly cheap, actually.
I thought that post was interesting when I read it over a year ago, but the startup seems to have gone dark since then.
They appear to be focusing on Europe, and have raised $11M (or maybe 11M euros, I'm not sure which). There is some favorable buzz in Germany, which makes sense because natural gas has become quite expensive there.
https://www.cleanthinking.de/thermischer-erdspeicher-erdhueg...
I just don't see it with thermal. You have to pay the Carnot tax, and you also need humongous amounts of material.
E.g. 100 GWh (4 days of 1GW thermal power) with a 100C temperature swing (you can't go down all the way to room temperature) will need around 3.6*10^4 tons of sand. That's a lot.
Honestly, power-to-gas sounds like the only reasonable way for now. In theory, with SOFC (Solid Oxide Fuel Cells) for power generation, it can beat the steam cycle.
The temperature swing can be much greater than 100 C. Heat can be extracted as a wave passing through the store, then heat added back by reversing the flow. It would operate like a counterflow heat exchanger.
View another way: if we hook several piles in series, then lukewarm air from a first mostly discharged pile can be directed into later piles for more heating. In the continuous limit this is the concept I described above.
> The temperature swing can be much greater than 100 C.
No, because your steam will be at a lower temperature as you draw down the heat, bringing down efficiency.
Realistic designs for this can achieve 450C delta t. Your energy store can store at ~1000C (slightly below rock melting point), and run steam turbines with a hot side of 600C and a cool side of 150C.
Over the season, your sand drops from ~1000 to ~600 (which is fine since your power needs drop in the spring)
Sorry, but 1000C is wildly unrealistic. There are no bulk materials that can be used to construct heat exchangers for this kind of environment. 600C is already a stretch.
At 1000C steel will react with _water_.
To be clear, I'm not talking about cooling a small crucible but a structure that is at least 20 meters in size.
That is wrong, and I already explained why.
36000 tons... doesn't actually sound like that much? That's a ~30x30m cube of dirt.
But I have no reference for the cost of setting up such a storage and how it compares to battery or hydro.
The ~grid scale design of this for reference is somewhere around 200mx200mx50m for above ground, or ~100m cube (or bigger) for quarry infill. Such a design is going to get crushed by battery/hydro over the hours/days, but wins on cost for seasonal usage.
The cost of putting dirt in a pile is $1-2/ton.
so $36-72k for days of 1GW of power? Sounds pretty cheap to me ...
They also state the cost per kWh(th) of storage capacity is about $0.10, or $100,000/GWh(th). This is thermal energy, which is converted to work at maybe 40% efficiency, mind you. There are costs over and above the dirt (for example, pipes laid through the dirt to carry heat in/out).
The biggest expense will be the pipework inside that pile. That you won't be able to service easily. And you'll also need a LOT of insulation around it to prevent heat from leaking out too quickly.
Thermal storage benefits from the square/cube scaling, so the amount of insulation goes down as you scale up the storage.
The insulation is just more dirt.
Homework: compute the heat flux from a 40 meter radius sphere, given the surface temperature 600C and the ambient temperature 0C. Now compute the amount of insulation needed to keep its temperature above 500C for 3 months, given that dry sand has an R value of 0.25 W/mK.
Won't be long, battery installation is bigger by GW than wing or gas:
https://www.eia.gov/todayinenergy/detail.php?id=67205
But for the most part it will trail solar, because the first chunk of the solar doesn't really need storage. But once there's a healthy percentage of solar, all new solar will have storage or it won't get paid.
This is solvable, but it will require international cooperation on a scale that is unlikely. But you wouldn't need any storage at all, just a large number of long distance HVDC lines to move the energy from wherever the sun is shining to where it isn't.
It solvable but very expensive.
The costs of large number long distance HVDC lines with accompaning invertor stations would be as expensive as a electric generation based on nuclear power.
I don't think that is true. The bigger problem is the international cooperation required, as well as that such a system would be vulnerable to attacks.
" The cost of the electrical equipment that brings the offshore renewable energy from the wind turbines to the shore is in the same range as the cost of the wind turbines themselves. The future offshore grid will need tens of billions of Euros of investments in HVDC transmission infrastructure. For instance, Dutch-German transmission system operator TenneT has contracted 30 G€ for such connections in the North Sea. "
https://blog.sintef.com/energy/future-hvdc-grids-yes-please-...
Yes. Those links will be built anyway. Once you have them it isn't a huge stretch of the imagination that you could cross connect them. Check out a map of how many of those we have now, compare with two years ago or so and see how fast the buildout is. North-South links would take care of the seasonal variation and East-West links would lengthen the day.
Aren’t lead acid batteries great for this purpose? They have advantage over lithium in stationary setups because weight is not an issue and they can be “daisy chained” many many times. I’m unaware of more cutting edge alternatives and the way the electrical companies handle solar is confusing IME
Lead acid batteries don't much like being cycled heavily. Even the ones explicitly designed for it (the average car battery is not) have about a tenth of the lifespan of lithium ion.
