Could Hot Rocks Help Solve the Climate Crisis? (cnn.com) 110
An anonymous reader shared this report from CNN:
"(The rocks) in the box right now are about 1,600 degrees Celsius," Andrew Ponec said, standing next to a thermal battery the size of a small building. That is nearly 3,000 degrees Fahrenheit, "Hotter than the melting point of steel," he explained.
But what makes his box of white-hot rocks so significant is they were not heated by burning tons of coal or gas, but by catching sunlight with the thousands of photovoltaic solar panels that surround his prototype west of Fresno. If successful, Ponec and his start-up Antora Energy could be part of a new, multi-trillion-dollar energy storage sector that simply uses sun or wind to make boxes of rocks hot enough to run the world's biggest factories. "People sometimes feel like they're insulting us by saying, 'Hey, that sounds really simple," Ponec laughed. "And we say, 'No, that's exactly the point'... The problem is you can't shut down your factory when the sun goes behind a cloud or the wind stops blowing, and that's exactly the problem that we focused on."
While the word "battery" most likely evokes the chemical kind found in cars and electronics in 2023, hot rocks currently store ten times as much energy as lithium ion around the world, thanks to an invention from the 1800s known as Cowper stoves. Often found in smelting plants, these massive towers of stacked bricks absorb the wasted heat of a blast furnace until it heats to nearly 3,000 degrees Fahrenheit, and then provides over 100 megawatts of heat energy for about 20 minutes. The process can be repeated 24 times a day for 30 years, and Antora is among the startups experimenting with different kinds of rocks in insulated boxes or molten salt in cylinders to find the most efficient combination...
Antora has managed to raise $80 million in seed money from investors that include Bill Gates, but their main competitor is another Bay Area startup called Rondo that uses abundant refractory brick, which is cheaper than carbon by weight but not as energy dense. Rondo has attracted even more funding than Antora and its first battery is producing commercial power for an ethanol plant in California... Tesla recently predicted a carbon-free world will need an astonishing 240 terawatt-hours of energy storage — more than 340 times the amount of storage built with lithium-ion batteries in 2022. Rondo CEO John O'Donnell predicts more than half of all that new capacity will come in the form of heat batteries, simply because the raw ingredients are so readily available.
By plugging their factories into as many thermal batteries as they need, manufacturers won't have to wait in a years-long line for grid connections and upgrades.
Ponec tells CNN that when it comes to de-carbonizing today, "we have the tools we need. We just need to deploy them.
"The transition is inevitable. It's going to happen. And if you talk behind closed doors to most of the people in the fossil fuel industry, they'll say the same thing."
But what makes his box of white-hot rocks so significant is they were not heated by burning tons of coal or gas, but by catching sunlight with the thousands of photovoltaic solar panels that surround his prototype west of Fresno. If successful, Ponec and his start-up Antora Energy could be part of a new, multi-trillion-dollar energy storage sector that simply uses sun or wind to make boxes of rocks hot enough to run the world's biggest factories. "People sometimes feel like they're insulting us by saying, 'Hey, that sounds really simple," Ponec laughed. "And we say, 'No, that's exactly the point'... The problem is you can't shut down your factory when the sun goes behind a cloud or the wind stops blowing, and that's exactly the problem that we focused on."
While the word "battery" most likely evokes the chemical kind found in cars and electronics in 2023, hot rocks currently store ten times as much energy as lithium ion around the world, thanks to an invention from the 1800s known as Cowper stoves. Often found in smelting plants, these massive towers of stacked bricks absorb the wasted heat of a blast furnace until it heats to nearly 3,000 degrees Fahrenheit, and then provides over 100 megawatts of heat energy for about 20 minutes. The process can be repeated 24 times a day for 30 years, and Antora is among the startups experimenting with different kinds of rocks in insulated boxes or molten salt in cylinders to find the most efficient combination...
Antora has managed to raise $80 million in seed money from investors that include Bill Gates, but their main competitor is another Bay Area startup called Rondo that uses abundant refractory brick, which is cheaper than carbon by weight but not as energy dense. Rondo has attracted even more funding than Antora and its first battery is producing commercial power for an ethanol plant in California... Tesla recently predicted a carbon-free world will need an astonishing 240 terawatt-hours of energy storage — more than 340 times the amount of storage built with lithium-ion batteries in 2022. Rondo CEO John O'Donnell predicts more than half of all that new capacity will come in the form of heat batteries, simply because the raw ingredients are so readily available.
