19 ms·
Gravity batteries try to beat chemical ones with winches, weights, mine shafts
- goldenkey 6y agoAnd these systems are way larger, more dangerous (wind) and not as efficient as magnetic bearing flywheels. https://en.wikipedia.org/wiki/Flywheel_energy_storage https://en.wikipedia.org/wiki/Flywheel_energy_storage
- xyzzyz 6y agoYeah, if you do the math, it turns out that you need impractically large weights lifted to unreasonable height. Like, suppose you’re lifting 100 ton weight 100 meters high. That’s a rather large and heavyweight system. How much energy you can store this way? Less than $5 worth of electricity, as it turn out. This is basically the same as pumped water storage, but instead of immense amount of water you can pump between very large reservoirs, you’re limited to one solid weight that’s too light to store nontrivial amount of energy, but heavy enough to be significant problem from engineering perspective. It just doesn’t make practical sense.
- ecpottinger 6y agoGreat, now calculate how much a flywheel system that stores that much energy will cost vs cheap concrete blocks. Magnetic bearings and large vacuum chambers do not come cheap.
- Mulpze15 6y agoYes, the math does not look good. I remember dreaming about a house that could go up and down like this. Then I went to buy a AAA battery... same. That said, if they can manage to find that 1km shaft in an old mine like they hope, and put some crazy amount of weight and make it work, that would be impressive and cool.
- tchvil 6y agoHow about to retrofit wind turbines? They are tall, strong, and empty inside.
- masklinn 6y ago> How about to retrofit wind turbines? They are tall, strong, and empty inside. It's still basically piss-stakes: the largest wind turbine right now (14MWe Haliade-X) has 765t sitting on top of a 150m tower, so let's say you keep the 150m tower, rejigger it so it can move a 765t weight up and down the shaft without crumpling, and add your weight (a lead weight 4m in diameter and 5.4m tall), how much energy does that store? 250kWh, 2.5 teslas, or a medium-large electric bus battery. And it's not like you can add that to a working turbine: the tower was set up for 765t not 1500, and you need space for the crane.
- ObscureScience 6y agoToo me, pumping water seems like a pretty good solutiuon. If you are located on the coast, and can move let's say a million tons something like 100-200m up, that's not trivial and doesn't seem that impractical.
- deleted 6y ago[deleted]
- labawi 6y agoThat's why you should use trains, which can safely go a few km high in good terrain.
- travisjungroth 6y agoNow I want one. Home powered by solar and a flywheel is so retro-future. How does your house get electricity? Oh, power from the sun gets this flywheel spinning super fast and then it slows down and powers the house all night.
- goldenkey 6y agoThe heavier the flywheel, the less rpm you'll need for your storage requirements. Not sure how efficiency factors in. But yeah, would be awesome!
- frankus 6y agoOne of the downsides (or maybe double-edged swords) of kinetic energy storage is that it's relatively easy to accidentally get all of the energy out at once. A stick of butter and an 2-tonne truck at 216 km/h both "contain" about 1 kilowatt-hour of energy. The butter could maybe burn your house down but the truck could easily kill a couple of dozen unprotected humans in a fraction of a second.
- goldenkey 6y agoFlywheels made for energy storage are vacuum chambered and surrounded by very very dense material, made to withstand any accidents. So it isn't an issue.
- robertlagrant 6y agoGravity based battery, stuffed full of lithium ion batteries?
- amanzi 6y agoNo - it's just storing potential energy.
- ChainOfFools 6y agoyeah this sounds like a pendulum but geared on the y axis instead of the x. in fact a pendulum seems more practical since it doesn't need a shaft, just an enclosure. I suppose a pendum is itself is just a special case of flywheel anyway.
- montag 6y agoCovered with solar panels and shaped into a giant flywheel?
- arketyp 6y agoFloating on the ocean catching waves.
- swagasaurus-rex 6y agoConverting H20 -> H2 and storing it in fuel cells
- julienfr112 6y agoWith a heavy water thermonuclear reactor
- raverbashing 6y agoMaybe the solution is using very dense material. Like nuclear power plant waste.
