In early 20th century in London there was an alternative hydraulic "power grid" with plants (aka pumps), storages and an underground distribution network of pipes. A building, for example, could connect to high pressure water mains and use it to power elevators. Electricity eventually won, but it's interesting to see an idea coming back.
This sort of system is used today in many modern industrial facilities. Case in point: Amazon warehouses.
Lots of the mechanical automations inside some of those warehouses are powered by compressed air in open loop systems. As the conveyor pushes the item off, onto a different lane, there's a distinct hiss of air escaping. The movement of the machine was powered by compressed air.
Out in the parking lot in these facilities, you'll see a huge compressed air tank (or many), constantly being refilled. Tubes from these go into the building like arteries in a body. Often inside the building there will be buffer tanks to help ensure constant pressure.
Source: worked for a few years with guys who maintained these systems. Some of what I learned may be wrong, so feel free to correct me.
The common term is "pneumatics" and the components are prevalent in all automation and manufacturing. The air required is typically compressed on site.
Pneumatic actuators are relatively inexpensive, have a binary state that is easy to control, and offer a high power density.
The air in industrial pneumatic systems is filtered and dried, which would prevent these issues.
Pneumatic systems often use small orifices and valves to control the air flow which would be quickly clogged by any debris, so cleanliness is important.
An aside: PID control was, back in the day, mostly implemented in pneumatic control systems (using a set of levers, bellows springs and nozzles). Pneumatic control systems were (and still are) used a LOT in industrial control systems where e.g. flammable environments where electrical equipment is too much of a risk.
Pneumatic "muscle pressure" is common in lots of industrial applications, especially those that operate in austere environments. But those are different than the tech being researched in the article in large part because the mechanical compressors in industrial applications are hugely inefficient. Many constant volume compressors have 90%+ of the energy as waste heat.
I believe the article is referencing isobaric (constant pressure) compressed air energy storage (CAES) that have much better efficiencies.
Oh I agree it's not quite the same as in the article. I was comparing to what the parent comment was saying about large pneumatic tube networks in ages past.
According to PV=nRT (ideal gas law), no you cannot in a closed system!!! But Hydrostor isn't violating any laws of physics -- they are simply capturing that heat so that it doesn't become waste heat!
Hydrostor has a thermal management system that captures the heat and stores is during compression. Then it reuses the heat when it is decompressing the air.[1]
This seem extremely promising as a much smaller footprint solution than pumped storage and much more sustainable and lower cost than any other energy storage solution. I just heard about them today, and I'm extremely impressed.
That doesn't seem isobaric. Searching if it's possible, I've seen mentions of condensing working fluids, and bumby mentions ocean floor bags which seem like a good solution.
An external pressure (usually water) keeps it at a constant pressure.
Think of a bag of air under water on the ocean floor. The height of the water column is (relatively) constant, so the pressure in the bag is also constant. The air is being compressed as it goes from sea level into the bag, but inside the bag, the pressure is always the same. If you define the system boundary as the bag, it's an isobaric system. The volume changes, but the pressure is constant. Contrast that to the compressor you might have in your garage where the rigid tank provides a constant volume, but the internal pressure changes.
It is pretty common in regular workshops. Compressed air powers drills, riveting machines, sprays guns, jack hammers... Tools powered by compressed air are simpler (no electronics), more durable and cheaper.
My favourite thing about air tools was not having to worry about batteries (most electric hand tools I've used are battery only so no opportunity to use an extension lead like you use an air hose)
Most electric hand tools are usually available for cheaper in a corded variety. The only electric hand tool I haven't seen come corded are impact drivers and most impact drivers I've used will last a day or two using it 8 hours a day even off a 2aH battery.
For me, I like air powered tools because of their power and reliability. They'll almost always have more torque and power than similar electric tools.
Air tools defintely don't have more torque than electric tools, they rely on speed to overcome their shortcomings in torque. The main high torque application in air tools is in impact wrenches, which use very fast hammering action. Modern battery impact wrenches can match the performance of the best air wrenches.
A top of the line M18 fuel impact (a $300 tool, before the $100 battery) is only equivalent with its air analog on the 1/365th of the year shop pressure runs at 90 because the OSHA guy is poking around and it's a heck of a lot bulkier.
When you start getting into 3/4 and 1" it's not even a comparison.
The cordless is nice to have but it's a luxury/convenience tool, not a replacement.
I saw a similar thing in a very old building, I think from the early 1900s.
The web of tubes was for messaging. (Just like some bank drive-ins work.) Users would put paper messages in capsules which were put into a pipe. Compressed air would carry the message to a central switching station, where human operators would re-route the message to the proper destination tube.
The district heating in Brno here in Czech Republic is in the process of converting from steam to hot water, mainly due to cost savings. Modern isolated hot water pipes loose a negligible ammount of heat in transfer while there was green grass growing on top of the old buried steam pipes even in winter.
That and the old textile industry that directly used steam no longer exists.
Downtown Ottawa has a similar steam system too, although I think it's mostly government buildings instead of private, commercial buildings that are hooked up to it.
There also used to be "central turbines" whereby there was a central spinning rod that one could attach belts to in order to spin a thing to get work out of it...
That was normal in the age of steam. Having lots of tiny steam engines on the factory floor does not make sense. Keeping them running is too labor intensive, they would be fire risks, and they’re less efficient.
Cool indeed, but pretty dangerous and difficult to reconfigure. Electric wires and motors are so much smaller, and easier to protect, and more interoperable, so you can see why they won out.
That was one of the reasons behind having factory whistles: all workers take their places, the whistle, then the whole thing is started. While it's running people are not supposed to move around.
"This was a crisis. Without electricity, the Amish couldn’t store milk, and the church was adamant that Amish were not going connect to the local electric company. Finally a solution was found. It was decided that diesel generators could be used to power the refrigerators. This decision allowed the Amish to continue their tradition as dairy farmers without having to use public electricity."
So the Amish are allowed to use electricity, just not from the public grid? Generators seem like a weird loophole to their own rules.
> So the Amish are allowed to use electricity, just not from the public grid? Generators seem like a weird loophole to their own rules.
That depends greatly on the congregation. Each congregation sets its own rules on how to deal with technology. "Not inside the home" is a very common technological limit. Cell phones might be stored in a shed, fed by solar chargers, for use out in the field. A workshop might have electricity from a wind/solar installation or even a diesel generator, but not the attached house.
If they are against centralisation, that makes sense; but then, unless you drill your own wells and refine the crude yourself, you're still getting fuel from someone else.
I think it's against against dependence. You can choose who you buy your diesel from, and you store a however big tank of diesel you deem appropriate. In stark contrast to a powerline.
I once took a tour of the Mabel Tainter theater in Menomonie Wisconsin. The original light fixtures had been built to work off of both gas and electricity, just in case the whole newfangled electricity thing didn’t work out.
The military is actually doing a ton of work with blimp and zeppelin like things currently - you do not hear about it much but there is a a ton of testing and research being done.
The University of Iowa campus has a steam system under the campus, installed in the last century. Nowadays the steam is recovered waste from the electric plant. But it's still in use!
If you want to find good candidates for saving the campus tons of money, go to the roof of one of the tallest buildings on a cold day and look for the buildings that are venting lots of steam. They likely have a failed steam trap somewhere in the building. It's not uncommon for failed steam traps to save thousands of dollars a year apiece when fixed.
After watching it, I now understand that they aren't flooding the entire borehole, but rather are building a smaller high-pressure chamber at the bottom. The chamber is connected to pipes to a surface reservoir. When air is pumped into the chamber, it displaces water up toward the surface. When generating, the water flows back into the subsurface chambers, forcing out the high pressured air.
A similar thing is done for natural gas storage. A well will be drilled into a rock dome that lies atop a layer of saltwater-saturated sandstone. Gas is then pumped into it, displacing the water, and then can be withdrawn later.
you don't have to build those caverns as they already exist and we have extracted gas and liquids from them, also the volume should be already known as we know how much we pumped out (unless it's an old site)
Not much, technologically this is a conventional mine project, only that you mine air volume instead of rock and have to take care of the cavern being reasonably airtight afterwards.