LiFePO4 is probably the chemistry best suited to it ATM. Lasts a long time, more stable, pretty cheap, and just a bit less energy density than other lithium ion options. Sodium-ion is looking promising but only just entering the market AFAIK.
Does this mean LA would be a feasible option for longer-cycle storage, IOW keeping a reserve topped up most of the year for those duldrums weeks with little solar or wind?
For long term storage, the right batteries don't exist yet (commercially). The good options are going to be one of sodium ion, flow batteries, or thermal batteries.
In addition to the fact that it doesn't really work better for that either, it's just not as safe as lithium iron phosphate.
I think it still loses out to lithium-ion on cost/kWh, and batteries in general are still a bit expensive for storage on the timescale of months.
I dumped my 24V dual LA battery setup for a single 24V LFP battery for my inverter/UPS backup. LFP supposedly has a 10-15y life based on the 4-5000 charge cycles most cells claim. Sodium ion is on the way as well. My setup gives me about 10-12h of backup for critical loads (my PC, lights, fans).
I have a 5 kWp solar plant that produces ~25kWh per day, but it is grid-tied. I considered a hybrid setup with LFP battery back up, but decided to separate the two systems to avoid a single point of failure.
They're not great.
LiFePo4 however is excellent and reasonably low cost these days
"PO" not "Po" (I was wondering what Polonium was doing in here lol)
Whatever it is doing, it won't be doing it for very long ;-)
We can simulate storage with overcapacity and broader geographical distribution networks, even if storage doesn’t become as cheap.
Fortunately that doesn’t seem like it will be an issue since battery storage costs are also seeing an exponential reduction.
Electricity is cheaper at night but only 20% of my consumption is at night, so I wouldn't mind if the situation was reversed.
I guess using electricity to heat during the night could be an issue, but we could also accept to let the temperature drop.
Around here late morning to mid afternoon (11 am to 4 pm) is now off-peak, alongside the old 10pm to 6 am.
With enough renewables the cost peaks are in the morning and evening when the sun is rising/setting and people are at home cooking.
There's also, like... winter. I'm fairly sure there's a calculation somewhere you could determine the number of deaths this will cause with pretty good accuracy.
Solar is never gonna be a complete solution. At the end of the day, we could do it more efficiently by just building suns here on earth for the panels, but of course then you've achieved fusion and you're already generating more than solar could ever hope to. We shouldn't hinge our future on half of a technology.
There's still sun during the winter; you just need more solar panels for the same amount of energy. Also, there tends to be more wind during the winter, so wind power makes a good complement to solar.
In lower latitudes, yes. Where I live December has an average of 4 hours of sunlight (yes, the entire month).
So the winter, by definition, will always generate less? or we're just like... covering up a bunch for half the year or something? I don't get your point.
My larger point is that solar is only ever going to be a piece of the puzzle at best. In space it might be quite nice, but otherwise it's kinda goofy to invest too much in.
With the way prices are trending, soon solar power is going to be the cheapest power source even in the winter. No one is going to complain that electricity is too cheap during the summer.
> My larger point is that solar is only ever going to be a piece of the puzzle at best.
Doesn’t that apply to any power source?
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Fusion, I hate to say it, is a pipe dream. Why? Because any fusion reactor loses a ton of energy to fast neutrons, which have the added negative of destroying the reactor. So-called aneutronic fusion (eg using He3) isn't zero neutrons. It's just fewer neutrons.
Stars don't have this problem because they're very large so there's only so far neutrons can go.
This is such a weird thing to assume is just impossible in physics, I don't quite know how to respond other than "yes, there are many unsolved problems in every energy sector, which is why it's an open question where we go from here"
Energy storage, on the other hand, has endless solutions which exist right now
I've heard every counterargument a million times at this point. And they fall into one of two buckets:
1. Stars do it. Yes. But stars also have size and gravity, something no nuclear plant will ever have; and
2. "People once said X was impossible" ie the Galileo Gambit. Just because Galileo was mocked for his heliocentric model but was later proven right does not mean everything is possible.
Thing is, I'm not even talking about physics. I'm talking about engineering. Something not only has to be possible but it has to be technically viable and sufficiently cheap. Put it this way: would you pay $60 billion for a 1GW power reactor with a lifespan of 30 years and an annual maintenance cost of $2B? Even if the fuel was completely free the wholesale cost per MWh would be ~$600. Nobody would build that.
Fusion research has been going on for decades and the best we've done thus far is fire a laser for about a second to induce a fusion reaction and also spend billions building magnets to try and contain a turbulent fluid at 100 million degrees, which, again, will do nothing about the neutrons that will destroy that vessel.
The joke is that fusion is always 50 years away and always will be. If you're an optimist it's always 30 years away and always will be.
Batteries already kill peaker plants as a grid-scale battery that lasts 4 hours became cheaper than running natural gas turbine to cover the evening demand peak.