By plugging their factories into as many thermal batteries as they need, manufacturers won't have to wait in a years-long line for grid connections and upgrades.
Ponec tells CNN that when it comes to de-carbonizing today, "we have the tools we need. We just need to deploy them.
"The transition is inevitable. It's going to happen. And if you talk behind closed doors to most of the people in the fossil fuel industry, they'll say the same thing."
This is already somewhat older tech (Score:3)
Seriously. Obviously, thermal storage is viable and there are several experimental plants already around the world. No "startup" needed.
Re: This is already somewhat older tech (Score:3)
Agreed. According to Wikipedia, concentrated solar might have been used as far back as 212 BC.
Re: This is already somewhat older tech (Score:5, Informative)
Meanwhile, this isn't concentrated solar. Reread.
Also, economically-efficient thermal storage of electricity is not in any way, shape or form mature tech.
What's interesting to me is the very high temperatures (I had to convert from Crazy American Units to metric, though :P). There's a potential max ~85% Carnot efficiency there. I wonder how much of that they can actually recover? They're storing at ~15% hotter than the flow through NG turbines, though that doesn't make a huge difference in terms of Carnot efficiencies, and I assume they'll be similarly limited by alloy limitations, so I'm betting that with a good combined cycle plant they'd get ~65%. Although if they're only planning to function as a peaker they might need to go with a cheaper simple gas turbine design to lower capital costs, maybe 40-45% efficiency.
Either way, you're similar to, say, hydrogen energy storage efficiencies, with a system that's probably vastly more capital efficient.
Big bonus points if you can connect the outflow to municipal or industrial heating systems - you can get some really amazing net efficiencies if you can use most of the waste heat as well. And when are heating demands highest in most places? In the winter, when peaking is most needed in renewables systems :)
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Many companies are having a go at this. Moving excess heat from industrial processes to municipal or industrial heating systems is definitely an option, as is simply capturing excess heat and one stage and using it at another.
https://www.youtube.com/watch?... [youtube.com]
https://www.youtube.com/watch?... [youtube.com]
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There's a project on thermal electric storage here [stiesdal.com]. They were going to build the first production unit last year but the hike in material cost put the project on pause.
Perhaps it's still a bit too early for the market opportunity.
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What's interesting to me is the very high temperatures (I had to convert from Crazy American Units to metric, though :P). There's a potential max ~85% Carnot efficiency there. I wonder how much of that they can actually recover?
A German "hot rock" storage prototype installation can recover about 50%. Apparently that is quite enough to make this worthwhile.
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Either way, you're similar to, say, hydrogen energy storage efficiencies, with a system that's probably vastly more capital efficient.
Sucks that there isn't a safe way to store HHO. Otherwise Hydrogen electrolysis would be an amazing way to store energy. However, even storing regular Hydrogen isn't a super safe prospect. I also wonder how the "hot rocks" solution compares with storing the energy as compressed air in underground tanks. There are also those solutions that use weights and towers to store potential energy. Raising rocks up with a wench seems even less complex of an engineering challenge than trying to infuse and extract heat.
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Agreed. According to Wikipedia, concentrated solar might have been used as far back as 212 BC.
This is not concentrated solar though. Perhaps that's not what you meant to imply, only that we have stored solar energy before.
There's a limit on how hot concentrated solar can get and it's actually not that hot when compared to things like rocket engines and coal furnaces. I recall an XKCD comic explaining the limit of concentrated solar before but I'm having trouble finding it, maybe someone knows what I'm thinking about and can help find it. The limit comes down to the sun can't heat anything hotter
Re: This is already somewhat older tech (Score:2)
Is https://what-if.xkcd.com/145/ [xkcd.com] what you were thinking of?
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Is https://what-if.xkcd.com/145/ [xkcd.com] what you were thinking of?