The video is from 2015, and says it was a 2 year pilot project. Do you know if there are there any updates on how the project went? Is it still operational? Did they build any more?
I don't have specific numbers, but in other batteries of this type, the length of storage time before discharge affects the efficiency. Heat stored from compression is lost over time.
I was curious about that as well. I think it's best application would be to compensate for large amounts of rising and falling generation from solar grids, that way the cycle is daily. Being quick to come online and meet demand makes it good for maintaining grid stability at a much lower cost as well, like the Hornsdale Power Reserve facility https://hornsdalepowerreserve.com.au/.
The big question is how on earth are they digging out these caverns? That seems like a huge challenge, given that they're so far underground. Everything else seems relatively straightforward
I had a similar idea for repurposing an old mining operation. You take a closed gold, uranium or copper mine which is 1000-2000 meters deep. You create a nuclear rector at the bottom with "fire and forget" design. Only robots can do the maintenance. After 60 years you disable it, pour concrete into the shaft and move to the next location. If it melts, who cares? It's not gonna poison water supply.
Why was this not built before? I have no idea. Maybe robots are essential, we didn't have deep enough mines that were abandoned, energy was cheaper, no push for no emissions, it's not economical, other risks.
In France we’re storing highly radioactive items underground. Here is how dissipation works:
- After a few dozen years, the concrete is expected to breach,
- Radioactive atoms mix up with soil and dissipate both upwards and downwards, mostly thanks to water,
- After 400 years and for thousands of years, they reach the surface, where they should be diluted enough to not be dangerous,
So I guess having badly contained radioactive containers would be much worse.
One thing to remember is that pressure underground is extremely high (stone weighs a lot more than water, and light rock tends to “float” onto denser rock). If a melted reactor were squeezed, it would spread materials into the soil much quicker.
You need a hot and cold reservoir to generate power. Where is the heat going to go? This is why power plants are often built on rivers or near the ocean.
The footprint of a nuclear power plant is pretty huge. That machinery is generally not optional even if doing a "fire and forget" design. Underground space would come at a premium cost, likely far more than could be saved on reactor design.
Also nuclear power plants obviously generate an absolutely massive amount of heat that needs to be dissipated, a task that would be difficult and expensive underground.
inb4: not a specialist. AFAIR remote control robots were tried when Chernobyl disaster was being cleared up, and the radiation destroyed the electronics. But perhaps the shielding technologies progressed enough to mitigate that.
Having nuclear stuff underground requires extremely precise geological surveys, so that the stuff does not wind up in aquifer.
I'm guessing not. Earth's heat is way lower down. Think of a cave: always cold. I think what's going on is they're taking the heat out and storing it more efficiently than just dumping it down the ground, where (1) it would leak away, representing energy loss, and (2) as it leaks away, the air would lose pressure. (It would leak away b/c it's harder to insulate an entire mine, basically.) So, they pull it out ahead of time and put it back in when they decompress the air (which I think would add pressure back in due to heating a gas and maybe reduce problems caused by super-chilling other plant hardware? Anyway, seems fitting to add back what you took out if you're shooting for a closed system.)
Do you have a source for that increase? I was not able to find it. Seems very suspect considering that the earths outer crust is approximately 20 to 30 miles thick. Are you suggesting that if we go approximately halfway through the outer crust, say 15 miles, the temperature is going to be 725 degrees warmer than surface temp?
> The heat is transferred from the interior towards the
surface mostly by conduction, and this conductive
heat flow makes temperature rise with increasing
depth in the crust on average 25-30°C/km
Not sure about the rate per-mile, but literally it's that hot, yes, but not even 15 miles. Just down 5-7km under the oceans, for example at the Mohorovičić discontinuity the temp ranges from 392 to 752F.
Under the ocean is already much, MUCH closer however to the mantle. Oceanic crust is drastically thinner than the land we walk on.
In the Nat Geo article they quote a mine in South Africa reaching up to 55C (131 F) at the bottom and the mine is 4km deep. At a rate 3 degrees Celsius per 100m it should be 120 degrees Celsius over ambient. Which obviously does not add up.
Naive question but couldn't our forerunners who otherwise succumbed to cold in harsher climates have exploited this fact to dig subterranean villages and towns?
What's the element I'm missing as to why they didn't?
Pre-industrial holes may collapse long before you reach -100 meters. Even -5 meters is a challenge in certain places.
Also, digging (or rather drilling) in bedrock is hard without motorized equipment and good steel.
Also, supplying fresh air down there is a problem.
Also, preventing the mine from flooding is usually a huge problem.
Mining is hard and a lot of people lost their lives doing that. That said, if your only intent is to get a bit warmer, you may basically try a good cave. Caves tend to have temperatures above freezing for the whole year.
Difficulty of digging with the tools they had, inability to stabilize the structure to prevent cave-ins, lack of pumps to remove accumulating water, insufficient ventilation and filtration technology/unable to deal with poison gases, inability to light their environment without contributing to the poor air quality, difficulty accessing resources like food and clean water, lack of desire to live in a damp, dusty hole.
Also for example Finland can be at least in north considered harsh climate. But these are also areas that suffered of ice age that scrapped most of the softer rocks away leaving only the tougher stuff like granite. Which makes digging very difficult, specially pre-industrial times.
More like, ever tried to dig down more than a foot or two? Unless you have really soft ground, even a good steel spade and shovel aren't any guarantee of success. Powered augers are often needed to make holes for fence posts, etc.
Have you been in a cave? They're chilly, usually around 50F, year round. IIRC those "deep mines" are a LOT deeper than any compressed air storage system is likely to be.
This comment is an example of why I’ve become skeptical of the downvote button. It sounds like people read it, knew better, and politely pointed out that it was incorrect.
Everyone who might have shared the same misapprehension learned something and the parent wasn’t being an asshole.
Yes, when considered along with the corrective responses, it adds to the discussion. This is why it shouldn't be flagged and removed. On the other hand, it's factually wrong and would be misleading if people were to trust the claims uncritically, which I think justifies a downvote. Keeping it visible but lower on the page and showing it in gray seems like a pretty good compromise. Can you suggest a better way of giving more prominence to correct information? Or do you think that's not the right priority for the site?
Side question - do you need to reach a certain level of membership with HN to see the downvote button? I may be missing something, but seems that's only allowed for certain individuals.
Didn't downvote, but I am not a big fan of simply making stuff up on the fly as response. I've met my share of people who rather go this route than put in a 5sec Google search or simply admit they don't know something, and I try to avoid them.
"Looked the temp gradients up, after 50ft, temp of the earth is 50F, and raises one degree F every 60ft." (So, at 300 feet, 54 degrees; at 500, 57.5 degrees.)
«The temperature on average is in the 50s, but you still sweat an enormous amount when you start laboring.“ - Alan Bates, working in the coal mines of Letcher County, Kentucky.»
what would be the benefit to it being heated by the earth during storage?
all the temperature management here looks to just be counteracting the temperature changes that naturally occur when you compress or expand a gas. i imagine if you compressed it and then pumped hot air into water-filled caverns you'd get some negative effects of thermal shock.
Hot air should have higher pressure, so theoretically you could get more displacement. But your pumps also have to work harder to create a pressure differential. Hard to say which effect would be bigger.
Grid storage is going to be big business in the future, on the order of size of storage for electrical vehicles. (And these will certainly not be mutually exclusive markets! Vehicle to grid tech will become widespread, as is already seen in the new F150 Lightning truck). Lithium ion will dominate for the foreseeable future, as the industry has scaled to massive sizes and already, and has the advantage of being currently unstoppable in the EV space.
Batteries with a design that can decouple the energy from the power ratings, like this one, will be able to address parts of the market that lithium ion cannot. And if the cost per MWh of additional energy is cheap, and round trip efficiency stays above 50% or so, that sort of battery will have a huge edge in a part of the market that currently has no clear winners.
There are many competitors in the non-lithium ion storage space, but one of the top contenders to watch is Form energy, which has a rust-based battery, and is rumored to have a cost as low as $20/MWh, about a tenth of that of lithium ion.