- amanzi 6y agoThis is a clever system. I remember reading about a similar system in Australia that used excess solar power to lift giant concrete bricks, and then these bricks were lowered to the ground in the evenings to drive generators. Not sure if this is the same one I read about, but it's the same concept: https://energyvault.com/ https://energyvault.com/
- blueblisters 6y agoWasn’t Energy Vault debunked as being too impractical? Here: https://youtu.be/NIhCuzxNvv0 https://youtu.be/NIhCuzxNvv0 These guys “solve” the wind and control problem by digging a 300m deep pipe for the weights.
- audunw 6y agoYou should not use Thunderf00t as an authority on this. He has no clue what he's talking about. That seems to be a problem in general, he doesn't actually do much research on the topics he talks about. So unless he already has some understanding of the topic, he doesn't provide much insight. He seems to think Energy Vault is an alternative to pumped hydro, which it is absolutely not. They're not solving the same problem. Pumped hydro is best suited for regulating power over days/weeks. You do not want to use it to do frequency regulation or regulate power fluctuations over hours/days. In fact, in Norway, where there's a whole lot of hydropower, and now an increasing amount of wind power, they're considering putting battery storage inside hydro power plants. This may seem really stupid until you understand that constantly regulating the output of a hydro power plant up and down wears down all the parts of the power plant much faster, and can cause issues for life in the river downstream. So it actually makes a lot of sense, since the hydro power plant has a good grid connection and may have some spare areas for batteries. Batteries and solutions like Energy Vault are primarily intended for frequency regulation and short term storage, and that covers most of what's needed to help balance renewables in most areas. There's a bunch of other serious flaws in his reasoning too, such as thinking that a marketing-material picture of Energy Vault next to wind turbines means that they actually propose putting Energy Vault towers right next to wind turbines, rather than just an illustration that the Energy Vault helps regulate output from renewables.
- apetrovic 6y agoHow efficient the system is? If, say, the machine uses 100KW to lift the weight, what's the output?
- alexchamberlain 6y agoBetween 80% and 90%. See https://gravitricity.com/technology/ https://gravitricity.com/technology/
- choeger 6y agoStopped reading at a total cost of more than $300 per MWh for batteries. Quick back-of-the-napkin calculation: Car batteries come in at less than $100/KWh. They're good for at least 1000 cycles at 80% capacity. That gives us at least 0.8MWh for a 100$ investment. It's very, very unlikely that initial construction of the site and operational costs more than triple that price.
- alexchamberlain 6y agoTheir marketing has the LCOS of those 2 solutions the other way around - $171 for Gravity, $367 for Litium Ion batteries. See https://gravitricity.com/technology/ https://gravitricity.com/technology/
- PeterisP 6y agoToo bad they don't seem to provide the actual report anywhere (and neither does ICL), they just quote a single chart from that without any details. This feels fishy to me - I'd want to look into the cost basis they used, as a key problem with comparisons against batteries is that the battery cost has changed so much over the recent years (halving every 5 years or so), and many studies quote their battery price calculations on older reports that are now off by a large multiple. $367 of LI batteries at year X is $171 of LI batteries at year X+5 and $86 at year X+10, so it's important to look at what the X is in their study. And of course, we should consider that chemical battery costs are expected to decrease in the near future, while the cost well-established mechanical components would stay stable.
- alexchamberlain 6y agoWhilst I agree the components of a mechanical battery are probably going to stay stable, I think Gravitricity have an opportunity to commoditise the design and install near sporadic renewables like wind. Bias: I participated in their crowdfunding campaign.
- _rpd 6y agoHere’s what the article says about cost: > For a 25-year project, he estimates that Gravitricity would cost $171 for each megawatt-hour. Jessika Trancik, an energy storage researcher at the Massachusetts Institute of Technology, says that number is aspirational and still needs to be supported with field data. But Schmidt’s calculation of the lifetime cost per megawatt-hour for lithium-ion batteries, $367, is more than twice as much. Flow batteries, a promising grid-scale technology that stores charge in large tanks of liquid electrolyte, come in at $274 per megawatt-hour
- sollewitt 6y agoWe already have pumped hydroelectric storage, it's used as a load balancer on some national grids.