That looks like it, thanks. An interesting point in that is the sun gets to about 5000C, which is hotter than I recall. There's someplace I saw which put a much lower practical limit on how hot concentrated sunlight could get something, and I believe it was something like 600C. Whatever the temperature was it created a problem because higher temperatures were easily possible with coal and nuclear fission, and if the solar thermal system can't get as hot then that removes a lot of room for heat storage an
Re: This is already somewhat older tech (Score:4, Informative)
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Seriously. Obviously, thermal storage is viable and there are several experimental plants already around the world. No "startup" needed.
Indeed, and precisely zero of them are half the size of a shipping container or run on electricity.
I get it, you live on headlines and reading is hard, but if all you can absorb are pretty pictures, there's a short video in TFA for you to watch that would help make it immediately obvious that there are no plants like it in the world.
No (Score:1)
No, this will not solve the "climate crisis".
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No, not on its own, but it probably could have prevented it.
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No, not on its own, but it probably could have prevented it.
Not likely. As described this thing needs "fields of solar cells" to heat it up, and then it can provide 100MW of heat energy for 20 minutes. So 100 MWH of battery needs 3 of these and 3 x the "fields of solar cells" to charge it up. And assuming the entire point is we need that 100MWH of energy all the time I will need to double the number of cells again. And this only provides energy for an hour. We're gonna need acres and acres of solar cells to power a plant, and still need backup for a utility to h
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As described this thing needs "fields of solar cells" to heat it up, and then it can provide 100MW of heat energy for 20 minutes.
I believe you are misreading the article and conflating Cowper stoves found in blast furnaces with this new solar thermal storage. Quoting from the article:
"Often found in smelting plants, these massive towers of stacked bricks absorb the wasted heat of a blast furnace until it heats to nearly 3,000 degrees Fahrenheit, and then provides over 100 megawatts of heat energy for about 20 minutes."
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Thankfully solar is one of the cheapest forms of electricity out there per kWh. As is wind, another intermittent energy source.
Yes, if you want to increase the length of time you're drawing power, obviously you need to correspondingly increase the mean power production of the system, which is a cost. But then you're also selling more power, so it's a wash. Actually better than a wash, because the costs of a lot of things don't scale linearly (or at all) with the capacity factor of a renewables + storage s
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Thankfully solar is one of the cheapest forms of electricity out there per kWh.
According to whom? Here's a few studies that show otherwise:
https://en.wikipedia.org/wiki/... [wikipedia.org]
Fixed axis utility scale solar PV might be competitive on cost but that is only useful for those with a lot of cheap empty land. Before someone mentions "agri-voltaics" I'll point out that agri-voltaics is not fixed axis utility scale solar PV. There's an added cost to spacing out the PV panels and such to allow crops to grow around the solar PV pedestals, and if someone could provide some citations on costs then
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> According to whom?
The Wikipedia article you linked?
I mean, unless you're dishonest and insist on focusing on data from ten years ago... it very clearly says that solar PV is one of the least expensive options.
=Smidge=
Re: No (Score:2)
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Solaris is not cheaper when it's dark .
I was talking about offshore wind. But obviously you don't try to match local solar to night time demand but rather daytime such as office space or aircon. There will be mismatches, especially in more seasonal locations but if you end up.displacing fossil fuels even if you have to run some natural gas plants in winter to cover gaps it's at least progress. Don't make perfect be the enemy of better than nothing.
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Don't make perfect be the enemy of better than nothing.
Agreed! I say use the best overall source. Consider cost, environmental impact, all of it and in proportion to how important it is to the folks who consume the service. I'd also say it's fair to separate energy storage and energy production, but consider that some production types inherently involve pre-stored energy, such as fossil fuels and others force you into a storage problem, like solar. If that's okay in your application, or you already have great storage, then excellent, party on, Wayne.
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Fixed axis utility scale solar PV might be competitive on cost but that is only useful for those with a lot of cheap empty land.
They're in Fresno. See my comment above.
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How would spacing out solar panels add extra cost?
On top of that: I would assume 90% of all roofs and parking lots that would be suitable for solar: are empty.