> one of the top contenders to watch is Form energy, which has a rust-based battery.
Form is still in the cell prototyping stage, as best I can tell - maybe not even that. There's zero information on their website about where they are in the development process or really anything substantial about their design.
Competition in the market is certainly a good thing, but Form needs to do more than just have a shiny website, a screengrab of a zoom employee meeting, and a blog with 'industry insight' posts (because they have nothing to show for tech/product.)
Agreed that Form has lots of hype, but that's one thing that can be needed in addition to working tech. Utility decision makers are not the best at adding new tech to the grid or dealing with innovation. Having some big industry names and the support of the business press that the utility execs and shareholders read is it's own form of currency when dealing with such archaic businesses.
Form has no working tech, as evidenced by the total absence of any mention of it. No specs, no pictures, no test installations, no whitepapers, nothing.
I have been saying for years that we should have a windmill system you could place on top of a building or home that powers a larger, highspeed flywheel buried underground below the house. Ideally with the flywheel in vacuum and balanced by magnets for reduced friction. This ensures no loss converting energy types (mechanical to mechanical) and it can be used later for electricity or other energy in small, large bursts (sort of like a capacitor). You would still want batteries for energy storage but this would drastically increase the lifespan of those batteries by reducing stress on their chemistry. Batteries really do not like to discharge in short, high intensity bursts. There are flywheel based UPS systems that work sort of in a similar principle and they have much longer maintenance intervals vs a battery type UPS>
I think both battery and solar tech has advanced to the point that solar plus batteries undercut a lot of grid supplied energy in costs.
Or at least it would, if the overhead for current solar installers wasn't so high. Retail prices for equipment are incredibly low, but the boom-and-bust cycle caused by uncertain regulatory terrain ends up requiring successful biz to have massive marketing costs, which results in really high prices overall.
I still believe that's why the U.S. invaded anyway. We didn't care about overtaking a country for some silly resistance leader. You do it for big money to bilk - like Iraq and oil.
But we left without taking any lithium. At some point second and third order hypotheticals are just conspiracy theories. There is no evidence we invaded Afghanistan to get lithium, and at the time (2001), we were not worried about lithium shortages or grid storage.
Like others I don't think that that's why the US invaded, but I do think it had something to do with the enormous shit-fit thrown by the DC foreign policy / national security / defense commentariat when we pulled out of Afghanistan last summer.
Lithium Ion is not sustainable for the long term - we have neither the materials nor the manufacturing to not only keep up what would be required for full scale car and grid uses, but don't forget Lithium Ion batteries have a finite lifespan and need to be replaced. The more you put into service, the more you have to manufacture beyond just the batteries needed for new requirements.
I'm not sure that your predictions will hold here. More lithium is discovered as demand grows, and there have been huge additions to known reserves in just the past few years. Looking at current numbers and saying "that's it" is clearly wrong, and given its overall abundance and lack of demand until now, it's a really strong prediction to say that we won't have enough for at least 500TWh of storage, if not more.
Manufacturing capacity is expected to increase 10x every five years, with roughly 20-30TWh/year production in 2031. I can't think of any fundamental constraints there, could you specify why that can't increase?
Lithium recycling is being planned by nearly all manufacturers and many countries will mandate it. If lithium supplies are short, recycling will be highly profitable. If lithium is super abundant, recycling may be more expensive than recycling, and a program like what we currently use for lead acid batteries might be needed for a circular economy. But the fundamental point is that end of life for the battery does not mean that the lithium is gone, it's not a fuel.
How did you collect this odd set of concerns? Did you think of them or did you find them in the media somewhere?
It's all a question of economics. I think technologies like the one in this article, or the one I think holds the best long term promise - super capacitors - are far more likely to displace lithium ion batteries before all that infrastructure you describe scales out. Recycling a battery pack out of a car like a Tesla is far different than recycling a traditional led acid battery from a car. Recycling the quantity of batteries required to support the grid at scale is even more of a non-trivial problem. And if recycling isn't economically viable because lithium is so abundant what do you do with the spent batteries? Bury them?
Especially for electric cars - without something like a supercapacitor or hydrogen that can charge quickly and doesn't have massive battery pack replacement costs built in to the total cost of ownership equation, electric cars are not going to become mainstream; they will remain fringe oddities.
I don't think Lithium is going away tomorrow - but I think it's crazy to bank on it for all our future needs or pitch it for grid storage. If it was so viable for grid storage then where are the really large deployments at scale? As you point out its mature tech. Someone would have scaled up production and done it already if it was such a no brainer. If Elon thought he could make more money at it than cars or space do you not think he would already be there focusing on it vs. those other ventures? Heck at one point Elon was thinking of doing his own candy but didn't since he didn't find anything really revolutionary enough to separate his potential offering from what was already out there. So it's not like he has a super narrow focus only on what he's already working on, and he already has a ton of in-house knowledge about lithium ion batteries.
That a company with as high knowledge of lithium battery tech like Tesla is only tangentially focused on grid power solutions instead of heavily diving in is, I think, one of the larger tells out there. And do you think Tesla would still be as successful if it didn't have substantial tax incentives? That's a distortion that's often overlooked when talking about overall economic viability.
There is far more than just raw resource availability or basic manufacturing capabilities at play here - and grid scale requirements just amplify those issues. I dunno why so many people are so eager to hand wave the limited lifetime of chemical batteries but it's a significant issue; any tech that doesn't have 100% replacement over a short fixed lifetime is going to beat the pants off of chemical batteries over the long haul. It isn't even remotely close. Utilities think in 50 year lifetimes, not 5. These aren't solutions for cars; this is base infrastructure that's COSTLY. There is probably some maintenance with these compressed air solutions, but I'm pretty confident it's no where near that of being forced to replacing the most expensive part of your entire storage solution every X years.
Just look at the value of a used electric cars vs. new. As people are learning about battery pack replacement costs or especially with Tesla, limited options on repair/partial replacement and probably loosing access to supercharging(one of the biggest reasons to pick Tesla right now), used prices on electric cars have steadily declined (and that's being a bit polite). When you have someone blowing up a used Tesla because they feel it's not economically viable to replace the battery pack, that' an issue that shouldn't just be hand waved away https://carbuzz.com/news/fed-up-tesla-owner-blows-up-his-mod...
All of this is in its infancy, but chemical batteries are already in a pretty deep hole from an economics perspective. Unless there is a breakthrough on preventing dendrite formation that dramatically (dramatically!) increases the lifespan of chemical batteries they are a transitory but not long term solution.
Supercapacitors aren't without their issues. You can fill them up instantly (if you have the means to move that much energy that quickly!) but they can also discharge all their energy instantly - which is a great way to also describe a bomb. So things like that will have to be worked out to make them safe - but I see that as far less of a problem than dealing with the perpetual churn of chemical batteries.
I knew Danielle Fong from Lightsail Energy, folded in 2016, and at that time compressed air seemed like a great solution especially for LatAm that needed robust low cost batteries for critical infrastructure (like hospitals) on an unreliable power grid. https://en.wikipedia.org/wiki/Danielle_Fong
Would be great to see this technology reach maturity!
I’m not an electrical engineer. But, thinking about the power storage/retrieval problem with a computer engineer’s lens, I can draw a parallel to data storage/retrieval.
L1/L2/L3 caches - expensive, small, but fast.
RAM - mid tier, still fast, bigger than cache, less expensive than cache, but limited in capacity compared to disk/flash based storage.
SSDs…
Disks….
You get the point.
Would it be the same with the grid?
Several power sources - nuclear, solar, wind, hydro, hopefully not coal and gas.
Banks of Lithium batteries acting as first level(efficient and immediate but limited capacity storage).
Whatever excess is directed to longer term, non immediate storage - pump up water to generate power later, molten salt, air compression etc.
Even more left? - spin up production of time insensitive materials that would be used anyway later - sea water desalination plants, green hydrogen generation, sewage treatment etc.
At large scale such tiered ecosystems would be very cool and super useful.