- jb775 6y agoIt's crazy how little we understand about gravity if you think about it. It's a perpetual energy source right in front of us, but we never really think about it, and can barely offer a basic explanation as to what powers it. It even impacts time itself[1] for christ sake. I think better understanding gravity is the solution to all human energy needs. (interesting to note I have heard stories of disappeared scientists who made advancements in gravity research years back) [1] http://thescienceexplorer.com/universe/how-gravity-changes-time-effect-known-gravitational-time-dilation http://thescienceexplorer.com/universe/how-gravity-changes-t...
- thaumasiotes 6y ago> It even impacts time itself for christ sake. I was under the impression that this is an effect of force generally, nothing to do with gravity in specific.
- function_seven 6y ago> It's a perpetual energy source right in front of us It's not. Once something has fallen down, it can't fall down again. To draw energy from the gravitational attraction of 2 bodies, you must first separate them. That consumes energy. On second thought, I suppose tidal energy fills the bill. Extracting that energy is really exploiting the Moon's motion, using gravity as the "conduit". Not strictly perpetual, but essentially so for our needs.
- tshaddox 6y agoIsn’t tidal energy just harnessing some of the existing gravitational potential energy of the Moon-Earth system, which is roughly similar to any system that harnesses energy from a massive object falling due to gravity?
- eraserj 6y agoBut again, slowing tidal currents must be drawing energy from somewhere until there is none left.
- guerby 6y ago"But Schmidt’s calculation of the lifetime cost per megawatt-hour for lithium-ion batteries, $367, is more than twice as much" This is ridiculous. I'm charging right now my EV from a 14 kWh 16S LFP pack which costed me $1400 tax paid and delivered. LFP properly managed will do minimum 3000 cycles, so that's 42 MWh for $1400 which gives $34 per MWh out of the battery. Note: 5kW 48V inverter cost $500.
- ardit33 6y agoIt is over 25 years, I don't think your battery will last 25 year. You probably have to replace it 3-4 times over that period of time. A mechanical system can last that much, even more, with minimal maintenance.
- kragen 6y agoYou may have accidentally responded to the wrong comment. The comment to which your response has been attached already takes into account the limited cycle life of batteries.
- guerby 6y agoAnd I didn't take into account that a third of the paid price was shipping, and that battery prices are dropping like a rock: https://pubs.rsc.org/en/content/articlelanding/2021/EE/D0EE02681F#!divAbstract https://pubs.rsc.org/en/content/articlelanding/2021/EE/D0EE0... Re-examining rates of lithium-ion battery technology improvement and cost decline
- tralarpa 6y ago> 14 kWh 16S LFP pack which costed me $1400 Wow, that's amazing. But why are home battery systems still so expensive? I see system prices in the range of $700 to $1200 per kWh. Even on aliexpress, it's minimum $550/kWh. Is the inverter so expensive?
- guerby 6y agoNiche market so high markup to pay for the maker margin and the seller margin. I found the vendor by following: https://diysolarforum.com/ https://diysolarforum.com/ https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q DIY Solar Power with Will Prowse
- 3dee 6y agoAres is another gravity battery system. They run electric trains up a hill to store energy. But looking at the size of the project, I have a hard time believing this is viable. https://aresnorthamerica.com/ https://aresnorthamerica.com/
- accrual 6y agoHigher materials density = higher energy density of the overall system. The more you're lifting (e.g. iron, steel, tungsten) the more you can get out in a smaller space. Kind of a cool way to increase the energy density.
- toast0 6y agoLead in an appropriate container is probably a good idea. Tungsten is denser, but lead is less expensive.
