23 ms·

Gravitricity – Fast, long-life energy storage

179 points by lelf 6y ago

MrLeap 6y ago
Is it really worth it to dig a hole? I seem to recall some other initiative that was stacking large blocks with some kind of tested COTS construction cranes. The stack-of-blocks way seems to intuitively scale better. You can increase capacity without digging another super deep hole, or ever upgrading your cabling.
- deleted 6y ago
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- reincarnate0x14 6y ago
  There are a bunch of these seemingly questionable ideas out there trying to score funding. A few years ago there was one to run a train up a mountain or create a giant compressed gas reservoir underground. It may seem strange to use energy density in this context but in many ways those are even worse than batteries due to the massive amount of work they require and poor scalability because of all the physical infrastructure and space. In fact, this exact scheme looks to have been posted to HN in 2014. From my understanding they are looking to re-purpose holes that have already been dug, for the most part, which is a good idea, but if the planned prototypes are only doing 250 kW nameplate with maybe 100 KWH of stored power, there is almost no way it's going to beat a battery plant you can have more or less just built to order already commercially. And said battery plants aren't even remotely good enough at purpose for meaningful energy storage, they're mostly used for what are considered "ancillary services" in the US power markets, like eating or producing reactive power, voltage support, etc, because the modern grid scale inverters can react to grid conditions faster than grid frequencies (50-60 Hz). More rarely they might be scaled big enough to shave the peak off a demand curve for 5-10 minutes to save transmission capacity or congestion. Keep in mind all this in happening when LNG is basically free except for the cost of moving it, so you can also put in 1-60 MW combined cycle gas plants in short amounts of time with very well understood technology and proven manufacturers.
  - dragontamer 6y ago
    > create a giant compressed gas reservoir underground. The McIntosh CAES plant began in 1991 and from my understanding, has been widely viewed as successful. https://www.smithsonianmag.com/innovation/salt-power-plant-most-valuable-180964307/ https://www.smithsonianmag.com/innovation/salt-power-plant-m... That's 110 MWs for 26 hours. Probably not 2.8 GW-hrs of energy storage (they can't sustain 110MWs for all 26 hours), but this plant is probably GW-hr range. I'm pretty sure all of Li-Ion right now is less than 2GW-hrs for the entirety of the USA. --------- The 290 MW plant in Huntorf Germany (1978) also is successful. -------- There's a 2nd, 300MW+ plant (that's 300MW power for multiple hours. So near GW-hr scale as well). This is the more recent Apex Bethel Energy Center you were badmouthing earlier. Its not fully built yet, but given the history of CAES, I'm optimistic. -------- There aren't many CAES plants in the world. But from what I can tell, they are all safe and successful. The one issue is that you need to reheat the air as it leaves the caverns: compressing it underground reduces its temperature. A bit of natural gas is used in this heating process, but not nearly as much as an actual natural-gas plant. ------------ The "Rail up a hill" project is 50MWs with 12.5 MWhr storage capacity: https://s3.amazonaws.com/siteninja/multitenant/assets/21126/files/original/ARES_Nevada_Technical_Specification_Sheet.pdf https://s3.amazonaws.com/siteninja/multitenant/assets/21126/... 50MWs is somewhat small, but there's something to be said about the simplicity and ease-of-deployment of rail energy storage. Those 50MWs were spec'd out with only 7 trains. It isn't too hard to imagine scaling the system up to support more than 7 trains.
    - reincarnate0x14 6y ago
      Indeed; I'm not sure why exactly so few of the CAES plants have been built, it's well understood, has minimal safety problems, and doesn't seem unreasonably expensive. If I had to wager an uneducated guess, workable salt mines may not be located anywhere the power pricing makes sense for long term storage offsetting like that.
      - jbay808 6y ago
        Compressed air storage has very bad efficiency, due to the adiabatic heating and cooling when the pressure changes.
- gpapilion 6y ago
  I think the stacked approach has people concerned about the towers falling. This approach might be safer, but I think the other thing is it may aesthetically pleasing since the working bits are hidden below ground. This increases its viability.
  - syllable_studio 6y ago
    Yeah, and as I mention above, the key thing is height. You can build 10x taller underground than above ground. And that gives you 10x more potential energy for the same amount of weight.
- 9nGQluzmnq3M 6y ago
  This proposal would likely be a lot more economic if they could reuse existing holes, like abandoned mines. However, mines tend not to dig down vertically and the cost of retrofitting and maintenance would be non-trivial.
  - dx034 6y ago
    The vertical train approach of terrament (linked above) could theoretically work with that. But we'll probably have to wait for the first prototype to see if it can really work with existing infrastructure.
- syllable_studio 6y ago
  It is worth it to dig a hole! Because building one tall tower is ~exponentially~ (edit: quadratically) better than building multiple shorter ones side by side with the same combined height. You can dig a mile deep which is about 10 times taller than the practical height of a tower. My startup, Terrament, is working on a similar technology, and there is a slide in our deck that illustrates this. https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44YhiHs7il8JvnxK-cV6_g_-cGo/edit#slide=id.g844fb8814b_1_136 https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh... Reusing abandoned mine shafts could have an advantage. But there is also ample researching showing that the cost of digging from scratch is still worth it. The US Dept of energy even studied it back in the 1980s when they were evaluating underground pumped hydro energy storage. I wrote a white paper on it that's linked from here. see here https://www.terramenthq.com/uphs/ https://www.terramenthq.com/uphs/
  - spot5010 6y ago
    It is not exponentially better. Energy stored in a stacked mass scales as n^2 whereas horizontal stacks scales as n. That’s quadratic scaling, not exponential.
    - syllable_studio 6y ago
      Damn, you're right - thanks spot5010. I thought that I could use "exponential" colloquially and it would still be accurate enough (because quadratic scaling is even more esoteric to most people). But thanks for the callout, you're right that saying exponential is technically just wrong. I'll figure out how to re-word.
    - tboerstad 6y ago
      Could you explain how it is quadratic? I would have thought it to be linear, by the formula for potential energy
      - extropy 6y ago
        Take a look at Terrament slides. They are driving a train vertically into the ground. With increased depth more cars can be added, increasing total weight, so m = Ch and ep =~ Ch*h/2
- etrabroline 6y ago
  Energy Vault: https://www.youtube.com/watch?v=NIhCuzxNvv0 https://www.youtube.com/watch?v=NIhCuzxNvv0
- bsza 6y ago
  From the News section: "We plan to roll out our technology in disused mine shafts worldwide."
simonebrunozzi 6y ago
Energy storage by lifting or releasing a weight, in their case, in a well underground. Nothing new; I am wondering what's special about them, compared to tens of other companies trying to offer the same type of energy storage. AFAIK, the most common is done around hydro dams, by pumping water upstream as a form of energy storage. The infra is already there, but it's not as efficient as systems like Gravitricity. But it costs a negligible amount of money to "activate" energy storage in a pre-existing dam.
- mNovak 6y ago
  I believe the argument for new storage concepts is that renewables will drive a need for large amounts of new energy storage capacity, batteries are expensive, and that not everyone is situated near a suitable geography for pumped hydro.
graiz 6y ago
Interesting concept but digging a big hole sounds expensive and prone to flooding. I can see how this would have better efficiency than pumped-storage hydro but I wonder if you couldn't raise and lower weight near cliffs rather than drilling wells. If it does work, I would imagine the Boring company would be all over this.
- codethief 6y ago
  > and prone to flooding. and prone to Earth quakes, I would assume.
- syllable_studio 6y ago
  I can see why you'd suspect that. But it turns out that the oil and gas industry has 100 years of precedent demonstrating how to build such shafts into bedrock. Flooding and earthquakes are all real concerns, but we have well-proven solutions.
  - imtringued 6y ago
    Oil rigs only need to drill a hole with the diameter of a pipe. With gravity storage you would want the hole to be as large as possible.
    - syllable_studio 6y ago
      Maybe not as large as possible, but we're looking at about 10m diameter and about 1 mile deep. Here's an example of existing mining tech that meets this capacity. https://www.youtube.com/watch?v=z5vAWR7rpco https://www.youtube.com/watch?v=z5vAWR7rpco
wqsz7xn 6y ago
Isn't this the exact same concept as a dam which pumps water back up when you have excess power? Also how heavy does that weight have to be to be able to store enough energy worth digging a hole that large? Can you even get a weight heavy enough to store a significant amount of energy?
- Baeocystin 6y ago
  Same concept, but the tl;dr is that no, you can't, unless you're talking hydro from a dam in a good location. It's not just a not-so good idea, it's an orders-of-magnitude-awful idea when you compare it to just about any other form of energy storage per dollar.
- reincarnate0x14 6y ago
  Anything involving dams typically also has to involve water release schedules, which at least in some parts of the western US will produce some of the most vicious political battles you can imagine.
- syllable_studio 6y ago
  You can in fact! Pumped hydro is already the cheapest form of energy storage - about 95% of all energy storage is pumped hydro. We can't build more pumped hydro because it's not feasible to build enough dams. (We've used up the best locations) The US Gov has studied plenty of research showing that underground pumped hydro is cost effective and obviates the need for dams. (See my white paper here: https://github.com/syllable-hq/uphs-feasibility-study https://github.com/syllable-hq/uphs-feasibility-study) So startups like Gravitricity (and Terrament, my startup) are innovating on what is already well-researched territory.
abdullahkhalids 6y ago
The video has some numbers in it about performance. They say dig a shaft of 150-1500m and hang a weight of 500-5000 tonnes. This translates to energy storage of between 204-20400 KWh storage. Obviously, this seems very technically challenging. 500 tonnes is 64 m^3 of iron. We will see if their engineering is good enough to pull off their claimed 171 US$/MWh.