Look into natural gas trading and scheduling. There's already an entire body of knowledge around storing energy, and sophisticated automated contracts, financial instruments, laws, and regulations. "Pools" are just energy storage, and the same geologic features used for those facilities could be used for compressed air storage.
Sounds trivial enough, now someone just has to built it all.
Jokes aside though everything has pros and cons. For storing large amounts of energy from the grid, are you sure lithium batteries make sense? Take a look at this, it's not a scientific article but it gives you a basic overview of the problems we'd face when storing energy in lithium batteries at scale: https://www.renewableenergyworld.com/storage/lithium-or-vana...
And that isn't to say that flow batteries are the ultimate solution either, we will have to do better because it's still very expensive.
That article is from 2014. Since then we have deployed dozens of GWh of grid storage. There have been a few small fires, but otherwise it's worked out really well. Lithium ion on the grid is nearly doubling every year, and in places like Texas. I'm having trouble finding a recent article, but this one from 2020 has 3x as many battery GW thank gas GW in the interconnection queue:
And if you check out RV and boat forums, you'll find that small scale lithium ion batteries plus solar are enabling a huge change in power for these mobile applications, because it's just damn cheap these days.
Just because something gets does doesn't mean it's sensible. That's like arguing coal is the future because China and India have brought online thousands of TWh since 2014. You did not actually address any of the points mentioned in the article explaining why Li-ion is not the go to solution for grid scale storage. Flow batteries have only become relatively cheaper since then btw.
The actual arguments in the article are weak enough that I'm having trouble paraphrasing them fairly. Instead, I'll point to the numbers:
1) li ion cost is at $150-$300/kWh today
2) these are for batteries that have warranties for 5000-7000 cycles, not the small number that the author got from a website
3) actual installation levels on the grid are far higher than the author estimated.
I have nothing against vanadium flow batteries, other than the aren't shipping much. If the can actually hit the $150/kWh mark they say they can in the article, they should be shipping a ton of batteries. And if they are shipping, they should publicize a bit more! California and other states are looking for non-lithium ion batteries with 8 hour+ duration, so there's a market for vanadium even if it can't compete on price.
I've wondered if putting an compressed air energy storage system under certain types of buildings would work. Any thoughts on that? E.g. Apple's Ring HQ is already on a floating system to counter earthquakes, so why not add a layer of air? Unnecessary? Much more expensive than other options? Else?
The round trip efficiencies for these compressed air storage have typically been terrible (<50%). That's mostly because compressing air is super inefficient (lots of wasted heat). Are they able to harness that waste heat in some productive way?
ETA: Just saw the video. Looks like they store the heat to boost generation on the return trip. This [1] says they get ~60% efficiency.
It's not quite lithium ion efficiency, but it serves a different duration energy storage market (up to 24 hours vs single hours for lithium ion battery storage), and it has a much longer service life (50 years), so the levelized cost of storage might be lower than lithium ion battery storage.
What I meant is that current grid scale lithium ion battery storage projects are designed for at maximum a few hours between charge and discharge. They are mostly for shorter window grid stabilization, not to store energy for days or weeks.
LiIon grid scale batteries are still very expensive as a long term energy storage solution, they are sized to provide higher value grid ancillary services, like frequence regulation.
Especially when you consider that the use case here is surplus energy, like when the wind is blowing harder than can be consumed. Efficiency might not be so important if you’re buying free wind or solar energy, as long as it’s above some minimum threshold. 60% feels pretty good.
It's probably some kind of hedge strategy for energy crises like the recent Texas disaster (which appears to have been very profitable for GS [1]). Having this capacity around when other sources go down means they'll be able to provide power in similar situations and so reap massive profits. Climate chaos == $$$ I guess.
> Bloomberg March 5, 2021
> Goldman Sachs Group Inc. could gain more than $200 million from the physical sale of power and natural gas and from financial hedges after spot prices surged across much of the U.S., according to people with knowledge of the matter. Morgan Stanley’s gains could come in under $200 million, according to a person with familiar with the matter, and Bank of America Corp. stands to rake in profits as well...
> The historic cold that battered the central U.S. last month led to sweeping blackouts as ice formed on wind turbines and pipelines froze, forcing oil and gas wells to shut. As traders and power suppliers struggled to find fuel to meet obligations, prices skyrocketed. In Oklahoma, gas traded at more than 300 times normal levels, while electricity in Texas surged to $9,000 per megawatt-hour.
> Having this capacity around when other sources go down means they'll be able to provide power in similar situations and so reap massive profits. Climate chaos == $$$ I guess.
I understand that people don't like when others profit from a crisis, but this is also how we solve these problems. Having more generation capacity than we otherwise would have is a good thing, even if Goldman make money on the back of it.
I'm not arguing there isn't more to be done, but when people say "greed is good" this is what they mean.
This is where capitalism goes off the rails. Instead of investing $250m into making the power grid more secure and reliable, they choose to invest in profiting off disaster.
providing instant-on, scalable energy capacity to the grid is both potentially profiting off disaster and investing 250m into making the grid more reliable and secure.
As others said, energy storage technology is going to be the only thing that makes renewable energy more than a curiosity. Renewable energy is neither reliable nor predictable which is why it can not replace base load requirements.
However, if we had sufficient energy storage capacity, they we could indeed fully transition to renewable energy once and for all!
You are sorely mistaken, this sort of battery is exactly what makes the grid more reliable and secure. Especially on grids like Texas, which have massive amounts of renewables.
Batteries are the Swiss Army knife of the grid, they can fix all sorts of problems, from inadequate transmission capacity, to frequency regulations, to peaking needs.
In the 80s my grandfather used to do this for the former Soviet Union. Long story short they were pressuring a salt mine at night for energy storage and somebody failed to report a water leak during the day. They tried to depressurize the mine but it ended up blowing up anyway killing a couple people in The process. This shit can be really dangerous if done incorrectly.
Lots of water in a reservoir is not particularly safe in itself. For example, in December 2000 at the Grande Dixence a high-pressure pipeline from the dam burst, causing a landslide that wiped out a small hamlet and killed three people. It's also not hard to find reports of massive amounts of casualties and/or property damage from dams that just outright fail.
Yeah a large pressure vessel is basically a bomb. No matter how many layers of protection you add on the technology always wants to go too a rapid critical failure. Using statistics and layers of protection you can always show it to be safe to handle anything but when you get to such low probability your models be always be off and variables that you think are independent are actually linked (bad maintenance practices being one)
Water reservoirs for energy generation/storage have gone through accidents killing thousands. I suggest looking up Vajont on Wikipedia.
The project mentioned in the article seems particularly safe to me as they seem to run it with constant pressure, defined by the hydrostatic head of their deeply dug cavities. They don't really have a pressure vessel, they have a flooded cavern where they create a bubble by pushing in air. If you pop off a seal from the pipes connecting compressors/turbines to the bubble could still hurt yourself a lot shooting parts through the room, but that should be all.
The cavity they build is 2000 feet deep, which equates to the pressure of a CO2 cartridge that you'd use for e.g. carbonating a beverage. Not coincidentally at all I think, they either aim for the deepest cavity were hydrostatic pressure isn't enough to liquefy parts of the air, or for the least deep dig that gives them liquefication, where the air "boils off" as they open the valves.
Pumped storage is a bit different than an ordinary reservoir with a dam, though. You have more opportunity to build it in a place where it's less likely to cause harm is something goes wrong. It has been used pretty effectively on both sides of the border near Niagara Falls for 60+ years.
Yeah I realized that pretty much right after writing it, that it's biased from having gone through many iterations of dangers, and by now we know how to do it safer than less well used methods. So we can't say it's intrinsically safe only relatively from experience of use.
The Lake Peigneur Drilling Accident is a tale of water getting into a salt mine from the lake above, due to drilling for oil in the wrong place. As the water dissolved the salt, the hole grew bigger and bigger, exponentially. The lake emptied into the salt mine, turning it into brine.
So I'm picturing water leaking into a salt mine full of pressurized air. Naively it makes a hole, and a hole is just a leak. But if the water starts dissolving the salt in a process that runs away, then it is more like popping a balloon, but on a grand scale.