- imtringued 6y agoMaterials density is irrelevant, materials abundance and scalability is far more important. The more you spend on dense materials, the less money you have left to actually store energy. We use pumped hydro because water is basically free and it is infinitely scalable depending on geography. Meanwhile the proposed system is limited by the size and existence of mineshafts. In other words this is a dead end. Energy vaults is impractical but it at least tried to solve the scalability problem by taking advantage of the fact that the energy storage grows quadratically with the length of the crane arm. Assuming it is possible to actually build that system in a sealed tower to protect it from the elements (wind makes the control problem almost impossible). Given a large enough energy vaults system there will be a point where its advantages massively outweigh its downsides. Going one step further, you could carve out a large cylinder of rock out of the landscape [0]. By using wiresaws you will only need to cut the surface area of the cylinder out. At this point your material costs are approaching 0. The only challenge is sealing the walls of the hole and sealing the walls of the cylinder to turn the system into a giant hydraulic cylinder. Storage scales with the fourth power of the radius. Considering the theoretical performance of a gravity storage system anything that is below r^2 scaling is just laughable, which is why the mineshaft idea will ultimately fail. [0] http://eduard-heindl.de/energy-storage/energy-storage-system.html http://eduard-heindl.de/energy-storage/energy-storage-system...
- o_p 6y agowhat if you lift ion batteries instead of iron
- exporectomy 6y agoIf it's cheaper than batteries, adding batteries will just make it less economical.
- dang 6y agoPast related threads: Gravity Energy Storage: Alternative to batteries for grid storage - https://news.ycombinator.com/item?id=25650551 https://news.ycombinator.com/item?id=25650551 - Jan 2021 (167 comments) Gravity-Based Energy Storage Begins Trials 2021 - https://news.ycombinator.com/item?id=24337537 https://news.ycombinator.com/item?id=24337537 - Sept 2020 (2 comments) To Store the Wind and Sun, Energy Startups Look to Gravity - https://news.ycombinator.com/item?id=22394154 https://news.ycombinator.com/item?id=22394154 - Feb 2020 (2 comments) Lifting rocks as a form of long term energy storage - https://news.ycombinator.com/item?id=21736607 https://news.ycombinator.com/item?id=21736607 - Dec 2019 (1 comment) Gravity Battery - https://news.ycombinator.com/item?id=6750276 https://news.ycombinator.com/item?id=6750276 - Nov 2013 (1 comment) Gravity Battery Concept - https://news.ycombinator.com/item?id=6739349 https://news.ycombinator.com/item?id=6739349 - Nov 2013 (72 comments) Others?
- inglor_cz 6y agoThis could give a new purpose for abandoned mines all around the world. The shafts already exist and are no longer in use, they would only need some repairs. I grew up in one such city, there were "covered holes" everywhere.
- inasio 6y agoGravity and electromagnetic forces are somewhat similar, they both have infinite range, decay as 1/r, one key difference is that the electromagnetic force is 10^36 stronger than gravity [0]. Just for that reason I'm always immediately skeptical of projects of this type. [0] https://en.wikipedia.org/wiki/Fundamental_interaction https://en.wikipedia.org/wiki/Fundamental_interaction
- flal_ 6y agoYet, gravity is strong enough to initiate nuclear fusion at the core of stars, or create black holes... That 10^36 argument is non sensical to me.
- tryonenow 6y agoIt's about energy density. Generally you can fit many orders of magnitude more energy in the same physical space when storing energy electromagnetically. The comparison implies some assumptions but the point stands. It's space inefficient.
- andijcr 6y agoit is strong enough at the scale of a star, on earth my foot electromagnetic repulsion against the floor is enough to counteract all of the planet pull
- imtringued 6y agoAre you suggesting we should build a bigger planet?
- f6v 6y agoWe should have been smaller people with fewer needs.
- sscarduzio 6y agoWould you say a magnetostatic (rather than gravitational) potential energy storage offer better performance?
- rakoo 6y agoAs usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land use. For reference (https://en.m.wikipedia.org/wiki/Coal-fired_power_station https://en.m.wikipedia.org/wiki/Coal-fired_power_station): > As of 2018 coal power under construction was 236 GW, planned 339 GW, and 50 GW was commissioned and 31 GW retired If we want to replace those new plants we'll need 100.000 of those shafts. And that's not counting the existing plants, and the other fossil-fuel based plants. Think of the quantity of concrete that involves. That's just insane. If we want to actively tackle electricity generation we need to use the most efficient low-carbon tech that we already know. Also, we already have gravity-based systems, only nature does all the work of raising the payload for us in gaseous form, and we let it fall in liquid forms. But it takes so much dam place.