- jayd16 6y ago
  26 m^3 of tungsten is what, less than a 3x3x3m cube? If they stack 10 cubes at the bottom they get mostly the full storage (-3m at least) for each weight. Seems feasible.
  - abdullahkhalids 6y ago
    There is 280x difference in price between iron and tungsten. https://www.metalary.com/tungsten-price/ https://www.metalary.com/tungsten-price/ 2000 tonnes of tungsten is 60 million USD, of iron is 200k USD.
  - 9nGQluzmnq3M 6y ago
    Tungsten costs around $30k/ton, so you'd be looking at a cool $15M for that 500T cube. Lead goes for around $2k/ton, so this might be a more feasible compromise.
    - deleted 6y ago
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    - brohee 6y ago
      Depleted uranium prices are very hard to find, but should come as cheaper than tungsten. Civilian sales look at least possible, I heard of at least one sailboat with a DU keel.
  - deleted 6y ago
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  - imtringued 6y ago
mNovak 6y ago
I always thought it'd be interesting to do the gravity storage inside the column of a wind turbine. After all you've already built a tall steel tower. Individually it's tiny storage, but in aggregate it's not meaningless, especially as we keep building more towers. But I assume there's structural issues with suspending a few extra tons on your structure.
- dragontamer 6y ago
  I feel like "gravity storage" should take advantage of natural landscapes better. ARES (rail energy storage) builds a rail-line uphill, for example. Rail cannot handle a very steep slope, but a gentle hill climb will build up potential energy fine. In the case of vertical-based gravity storage, I'd imagine that lifting blocks to the top of a cliff (or down a valley) would be most efficient. I mean, Pumped Hydro is gravity storage, and does just that. Pumping water up a mountain and generating energy by dropping it back down. But presumably, we don't want to use water in the Western states (where water is scarce). So Gravity-energy storage WITHOUT water is the goal.
  - syllable_studio 6y ago
    The issue with using natural landscapes is that it limits your height. And adding more height is ~exponentially~ (edit: quadratically) better than just adding more installations with an equivalent total height. (You can dig about a mile deep). You can see more details in my comments below - search for the text "It is worth it to dig a hole!"
    - dragontamer 6y ago
      I was thinking of combining techniques. Best case scenario in USA is something like Owens Valley: 14,000 at its peak, but 4000 feet at the bottom of the valley. Leading to ~10,000 feet (or nearly 2-miles) of elevation change. From there, you can dig another mile underground, leading to 1-mile (under ground), or -1000 feet elevation, to a peak elevation of 14,000. If a tower were built on the top of the mountain: you could gain another 2000 feet or so on top: so maybe 16,000 (a 2000 foot tower on top of the mountain peak) to -1000ft (1-mile deep from the bottom of the 4000-ft elevation valley), for a total differential of 17,000 feet. Ignoring earthquakes and other issues, of course. :-) Just purely from a hypothetical perspective: working with nature and the natural landscape seems like it'd be better than "just" digging a hole. EDIT: Repurposing abandoned mine shafts might be worthwhile, depending how deep they are.
syllable_studio 6y ago
I love Gravitricity. I'm the founder of a similar startup called Terrament. We are also building gravity storage underground, but our patents are extending this idea to use autonomous, modular weights. This enables us to maximize both height and weight, which is the simple recipe for cheap gravitational energy storage. We are also working on a seed-round of investment. It's an exciting field with plenty of room for competition. And it's so important for fighting climate change! We need to build this asap. https://www.terramenthq.com/ https://www.terramenthq.com/
- rsync 6y ago
  What are they patenting ? I note from the website: "Our patented technology is based on a simple principle ..." I think it's a great idea but I don't see what there is to patent or what IP they could defend ...
  - syllable_studio 6y ago
    Terrament is patenting a number of different designs which enable us to maximize both height and weight to nearly 100% of a mine shaft. When you think about the physics of suspending thousands of tons inside a mile deep hole, the devil is in the details. To paraphrase Boromir, One does not simply hang a mile of concrete and steel from a cable ;) There are already some videos on the website that give away some details. We're waiting to secure funding before sharing the rest. edit: oh sorry, I think you meant gravitricity sorry. I'm not sure what they're patenting. Also I don't think their patents are in the US.
- mike_d 6y ago
  Can you explain why this is better/different than flywheels? I know Pennsylvania and New York both have 20 MW storage systems that takes up a few acres and are relatively cheap per unit of storage.
  - TylerE 6y ago
    The problem with a flywheel is that you ha w to keep it moving. Bearing wear out, require lubrication... A weight you can just hang there
um_ya 6y ago
Can we stop with these convoluted systems and just do nuclear already?
- X6S1x6Okd1st 6y ago
  With nuclear you still need storage to flatten the peaks and troughs though right? Also this does not seem very convoluted, it's using an electric engine pretty directly. If you are actually boring straight down it seems like the failure modes are pretty okay.
  - core-questions 6y ago
    > With nuclear you still need storage to flatten the peaks and troughs though right? Why? Just build more. Keep expanding capacity so the base load covers the peaks and thensome. Push the price of electricity down while keeping it carbon-neutral and crush competition. Get everyone 2c/kwh power. Wouldn't that be more fun?
    - _ph_ 6y ago
      The problem is the speed at which the reactors can be ramped up and down, this is very limited. Also, if you have enough capacity to cover all peaks, most of the time the reactors are not running at full power. That increases the cost of operating the reactors, which is far higher than you claim. Currently, projects building new nuclear reactors are challenged by their costs. Never mention the safety concerns and of course the waste problem.
      - core-questions 6y ago
        So print more money, what does it even matter anymore in the land of MMT? > the waste problem. Ehh, it's well managed in Canada and France, I don't see why Americans can't handle it. Just keep it away from fault lines, right? I bet some of those old missile silos would be perfect.
        6y ago
beefman 6y ago
If that weight were a fission reactor you wouldn't have to move it up and down. And it would be 100% efficient. And you wouldn't need an external power plant.
- syllable_studio 6y ago
  The nuclear debate is interesting, with valid talking points on both sides. But even if nuclear were safer and cheaper than wind+solar+storage (which it isn't), it would take decades to build. We might not have that much time. Climate change is urgent and we need all hands on deck to build as fast and as cheap as possible. May the best designs win asap in this fight!
  - p_l 6y ago
    Some of the known SMR designs are amenable for mass production, if someone would kickstart the line by putting money on the table. Very safe ones at that. A lot of the cost goes down when the reactor isn't a practically one-off build, and when you can for example use prefabricated components to "assemble" a power plant quickly. Some designs go even further, and have power blocks that are essentially something you slap on large railcar, including option that instead of refueling you send back the module while the vendor sends you a freshly-fueled one.
zaroth 6y ago
If you wanted to build one at the scale of a PowerWall (5kW/13.5kWh) what kind of height/weight combinations would be required? By my calculations you would need to raise 40 tons up 3 meters to store 13.5kWh. Definitely not a home storage revolution! Now, if the entire house was built on a lift....
- mkj 6y ago
  Isn't that 0.326 kWh? 40e3 * 9.8 * 3 / 3600
  - zaroth 6y ago
    Damn, you're absolutely right. Off by a factor of ~40... You would need to raise the 40 tons up 120 meters, or conversely, you would need to raise 1,600 tons up 3 meters.
scythe 6y ago
If you dig a well with cross-sectional area A and depth D, the amount of energy you can store with compressed air at 10 MPa is 10AD MJ if A and D are expressed in m^2 and m respectively. [1] If you drop a steel weight down the same well of cross-section A and height H in the same units the energy stored is 0.08HA(D-H) MJ[2]. Again, H is in meters, and AD > A(D-H), and in order to beat compressed air 0.08H > 10, so your steel weight needs to be 10/0.08 = 125 meters long! That's taller than most of the buildings in downtown San Francisco -- and in order to get any use out of this thing, your hole should be at least twice that deep. Of course, compressed air has its inefficiencies and complexity, but the feasibility of a metal rod even close to that long seems pretty low to me. Compressed-air caverns use as much as 7.5 MPa, but a purpose-built well could potentially go much higher. Plus you don't have to deal with the damn thing vibrating from Coriolis forces and seismicity. Now, I know what you're saying -- you're saying, if you're so smart, why don't you do it? -- but there are simply too many huge caverns out there to even think about constructing CAES chambers. There are several GW in service today. And even with that huge resource people wonder if batteries won't simply corner the market. Storage is getting here painfully slow, it seems like, but the competition is very fierce. 1: True isothermal decompression cycles are impossible, so of course I'm approximating by using the ideal gas law. 2: (8000 kg/m^3)(10 m/s^2)/(mega = 1000000) = 0.08
- syllable_studio 6y ago
  Yeah, compressed air is a very viable and promising solution. It does have efficiency trade-offs as you mention though. And typical compressed air designs still use fossil fuels in the compression process. There are some new designs I've seen that get around using fossil fuels. One of the most prominent new startups out there exploring advanced compressed air is hydrostor. Note that they also dig underground :) https://www.hydrostor.ca/technology/ https://www.hydrostor.ca/technology/
yongjik 6y ago
Sorry for repeating myself, but gravity is weak. If you hang a 500t weight in a 150m vertical tunnel, it only holds 500 * 1000 * 9.8 * 150 = 735000000 J, or 735 MJ, that is, 204 kWh. A Tesla model 3, basic model (MSRP ~$38k) has battery capacity of 50 kWh, so we're talking about four Tesla 3's. I don't think digging a 150m hole is cheaper than four Teslas - and Teslas come with the rest of the car you can use for driving.