They claim 1m in revenue from their existing product which is:
"1.75 megawatts (MW) of peak power output; a 2.2 MW charge rating; and 10+ megawatt-hours (MWh) of storage capacity"
How does that equal 1m in revenue? You have to pay to charge your air-battery during low-cost hours and then discharge it during high cost hours to make the difference in revenue.
The issue is, you can buy 2 megawatts of power 24/7 at average datacenter energy pricing (~5c/kwh) for $2400/day or 876k/year. Who is paying more than that for less energy and only at certain hours?
Is there some energy company somewhere that sells power during the day at like 50c/kwh and 1c/kwh at night???
These kinds of utility-run storage facilities usually buy and sell on the wholesale spot market, which swings much more than retail prices do. Somewhat similar economics to gas "peaker" plants, which only fire up when supply is tight and prices spike, making it economical to run a higher-cost generator.
The Hydrostor plant is in Ontario. Here's an archive of hourly spot-market electricity prices there (in dollars per MWh): http://reports.ieso.ca/public/PriceHOEPPredispOR/. So far in 2022, prices have been as low as $0.00/MWh (during a few hours overnight on Jan 5) and as high as $230.87/MWh (during the morning of Jan 11). In 2021, hourly average prices even exceeded $1000/MWh ($1/kWh) twice, on March 28 and October 10.
I would need to see the math, because nothing adds up to even 1/10th of their claimed revenue. Best case, they bought 10mwh on jan 5th and sold it at the perfect time on jan 11th. This would give them 2k in revenue in 6 days.
Wheres the rest? And what about if you cant nostradamus predict the best times to buy and sell?
Sometimes utilities only need a few minutes of power to cover small gaps while ramping up/down powerplants, or if a cloud passes over a solar generation facility. Since these volumes are very small but critical, the effective price per MWH is extremely high.
When Tesla did their grid scale battery installation in Australia, this is how they made their money. Not via energy arbitrage, but with selling frequency response services. I have no idea if this is the same thing, but there are other ways to make money with energy storage as well.
Still seems extreme. IF my math is right, they would need to buy and sell 10MWh every day at a 27c/KWh markup. Given they they deliver at ~2.2 MW, This means that they would have to hit this markup for a 4 hour duration, every day.
They are likely operating on the wholesale markets, which are market priced. For the western grid there is a significantly wider price range of prices. On peak days in the summer, prices can go up above $1,000/mwh in the late afternoon for several days. During the late fall/early spring, there are negative prices in the late morning (like $20-$50/mwh) due to extremely high solar production and low demand, so utilities are literally paying you to use electricity. It's not inconceivable to get to $1 million a year on 1 mwh of storage.
A lot of people look at these and think "that doesn't seem like it'd be remotely worth it for something that size" but it's really hard to explain just how badly California has painted itself into a corner on distant generation, huge variance between excess renewable capacity and peak load, and transmission congestion. The numbers don't make sense to people.
Pretty much all the solar plants we're putting in now have combined battery storage systems either for voltage support or "peaker" sales opportunities. In some places (like literal islands) it's about capacity smoothing or resilience, but the driving force behind all the investment is the US western interconnect with arbitrage opportunism starting to make real money and looking to make much, much more over the next decade.
If government-sachs is betting on this, they've probably got an even more pessimistic take on the CAISO market than I do.
Just read the constant stream of news about it? They keep shutting down power plants in the name of the environment, but just shift the generation outside of the state. It's a numbers game that's meaningless as long as they still consume power, but it lets them virtue signal all over the place to people who don't pay attention to details - which sadly is most of us. How many times when we are give stats do we really wonder about the context around them?
Im familiar with energy markets. Im also familiar with the fact that any serious seller or buyer of energy locks in yearly pricing contracts and is unaffected by these swings. Any serious datacenter or industrial buyer is not relying on spot pricing. These energy markets also dont exist in every state.
If you are familiar with energy markets then by all means tell us the percentage breakdown of electricity consumed that is covered by long term contracts vs the spot market.
There are times where the rooftop solar and base load generation for a utility is greater than the total electricity demand. Demand and supply for the grid have to be balanced, or else you will end up tripping plants and/or damaging equipment. Since they can't "turn off" rooftop and most grid scale solar generation, and they can't really turn off and on their base load plants throughout the day, their best option is to try to sell the excess electricity on the wholesale market. The problem is that the other utilities are in the same situation, and they need to offload electricity. Since no one wants the electricity, wholesale prices will actually go negative. Basically a utility will pay another utility to turn off a base load plant and take the excess electricity from them.
This is why grid scale energy storage is such a hyped technology - if you can store that energy when supply is way too high and dispatch it when renewable generation is low (no wind/solar), you can maintain high renewable percentage in the generation mix. Without it, you can only really go up to a certain percentage of renewables.
Buy low and sell high. They can find surplus power and buy it cheap, then wait until there are unmet demands and sell high.
These crazy things called computers make creating and automating markets like that pretty easy :)
It's win win - the people with surplus power can at least get some money for energy that would otherwise likely go to waste (large base load power plants can't ramp up and down on a dime) and on the flip side if you have an energy provider that only occasionally needs capacity in excess of their inherent generation even though the immediate cost is higher for spot power, it can still be far cheaper in the long term than building more base load generation (often fossil fuel because renewable still isn't a viable replacement for base loads). And running base load generation under capacity is wasteful for emissions and overall efficiency.
Once we start to crack the whole energy storage thing renewables will be A LOT more valuable since we will be able to start to use them for base load. Storage allows you to create reliable energy delivery that's predictable - that's essential if we ever want to eject fossil fuels from the grid. Or we could stop being childish about nuclear power - frankly I think we can solve the storage problem long before we can convince people to be rational about nuclear :p
It probably seems crazy for the uninitiated, but there are a lot of efficiencies in markets that occur naturally over time. You see distortions in the market from CA's stupid and politically motivated choices - what seems crazy to you is the market adapting to the model that CA is forcing. Is it nuts? Yup. Is it necessary? Nope - these wounds are entirely self inflicted. Pretending the world is different than it actually is doesn't solve anything and the people of CA are paying a hell of a lot more for electricity because they are trying to live in a pipe dream for where we are today.
IF 10MWh is their daily cycle, they are selling 3,650,000 kWh/year.
To hit $1M per year, they would need to be selling ~27c/KWh above their buying price.
I get that you can have a big spread if you are being paid to take power, and paid again to sell it.
I think that’s it basically. New England consumers pay ~$.22/kWh. We’re going to have offshore wind energy in the next decade that might conceivably have surplus power quite a lot. It’s not beyond the realm of possibility that these plants could have a deal with the power plants to take extra power for free so long as they have guarantees on filling the expected gaps or meeting expected spikes in usage. Everyone wins.
This brings to mind the other post about the Amish that's on today's front page. I believe the Amish sometimes use compressed air as an alternative form of power.
I read an article in a woodworking magazine about how one Amish woodworking shop was built to avoid using electricity. The whole shop ran off a stationary diesel engine driving a shaft in a floor trench and belt drove the larger stationary machinery like band saws, table saws, planers, drill presses, joiners and so on. But what about hand tools? A large belt driven air compressor off the diesel engine handled a myriad of air power tools like drills, orbital sanders, buffers and all that. Really neat setup.
This is basically how most indistrial setups was before engines and motors became a commodity. You had water wheels as your main power source, from which other tools was driven via belts and gears.
Later the waterwheel was replaced by an electric motor or a fuel powered engine - but still built around just one source of power, with elaborate setups to drive different tools. With the added benefits you could build factories and workshops outside main water sources.
There is a wonderful museum in Windsor Vermont called American Precision Museum which still has the original overhead shaft and pulley system along with machinery. Went there in the early 90's as a kid and they did mention that it was converted to electric and the motors were still working supposedly.
The Edison museum in Orange NJ also has such a preserved shop setup but electric driven by one or two big motors on an elevated platform.