- pedrocr 6y agoThat's the wrong comparison. We don't need to replace generation capacity with the same capacity of batteries. Batteries don't generate any electricity after all. We need batteries to smooth out differences between demand and generation. The total amount we'll need is very much still up in the air. Better interconnects, good use of existing hydro, overbuilding renewables, shaping demand, are all other ways to balance loads and guarantee enough power at all times, all of which reduce the need for batteries.
- ben_w 6y agoI think[0] we should probably be aiming for a few hours of storage, even with every affordable grid interconnect (which would help a lot with short winter days). We use less power at night — and some of what we do use is incentivised by lower nighttime electricity costs from power plants that don’t scale down well — but I expect we will continue to use some at night forever. For the sake of Fermi estimation, I assume average electricity use in a developed nation is 1kW/person, and that average all-forms power use in the same is 5kW/person. Transportation is almost certainly going to be batteries or synthesised fuels like hydrogen, and can only be backed by gravity storage if you have the kind of beamed power that would be banned by international treaty on the grounds of being too easily weaponizable[1]. If you’ll permit me to assume grid interconnects and lower nighttime demand than at present due to different pricing incentives, we might be able to need a mere 3kW-hours/person of electricity storage per night. Using the lifetime cost estimates in the article, 3kWh/person/night is about $0.51/person/night for gravity storage and $1.10/person/night for LiIon. Neither is bank-breaking, but cheaper is better. However, the volume required is a different question: 3kWh of batteries has a volume of 4.3 to 12 litres, while 3kWh of gravity storage is 1.1 metric ton kilometres[2]. You can make the distance required smaller by using more mass, but if I assume the average home mass is about 200 tons, you’d still have to raise the entire building 5.5 meters every day to store the same energy as a backpack of batteries. I do not expect construction on this scale to be the optimal solution in general, despite it being a very good idea in some specific cases such as hydro dams and preexisting deep shafts. [0] Armchair opinion — I’m a software engineer not a civil engineer. [1] Assuming they’ve read or watched any Larry Niven, the Bobbiverse, The Expanse, Babylon 5, or the news at any point in the decade following the second week of September 2001 — 'A reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive.' [2] http://www.wolframalpha.com/input/?i=3kWh%2F%289.8m%2Fs%2Fs%29%20in%20%28metric%20ton%20km%29 http://www.wolframalpha.com/input/?i=3kWh%2F%289.8m%2Fs%2Fs%...
- Gauge_Irrahphe 6y agoThe technology isn't incredibly immature. On the contrary, it's understood to the tiniest detail. If it doesn't work, it won't work.
- PurpleFoxy 6y agoIsn’t pumped hydro a realistic solution? There should be a massive amount of energy in moving all that water up a mountain.
- bluescrn 6y agoPumped storage hydro makes far more sense. Which is why it's already in use. Maybe the efficiency can be improved upon with a small-scale 'gravity battery', but water has massive advantages when it comes to scaling it up, as well as being able to combine it with traditional hydro, where nature moves much of the water for you.
- RosanaAnaDana 6y agoPlenty of issues with hydro, but in the grand scheme of things, it does seem like by far the most accessible, actionable, least polluting option. I've often wondered what scale of a system would be required to power a fully off the grid home at say 30kwh/ day, for say, 6 days? I'm imagining a tank based system with two tanks where the fluid is effectively just exchanged (so one doesn't have to account for the environmental impacts of a dam or for losses due to evaporation).. After some googling: https://www.edie.net/library/Using-pumps-as-turbines-to-generate-power/5998 https://www.edie.net/library/Using-pumps-as-turbines-to-gene...
- walshemj 6y agoLimited places it will work and you cant just flood valleys and displace the residents anymore in the west.
- ascorbic 6y agoPumped hydro's main drawback is that it has very specific requirements in terms of geography.
- timonoko 6y agoIf you pump one cubic meter of air 100 meter deep, the energy stored equals a tonweight at 100 meter up. That is 9.81 kJ aka 2.7 Wh. This is inifinitely scalable and suits flat places like Australia. One and only minor problem is how we prevent the 2.7 GWh energy storage, which is 1E9 m^3 aka one cubic kilometer inflatable container, not rupturing or raising up. But otherwise ingenious nicht wahr?