- syllable_studio 6y ago
  Gravity is weak, but it's cheap. It is indeed surprising, but plenty of research shows that the levelized cost of gravity storage is cheaper than Li-ion batteries - even if you assume that Li-ion will get 4x cheaper in the next 20 years. There are other problems with Li-ion as well that will prevent it from scaling up to the amount of storage that our grid will need. I discuss all this with lots of citations in a white paper here https://github.com/syllable-hq/uphs-feasibility-study https://github.com/syllable-hq/uphs-feasibility-study
  - gspr 6y ago
    > Gravity is weak, but it's cheap. I'm sorry, I'm not trying to be pedantic, but what does "gravity is cheap" even mean?
    - syllable_studio 6y ago
      No worries. Here is a good resource that talks about the levelized costs of gravity storage. It's estimated to be much cheaper than Li-ion battery storage on large scales. https://www.storage-lab.com/gravity-based-storage https://www.storage-lab.com/gravity-based-storage
- imtringued 6y ago
  The primary benefit is reliability and lifetime. Your lifted rock isn't going to "malfunction" and suddenly weigh less. I agree that gravity based energy technologies are mostly junk though. There are two important factors: cheap weights and unlimited scalability. Doing something "cute" such as using a mountain side or old mineshaft is reducing the scalability.
throwaway189262 6y ago
Isn't pumped water storage the same thing but much easier to manage? Like think of a 10 ton weight suspended from cables 100m high vs a $300 above ground pool on a 300 foot hill. Isn't pumped water storage going to be hundreds of times cheaper for amount of energy stored? I didn't do the math but this reeks scam to me
- shajznnckfke 6y ago
  $300 for an above ground pool? Where do I sign up?
  - throwaway189262 6y ago
    All you need is walmart, a hose, and a parking lot!
peter_d_sherman 6y ago
>"Our patented technology is based on a simple principle: raising and lowering a heavy weight to store and release energy. The Gravitricity system suspends weights of 500 - 5000 tonnes in a deep shaft by a number of cables, each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed or generated by raising or lowering the weight." Idea: Could elevators be retrofitted with something like this? Then they could use/store energy only while going up, and regenerate some of it going down... and take passengers to various floors while doing that! "The Regenerative Elevator"! Stores energy going up, regenerates some of it while going down! Invented here on Hacker News, by yours truly, 9/8/2020! (Yes, I know, it's a stupid related idea! <g>. But my other related idea was more stupid, and that one was to fill up a U-Haul truck with trash, put a steel cable on it, find a hill, and use the steel cable (in conjunction with the overweighted U-Haul truck and hill!) to drive a motor/generator/winch assembly that uses electricity going up the hill, and regenerates some of it back, going down the hill... <g>) On a serious note however (for non-passenger elevator energy storage), I think Gravitricity has a good idea, and I wish them much success with it!
- orthecreedence 6y ago
  > Idea: Could elevators be retrofitted with something like this? I think it would not work so well because they have counterweights to make the up-down operation much easier. If you remove the counterweight, it would store energy, but be prohibitively slow when going up and probably frighteningly fast going down. Regarding the uhaul, this is not too far off from other people mentioning driving a train uphill and letting it fall downhill to generate electricity. Interesting ideas.
- hoytech 6y ago
  I'm not sure if you are joking or not, but regenerative elevators exist, and have existed for over 100 years: > DC-driven winding-drum elevators—the leading design until the 1930s—use a DC motor in the basement that winds and unwinds the elevator’s steel cable on a steel drum, thus lifting and lowering the car from pulleys atop the elevator shaft. DC drive was the only way to go at the time for a speedy elevator, because only DC could deliver variable-speed operation for smooth starts and stops. The DC motors were also energy efficient, capable of something that has only recently become possible with modern elevator designs: regenerating power when the elevator descends. https://spectrum.ieee.org/tech-history/dawn-of-electronics/san-franciscos-secret-dc-grid https://spectrum.ieee.org/tech-history/dawn-of-electronics/s...
syllable_studio 6y ago
Quite a few comments question the cost of digging -- which is understandable. But the context to remember is that these are huge infrastructure investments that will return revenue from that investment over 20-100 years with little maintenance costs. The excavated shaft is like a factory not a product. The product is each cycle of energy generation giving you a profit day after day. The shaft is a one time investment that will yield that product forever. There's lots of research showing how the costs work out (see my other comments here)
- deleted 6y ago
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- dx034 6y ago
  Also, hasn't digging become much cheaper in recent years with new technologies from the oil industry? I'm sure some of that efficiency gain can be used for those shafts (they're obviously bigger than a bore hole for oil).
mullingitover 6y ago
Why not merge all the energy storage ideas? Pump air into a giant pressure chamber...that's also a super-deep hole with a pulley system...and the weight for the pulley is a flywheel sealed in a vacuum chamber, magnetically levitating to avoid any friction losses. Oh, and the mass for the flywheel? A bunch of batteries.
- syllable_studio 6y ago
  This is probably a joke, but it's not so crazy. Many designs are combining one or more of these.
  - mullingitover 6y ago
    Not entirely joking. I just saw the big hole and immediately thought it'd be a great place to store pressurized air, and then I continued thinking of other energy storage mechanisms you could cram in there.
rklaehn 6y ago
This will work, obviously. But I don't see how it can be competitive with batteries. High energy density lithium batteries are currently being commoditized. They are also increasingly able to handle many thousands of cycles. E.g LiFePo4 cells. The raw materials for batteries are not actually that expensive or rare, so that leaves the manufacturing. You might think that making something as complex as a battery can never be as cheap as hanging a weight from a rope. But there are examples of very complex products (solar cells, LCD displays) that became incredibly cheap due to mass manufacturing. A square meter of solar cells, requiring extremely pure silicon and nanometer scale engineering, is now not much more expensive than a square meter of good roofing shingles.
neilwilson 6y ago
Interesting idea. Why would this be better than a set of railway lines down a hill side into a forest pulling up standard goods carriages full of rocks? You get a forest (which buffers runaway carriages and does all the other lovely forest things) and energy storage on the hill. All using largely commodity items and you can build it anywhere there's a spare slope.
- dx034 6y ago
  That's what ARES promised 4 years ago. But their website looks abandoned. [1] [1] https://www.aresnorthamerica.com/ https://www.aresnorthamerica.com/
Yan-solucracy 6y ago
Why not use water ? Is it not heavy enough ?
andbberger 6y ago
I don't get how any of these gravitational energy storage startups get past the napkin phase. There is no competition with pumped hydro. Who cares if weights on winches are marginally more efficient when you have many orders of magnitude more mass to move. This site claims a max weight of 4.5e6 kg. Lake Powell, for example, has a max capacity of 3e13 kg! So, SEVEN orders of magnitude less mass to move. Sounds competitive.
- dx034 6y ago
  Pumped hydro is great but unrealistic in many countries. You need hills or mountains with space for new lakes. All obvious places already have them, for the others the ecological impact often is quite significant.
  - andbberger 6y ago
    All obvious places may have hydro plants already, but not all hydro plants are reversible. The country point is interesting, so the market is countries lacking topography suited to hydro plants? How big is that market really? And considering that pumped hydro is currently the only viable grid scale energy storage mechanism (inb4 but li-on), those countries currently either 1) share a grid with neighboring countries that do have pumped hydro, or 2) forego energy storage altogether and use peaker plants like everyone else. If you do 1 you better trust your neighbors to never go to war with you, otherwise you better have 2. So the market is: countries lacking topography suited to hydro plants, who currently share energy storage with neighbors who they don't trust, and who for some reason aren't just building peaker plants (which are essentially just normal fossil fuel power plants) and are holding out for a non-extant technology to be developed. I'm not much of a capitalist myself, but even I can tell that that's a bad investment.
    - imtringued 6y ago
      Power to gas is promising. Just generate hydrogen or methane and feed it into existing gas pipelines. Storage infrastructure for gas already exists and has several TWh of capacity.
diimdeep 6y ago
Where is innovation and efficiency ? To me it smells like https://www.youtube.com/watch?v=uzV_uzSTCTM https://www.youtube.com/watch?v=uzV_uzSTCTM and all about patents, marketing and money burning, but I don't know as much as these professors do so maybe I am wrong.
- Blammar 6y ago
  Oh, there are definitely interesting problems to solve. See my post below for some issues.
_ph_ 6y ago
The concept is quite obvious and has been proposed several times in the past. The key question is, what are the costs? Even if the costs for drilling the hole are written off over a very long time span, the wires that hold the weight and the machinery have constant operation costs. It probably can't compete with pumped storage, but pumped storage isn't viable without at least some hills. This concept could be deployed in many regions, also wouldn't take much surface space, you could deploy it even in densely populated regions. The question is: how does it compete with e.g. batteries?
markvdb 6y ago
Does anyone know if something like this has been implemented in some way already? In old mine shafts maybe? The geology has been studied, and some shafts at least there already...
- syllable_studio 6y ago