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Re: No (Score:2)
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On the other hand, it is extremely difficult to conceive of a web of sources that can satisfy heating throughout the USA if we also assume that most of the heating will come from grid-supplied energy. Currently, averaged over the year, we get 80 percent of our total energy from fossil fuels. In the winter months t
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Another idea is to run things like hydrogen production
The UK was suggesting this but has dropped it on the basis of the hydrogen being too difficult to use. It's only practical to handle if built into longer chain molecu
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I know here in California, it would be nice to have some desalination plants to ease our water supply issues. Maybe those could run on intermittent excess power.
It depends on the time duration of excesses. It's unlikely that you'd be able to run desalination for a half-an-hour here-and-there and excess for a period of days would be more advisable. The other dimension here is that if you start relying on the desalination for water and you have periods where there is no excess power and the water supplies are running low then what is it that you cut to ensure there is water? Or do you now start adding power generation for the desalination. So you have to be careful a
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I think you're massively underestimating how truly enormous the Mojave desert is, and how truly useless it is for everything aside from collecting sunlight.
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Being a desert doesn't mean it is devoid of life.
https://en.wikipedia.org/wiki/... [wikipedia.org]
If the goal is to lower impact on wildlife then I suggest looking for energy from sources other than solar. Solar power should be the means of last resort, not the first. We have far better options, options with lower impact on the environment, lower CO2 emissions, lower cost, lower demand for labor and materials (which gets to cost and environmental impact), and more. Ivanpah was bad enough, we should think real hard about
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Being a desert doesn't mean it is devoid of life.
You gotta know a little bit about deserts first to start throwing about implications such as this. A tiny bit of extra shade under a field of solar panels will make life in their immediate vicinity thrive. And even if it didn't, scorpions are a pest and nobody would miss a few of them. The thought of making a material dent in the total geographic area of the Mojave that's large enough to harm... anything at all, is equally absurd of a notion.
If the goal is to lower impact on wildlife then I suggest looking for energy from sources other than solar.
Ridiculous. How do you think plants work? This is pure nonsense at
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Ridiculous. How do you think plants work? This is pure nonsense at best, giving you the greatest benefit of the doubt, but it sounds a lot like the tortured logic of someone with a deeply embedded conflict of interest.
Sure, only people opposed to solar power must have a conflict of interest, and every proponent must be the pure of heart only looking out for the best interest of society.
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Come on, get real man. I'm not saying we don't need multiple solutions for renewal energy globally, but you just tried to argue that solar panels were going to hurt the fucking desert. In case it's not clear, desert is every environment's failure state already. We can afford to lose a lot more of it than forest or grassland.
Re: No (Score:2)
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There's always some dumbass in these arguments arguing that a desert should be preserved because of the species that live there despite all evidence that those same species that somehow eek out a living there would actually thrive if given more resources on which to live on.
> I'm 100% certain you don't really know anything about the Mojave, or pretty much any desert on planet Earth from this post.
Fuck you and your bullshit high horse. I despise you. Fucking dumb piece of shit /. commentator with zero und
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or pretty much any desert on planet Earth from this post.
By definition [merriam-webster.com] it's a place of "sparse vegetation" that is "desolate and sparsely occupied or unoccupied". So, it appears you either aren't following the conversation you are participating in or your grasp of basic English is tenuous. The density of life in the desert is, by it's every definition, less or lower than that of other areas such as forest or jungle.
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You're one of those people that argues global warming isn't real because humans are insignificant aren't you?
No, absolutely not. Global warming is completely real, and it will turn the entire planet into a desert. We want less desert, not more, it's that simple. Nobody is going to miss a few hundred square miles of wasteland as long as it doesn't have a negative impact on indigenous fruit bat populations.
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I despise people like you. Eat a bag of dicks.
And normal people despise people who use statements like this to make a point.
The rest of your post was oki: till that line.
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Hehe. Forgive him, the desert is a hash mistress.
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You mean his girlfriend is called Manuela?
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The desert is not a dead zone. There is a lot more life there then you realize. If you cover it all with solar panels, you are still causing a great deal of harm to that ecosystem. All those little shrubs you see have massive root systems and just because you don't see all the life, doesn't mean it isn't there.
Besides, there are Joshua trees all over the Mojave and those are a protected species of tree as they only grow in two places in the world.
So it's not just open space with no life.