My father once told me that a lot of machine shops used to be set up that way, except that the powered shaft ran along the ceiling instead of in a floor trench. "Just throw a belt up over the shaft" and attach it to the machine you want to use, was how he described it.
I don't know if it's still there, but there used to be a fancy restaurant in the Eastlake part of Seattle that had started out that way, and still had the old Art Deco-ish drive shaft running around the ceiling. It was a neat touch point when I saw it and remembered my dad's description from years before.
My understanding is that this paradigm was incredibly dangerous, with a lot of workers losing hands and arms in accidents. Turning on or off a given machine involved physically putting the belt on or pulling it off, and you could easily get caught in it. A very clever system for the technology of the day, but it's good we don't use it anymore, at least without more advanced safety mechanisms and practices.
I would have assumed they would have clutches so that individual machines could be disengaged. The large open belts running up to the drive shaft on the ceiling were dangerous regardless.
Also adds a ton of pollution from using (often old and poorly maintained) Diesel engines in the name of avoiding the electric grid. Adding to that, compressed air is a much less efficient source of power than using electricity directly.
Yes, but air tools can be really nice to use,esp for grinding, cutting, sanding operations. For one, you can press/dig hard enough to bog or stop the tool and nothing hapoens - you just pick it uo and it speeds back uo again - do that with an electric tool and you'll have a dead motor paperweight real soon.
Air tools can also be lighter and no worries abt damaging the cord or carrying the battery.
Many good air tools can also have a better feel, especially if you can control the air flow trigger.
(I don't have a bias either way, use both in my shop, but just wanted to point out that both have advantages)
I agree - air tools are awesome in some cases, although modern brushless tools are often competitive if not superior to air tools compared to how things were a decade ago.
My complaint, really, is just how selfish it is to go out of your way to use a dirty energy source as a workaround for limits in your personal belief system.
Yes, I've also noticed that the new brushless motor tools are often great!
And yes, using diesel to power your compressor on a regular (non-emergency) is more than a bit wasteful.
I totally get their insistence on staying off-grid, and it is good to read that they seem to be positive towards solar, so we can hope that takes over soon! From the bits I've read about their ethos, it certainly should have the advantage of further reduced dependency on outside systems, in this case, a one-off purchase of solar panels & kit will eliminate ongoing dependence on the entire fossil fuel supply chain.
I thought the whole schtick of the Amish was that they don't allow themselves to become reliant on technology, electricity just being an example. I doubt that Amish guy knows how to rebuild that engine should it fail.
They don't believe in having technology in the home. Most Amish are perfectly willing to work with modern equipment for their shops and businesses. Go by an Amish milking shed anywhere in the country--as my dad would say 'they're lit up like a shit house in the fog'. Electric lights from one end to the other with modern milkers inside.
The Amish only allow technology that they think will improve their lives. Many have cell phones, but don't use Facebook for example. I'd also bet he could repair the engine if he needed to.
How does the economics of this look like, and how do they intended to get back the investment. If its to buy low when wind/solar production is high and sell when production is low, what will the cost per watt be? If its subsidies, how much will this cost the government?
The article seem to mostly describe this as a technology project to test the technology at scale, but they do also mention profits. Is the basic premise of buy low sell high, exclusively on renewables, enough to offset the cost from energy conversion, building, staff and other costs, and if so, by what degree compared to other method to produce energy? When is it estimated to have paid its initial investment?
Energy storage if you want to rely solely on renewable energy sources is THE KEY to making that even remotely feasible.
Current solar and wind renewables are NOT predictable nor reliable for sustained power generation. With Coal, Natural Gas, Nuclear and Hydro you can generate power on demand, no matter what the environment is doing. Well, Hydro in the west is getting dicey with the drought - but even that is far more stable than wind/sun which can vary wildly week to week, day to day or even hour to hour.
That's why technology like this is so exciting. If you can look at the average production of a renewable over a month, then within a year the peak month, then look at the worst months, then have enough storage to cover a percentage of a peak month based off the hedge of the worst month then you are getting to a point where a solar farm isn't just an opportunistic source of power based on how much the sun is shining, but a reliable energy source that can be counted on whether the sun is shining or not.
Same for wind farms.
Energy storage is crucial if we seriously want to transition to renewables and hence the investment from Goldman Sachs.
If this company is even remotely successful in actually delivering then $250M is a pittance to what they will receive back in the long term.
There are also a lot of unused/abandoned underground structures - from various wells that are now dry of the resource they were originally drilled for to mines that are no longer productive. The problem has been sealing them from seepage so you don't loose your stored air - this article was light on details but that seems to be this companies claim to fame. They seem to have found economical ways to deal with those issues - enough to convince the boffins at Goldman Sachs they are worthy of investment. I guarantee you Goldman is not just tossing out money willy-nilley without performing some significant due diligence!
The question is still economics. At minimum the cost per watt/h need to be cheaper than to build a nuclear plant and have it run when demand exceed supply from renewables. Is this true for compressed air?
When people discuss green hydro as a storage solution the numbers so far, from what I have managed to interpret, is around 3-5 times that off nuclear for the same amount of energy delivered. It is still technically possible to make a profit given enough subsidies and time, and it get much more economically if the hydrogen can be used directly in the production chain like steel and fertilizer. Right now there are a steel foundry in Sweden testing the technology and economics doing that, through I don't know how much subsidies and tax reductions were involved.
Which all means the question about economics remains. There are many alternatives to fossil fuels but the primary question everyone debates is the issue of price. Without a price per watt/h or a time frame for when the investment get repaid its impossible to separate the practical from impractical, and the subsidy question is very relevant when discussing this on a national level.
Curiously there's a second article discussing compressed air energy on the front-page of Hacker News at the moment - it's about the Amish and their hacker mentality [0]. There's a beautiful discontinuity between one of the more tech-savvy old-guard banks and the technology-careful Amish adopting the same technology.
I would like more detail on the "Thermal management system" and how long it could store the heat it captures.
One of the benefits they touting is "Long duration energy storage" I would think the limiting factor would be the ability of the thermal management system to retain the energy it captured to reheat the compressed air. Am I thinking about this correctly?
> One of the benefits they touting is "Long duration energy storage"
According to their marketing video [1] "Long duration" is relative to current lithium ion battery-based storage. So their system can store energy up to 24 hours vs a few hours for batteries.
For even longer term storage (weeks, months, seasons), some time of chemical storage will be needed. Currently, both hydrogen electrolysis and ammonia synthesis [2] are being explored for that.
To the best of my knowledge that thinking is spot on.
A possible component that might be missing (in the thinking and/or in the proposed implementation): the stored heat could also be utilised separately if needed, so if you have an intermittent heat consumer and an intermittent electricity consumer you could consume the heat first, then leave the remaining compression energy (what you could recover without reheating) "forever". Bonus points if you also happen to have a coolant consumer to benefit from the temperature delta caused heat loss or premature heat consumption.
After seeing videos of lava pouring into the ocean I have fantasized about a power generation system:
Artificial geo-thermal power gen:
Dig a deep enough hole but near the ocean, and let ocean water pour into the hole that gets close enough to magma such that the magma creates a steam blast back out a tube with a bunch of turbines to spin.
Warm air takes up more space. If you cool it before pumping it into the ground you will not waste time/energy.
If you pump warm air down it will lose heat into the ground and shrink and you would lose capacity - pumping that last x% the tanks will be fuller until they cool down.
You warm up the air on the way out to expand it and you get more air to spin the turbine. More bang for your buck.
> Warm air takes up more space. If you cool it before pumping it into the ground you will not waste time/energy.
The real masterstroke here might then be to put this system in an area with large diurnal temp changes like the desert, then charge this system with cool night air, and then reheat it and generate electricity during the day with warm daytime air. Heat pumps could be used to nudge the temp on either end into it's optimal range.
It then becomes a solar thermal hybrid compressed air energy storage.
This could pair well with renewables that are more available at night like onshore wind.
Many years ago I was doing shrooms in the Nevada desert -- and the epiphany I had was that the desert, and the caves all around and throughout the deserts served as "the lungs of the earth" -- they would heat and cool and would suck air in and out based on this...