  Yeah, I did a feasibility study on underground pumped hydro which you can find here: https://www.terramenthq.com/uphs/ https://www.terramenthq.com/uphs/ UPHS has never been fully built to my knowledge, but it's been well studied and quite a few projects have tried to get funding for it. U.S. DOE research from 1984: https://www.osti.gov/biblio/6517343.pdf https://www.osti.gov/biblio/6517343.pdf Projects trying to work on this: https://utilitymagazine.com.au/pumped-hydro-storage-the-future-for-old-mines/ https://utilitymagazine.com.au/pumped-hydro-storage-the-futu... Other proposed projects: - https://www.waterpowermagazine.com/features/featureinvestigating-aquabank- https://www.waterpowermagazine.com/features/featureinvestiga... - http://www.eaglecrestenergy.com/project-description.html http://www.eaglecrestenergy.com/project-description.html https://www.osti.gov/biblio/6517343.pdf https://www.osti.gov/biblio/6517343.pdf
klunger 6y ago
This reminds of Energy Vault [1], which is based on the same principle, just above ground. Doing this above ground seems to make a lot more sense when you consider all of the additional costs associated with digging and maintain massive shafts. I am not clear why the underground approach is at all appealing. Can anyone explain? [1] https://energyvault.com/ https://energyvault.com/
- kijin 6y ago
  An underground facility is arguably less unsightly than a tower. You might also be able to repurpose an unused mine shaft, though I'm not sure how common that scenario is going to be.
- gameswithgo 6y ago
  is digging a shaft more expensive than building a tower taller than the sears tower that can hold 5,000 tons?
- syllable_studio 6y ago
  Yeah, very similar. The main reason is that you can get about 10x more height underground. You can dig about a mile deep. An Energy Vault tower is about 500 feet tall. And as mentioned below in other comments, adding more height gives you more storage per weight, so it's super important. Adding more height and weight scales quadratically while just adding more weight (in side by side towers) only scales linearly. https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44YhiHs7il8JvnxK-cV6_g_-cGo/edit#slide=id.g844fb8814b_1_136 https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
  - klunger 6y ago
    Wow, I see you have already thought about this exact question a great deal. This was a clear and compelling answer. Your pitch deck is impressive. Good luck!
    - syllable_studio 6y ago
      thx!
LordHeini 6y ago
Why do so many of these gravity thingies show up lately? An easy calculation shows how low the storage potential is. Lets take a weight of 500 tones of steel, which would be 63.29 cubic meters. Now sink those 500 tonnes into a hole a 100 meters deep that would make a rather lowly 0.1362 MWh of storage. https://www.wolframalpha.com/input/?i=500+*+1000+kilograms+*+StandardAcceleration+*+100+ https://www.wolframalpha.com/input/?i=500+*+1000+kilograms+*... Not sure what the cost of digging a 100 meter hole where you can sink 63 cubic meters of steel in would be, specially since water management is needed too. I am not convinced that it is worth it.
- gameswithgo 6y ago
  Gravitricity is claiming weights as massive as 5,000 tons and shaft depths from 150m to 1,500m
  - ben_w 6y ago
    That’s equivalent to ~83 tons of lithium ion battery: http://www.wolframalpha.com/input/?i=5000%20tons%20%2A%209.8m%2Fs%2Fs%20%2A%201500m%20%2F%20%280.8MJ%2Fkg%29 http://www.wolframalpha.com/input/?i=5000%20tons%20%2A%209.8...
    - twic 6y ago
      Ah - so we can measure the specific capacity of a battery in kilometres of altitude. e = mgh, so h = e/mg. Lead-acid = 0.14 MJ/kg = 14.3 km LiFePO4 = 0.58 MJ/kg = 59.1 km LiNiMnCoO2 = 0.74 MJ/kg = 75.5 km
      - ben_w 6y ago
        Yes; how high a fully charged battery could lift itself. I guess it’s similar to counting rocket fuel in seconds (lb_force-seconds per lb_weight).
        tgb 6y ago
kaliszad 6y ago
My father has an idea to use sodium (Na) as fuel for fuel cells. This could easily replace batteries by having more or less instant reactions to demand, being much more energy dense and being simple to handle. Also, there is no CO_2 that would need to be captured compared to "bio" fuels. The resulting sodium hydroxide (NaOH) and hydrogen (H_2) can easily be used further e.g. in the chemical industry or recycled, electrolysis of NaOH is well known and also produces hydrogen as a byproduct. The resulting sodium metal can again be used as fuel. It creates a circular economy. Handling sodium securely at scale is also probably even easier than handling gasoline or diesel. Most of these reactions at industrial scale are more than 50 years old but nobody bothered to actually implement it (even though a hint about sodium cells for electricity generation is present in "Twenty Thousand Leagues Under the Seas: A World Tour Underwater" by Jules Verne already) instead of the more complex approaches like e.g. synthetic gasoline. You can look at the orgpage about these ideas https://orgpad.com/s/energiewende https://orgpad.com/s/energiewende my father also gave a talk last week about it, there is a recording, which will be posted during the next days. Disclaimer: I work for the small startup OrgPad, which tries to create a tool for easier decomposition of linear ideas/ content into a network of ideas/ content. An ex-Googler, Pavel Klavík PhD. describes the technology (hint Clojure and ClojureScript) and approaches behind OrgPad in a recent talk https://www.youtube.com/watch?v=4UoIfeb31UU https://www.youtube.com/watch?v=4UoIfeb31UU
- willis936 6y ago
  Many years ago I briefly had a thought experiment about converting a gasoline/oxygen combustion engine into a sodium/water combustion engine. Solid fuel mixing concerns aren’t the primary issue. The primary issue is the energy density is just so danged low compared to gasoline. However, compared to electric batteries, sodium is far more energy dense.
  - kaliszad 6y ago
    Well, there are patents for running diesel engines with sodium, at least I was told so much by my father who researched the problem thoroughly. The density isn't that low considering using a fuel cell, you can convert the energy a lot more efficiently. Also you don't just burn up the fuel into the air as currently, there is no industrial process to collect the CO_2 and other gases produced from the exhaust.
nicexe 6y ago
You could theoretically store energy by winding springs and making use of it by letting them unwind (by spinning a generator or whatever). Toy-car style. This doesn't involve digging a deep hole in the ground and hope that the earth keeps it level. A drawback would be the hazards that heavy tension/forces bring with them.
- tgvaughan 6y ago
  This was precisely the basis of the energy storage systems in Paolo Bacigalupi's novel, The Windup Girl.
deleted 6y ago
[deleted]
gglon 6y ago
Eduard Heindl's gravity storage: https://heindl-energy.com/ https://heindl-energy.com/ Potentially reaches a storage capacity between 1 and 10 GWh. Lifting a (huge) rock by pumping water underneath. Interview: https://omegataupodcast.net/299-gravity-storage/ https://omegataupodcast.net/299-gravity-storage/
- sandworm101 6y ago
  Pumping water comes with host of fluid-related inefficiencies. And you need pressure vessels. The big advantage of the OP is that there are no potential leak points. Worst case scenario, cables break and the rock drops.
- syllable_studio 6y ago
  Yeah, this is another promising one. The other disadvantage with that design is that the weight of the water is actually working against them. So if their rock/concrete is about 2.5x heavier than water, the weight of water is subtracted and you only get 1.5x the weight of water. Also their height is limited by the height of their piston. So I'm not yet convinced that their solution is better than just using underground pumped hydro.
  - gglon 6y ago
    It may be so. But an underground pump hydro is just boring.
    - deleted 6y ago
      [deleted]
- patall 6y ago
  Unfortunately, Heidl Energy is no more: "Heindl Energy GmbH ran out of cash in 2020 and filed for insolvency. The patents and the engineering work has been sold to an interim investor, New Energy Let´s Go, who is now looking for a new strategic investor willing to continue the development with the goal of constructing a pilot project to prrof the concept." from: https://heindl-energy.com/about-us/ https://heindl-energy.com/about-us/
lebuffon 6y ago
How does it compare to liquified air storage? It might have a sweetspot somewhere but liquid air uses a lot of off-the-shelf technology. https://www.rechargenews.com/transition/liquid-air-storage-offers-cheapest-route-to-24-hour-wind-and-solar/2-1-635666 https://www.rechargenews.com/transition/liquid-air-storage-o...
steeve 6y ago
5000 tons at 1500m is ~20MWh [1], assuming 100% efficiency (frictionless free fall). That means that the theoretical maximum is 50x (!) less than 1 nuclear reactor can do in 1 hour (1000 MW for 18 months or 13 140 000 MWh). Put it differently, you'd need to dig 50 of these to output the equivalent of 1 nuclear reactor (and nuclear plants have 2 or more reactors) for one hour. That's also assuming digging a hole this deep in a stable manner. [1]. https://www.wolframalpha.com/input/?i=5000+tons+*+9.8m%2Fs%2Fs+*+1500m https://www.wolframalpha.com/input/?i=5000+tons+*+9.8m%2Fs%2...
- LordHeini 6y ago
  You are completely mixing up MWh and MW which are two different things.
  - steeve 6y ago
    You are right. The actual number for a nuclear reactor is 13 140 000 MWh. (1000MW * 18 months). But I figure people would get the idea better.
- novaleaf 6y ago
  Different categories/uses. This is storage and on-demand production. Also, I would assume that 50x of these wells is cheaper than 1x nuclear (especially operational costs). But again, not in the same category.
dave333 6y ago
All this is moot. Hydrino energy will make storage largely unnecessary except possibly for small handheld devices. https://brilliantlightpower.com/news/ https://brilliantlightpower.com/news/
- gryfft 6y ago
  Is this a joke?
  - dave333 6y ago
    Did you check out their web site? - does it look like a joke?
    - gryfft 6y ago
      Considering they've apparently been claiming for years to be able to convert the humidity in the air into the same mysterious dark matter that makes up much of the universe but whose composition and nature is currently unknown? Yes. It's about as believable as a product to convert belly button lint into plutonium.
    - jasonwatkinspdx 6y ago
      It looks like crank nonsense.
    - dave333 6y ago
      Don't take my word for it - check out the experiments and prototypes yourself at https://brilliantlightpower.com/ https://brilliantlightpower.com/
- syllable_studio 6y ago
  Wow, this is surprisingly less-debunked than I expected. Though, of course my first reaction is extreme skepticism. But I guess we'll see! https://www.quora.com/What-is-wrong-with-Dr-Mills-Hydrino-Theory?share=1 https://www.quora.com/What-is-wrong-with-Dr-Mills-Hydrino-Th... https://en.m.wikipedia.org/wiki/Brilliant_Light_Power https://en.m.wikipedia.org/wiki/Brilliant_Light_Power
deeviant 6y ago
Why does every gravity storage startup claim they invented gravity storage? It's not just not true, it's like, obviously not true. Anybody that took high-school level physics understands gravitation potential energy and it's not a huge leap from there.
thelastname 6y ago
Am I the only one to expect the goatse on the bottom of the site?