- joss82 6y agoThe system bring talked about here can deliver 250kW during 11 seconds max. That is LESS than 1 kWh of energy storage. I hope it's not the one on the picture otherwise their cost estimates are way off and two orders of magnitude larger than current lithium batteries, even taking into account battery replacement. Another problem would be the ever-lowering price of batteries comparing unfavorably against this good old tech with stable or raising costs (human costs tend to rise over time)
- nixpulvis 6y agoI had the same thought. They do make it clear that this is a demonstration, but I'm curious how this scales with larger weights and heights; both in capital cost, and efficiency. I'm also curious if anyone's seen a good comparison to hydro/dam based gravity batteries? Or even to the gimmicky sounding electric train based ones I've read about before? My understanding is that anything near or past 90% efficiency gets very hard to achieve, but perhaps there are special cases where this isn't true? Finally, I'm also curious how these compare to flywheels, which offer a similar style of energy storage, but with rotational potential instead of gravitational. Storage is clearly one of the largest barriers to large scale adoption of many renewable sources of power we have. And, chemical batteries raise a lot of valid concerns in terms of safety and environmental impact.
- runeks 6y agoHere's an idea: what if -- instead of digging a deep hole into the ground -- we use the tower of a wind turbine as the vertical space in which the weight is raised/lowered? A wind turbine is already equipped with a generator, so it'd be a matter of building some sort of "switch" which would make it either: (a) generate electricity using the turbine, as per usual; (b) raise the weight using the turbine, thus not producing electricity; (c) generate electricity by connecting the weight to the rotor/generator, while lowering the weight.
- masklinn 6y ago> Here's an idea: what if -- instead of digging a deep hole into the ground -- we use the tower of a wind turbine as the vertical space in which the weight is raised/lowered? First, there's not really any room in there, wind towers are built for the job, we don't add twice the amount of steel and an elevator shaft for funsies. Second, even if there were some room it would be inconsequential, you need a lot of crap very high up to get significant amount of energy. As demo, let us take the largest turbine available right now and lift the entire thing up and down its tower. The Haliade-X has a hub height of 150m, a 600t nacelle, and 165t blades. In normal operations it's rated for 14MWe. 765t at 150m is 250kWh. You can get electric buses with larger battery packs than that. For reference, US households use about 29kWh/day. That's the issue with gravity: it's really not that strong, so to store significant amounts of energy you need either ridiculous amounts of weight (hence dams and pumped hydro which can manage unfathomable weights), or extreme height difference (hence… still dams, pumped hydro a bit less so I think). As a point of comparison, Bath County (the largest pumped-storage station in the world) has a hydraulic head of 270~385m and the upper reservoir stores 44 million tons of water. Now taking in account that you can't really empty the entire thing, that it's not perfectly efficient, etc… Bath has a storage capacity of "only" 24GWh, it's not actually moving 44 million tons up and down 400m.
- thirdlamp 6y agoWhat if we used load bearing batteries as part of the tower structure?
- mbar84 6y agoSince scale and locality is such an issue here, I wonder if there are any concepts for integrating such a system in new mid-rise buildings. Similar to an elevator shaft, but with a weight of depleted uranium instead of the passenger car. You're digging for the foundation anyway, maybe maybe the marginal cost to dig a few meters deeper is worth it. You're building with a crane anyway, maybe the marginal cost to build a steel frame tower on the roof is worth it. It's certainly not a mine shaft, but perhaps better than nothing.
- deleted 6y ago[deleted]
- kerbobotat 6y agoDoes it need to expend the energy to winch it up? Would it not be simpler to have a set of these weights, and a ramp system to deliver them to the top, and use vehicles to unload at the base and drive them back to the top to be hooked up again in sequence? Surely there would be less energy loss moving it up a ramp than fighting gravity in a vertical shaft to winch it directly upwards.