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The Mojave has a giant chunk of it that is completely devoid of any vegetation. No Joshua trees there already. Joshua trees only survive in the milder parts of the Mojave.
This is plainly obvious when you drive from Vegas to LA.
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If you cover it all with solar panels, you are still causing a great deal of harm to that ecosystem. ... we probably never will be able to "destroy" a desert.
Something like 4% of one big desert would power the whole planet.
However as we produce deserts quicker than we build solar panels
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Yes, but as shown from other studies, if we were to just try and build one huge solar farm for the whole world, we would lose a lot of electricity during transmission over large distances. Solar definitely has it's uses and it's part of a sustainable future for sure.
Oh and huge solar farms are also bad for birds because they mistake the panels for water surfaces and tend to not do so well when they come in for a landing only to find out it's not water. The reflectivity of those panels is what causes this.
So
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Birds in a desert. Rare.
Strange priorities.
Birds or Humans? What is your priority?
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Shade in a desert generally improves the ecosystem because it helps retaining water. This has been known for a very long time.
https://www.sciencedirect.com/... [sciencedirect.com]
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The point is to provide stability and short term storage. Say you have some clouds moving over the sky, so your solar output fluctuates a bit. If you can store energy then you can smooth the output to be more consistent.
Short term storage for a few hours is also useful for time shifting. We keep hearing about how people want air conditioning in the evening. Well, now you can collect solar energy during the day and use it in the evening.
It's not supposed to provide city level amounts of storage, it's suppose
Re: No (Score:2)
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No, this will not solve the "climate crisis".
Exactly. Because it doesn't 100% solve anything, it is completey worthless. It should be tossed on the scrap heap of history just like seat belts or air bags or anti-lock brakes.
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No, this will not solve the "climate crisis".
Exactly. Because it doesn't 100% solve anything, it is completey worthless. It should be tossed on the scrap heap of history just like seat belts or air bags or anti-lock brakes.
None of those things claim to "solve the accident crisis". Two of them protect occupants and one may avoid a particular type of accident.
Heat storage is already a proven technology. It is useful in some scenarios but it will not "solve the climate crisis"
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The keyword you have omitted is "help".
Talking about some theoretical accident crisis is a red herring.
> Two of them protect occupants
So maybe you do get it, but just want to argue. Nice troll.
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About 40% of our energy budget goes to producing heat, residential and industrial. Anything which lets us better utilize or produce said heat helps.
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Nobody reads an article like that, though. They want to affirm their belief that "the nerds" will solve it with magical future tech. Just like how AI is going to cure cancer, so it shouldn't be regulated. They always work in a "might cure cancer" or "new miracle drugs" instead of the far more likely outcome of selling you more shit you don't need and increasing inequality.
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True.
Only eating bugs, a switch to public transportation (with the resulting loss of freedom) and a massive wealth transfer from first to third world nations can solve that.
"They" don't even need to make you eat bugs. These days, just using public transportation means a massive wealth transfer from you to the thugs infesting the subways and buses.
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My public transportation is free.
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My public transportation is free.
You likely pay for it with your taxes. Perhaps you don't pay these taxes directly but it shows up in the costs of the products and services you buy, because the people providing those are paying taxes. Nothing is free, you pay for it somehow.
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It didn't use to be free. Now it is. No, increases in local taxes. So, while I'm sure you are right in that are probably using tax money, since there haven't been any increases, it sure doesn't feel like we're paying for it.
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My public transportation is free.
When your public transport is made free-to-ride, which some cities have tried as a way of increasing patronage, the riffraff problem gets even worse. I would rather see it made subscription-only, with each rider identifying himself by maintaining an account. A safer system would be a system that ordinary middle-class [eople would use once more.
Nothing new? (Score:2, Informative)
This is literally how solar concentrator power plants work. They point a bunch of mirrors at a receiver, and some variants dump that heat into molten salt, so that the power plants can provide constant power for the entire day.
The thermal storage variant has existed in real-world power plants for nearly three decades, but this type of plant has been on the decline because the falling price of photovoltaics made it a far more economical option, and this will only be more true in the future.
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I think the idea is to store waste heat from PV cells.