179 points by lelf 6y ago

Is it really worth it to dig a hole? I seem to recall some other initiative that was stacking large blocks with some kind of tested COTS construction cranes. The stack-of-blocks way seems to intuitively scale better. You can increase capacity without digging another super deep hole, or ever upgrading your cabling.

deleted 6y ago
[deleted]
reincarnate0x14 6y ago
There are a bunch of these seemingly questionable ideas out there trying to score funding. A few years ago there was one to run a train up a mountain or create a giant compressed gas reservoir underground. It may seem strange to use energy density in this context but in many ways those are even worse than batteries due to the massive amount of work they require and poor scalability because of all the physical infrastructure and space. In fact, this exact scheme looks to have been posted to HN in 2014. From my understanding they are looking to re-purpose holes that have already been dug, for the most part, which is a good idea, but if the planned prototypes are only doing 250 kW nameplate with maybe 100 KWH of stored power, there is almost no way it's going to beat a battery plant you can have more or less just built to order already commercially. And said battery plants aren't even remotely good enough at purpose for meaningful energy storage, they're mostly used for what are considered "ancillary services" in the US power markets, like eating or producing reactive power, voltage support, etc, because the modern grid scale inverters can react to grid conditions faster than grid frequencies (50-60 Hz). More rarely they might be scaled big enough to shave the peak off a demand curve for 5-10 minutes to save transmission capacity or congestion. Keep in mind all this in happening when LNG is basically free except for the cost of moving it, so you can also put in 1-60 MW combined cycle gas plants in short amounts of time with very well understood technology and proven manufacturers.
- dragontamer 6y ago
  > create a giant compressed gas reservoir underground. The McIntosh CAES plant began in 1991 and from my understanding, has been widely viewed as successful. https://www.smithsonianmag.com/innovation/salt-power-plant-most-valuable-180964307/ https://www.smithsonianmag.com/innovation/salt-power-plant-m... That's 110 MWs for 26 hours. Probably not 2.8 GW-hrs of energy storage (they can't sustain 110MWs for all 26 hours), but this plant is probably GW-hr range. I'm pretty sure all of Li-Ion right now is less than 2GW-hrs for the entirety of the USA. --------- The 290 MW plant in Huntorf Germany (1978) also is successful. -------- There's a 2nd, 300MW+ plant (that's 300MW power for multiple hours. So near GW-hr scale as well). This is the more recent Apex Bethel Energy Center you were badmouthing earlier. Its not fully built yet, but given the history of CAES, I'm optimistic. -------- There aren't many CAES plants in the world. But from what I can tell, they are all safe and successful. The one issue is that you need to reheat the air as it leaves the caverns: compressing it underground reduces its temperature. A bit of natural gas is used in this heating process, but not nearly as much as an actual natural-gas plant. ------------ The "Rail up a hill" project is 50MWs with 12.5 MWhr storage capacity: https://s3.amazonaws.com/siteninja/multitenant/assets/21126/files/original/ARES_Nevada_Technical_Specification_Sheet.pdf https://s3.amazonaws.com/siteninja/multitenant/assets/21126/... 50MWs is somewhat small, but there's something to be said about the simplicity and ease-of-deployment of rail energy storage. Those 50MWs were spec'd out with only 7 trains. It isn't too hard to imagine scaling the system up to support more than 7 trains.
  - reincarnate0x14 6y ago
    Indeed; I'm not sure why exactly so few of the CAES plants have been built, it's well understood, has minimal safety problems, and doesn't seem unreasonably expensive. If I had to wager an uneducated guess, workable salt mines may not be located anywhere the power pricing makes sense for long term storage offsetting like that.
    - jbay808 6y ago
      Compressed air storage has very bad efficiency, due to the adiabatic heating and cooling when the pressure changes.
gpapilion 6y ago
I think the stacked approach has people concerned about the towers falling. This approach might be safer, but I think the other thing is it may aesthetically pleasing since the working bits are hidden below ground. This increases its viability.
- syllable_studio 6y ago
  Yeah, and as I mention above, the key thing is height. You can build 10x taller underground than above ground. And that gives you 10x more potential energy for the same amount of weight.
9nGQluzmnq3M 6y ago
This proposal would likely be a lot more economic if they could reuse existing holes, like abandoned mines. However, mines tend not to dig down vertically and the cost of retrofitting and maintenance would be non-trivial.
- dx034 6y ago
  The vertical train approach of terrament (linked above) could theoretically work with that. But we'll probably have to wait for the first prototype to see if it can really work with existing infrastructure.
syllable_studio 6y ago
It is worth it to dig a hole! Because building one tall tower is ~exponentially~ (edit: quadratically) better than building multiple shorter ones side by side with the same combined height. You can dig a mile deep which is about 10 times taller than the practical height of a tower. My startup, Terrament, is working on a similar technology, and there is a slide in our deck that illustrates this. https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44YhiHs7il8JvnxK-cV6_g_-cGo/edit#slide=id.g844fb8814b_1_136 https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh... Reusing abandoned mine shafts could have an advantage. But there is also ample researching showing that the cost of digging from scratch is still worth it. The US Dept of energy even studied it back in the 1980s when they were evaluating underground pumped hydro energy storage. I wrote a white paper on it that's linked from here. see here https://www.terramenthq.com/uphs/ https://www.terramenthq.com/uphs/
- spot5010 6y ago
  It is not exponentially better. Energy stored in a stacked mass scales as n^2 whereas horizontal stacks scales as n. That’s quadratic scaling, not exponential.
  - syllable_studio 6y ago
    Damn, you're right - thanks spot5010. I thought that I could use "exponential" colloquially and it would still be accurate enough (because quadratic scaling is even more esoteric to most people). But thanks for the callout, you're right that saying exponential is technically just wrong. I'll figure out how to re-word.
  - tboerstad 6y ago
    Could you explain how it is quadratic? I would have thought it to be linear, by the formula for potential energy
    - extropy 6y ago
      Take a look at Terrament slides. They are driving a train vertically into the ground. With increased depth more cars can be added, increasing total weight, so m = Ch and ep =~ Ch*h/2
etrabroline 6y ago
Energy Vault: https://www.youtube.com/watch?v=NIhCuzxNvv0 https://www.youtube.com/watch?v=NIhCuzxNvv0
bsza 6y ago
From the News section: "We plan to roll out our technology in disused mine shafts worldwide."

simonebrunozzi 6y ago

Energy storage by lifting or releasing a weight, in their case, in a well underground. Nothing new; I am wondering what's special about them, compared to tens of other companies trying to offer the same type of energy storage. AFAIK, the most common is done around hydro dams, by pumping water upstream as a form of energy storage. The infra is already there, but it's not as efficient as systems like Gravitricity. But it costs a negligible amount of money to "activate" energy storage in a pre-existing dam.

mNovak 6y ago
I believe the argument for new storage concepts is that renewables will drive a need for large amounts of new energy storage capacity, batteries are expensive, and that not everyone is situated near a suitable geography for pumped hydro.

graiz 6y ago

Interesting concept but digging a big hole sounds expensive and prone to flooding. I can see how this would have better efficiency than pumped-storage hydro but I wonder if you couldn't raise and lower weight near cliffs rather than drilling wells. If it does work, I would imagine the Boring company would be all over this.

codethief 6y ago
> and prone to flooding. and prone to Earth quakes, I would assume.
syllable_studio 6y ago
I can see why you'd suspect that. But it turns out that the oil and gas industry has 100 years of precedent demonstrating how to build such shafts into bedrock. Flooding and earthquakes are all real concerns, but we have well-proven solutions.
- imtringued 6y ago
  Oil rigs only need to drill a hole with the diameter of a pipe. With gravity storage you would want the hole to be as large as possible.
  - syllable_studio 6y ago
    Maybe not as large as possible, but we're looking at about 10m diameter and about 1 mile deep. Here's an example of existing mining tech that meets this capacity. https://www.youtube.com/watch?v=z5vAWR7rpco https://www.youtube.com/watch?v=z5vAWR7rpco

wqsz7xn 6y ago

Isn't this the exact same concept as a dam which pumps water back up when you have excess power? Also how heavy does that weight have to be to be able to store enough energy worth digging a hole that large? Can you even get a weight heavy enough to store a significant amount of energy?