- JBorrow 6y agoNo, gravitational potential energy is linearly proportional to the height over which you raise the weight. http://hyperphysics.phy-astr.gsu.edu/hbase/gpot.html http://hyperphysics.phy-astr.gsu.edu/hbase/gpot.html
- throwaway189262 6y agoThis is an obvious scam if you do the math. Assuming the full scale version delivers peak power for 11 seconds like the prototype, 2MW peak power would be 6 kilowatt hours of energy. That's terrible. We're taking about dropping hundreds, maybe thousands of tons down a mine shaft to get the same amount of power as $700 of lithium batteries you could carry in a backpack. For instantaneous loads you're way better off using flywheels, which we've already had for decades. Gravity is weak, literally. The only realistic use case for gravity generation is hydro power. And MAYBE reverse hydro power where we put giant gas bags underwater and they make energy floating up
- hn_throwaway_99 6y agoAgreed. I'm glad that people and companies are trying different solutions for our energy challenges, but I see so many examples where the basic physics make these solutions impossible to scale, that it seems like these are primarily just schemes to suck government money. Gravity solutions like these will never be feasible, because as you point out, gravity is just plain too weak of a force. I mean, it looks like pumped hydro will be viable, but when you think of the sheer mass of water that can be pumped behind the Hoover damn you realize stacking a bunch of bricks is ridiculous in comparison. There was another recent article on HN about a giant tidal generator, and I was glad to see the top comment pointing out that basically over 50 years all these tidal projects have been failures (at least when it comes to ever being able to provide decent power in a fashion that shows it can scale). It's time we start calling out these schemes for what they are, because they take funding away from solutions that we now we'll need now to fight climate change.
- ionwake 6y agoPlease excuse me if I am terribly ignorant. In my head, liquid must be easier to play with than a solid. So displacement of water or air should be done. The displacement of air, being pumped into a balloon under water seems like a great idea. I know many solutions must have been thought of, but is the inflate balloon under water , then let it float up - the most efficient way of storing energy? Lithium batteries wear out, but are more energy dense and so arent comparable ( regardless of size). Forgive me for ruminating I think this is a problem with an already identified solution though?
- kvutza 6y agoCould they make it a space elevator?
- GuB-42 6y agoNot the first time I have heard of gravity batteries, and with the exception of dams, they all look unconvincing. To make a comparison, there is a human-scaled variant of the concept in the GravityLight by Deciwatt. The concept is clever, it involves lifting a bag of rocks to get a bit of light for 20 minutes. But if you run the numbers, it is tiny. As the name of the company suggests, the generator outputs 0.1W, enough to power a 15lm LED. For 20 minutes you need to lift a 12.5kg bag 1.8m. That's around 0.03 Wh per lift. By comparison, a good 18650 battery is around 13 Wh, about 400x more. As a niche product, GravityLight is not a bad idea, but it is telling that their new product, NowLight operates the same way, but they replaced the bag of rocks by... a 18650 battery. Back to the topic, it looks like that "drop a weight in a mine shaft" idea does worse than what you can do with a single Tesla car, which have more energy storage and more power at the wheels. Plus, it is cheaper and you get a whole car with it.
- rafaelturk 6y agoI realy like the design of this baterry: Its simple, easy to build and mantain.
- isoprophlex 6y agoSo, let's look at doing this in a distributed manner: giving every household their own gravity battery. A 1 m3 cube of concrete weighs 2400 kg; moving this over 6 meters yields (mass * gravity acceleration * height) = 140 MJ, = 39 kWh. Lets say 34 kWh after accounting for energy losses. A european household uses approx 3500 kwh/year; americans use upwards of 10000 kwh/year. Clearly such a slab of concrete will comfortably allow buffering an entire day's worth of power, and then some. Edit: fuck me I'm dumb. Off by a factor 1000. 39 watthour in that cube, not 39 kWh. Ignore everything I said.
- _ph_ 6y agoAn European household rather uses 10-20kWh/day, usually closer to 10. The question is, what is cheaper, to build a 6 M tower that can lift 2 tons of concrete or a nice Lithium battery pack which uses a lot less volume too?
- isoprophlex 6y agoConsidering that i messed up by a factor 1000, a battery pack is probably cheaper than a 6 km high tower...