I was 17 at the time, and I have been into some of the most incredible caves - the best in Ganung Mulu National Park in Borneo Malaysia...
As the rains flowed out and carried the guano from 5 million bats into the forest to fertilize it...
And then I realized it wasnt just the desert - it was the caves...
Caves (giant ones) are really important for planet health.
Air pressure is strongly correlated to temperature. Cooling the air after compression reduces pumping effort during storage, reheating it increases turbine head pressure during generation.
In other words: gas compression storage suffers from temperature losses. The compressed gas is hot, the heat dissipates from storage and that energy won't be coming back.
But if you extract that heat during compression you can put in a separate storage, one that is much easier to insulate than the compression tanks, and "mix it back in" during recompression, avoiding a large part of those losses.
> In other words: gas compression storage suffers from temperature losses.
Yes, and you can also compress air further when it's cooled (this is why there is an intercooler on turbocharged cars, as an example), this means your density per volume of storage is higher at a given pressure.
The reality though is that this is likely less efficient than many other storage mechanisms. Additionally, this may require some sort of additional energy input for reheating if the heat storage is not capable of holding long enough to fully reheat the air on release to get the highest turbine efficiency.
Dave Borlace (Just Have a Think) has been covering this space a bit. There's a whole space in power storage that also overlaps with carbon capture that I suspect will probably end up being the winning play because cogeneration can often double system efficiency, making unprofitable things profitable.
One way we can reduce carbon intensity is to stop using fossil fuels to generate industrial CO2.
There's a kind of metal-air battery that actually absorbs CO2 while charging, and emits it while discharging. There is also air liquification as power storage, in which you can separate the oxygen, carbon dioxide and nitrogen into different containers.
Compressed air still seems like a promising idea to help solve the scale of energy storage we need, so I’m happy to see more companies taking a crack at it.
I think this is a great idea if you have systems that also use compressed air to function. If you need to convert compressed air to electricity the inherent losses in that conversion seem like they just would not be worth it as battery tech increases.
Would love to see DC to DC grids become a thing again and it looks like they may - crazy to think that SF still has a fully operating DC grid powering all kinds of stuff.
> Goldman Sachs agreed and invested $250 million from its private equity division.
Maybe they're referring to Goldman Sachs Capital partners which has 39.9B[0] under management which means this is 0.62% of their portfolio. In a totally chalk and cheese comparison that would be having 200k in your 401k and taking a $1,250 position in a stock, which isn't nothing but is a pretty small bet, I agree. Curious though if I'm guessing the part of GS correctly; I have no idea how they're structured and just spent like three minutes searching.
Cavallo, A. (2005). Controllable and affordable utility-scale electricity from
intermittent wind resources and compressed air energy storage (CAES).
Science Direct.
Well, yeah, this is in the opening of the article:
> It updates a long-standing technology that never took off for electrical storage.
There is/was plant operational since 1970s in Germany[1], which looks similar to the Wired article, but different from some other solutions posted in comments. Missing some parts perhaps to be viable.
The German energy company RWE has announced a while ago that they want to build a compressed air storage facility. However the project went nowhere and was silently buried at some point.
Just cheeked some levelized utility scale costs for the US:
Advanced Nuclear is of $72/MWh.
Wind onshore $30/Mwh
Solar photovoltaic (PV) $30/Mwh
Lithium-ion battery storage is roughly $180/Mwh.
At the moment, if you want to provide baseload better than nuclear using renewables, the cost must of storage must not exceed $30-$40/Mwh.
(grid baseload is the minimum level of demand on an electrical grid over a span of time, something unvarying power plants are best suited for. Renewables require storage and advanced grid to provide baseload.)
Can someone explain why this is better than just using pumps to pump water up from the reservoir and extract the energy with when the water returned back?
Pumped water only works if you have the right conditions. I.e. you need a certain altitude difference and enough space to have an upper and a lower water storage facility.
Pumped water storage is very efficient and an established technology, so when it's possible it's a good choice, but it's not possible everywhere.
It's not, but it doesn't require a giant reservoir next to a 100m+ elevation change. Almost all of the really good locations for dams already have them, and their water discharge rates are driven by a lot more than just power generation.
It requires less surface area, both due to compressibility and due to hydrodynamics. Additionally, water is a strong erosion source, air is not, so this can make use of existing excavations much easier and deep excavation is very very expensive.
not a lot of places have enough terrain to create a lake, plus in some places there's already shortage of water so removing it from usage would be pretty bad
Air is kind of a shitty working fluid. I always kind of dismiss compressed air storage because of that.
I saw a video recently that pumped water into tanks and used used the air as a spring. Just dip a pipe down and use the air to move the water. Extracting energy from a hyrdo generator.
It is pumped hydro, but you don't have the same mass of water because of the dramatically different pressures involved. Smaller water mass is the advantage to this, but the problem of managing heat is the downside that pumped storage doesn't face.
This general technique is known as "liquid piston".
Thanks for the search term.
I am not a huge fan of the "advanced polymer" wank of that video but liquid piston seems very practical compared most of the "air powered car" nonsense compressed air systems that show up.
I really enjoy learning about quirky ways to "store" energy, there is also one case that allows "storing" of energy by pushing massive concrete blocks uphill and when energy is needed, blocks simply slide down and generate energy. Not sure if this can be called "Storing" though.
I think the video said the system runs a cycle within a period of around 24 hours. What would it take to store energy in compressed air for ~6 months? This is what high-latitude dark-winter countries need: the ability to over-generate in the summer and draw down on stored energy in the winter.
Pumped hydroelectric storage is an obvious choice for the countries that have the geography, in effect meaning that most of the infrastructure for doing it is already in place. Hydroelectric reservoirs allow storing energy more or less indefinitely.
Of course, the capacity will rarely have been dimensioned for keeping 6 months of usage on hand, but combining pumped storage with over-provisioned wind energy would allow for living through months of unfavorable sun, rain or wind conditions.
CAES has lower efficiency, probably closer to 70% and only if you use something to reheat the air. (Compressed air loses temperature and needs an external source of heat to restore it to full volume)
Even if you use natural gas as a reheating element, the compressed air stores a significant amount of energy and is doing the majority of the work.
I too was wondering that as the ideal gas law states that PV = nRT. When you compress a gas it gets hotter, conversely, allowing it to decompress cools it. I assume they store the heat energy...
If you ignore efficiency then you stop making a profit pretty quickly. You can solely focus all you want on cost; sooner or later efficiency will make you pay.
Goldman wouldn't be making that kind of an investment if they didn't have a handle on both parts of the equation. Indeed efficiency (dealing with losses from seepage) have been the nut that hasn't been cracked with compressed air storage; these guys seem to have an economical (efficient) way to deal with that problem. If true, then they really are worthy of Goldman's investment.
Based on my reading, these systems are, at best, in the order of 60% efficient. To state the obvious, this means that fully 40% of the energy they pull from the grid will be wasted. Burned. Never to be recovered. How is that a good idea?
Solar? Well, solar isn't free energy. What's the comparison to grid scale batteries for storage? That process is far more favorable, with efficiency exceeding 80%.
I have to admit not understanding how this kind of an investment happens. I don't see this as viable technology at scale. We are far better off building nuclear power plants (talk about dense energy storage!).
Here's a good article on pumped thermal energy storage systems and how they compare to alternatives. The authors cover thermal storage in some detail.
You are spot on - the real answer is readily available: nuclear. We have reactor designs that if the active systems fail the reactors shut down naturally instead of running away. We have designs that can be burning all that "spent" fuel we are currently trying to bury for 10,000 years (!). Modular reactor designs in particular have incredible promise to provide for infinite scaling (just add more modules as needs increase), deal with the inefficient building, maintenance and decommissioning costs of todays light water reactor designs, and being modular provide far more granularity in power delivery further negating the need for energy storage to smooth out spikes and troughs in demands; allowing energy producers to far better match generation to power requirements.