Baeocystin 6y ago
Same concept, but the tl;dr is that no, you can't, unless you're talking hydro from a dam in a good location. It's not just a not-so good idea, it's an orders-of-magnitude-awful idea when you compare it to just about any other form of energy storage per dollar.
reincarnate0x14 6y ago
Anything involving dams typically also has to involve water release schedules, which at least in some parts of the western US will produce some of the most vicious political battles you can imagine.
syllable_studio 6y ago
You can in fact! Pumped hydro is already the cheapest form of energy storage - about 95% of all energy storage is pumped hydro. We can't build more pumped hydro because it's not feasible to build enough dams. (We've used up the best locations) The US Gov has studied plenty of research showing that underground pumped hydro is cost effective and obviates the need for dams. (See my white paper here: https://github.com/syllable-hq/uphs-feasibility-study https://github.com/syllable-hq/uphs-feasibility-study) So startups like Gravitricity (and Terrament, my startup) are innovating on what is already well-researched territory.

abdullahkhalids 6y ago

The video has some numbers in it about performance. They say dig a shaft of 150-1500m and hang a weight of 500-5000 tonnes. This translates to energy storage of between 204-20400 KWh storage. Obviously, this seems very technically challenging. 500 tonnes is 64 m^3 of iron. We will see if their engineering is good enough to pull off their claimed 171 US$/MWh.

jayd16 6y ago
26 m^3 of tungsten is what, less than a 3x3x3m cube? If they stack 10 cubes at the bottom they get mostly the full storage (-3m at least) for each weight. Seems feasible.
- abdullahkhalids 6y ago
  There is 280x difference in price between iron and tungsten. https://www.metalary.com/tungsten-price/ https://www.metalary.com/tungsten-price/ 2000 tonnes of tungsten is 60 million USD, of iron is 200k USD.
- 9nGQluzmnq3M 6y ago
  Tungsten costs around $30k/ton, so you'd be looking at a cool $15M for that 500T cube. Lead goes for around $2k/ton, so this might be a more feasible compromise.
  - deleted 6y ago
    [deleted]
  - brohee 6y ago
    Depleted uranium prices are very hard to find, but should come as cheaper than tungsten. Civilian sales look at least possible, I heard of at least one sailboat with a DU keel.
- deleted 6y ago
  [deleted]
- imtringued 6y ago

mNovak 6y ago

I always thought it'd be interesting to do the gravity storage inside the column of a wind turbine. After all you've already built a tall steel tower. Individually it's tiny storage, but in aggregate it's not meaningless, especially as we keep building more towers. But I assume there's structural issues with suspending a few extra tons on your structure.

dragontamer 6y ago
I feel like "gravity storage" should take advantage of natural landscapes better. ARES (rail energy storage) builds a rail-line uphill, for example. Rail cannot handle a very steep slope, but a gentle hill climb will build up potential energy fine. In the case of vertical-based gravity storage, I'd imagine that lifting blocks to the top of a cliff (or down a valley) would be most efficient. I mean, Pumped Hydro is gravity storage, and does just that. Pumping water up a mountain and generating energy by dropping it back down. But presumably, we don't want to use water in the Western states (where water is scarce). So Gravity-energy storage WITHOUT water is the goal.
- syllable_studio 6y ago
  The issue with using natural landscapes is that it limits your height. And adding more height is ~exponentially~ (edit: quadratically) better than just adding more installations with an equivalent total height. (You can dig about a mile deep). You can see more details in my comments below - search for the text "It is worth it to dig a hole!"
  - dragontamer 6y ago
    I was thinking of combining techniques. Best case scenario in USA is something like Owens Valley: 14,000 at its peak, but 4000 feet at the bottom of the valley. Leading to ~10,000 feet (or nearly 2-miles) of elevation change. From there, you can dig another mile underground, leading to 1-mile (under ground), or -1000 feet elevation, to a peak elevation of 14,000. If a tower were built on the top of the mountain: you could gain another 2000 feet or so on top: so maybe 16,000 (a 2000 foot tower on top of the mountain peak) to -1000ft (1-mile deep from the bottom of the 4000-ft elevation valley), for a total differential of 17,000 feet. Ignoring earthquakes and other issues, of course. :-) Just purely from a hypothetical perspective: working with nature and the natural landscape seems like it'd be better than "just" digging a hole. EDIT: Repurposing abandoned mine shafts might be worthwhile, depending how deep they are.

syllable_studio 6y ago

I love Gravitricity. I'm the founder of a similar startup called Terrament. We are also building gravity storage underground, but our patents are extending this idea to use autonomous, modular weights. This enables us to maximize both height and weight, which is the simple recipe for cheap gravitational energy storage. We are also working on a seed-round of investment. It's an exciting field with plenty of room for competition. And it's so important for fighting climate change! We need to build this asap. https://www.terramenthq.com/ https://www.terramenthq.com/

rsync 6y ago
What are they patenting ? I note from the website: "Our patented technology is based on a simple principle ..." I think it's a great idea but I don't see what there is to patent or what IP they could defend ...
- syllable_studio 6y ago
  Terrament is patenting a number of different designs which enable us to maximize both height and weight to nearly 100% of a mine shaft. When you think about the physics of suspending thousands of tons inside a mile deep hole, the devil is in the details. To paraphrase Boromir, One does not simply hang a mile of concrete and steel from a cable ;) There are already some videos on the website that give away some details. We're waiting to secure funding before sharing the rest. edit: oh sorry, I think you meant gravitricity sorry. I'm not sure what they're patenting. Also I don't think their patents are in the US.
mike_d 6y ago
Can you explain why this is better/different than flywheels? I know Pennsylvania and New York both have 20 MW storage systems that takes up a few acres and are relatively cheap per unit of storage.
- TylerE 6y ago
  The problem with a flywheel is that you ha w to keep it moving. Bearing wear out, require lubrication... A weight you can just hang there

um_ya 6y ago

Can we stop with these convoluted systems and just do nuclear already?

X6S1x6Okd1st 6y ago
With nuclear you still need storage to flatten the peaks and troughs though right? Also this does not seem very convoluted, it's using an electric engine pretty directly. If you are actually boring straight down it seems like the failure modes are pretty okay.
- core-questions 6y ago
  > With nuclear you still need storage to flatten the peaks and troughs though right? Why? Just build more. Keep expanding capacity so the base load covers the peaks and thensome. Push the price of electricity down while keeping it carbon-neutral and crush competition. Get everyone 2c/kwh power. Wouldn't that be more fun?
  - _ph_ 6y ago
    The problem is the speed at which the reactors can be ramped up and down, this is very limited. Also, if you have enough capacity to cover all peaks, most of the time the reactors are not running at full power. That increases the cost of operating the reactors, which is far higher than you claim. Currently, projects building new nuclear reactors are challenged by their costs. Never mention the safety concerns and of course the waste problem.
    - core-questions 6y ago
      So print more money, what does it even matter anymore in the land of MMT? > the waste problem. Ehh, it's well managed in Canada and France, I don't see why Americans can't handle it. Just keep it away from fault lines, right? I bet some of those old missile silos would be perfect.
      - 6y ago

beefman 6y ago

If that weight were a fission reactor you wouldn't have to move it up and down. And it would be 100% efficient. And you wouldn't need an external power plant.

syllable_studio 6y ago
The nuclear debate is interesting, with valid talking points on both sides. But even if nuclear were safer and cheaper than wind+solar+storage (which it isn't), it would take decades to build. We might not have that much time. Climate change is urgent and we need all hands on deck to build as fast and as cheap as possible. May the best designs win asap in this fight!
- p_l 6y ago
  Some of the known SMR designs are amenable for mass production, if someone would kickstart the line by putting money on the table. Very safe ones at that. A lot of the cost goes down when the reactor isn't a practically one-off build, and when you can for example use prefabricated components to "assemble" a power plant quickly. Some designs go even further, and have power blocks that are essentially something you slap on large railcar, including option that instead of refueling you send back the module while the vendor sends you a freshly-fueled one.

zaroth 6y ago

If you wanted to build one at the scale of a PowerWall (5kW/13.5kWh) what kind of height/weight combinations would be required? By my calculations you would need to raise 40 tons up 3 meters to store 13.5kWh. Definitely not a home storage revolution! Now, if the entire house was built on a lift....

mkj 6y ago
Isn't that 0.326 kWh? 40e3 * 9.8 * 3 / 3600
- zaroth 6y ago
  Damn, you're absolutely right. Off by a factor of ~40... You would need to raise the 40 tons up 120 meters, or conversely, you would need to raise 1,600 tons up 3 meters.

scythe 6y ago

If you dig a well with cross-sectional area A and depth D, the amount of energy you can store with compressed air at 10 MPa is 10AD MJ if A and D are expressed in m^2 and m respectively. [1] If you drop a steel weight down the same well of cross-section A and height H in the same units the energy stored is 0.08HA(D-H) MJ[2]. Again, H is in meters, and AD > A(D-H), and in order to beat compressed air 0.08H > 10, so your steel weight needs to be 10/0.08 = 125 meters long! That's taller than most of the buildings in downtown San Francisco -- and in order to get any use out of this thing, your hole should be at least twice that deep. Of course, compressed air has its inefficiencies and complexity, but the feasibility of a metal rod even close to that long seems pretty low to me. Compressed-air caverns use as much as 7.5 MPa, but a purpose-built well could potentially go much higher. Plus you don't have to deal with the damn thing vibrating from Coriolis forces and seismicity. Now, I know what you're saying -- you're saying, if you're so smart, why don't you do it? -- but there are simply too many huge caverns out there to even think about constructing CAES chambers. There are several GW in service today. And even with that huge resource people wonder if batteries won't simply corner the market. Storage is getting here painfully slow, it seems like, but the competition is very fierce. 1: True isothermal decompression cycles are impossible, so of course I'm approximating by using the ideal gas law. 2: (8000 kg/m^3)(10 m/s^2)/(mega = 1000000) = 0.08

syllable_studio 6y ago
Yeah, compressed air is a very viable and promising solution. It does have efficiency trade-offs as you mention though. And typical compressed air designs still use fossil fuels in the compression process. There are some new designs I've seen that get around using fossil fuels. One of the most prominent new startups out there exploring advanced compressed air is hydrostor. Note that they also dig underground :) https://www.hydrostor.ca/technology/ https://www.hydrostor.ca/technology/

yongjik 6y ago

Sorry for repeating myself, but gravity is weak. If you hang a 500t weight in a 150m vertical tunnel, it only holds 500 * 1000 * 9.8 * 150 = 735000000 J, or 735 MJ, that is, 204 kWh. A Tesla model 3, basic model (MSRP ~$38k) has battery capacity of 50 kWh, so we're talking about four Tesla 3's. I don't think digging a 150m hole is cheaper than four Teslas - and Teslas come with the rest of the car you can use for driving.