The cheaper solar gets the more of a gold rush there has been to develop projects/technologies that take advantage.
Its also tricky to defend in war prone locations.
I think solar is amazing and we need more of it - but I can't stand this solar and storage go at it alone mentality. It's pretty thickheaded to discount the other forms of energy that we can use and will need.
A nuclear plant in a war zone is a dirty bomb waiting to be set off, which is incredibly easy to do, technically. Gas and coal plants are also end up being easy targets, as the war in Ukraine has shown. The most reliable one is solar because of how distributed it is. You can knock off one solar field, but then there are rooftops. You really need to destroy a city if you want to get it rid of power completely.
(Diesel power generators also work, but they require constant fuel supply, which can be complicated in a war zone)
In practice, in Ukraine distributed solar power has been an increasingly important source of resilience in their power supply system.
There are legit reasons to push back against “solar and batteries everywhere” but I find it hard to credit resilience in a conflict situation as one of them.
I think I'd rather a solar panel array be bombed than a nuclear power plant.
Solar has the advantage that it can be widely distributed on buildings rather than in just a few centralized locations.
I don't see how anything would be more resilient than solar.
Gravity just needs mass not fusion but your point remains.
> More stoked for when the same is said for storage
Batteries have use in war and power. It will likely scale faster than PV. What we need is the second derivative, so production of the latter can be turbocharged just before battery production is about to break through.
It's encouraging- when one part improves usually the others follow.
Most of our chemistries are targeting things like cars and consumer electronics.
Ideally we see people like Form Energies, using iron-air (rust) batteries, for much easier to scale storage. https://www.technologyreview.com/2026/10/06/1145020/2026-cli...
https://www.iea.org/commentaries/global-battery-markets-are-...
- Battery energy storage has grown at an exceptional pace, with global installations increasing more than 20-fold in storage capacity over the past five years. This growth has been driven by falling battery prices, abundant supply and relatively short project lead times. As variable renewable generation expands in many markets, battery storage is becoming an important source of flexibility and resilience for power systems, while also representing a growing commercial opportunity for battery manufacturers.
- However, more than 90% of battery storage applications rely on LFP batteries that are almost exclusively supplied from China, which accounts for almost all global manufacturing capacity and the associated technical expertise. Korean producers are investing to scale up LFP battery production that can offer an alternative, but they face intense competition from established, lower-cost Chinese producers in an oversupplied market.
https://www.iea.org/commentaries/battery-storage-is-scaling-...
- Battery storage now accounts for around 18% of installed dispatchable capacity in Australia, compared with 7% in China, 5% in the United States and 4% in Europe – underlining how rapidly batteries are becoming an important part of the electricity systems in some regions.
https://www.ess-news.com/2026/06/02/global-battery-additions...
Battery storage is right behind the solar adoption curve. Net zero in five years? Probably not. Ten to fifteen years? Almost assured considering rate of change and the overall economics (assuming ~1TW/year of solar PV deployment and enough battery storage to soak up that low carbon generation while also providing grid services to replace thermal generation grid support [voltage, frequency, etc]).
(China is curtailing renewables equal to the annual combined generation of Spain and the Philippines every six months, and India about ~100-120GW/month due to not enough battery storage, for example)
https://news.ycombinator.com/item?id=50132343
https://news.ycombinator.com/item?id=50198882
I am desperate to find a battery inverter that can be used to supplement my existing grid-tied home solar setup. I only need about 5kW and 10kWh of batteries, but everything I can find is geared towards whole-home power at like 12kW. Way way more than I need. I understand I’m in the minority and there’s probably not a market, but I’d love to find something
Transparency: I live in a 240v land, I have a Siggen.[0]
Not sure whether other brands could be better but there seem to be various options that would suit. If you are in 120v land you may need to check if there are models to suit.
Its largely modular, inverter sits on top of modular batteries in 8-9kw chunks.
But they are app-infested. IE wants a wifi connection, app on your phone to their servers... etc etc.
I hate it, but the wife likes it. This is a recent thing so I am still working out if there are possible solutions for privacy and control over my own objects.
[0]https://solarbatterysupermarket.com.au/products/sigenergy-ba...
> IE wants a wifi connection
Their car charger was doing my head in.
I pulled it apart and found an Ethernet plug and it was a complete game changer.
But: the app and their servers remain.
Unfortunately, the market is somewhat bifurcated between what Anker, Jackery, Ecopower provide and stepping up to Base Power, Powerwalls, and other bigger system components.
My recommendation would be to see if Ecopower storage and inverters are a good fit for your use case. If you're feeling adventurous, you could build your own battery pack, but I only recommend if you are knowledgeable and confident. This comes with substantial property and life safety risk, only proceed if you know what you're doing and understand the risk (I'll work on my high voltage EV battery packs, but only with a helper nearby holding a 2x4, for example).
https://hackaday.com/tag/battery-pack/