Sadly I think it will be far more feasible to develop energy storage technologies than hope we can ever get enough people to be rational about nuclear. I mean how asinine is it for Germany to have turned off perfectly working and economically viable nuclear plants to then be dependent on RUSSIA for natural gas? How dumb do you have to be to be to think that's a REMOTELY good idea? Yet here we are (thankfully France seems to be far more rational - you don't hear them even suggesting they plan to be equally idiotic).
Many battery storage studies don't account for replacement/maintenance, or the infrastructure that would be required to sustain replacement/maintenance at grid scale, let alone the resources required to scale up to handle initial deployment of batteries in sufficient quantities to support the entire grid. Where are we going to get the manufacturing capacity, let alone materials? The scale here is pretty mind boggling if you start to do the math.
Our current battery tech is nothing more than a transitory technology - they are far from sustainable long term. Personally I think super capacitors will be our ultimate solution, but in the meantime if these guys really have dealt with the seepage issues of compressed air, this is are next best bet for MASS energy storage at scale. You only have the privilege of worrying about efficiency if you have a working system. Wood driven steam sucked, but it drove the industrial revolution because there was literally no other viable alternative at the time that could have remotely scaled in the same way.
Remember grid scale solutions require MASSIVE energy capabilities. The scale here is ridiculous compared to home or vehicle energy requirements. If you don't think Goldman Sachs took all of this into account before they made their investment - well, you are grossly mistaken. You don't get to be their size by continually placing bad bets.
If I am going to put on my conspiracy theory hat on for a moment, here's the only reason I would think the investment is sound: Goldman Sachs knows our government will throw money at this despite it being a bad idea. Therefore, the company will make money on paper by effectively becoming yet another subsidized entity of sorts...all in the name of saving the planet (or some other popular delusional statement).
Nuclear is probably the only path to long term clean energy. I hope people eventually wake up to that reality. Sadly, we are going to burn lots of time, money and resources before we get to that moment.
That's a really popular idea on the internet because it's very easy to grasp, but the numbers don't work out well. The weights you can actually lift aren't much compared to the volume of a reservoir of water, and the heights you can lift them are but a fraction of the thousands of meters being discussed here. Yes, the concrete isn't going to require much maintenance, but the gearboxes needed are a significant engineering challenge. Pumping water or compressing air are a lot easier, and batteries are going to be hard to beat.
Except it is already being done by multiple companies [0], Energy Vault in Switzerland [1], Gravitricity in Scotland [2], New Energy Lets go [3], and Gravity Power [4]. All have raised substantial funds and are building.
Sure, pumped hydro has advantages, but has serious geographic limitations - you need a fairly ideal site. The key is that these can be built almost anywhere.
Good point, and good examples. Excited online discussion about companies like those are what I mean when I say it's popular on the internet. It's not impossible, it's just not the technology I would be betting on. To get a sense of what one is up against, you can work through the math comparing gravitational potential energy to electrical potential in typical batteries. I can't find a good link right now, but what I remember finding is that (in the ideal) a typical lead acid car battery has enough stored energy to lift itself into space! Conversely, if you wanted to store the same amount of energy as in a typical car battery, you'd need to be dropping that amount of weight from the top of the atmosphere all the way to the ground.
But the point about little progress by these companies still holds. ARES has been around for 11 years now and has one 50MWh project to talk about that covers 20 acres.
Appropriate natural caverns do exist, but are not common. One of the main differentiating factor between this approach and others is that they drill a man-made borehole rather than depending on finding a pre-existing cavern.
If you're thinking of a direct mechanical linkage, you wouldn't want to put it up on the tower because the mass to effectively store megawatt-scale power is way more than you'd want to support up high. Also, since the wind blade usually swivels to the wind, you'd want to avoid the rotational inertia. So, you'd need a mechanical linkage to transmit the power to the ground, maybe installing it under the tower base.
You would not want to use a direct mechanical attachment, i.e., resembling a combustion engine - transmission flywheel, because this would impair the ability of the wind turbine to start. Generally, turbines are designed for minimum inertia to easily start in low-wind conditions. A direct connection would impede that.
Now, we're adding a clutch-sort of mechanism, and that has its own additional complexity, weight, and energy.
Moreover, considering that we're trying to store megawatt-scale energies, we are at a large mass spinning very fast, and probably spun up with an electric motor.
So, it would seem the best way to do that would be to make a flywheel farm, with the flywheels below ground to contain failures. At this point, why locate it in the probably inconvenient location where the wind turbines are located, and instead put it somewhere more convenient, such as nearer to the consumption areas?
I'm not sure how that would help? If you had a flywheel and you didn't need the energy, what do you do with it? At least without a flywheel, you can easily stop the turbine.
Also, any flywheel that would add significant difference would probably weigh hundreds of tonnes, which would make construction massively more expensive and difficult.
If you don't need the energy you just let the flywheel spin freely. It's a mechanical battery. I agree with your second point though- it would add considerable mass to the hub assembly of the wind turbine and there is no clear way to transmit the mechanical energy to ground level.
Yes, except with several orders of magnitude more energy and rotating mass.
Wind turbine blades are engineered for minimum mass and inertia, are manufactured primarily from fiberglass and/or carbon fiber, are hollow, and the largest mass is in the center.
In contrast, flywheels are engineered for the highest practical inertia, are manufactured from the highest density material that works, and concentrate that mass as far out as possible.
When a wind blade fails catastrophically, it makes a mess of splinters right around the tower, as shown in [0] and [1].
In contrast, just a small automotive flywheel explosion, contained in a legally mandated scattershield, is almost as spectacular [2], [3]. Now, magnify that from a flywheel just designed to smooth the power from a 375kW (500HP) engine to the scale of a flywheel to STORE the energy of a megawatt-scale wind turbine.
So, no, the danger of a megawatt-scale energy storage flywheel is NOT like the danger of a "giant rotating wind turbine".
Ha! Interesting, I had noticed the horses seemed off. In the comments it looks like the author was playing with CGI and modeled it on the Dutch failure video. I'd obviously just posted results of a quick search for short vids.
i agree, wind turbines do rotate but not at high speeds, disintegration of one doesn’t lead to catastrophic outcomes. Flywheels on the other hand are meant to rotate at high speeds and hold lots of energy, so destruction of the spindle would lead to some pretty big bad results
I remember reading this article a few years ago that Goldman Sachs. It's paywalled but the basics was that GS stores energy during the night, and uses the energy during the day. I thought it was neat, but they're obviously not new to this concept.
But Goldman Sachs can blow their money however they wish. Although no doubt governments will also throw bad money into this, but I guess if people want their government to fake their lives, so be it. It seems that's living in The Jetsons future HN idolises.
Would energy storage not be a good use of that money? Society is facing a large problem: climate change. One way to reduce the impact of climate change is to use renewable energy like solar and wind. Solar and wind have a big problem; they can't be turned on and off. That means to displace fossil fuels, we need to store energy when it's sunny and windy, and release that energy when it's not. Hence, things like compressed air energy storage. This is the kind of technology that can prevent entire cities from disappearing over the next 100 years. Seems pretty valuable to me.
Small nitpick. Wind can be turned off. The turbines can be equipped with brakes to stop power generation in case of oversupply, in addition to other uses.
GS isn't known for their scientific prowess - signal that they believe there is money in large scale ESS. Not sure if it's validating the technology at all though. Compressed air has been around for a long time at this point.
Who is known for their scientific prowess? A16z and with sprawling investments in web3? Capital is capital. We should be cheering on these types of investments regardless. Electric motors have been around for a looong time as well..
The VC and investment world in energy technology is quite different then the A16z and traditional VC world or financial heavyweights.
Having had GS invest in companies in the energy tech space in the past and having not particularly great success - I wouldn't think this is a strong signal. More that the financial heavyweights think there is action and they want to get in.
Goldman has army of analysts that are covering the field. Many many more than Even VCs that specialize in it. I would definitely write them off when it comes to smart investing.
Put another way it sounds like a corporate investor or VC into an industry they know a little about but have heard good things. Goldman Sachs is not known to be a good energy investor. Who knows maybe now they are.
Zeppelins next!
[1] https://en.wikipedia.org/wiki/London_Hydraulic_Power_Company