syllable_studio 6y ago
Gravity is weak, but it's cheap. It is indeed surprising, but plenty of research shows that the levelized cost of gravity storage is cheaper than Li-ion batteries - even if you assume that Li-ion will get 4x cheaper in the next 20 years. There are other problems with Li-ion as well that will prevent it from scaling up to the amount of storage that our grid will need. I discuss all this with lots of citations in a white paper here https://github.com/syllable-hq/uphs-feasibility-study https://github.com/syllable-hq/uphs-feasibility-study
- gspr 6y ago
  > Gravity is weak, but it's cheap. I'm sorry, I'm not trying to be pedantic, but what does "gravity is cheap" even mean?
  - syllable_studio 6y ago
    No worries. Here is a good resource that talks about the levelized costs of gravity storage. It's estimated to be much cheaper than Li-ion battery storage on large scales. https://www.storage-lab.com/gravity-based-storage https://www.storage-lab.com/gravity-based-storage
imtringued 6y ago
The primary benefit is reliability and lifetime. Your lifted rock isn't going to "malfunction" and suddenly weigh less. I agree that gravity based energy technologies are mostly junk though. There are two important factors: cheap weights and unlimited scalability. Doing something "cute" such as using a mountain side or old mineshaft is reducing the scalability.

throwaway189262 6y ago

Isn't pumped water storage the same thing but much easier to manage? Like think of a 10 ton weight suspended from cables 100m high vs a $300 above ground pool on a 300 foot hill. Isn't pumped water storage going to be hundreds of times cheaper for amount of energy stored? I didn't do the math but this reeks scam to me

shajznnckfke 6y ago
$300 for an above ground pool? Where do I sign up?
- throwaway189262 6y ago
  All you need is walmart, a hose, and a parking lot!

peter_d_sherman 6y ago

>"Our patented technology is based on a simple principle: raising and lowering a heavy weight to store and release energy. The Gravitricity system suspends weights of 500 - 5000 tonnes in a deep shaft by a number of cables, each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed or generated by raising or lowering the weight." Idea: Could elevators be retrofitted with something like this? Then they could use/store energy only while going up, and regenerate some of it going down... and take passengers to various floors while doing that! "The Regenerative Elevator"! Stores energy going up, regenerates some of it while going down! Invented here on Hacker News, by yours truly, 9/8/2020! (Yes, I know, it's a stupid related idea! <g>. But my other related idea was more stupid, and that one was to fill up a U-Haul truck with trash, put a steel cable on it, find a hill, and use the steel cable (in conjunction with the overweighted U-Haul truck and hill!) to drive a motor/generator/winch assembly that uses electricity going up the hill, and regenerates some of it back, going down the hill... <g>) On a serious note however (for non-passenger elevator energy storage), I think Gravitricity has a good idea, and I wish them much success with it!

orthecreedence 6y ago
> Idea: Could elevators be retrofitted with something like this? I think it would not work so well because they have counterweights to make the up-down operation much easier. If you remove the counterweight, it would store energy, but be prohibitively slow when going up and probably frighteningly fast going down. Regarding the uhaul, this is not too far off from other people mentioning driving a train uphill and letting it fall downhill to generate electricity. Interesting ideas.
hoytech 6y ago
I'm not sure if you are joking or not, but regenerative elevators exist, and have existed for over 100 years: > DC-driven winding-drum elevators—the leading design until the 1930s—use a DC motor in the basement that winds and unwinds the elevator’s steel cable on a steel drum, thus lifting and lowering the car from pulleys atop the elevator shaft. DC drive was the only way to go at the time for a speedy elevator, because only DC could deliver variable-speed operation for smooth starts and stops. The DC motors were also energy efficient, capable of something that has only recently become possible with modern elevator designs: regenerating power when the elevator descends. https://spectrum.ieee.org/tech-history/dawn-of-electronics/san-franciscos-secret-dc-grid https://spectrum.ieee.org/tech-history/dawn-of-electronics/s...

syllable_studio 6y ago

Quite a few comments question the cost of digging -- which is understandable. But the context to remember is that these are huge infrastructure investments that will return revenue from that investment over 20-100 years with little maintenance costs. The excavated shaft is like a factory not a product. The product is each cycle of energy generation giving you a profit day after day. The shaft is a one time investment that will yield that product forever. There's lots of research showing how the costs work out (see my other comments here)

deleted 6y ago
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dx034 6y ago
Also, hasn't digging become much cheaper in recent years with new technologies from the oil industry? I'm sure some of that efficiency gain can be used for those shafts (they're obviously bigger than a bore hole for oil).

mullingitover 6y ago

Why not merge all the energy storage ideas? Pump air into a giant pressure chamber...that's also a super-deep hole with a pulley system...and the weight for the pulley is a flywheel sealed in a vacuum chamber, magnetically levitating to avoid any friction losses. Oh, and the mass for the flywheel? A bunch of batteries.

syllable_studio 6y ago
This is probably a joke, but it's not so crazy. Many designs are combining one or more of these.
- mullingitover 6y ago
  Not entirely joking. I just saw the big hole and immediately thought it'd be a great place to store pressurized air, and then I continued thinking of other energy storage mechanisms you could cram in there.

rklaehn 6y ago

This will work, obviously. But I don't see how it can be competitive with batteries. High energy density lithium batteries are currently being commoditized. They are also increasingly able to handle many thousands of cycles. E.g LiFePo4 cells. The raw materials for batteries are not actually that expensive or rare, so that leaves the manufacturing. You might think that making something as complex as a battery can never be as cheap as hanging a weight from a rope. But there are examples of very complex products (solar cells, LCD displays) that became incredibly cheap due to mass manufacturing. A square meter of solar cells, requiring extremely pure silicon and nanometer scale engineering, is now not much more expensive than a square meter of good roofing shingles.

neilwilson 6y ago

Interesting idea. Why would this be better than a set of railway lines down a hill side into a forest pulling up standard goods carriages full of rocks? You get a forest (which buffers runaway carriages and does all the other lovely forest things) and energy storage on the hill. All using largely commodity items and you can build it anywhere there's a spare slope.

dx034 6y ago
That's what ARES promised 4 years ago. But their website looks abandoned. [1] [1] https://www.aresnorthamerica.com/ https://www.aresnorthamerica.com/

Yan-solucracy 6y ago

Why not use water ? Is it not heavy enough ?

andbberger 6y ago

I don't get how any of these gravitational energy storage startups get past the napkin phase. There is no competition with pumped hydro. Who cares if weights on winches are marginally more efficient when you have many orders of magnitude more mass to move. This site claims a max weight of 4.5e6 kg. Lake Powell, for example, has a max capacity of 3e13 kg! So, SEVEN orders of magnitude less mass to move. Sounds competitive.

dx034 6y ago
Pumped hydro is great but unrealistic in many countries. You need hills or mountains with space for new lakes. All obvious places already have them, for the others the ecological impact often is quite significant.
- andbberger 6y ago
  All obvious places may have hydro plants already, but not all hydro plants are reversible. The country point is interesting, so the market is countries lacking topography suited to hydro plants? How big is that market really? And considering that pumped hydro is currently the only viable grid scale energy storage mechanism (inb4 but li-on), those countries currently either 1) share a grid with neighboring countries that do have pumped hydro, or 2) forego energy storage altogether and use peaker plants like everyone else. If you do 1 you better trust your neighbors to never go to war with you, otherwise you better have 2. So the market is: countries lacking topography suited to hydro plants, who currently share energy storage with neighbors who they don't trust, and who for some reason aren't just building peaker plants (which are essentially just normal fossil fuel power plants) and are holding out for a non-extant technology to be developed. I'm not much of a capitalist myself, but even I can tell that that's a bad investment.
  - imtringued 6y ago
    Power to gas is promising. Just generate hydrogen or methane and feed it into existing gas pipelines. Storage infrastructure for gas already exists and has several TWh of capacity.

diimdeep 6y ago

Where is innovation and efficiency ? To me it smells like https://www.youtube.com/watch?v=uzV_uzSTCTM https://www.youtube.com/watch?v=uzV_uzSTCTM and all about patents, marketing and money burning, but I don't know as much as these professors do so maybe I am wrong.

Blammar 6y ago
Oh, there are definitely interesting problems to solve. See my post below for some issues.

_ph_ 6y ago

The concept is quite obvious and has been proposed several times in the past. The key question is, what are the costs? Even if the costs for drilling the hole are written off over a very long time span, the wires that hold the weight and the machinery have constant operation costs. It probably can't compete with pumped storage, but pumped storage isn't viable without at least some hills. This concept could be deployed in many regions, also wouldn't take much surface space, you could deploy it even in densely populated regions. The question is: how does it compete with e.g. batteries?

markvdb 6y ago

Does anyone know if something like this has been implemented in some way already? In old mine shafts maybe? The geology has been studied, and some shafts at least there already...

syllable_studio 6y ago
Yeah, I did a feasibility study on underground pumped hydro which you can find here: https://www.terramenthq.com/uphs/ https://www.terramenthq.com/uphs/ UPHS has never been fully built to my knowledge, but it's been well studied and quite a few projects have tried to get funding for it. U.S. DOE research from 1984: https://www.osti.gov/biblio/6517343.pdf https://www.osti.gov/biblio/6517343.pdf Projects trying to work on this: https://utilitymagazine.com.au/pumped-hydro-storage-the-future-for-old-mines/ https://utilitymagazine.com.au/pumped-hydro-storage-the-futu... Other proposed projects: - https://www.waterpowermagazine.com/features/featureinvestigating-aquabank- https://www.waterpowermagazine.com/features/featureinvestiga... - http://www.eaglecrestenergy.com/project-description.html http://www.eaglecrestenergy.com/project-description.html https://www.osti.gov/biblio/6517343.pdf https://www.osti.gov/biblio/6517343.pdf

klunger 6y ago

This reminds of Energy Vault [1], which is based on the same principle, just above ground. Doing this above ground seems to make a lot more sense when you consider all of the additional costs associated with digging and maintain massive shafts. I am not clear why the underground approach is at all appealing. Can anyone explain? [1] https://energyvault.com/ https://energyvault.com/

kijin 6y ago
An underground facility is arguably less unsightly than a tower. You might also be able to repurpose an unused mine shaft, though I'm not sure how common that scenario is going to be.
gameswithgo 6y ago
is digging a shaft more expensive than building a tower taller than the sears tower that can hold 5,000 tons?
syllable_studio 6y ago
Yeah, very similar. The main reason is that you can get about 10x more height underground. You can dig about a mile deep. An Energy Vault tower is about 500 feet tall. And as mentioned below in other comments, adding more height gives you more storage per weight, so it's super important. Adding more height and weight scales quadratically while just adding more weight (in side by side towers) only scales linearly. https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44YhiHs7il8JvnxK-cV6_g_-cGo/edit#slide=id.g844fb8814b_1_136 https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
- klunger 6y ago
  Wow, I see you have already thought about this exact question a great deal. This was a clear and compelling answer. Your pitch deck is impressive. Good luck!
  - syllable_studio 6y ago
    thx!