Re:Nothing new? (Score:5, Informative)
This is not a solar concentrator. It uses electricity from photovoltaics - which, as you note, are a far more economical option - or any other power source, to generate heat. This heat can be stored for very long periods of time, and used to generate electricity when the sun isn't shining. It's basically a battery, except that the storage medium is "hot rock".
What's IMHO kinda cool is how they extract the heat from a container that's hot enough to melt steel. They make use of the fact that matter at those temperatures radiates incredibly intensively, so they leave gaps and when they want to harvest the heat, they open the "doors" and let it radiatively heat the working surface, whether a boiler for electricity generation or various industrial processes that need high temperatures (cement, steel, etc).
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No heat pumps involved.
Storage: electricity to heat (near-100% efficiency, but no CoP)
Usage: heat either directly as high-temperature process heat (concrete, steel, etc), or to run an electric generator (and thus subject to Carnot losses + additional generation losses)
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I read too quickly, I saw "But what makes his box of white-hot rocks so significant is they were not heated by burning tons of coal or gas, but by catching sunlight with the thousands of photovoltaic solar panels that surround his prototype west of Fresno." and summarized it in my head as concentrated solar due to the whole "catching sunlight with panels that surround the prototype" bit, missing the word "photovoltaic". In reality, there's no need for the photovoltaic panels to be near the hot rocks, let al
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This is literally how solar concentrator power plants work.
Not quite, this gets much hotter than concentrated solar thermal can get, or at least as best I can recall. I can't find the maximum temperature limit on solar thermal right now but it is something like 800C while this gets to 1600C. I've seen this idea of solar heating before described as a "heat pump" which I guess is true to a point but it is not operating as most people think of a heat pump.
The thermal storage variant has existed in real-world power plants for nearly three decades, but this type of plant has been on the decline because the falling price of photovoltaics made it a far more economical option, and this will only be more true in the future.
My guess is that they are trying this kind of energy storage precisely because of the falling price of solar PV.
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Why are you obsesses with capacity factors, when you still not know what it actually is/means?
A solar thermal power plant obviously has an CF in the 65% to 75% range.
So why are you pulling numbers out of thin at that makes no sense, and are in practice irrelevant anyway?
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This is literally how solar concentrator power plants work.
I've never seen a solar power concentrator which can fit in my dining room. Also no one is using mirrors here. Please put a minimum amount of effort into understanding what is discussed before posting.
And if Hot Rocks won't work... (Score:2)
How about Pop Rocks [wikipedia.org]?
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No. Now get out of your stinking car (Score:2)
Save our fucking planet by staying the fuck out of your dirty, stinking autombile.
THAT IS HOW TO STOP GLOBAL WARMING.
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Stop hyping nonsense excuses. Save our fucking planet by staying the fuck out of your dirty, stinking autombile. THAT IS HOW TO STOP GLOBAL WARMING.
Nope. Global warming is a collective effect. Telling one person to "stay the fuck out of their dirty, stinking autombile" is not going to stop global warming.
You need to convince 1.446 billion people to "stay the fuck out of their dirty, stinking autombile".
This is why it is a hard problem.
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We can but hope that, eventually, the sheer embarrassment of being a cunt will make most people stop driving private cars.
And whether that happens before or after the planet is totally, irreversibly fucked, we will see, all-to-soon.
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Nah fuck that. Come up with a better solution because I'm not taking my kids on the fucking bus. Too many stabbings and feral crackheads. It's just not happening, drop this line of reasoning at once.
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Private passenger vehicles account for about 8% of carbon emissions. Getting rid of them would be helpful, but it's no more the silver bullet solution you claim than a thermal battery is.
What am I missing? (Score:3)
I get that with wind as a power source, heating the 'rock battery' electrically is necessary. But with the sun as a source, why take both the efficiency hit and the cost hit of using solar panels? Why not use parabolic mirrors and/or Fresnel lenses to concentrate the light energy directly where it's needed to heat the rocks, molten salt, or whatever?
Even if some solar panels are needed to increase the max temp on cloudy days when the light concentration alone isn't enough, wouldn't having direct heating of the rocks as a component of the system increase overall efficiency and reduce costs?
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You could ask the same question of heat for buildings. A decade or two ago, solar heating systems were gaining in popularity, but they're PV is used instead.