- prof-dr-ir 6y ago140 kJ, not MJ [0]. So you'd need a thousand of these cubes for 39kWh. But you can also just raise your single cube by 6km. [0] https://www.google.com/search?q=2400+kg+*+10+m+%2F+s%5E2+*+6+m https://www.google.com/search?q=2400+kg+*+10+m+%2F+s%5E2+*+6...
- isoprophlex 6y agoO wow. Off by only three orders of magnitude. How embarrassing, thanks for the correction!
- Ekaros 6y agoI wonder what is the limit when this kind of storage would only consist of single steel cable. As at certain point weight of cable is so big that it can't support even itself anymore.
- lebuffon 6y agoI think this guy is onto something... Liquid metal batteries will be better than gravity storage IMHO. https://www.youtube.com/watch?v=NiRrvxjrJ1U https://www.youtube.com/watch?v=NiRrvxjrJ1U First commercial scale system is going live in 2021 so we shall see how it works out.
- xutopia 6y agoI don't understand how that would be feasible... wouldn't the battery need to be kept at a really hot temperature somehow to function?
- lebuffon 6y agoUsing it causes the heat. It is in an insulated container so the heat stays around for about 4 hrs I think he said. So applying first charge must heat it to melting temperature but then it's working. Then when you discharge it, electron flow cause heating again. So if it is constant use it just works.
- SarbinBracklur 6y agoThe numbers in this article seem off. 250kW (peak power) for 11s (time at peak power) is 2.75 MJ. That's only about 51 10000mAh D batteries. Of course, the peak power of the gravity battery is much higher than the chemical batteries, but still.
- iandanforth 6y agoOk, ok, everyone, I've got it. It's great. As you know, two meh ideas together make one galaxy-brain idea so here it is. Gravity batteries + vertical farming. This is so amazing I'm just jittering over here. So what are big shafts filled with before they are shafts? Dirt! What do plants need to grow? Dirt! So what you do is ... wow this is great ... what you do is you take the dirt out, then you make this big battery thing a stack of dirt shelves that go up and down and while they are going up and down they also grow plants in the dirt. So now you have a big field of these dirt stacks going up and down and in the middle you have a big farmers market. Money from dirt two ways. God how is this not already a thing. Problems solved. Done.
- f6v 6y agoPeak HN, right here.
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- RosanaAnaDana 6y agoWhat about pumping water up hill into reservoirs? I know not every where is suitable for reservoirs but this seems pretty obvious. Run renewable to pump the water up hills, all the 'battery' components of the tech are well established. You're creating additional benefit by storing potentially potable water. It seems like the tech for water storage/ transport/ regeneration to electricity is all pretty well figured out. I'm thinking some place like the Columbia gorge where there is high capacity for wind and for hydro.
- PicassoCTs 6y agoThe cheapest gravity storage is capable of holding itself up. Which is why vertical glaciers are so tempting. Its just ice, you pile it up, in large columns, with a puddle of water beneath. Energy is extracted by warming the water and taking part of the pressure to a turbine. Energy is added by pumping and freezing water on top, while the extracted heat is stored in a side tank for later usage. Insulation against heat prevents energy loss for longer times. Four T-beams hold up the freezing machinery on top. Storage grows with demand. If the ice starts to deform, added carbon-flakes, can increase tensile strength. Pressure in the pool is kept via onion-seals https://imgur.com/iCg9LzY https://imgur.com/iCg9LzY
- sdenton4 6y ago'Switzerland-based Energy Vault wants to use a multiarmed crane with motors-cum-generators to stack and disassemble a 120-meter-tall tower made of hundreds of 35-ton bricks, like a Tower of Babel that rises and falls with the vagaries of energy demand.' This sounds amazing. It's like the repetitive, seemingly-pointless behavior you see in the background in videogames...
- geosimcos 6y agoA long time ago I was interested in alternative ways to store energy, one good method but quite expensive is to convert it to Rotational energy of a flywheel, NASA had pretty good results with magnetic bearings and vacuum. https://en.m.wikipedia.org/wiki/Flywheel_energy_storage https://en.m.wikipedia.org/wiki/Flywheel_energy_storage It isn't practical and much more complicated than the other alternatives mentioned