LordHeini 6y ago

Why do so many of these gravity thingies show up lately? An easy calculation shows how low the storage potential is. Lets take a weight of 500 tones of steel, which would be 63.29 cubic meters. Now sink those 500 tonnes into a hole a 100 meters deep that would make a rather lowly 0.1362 MWh of storage. https://www.wolframalpha.com/input/?i=500+*+1000+kilograms+*+StandardAcceleration+*+100+ https://www.wolframalpha.com/input/?i=500+*+1000+kilograms+*... Not sure what the cost of digging a 100 meter hole where you can sink 63 cubic meters of steel in would be, specially since water management is needed too. I am not convinced that it is worth it.

gameswithgo 6y ago
Gravitricity is claiming weights as massive as 5,000 tons and shaft depths from 150m to 1,500m
- ben_w 6y ago
  That’s equivalent to ~83 tons of lithium ion battery: http://www.wolframalpha.com/input/?i=5000%20tons%20%2A%209.8m%2Fs%2Fs%20%2A%201500m%20%2F%20%280.8MJ%2Fkg%29 http://www.wolframalpha.com/input/?i=5000%20tons%20%2A%209.8...
  - twic 6y ago
    Ah - so we can measure the specific capacity of a battery in kilometres of altitude. e = mgh, so h = e/mg. Lead-acid = 0.14 MJ/kg = 14.3 km LiFePO4 = 0.58 MJ/kg = 59.1 km LiNiMnCoO2 = 0.74 MJ/kg = 75.5 km
    - ben_w 6y ago
      Yes; how high a fully charged battery could lift itself. I guess it’s similar to counting rocket fuel in seconds (lb_force-seconds per lb_weight).
      - tgb 6y ago

kaliszad 6y ago

My father has an idea to use sodium (Na) as fuel for fuel cells. This could easily replace batteries by having more or less instant reactions to demand, being much more energy dense and being simple to handle. Also, there is no CO_2 that would need to be captured compared to "bio" fuels. The resulting sodium hydroxide (NaOH) and hydrogen (H_2) can easily be used further e.g. in the chemical industry or recycled, electrolysis of NaOH is well known and also produces hydrogen as a byproduct. The resulting sodium metal can again be used as fuel. It creates a circular economy. Handling sodium securely at scale is also probably even easier than handling gasoline or diesel. Most of these reactions at industrial scale are more than 50 years old but nobody bothered to actually implement it (even though a hint about sodium cells for electricity generation is present in "Twenty Thousand Leagues Under the Seas: A World Tour Underwater" by Jules Verne already) instead of the more complex approaches like e.g. synthetic gasoline. You can look at the orgpage about these ideas https://orgpad.com/s/energiewende https://orgpad.com/s/energiewende my father also gave a talk last week about it, there is a recording, which will be posted during the next days. Disclaimer: I work for the small startup OrgPad, which tries to create a tool for easier decomposition of linear ideas/ content into a network of ideas/ content. An ex-Googler, Pavel Klavík PhD. describes the technology (hint Clojure and ClojureScript) and approaches behind OrgPad in a recent talk https://www.youtube.com/watch?v=4UoIfeb31UU https://www.youtube.com/watch?v=4UoIfeb31UU

willis936 6y ago
Many years ago I briefly had a thought experiment about converting a gasoline/oxygen combustion engine into a sodium/water combustion engine. Solid fuel mixing concerns aren’t the primary issue. The primary issue is the energy density is just so danged low compared to gasoline. However, compared to electric batteries, sodium is far more energy dense.
- kaliszad 6y ago
  Well, there are patents for running diesel engines with sodium, at least I was told so much by my father who researched the problem thoroughly. The density isn't that low considering using a fuel cell, you can convert the energy a lot more efficiently. Also you don't just burn up the fuel into the air as currently, there is no industrial process to collect the CO_2 and other gases produced from the exhaust.

nicexe 6y ago

You could theoretically store energy by winding springs and making use of it by letting them unwind (by spinning a generator or whatever). Toy-car style. This doesn't involve digging a deep hole in the ground and hope that the earth keeps it level. A drawback would be the hazards that heavy tension/forces bring with them.

tgvaughan 6y ago
This was precisely the basis of the energy storage systems in Paolo Bacigalupi's novel, The Windup Girl.

deleted 6y ago

[deleted]

gglon 6y ago

Eduard Heindl's gravity storage: https://heindl-energy.com/ https://heindl-energy.com/ Potentially reaches a storage capacity between 1 and 10 GWh. Lifting a (huge) rock by pumping water underneath. Interview: https://omegataupodcast.net/299-gravity-storage/ https://omegataupodcast.net/299-gravity-storage/

sandworm101 6y ago
Pumping water comes with host of fluid-related inefficiencies. And you need pressure vessels. The big advantage of the OP is that there are no potential leak points. Worst case scenario, cables break and the rock drops.
syllable_studio 6y ago
Yeah, this is another promising one. The other disadvantage with that design is that the weight of the water is actually working against them. So if their rock/concrete is about 2.5x heavier than water, the weight of water is subtracted and you only get 1.5x the weight of water. Also their height is limited by the height of their piston. So I'm not yet convinced that their solution is better than just using underground pumped hydro.
- gglon 6y ago
  It may be so. But an underground pump hydro is just boring.
  - deleted 6y ago
    [deleted]
patall 6y ago
Unfortunately, Heidl Energy is no more: "Heindl Energy GmbH ran out of cash in 2020 and filed for insolvency. The patents and the engineering work has been sold to an interim investor, New Energy Let´s Go, who is now looking for a new strategic investor willing to continue the development with the goal of constructing a pilot project to prrof the concept." from: https://heindl-energy.com/about-us/ https://heindl-energy.com/about-us/

lebuffon 6y ago

How does it compare to liquified air storage? It might have a sweetspot somewhere but liquid air uses a lot of off-the-shelf technology. https://www.rechargenews.com/transition/liquid-air-storage-offers-cheapest-route-to-24-hour-wind-and-solar/2-1-635666 https://www.rechargenews.com/transition/liquid-air-storage-o...

steeve 6y ago

5000 tons at 1500m is ~20MWh [1], assuming 100% efficiency (frictionless free fall). That means that the theoretical maximum is 50x (!) less than 1 nuclear reactor can do in 1 hour (1000 MW for 18 months or 13 140 000 MWh). Put it differently, you'd need to dig 50 of these to output the equivalent of 1 nuclear reactor (and nuclear plants have 2 or more reactors) for one hour. That's also assuming digging a hole this deep in a stable manner. [1]. https://www.wolframalpha.com/input/?i=5000+tons+*+9.8m%2Fs%2Fs+*+1500m https://www.wolframalpha.com/input/?i=5000+tons+*+9.8m%2Fs%2...

LordHeini 6y ago
You are completely mixing up MWh and MW which are two different things.
- steeve 6y ago
  You are right. The actual number for a nuclear reactor is 13 140 000 MWh. (1000MW * 18 months). But I figure people would get the idea better.
novaleaf 6y ago
Different categories/uses. This is storage and on-demand production. Also, I would assume that 50x of these wells is cheaper than 1x nuclear (especially operational costs). But again, not in the same category.

dave333 6y ago

All this is moot. Hydrino energy will make storage largely unnecessary except possibly for small handheld devices. https://brilliantlightpower.com/news/ https://brilliantlightpower.com/news/

gryfft 6y ago
Is this a joke?
- dave333 6y ago
  Did you check out their web site? - does it look like a joke?
  - gryfft 6y ago
    Considering they've apparently been claiming for years to be able to convert the humidity in the air into the same mysterious dark matter that makes up much of the universe but whose composition and nature is currently unknown? Yes. It's about as believable as a product to convert belly button lint into plutonium.
  - jasonwatkinspdx 6y ago
    It looks like crank nonsense.
  - dave333 6y ago
    Don't take my word for it - check out the experiments and prototypes yourself at https://brilliantlightpower.com/ https://brilliantlightpower.com/
syllable_studio 6y ago
Wow, this is surprisingly less-debunked than I expected. Though, of course my first reaction is extreme skepticism. But I guess we'll see! https://www.quora.com/What-is-wrong-with-Dr-Mills-Hydrino-Theory?share=1 https://www.quora.com/What-is-wrong-with-Dr-Mills-Hydrino-Th... https://en.m.wikipedia.org/wiki/Brilliant_Light_Power https://en.m.wikipedia.org/wiki/Brilliant_Light_Power

deeviant 6y ago

Why does every gravity storage startup claim they invented gravity storage? It's not just not true, it's like, obviously not true. Anybody that took high-school level physics understands gravitation potential energy and it's not a huge leap from there.

thelastname 6y ago

Am I the only one to expect the goatse on the bottom of the site?