PV panels are truly mass-produced these days, so cheap, and the infrastructure and maintenance is simple, just wires, compared to pumping around water.
So I think the answer is that concentrating solar is probably a lot more complicated and expensive to get right than just putting up a bunch of PV panels and wiring them together.
Besides, using electricit
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Thanks - that makes sense.
Hot Rocks For Global Warming? (Score:2)
Hmmm. So do we put the hot rocks on the ice sheets to speed things along? Maybe if we get enough steam generated we can make a giant cloud that filters out the Sun so that the temperatures will be close to the same world wide.
I like it.
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Hmmm. So do we put the hot rocks on the ice sheets to speed things along? Maybe if we get enough steam generated we can make a giant cloud that filters out the Sun so that the temperatures will be close to the same world wide.
I like it.
What about using small domestic versions to warm up pilates balls?
People wouldn't need those ugly puffy coats or chairs because they could bounce to work and sit at their desks on the same warm balls.
Eclipsed (Score:2)
This is nothing new, it's "old tech" - but it's superior technology to the fledgeling lithium-based technologies which have insurmountable hurdles to environmental friendliness and broad utility.
Similar (Score:2)
https://www.scientificamerican... [scientificamerican.com]
This is the same principle except dialed up a few notches further.
Isn't that... (Score:1)
Just called "geothermal"?
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Sort of "artificial geothermal". And not in the ground, although there are different companies pursuing exactly that :)
Kinda like molten salt reactors? (Score:2)
But what makes his box of white-hot rocks so significant is they were not heated by burning tons of coal or gas, but by catching sunlight with the thousands of photovoltaic solar panels that surround his prototype west of Fresno.
Wouldn't this be similar to proposed molten salt technology [wikipedia.org]?
universal answer to headline question (Score:2)
Universal answer. Do I really have to say it?
Active solar heating article from 40 years ago. (Score:2)
New Shelter Magazine had a great article on home heat storage in the March/83 issue, "Active Solar."
(article reprint via Radiant Solar) http://www.radiantsolar.com/pd... [radiantsolar.com]
I've read a couple others in "NS." That's the only one I can find.
Re: (Score:2)
Well, you only get less than 20% conversion with photovoltaic.
Unless someone has serious constraints on size and/or weight this conversion efficiency doesn't really factor in. I'm already seeing cases where people choose less efficient PV panels because the panels are cheap, and the area they cover is cheap.
This is why actual thermal capture systems use mirrors. You can get up to 40% efficiency. Mirrors are also cheaper and easier to maintain.
Moving mirrors are cheaper to maintain than stationary PV panels? I have my doubts.
With actual batteries, you have an instant turn on. You can cover short glitches. What do you do with a pile of hot ceramics? Just -exactly- how do they currently produce 100 megawatts for 20 minutes? Oh wait, they don't and they can't.
With gas turbines. https://en.wikipedia.org/wiki/... [wikipedia.org]
A gas turbine doesn't provide power as quickly as a reciprocating engine, or a battery, but with a heat transfer fluid between
Re: (Score:2)
Mirrors are also cheaper and easier to maintain.
Moving mirrors are cheaper to maintain than stationary PV panels? I have my doubts.
Yes, good catch. A thin layer of dust is mostly forward-scattering, so dust doesn't have much effect on solar panel efficiency until it gets pretty thick. Even a monolayer of dust, however, will destroy the specular reflection from a mirror. So mirrors have to be cleaned much more often, and the cleaning has to be much more thorough.
And the tracking has to be much more accurate with concentration. You don't lose much power if a flat-plate array is ten or even twenty degrees offpointed, but that would kill
Efficiency (Score:2)
So... where to start? Well, you only get less than 20% conversion with photovoltaic.
Maybe for single-junction silicon arrays. If you go to multi-junction cells, the current efficiency record is 44%. https://en.wikipedia.org/wiki/... [wikipedia.org]
Now, admittedly these are very expensive cells, not low-cost silicon panels. But there are people working hard at making them cheaper. Also, you can use high-efficiency cells in concentrators, where the cell itself can be very small, often only a few mm across, and thus the cell cost is not as important.
This is why actual thermal capture systems use mirror