Gravity Energy Storage. Who's right and who's wrong?

[@westrim]

Energy vault feels like a crane salesman, a concrete supplier, and a computer animator got together for some beers.

[@rulesofimgur]

Don't forget a guy from silicon valley.

[@Kiyoone]

Don't forget to add: "made by *clever* engineer grad students start-up"!! It works people, they confirm it.

[@webstercat]

You noticed that right..

[@Belthazar1113]

It sounds like something as simple as closing the system inside of a silo would have solved 99% of the "debunking" that went on about it.

[@westrim]

@@Belthazar1113 As long as that 100% is weather related concerns, possibly. Otherwise, no. Pop quiz! What's the energy potential stored in a concrete block at the bottom of a stack?

[@Jedward108]

You've done the public a good service by following up on these companies' progress. Please do continue to provide videos when there is news to share.

[@brendanwallace4661]

Fair play Dave. I love the fact that you circle back. Keep it going. These progress reports are interesting. Thank you

[@JustHaveaThink]

Cheers Brendan. Much appreciated.

[@CHIEF_420]

@@JustHaveaThink 🎓

[@michaelmoorrees3585]

You know he takes this seriously, and has an open mind, and just not gullible, as he takes in account debunker channel input. Much more credible than your typical Tesla fan boy.

[@beyondEV]

@@Freja_Solstheim There is a reason they didn't compare it to hydro. this is so laughable tiny (24.4MWh), nobody would consider to build a hydro this tiny. LCOS scale mostly with size (especially for hydro). Actual average Data from Lazard (same source the imperial college of London uses sometimes): compressed air, pumped hydro, and lithium ion batteries are $128/MWh, $175/MWh, and $414/MWh But that's real data including the cost overrun during construction etc. Meanwhile the calculated number for the "new" tech is the estimate of the enterprise proposing it. I didn't find this Study, but another one for gravitational storage: heindl-energy.com/wp-content/uploads/2018/10/LCOS_GravityStorage-II-Okt-2018.pdf Something a bit more serious, as the stored values are of significance (it's basically a hydro which could be built anywhere, again numbers are estimate (probably optimistic ones)). Page 8 also reveals why we don't just make it all compressed air: compared it's rather inefficient with only 42% of the energy recovered.

[@jamesgrover2005]

@@JustHaveaThink just been reading an article about algae being used in glass panels on buildings which sounds interesting. >Beautifully designed, energy-generating bio-panels that suck up carbon dioxide and pump out biomass for use as fuel or fertilizer - that's the idea behind Mexican startup Greenfluidics and its nanotech-enhanced microalgae bioreactor building panels.

[@paulogden7417]

I would like to know the actual number of "vertical mineshafts" available with sufficient depth, no water intrusion and other factors to support this. I think that will limit scale. I would also like to know the levelized cost to develop a virgin site under reasonable conditions, ie no worries about water infiltration. That number would represent a scaleable solution. Anything else I think would be less interesting. We can't rely on old mine shafts for a critical new energy storage technology.

[@bobbycrosby9765]

I tried to find this but was unsuccessful. I did find out that there are 500,000 abandoned hardrock mines in the USA. But that doesn't give much further information on how suitable for this project they would be. But 500k is a pretty big number - even if a fraction of these are suitable that's still a lot of sites. I also don't think hardrock mines includes coal mines.

[@misamsung6191]

Using a water/air tight shaft lining the water intrusion point become moot. As in my mind Gravitricity would want to keep the shaft as clean and dry as possible. Which means that they would have to use some kind of lining in the drop shaft

[@charlesmartin1972]

It's gonna take a while to get firm numbers, but my findings so far: Considering the worst-case scenario of a reinforced-concrete-lined vertical borehole gravity energy storage system in, say, the Amazon rainforest where the ground is always saturated; seepage rate across a given section of the inevitably-porous concrete is ((groundwater head pressure) -(viscous back-pressure))•(area of section); taking the integral of this function with respect to area will give us a flow rate value in units of volume per unit time. Due to this, out-pumping costs scale with the square of borehole depth, so there is definitely a limit to scalability *in certain biomes*

[@johndododoe1411]

@@charlesmartin1972 Heavy water seepage just provides an opportunity to build it as pumped storage instead, with the lower reservoir at the bottom of the hole. Shaft cleanliness seems a non-issue with enough slippage space between the weight and the walls. Remember that whomever used the hole for mining was already lifting things and people in and out of the hole. Graviticity doesn't need the hole to be safe for humans and don't need the various side shafts (all except construction and maintenance work of cause). A thin (2 inch) concrete lining like in sewer pipes and manholes would be enough for a hole in regular ground conditions rather than mine shafts. 500m depth could also be a repurposed elevator shaft in an economically failed skyscraper (originally built at prohibitive cost) or an intentional design feature in new skyscrapers where most of the building is making rent income to fund everything.

[@charlesmartin1972]

@@johndododoe1411 the volume occupied by free water represents a loss of gravitational potential energy available to the weights. Also, seepage through the walls is not passing over a turbine and is thus a net efficiency loss

[@chuckoneill2023]

If they're planning to build a facility into an old mine, pumped storage with water is still better than moving ore around. Many old mines are full of water --- ground water intrusion is a major engineering concern in most active mines, many of them flood almost as soon as they're decommissioned, and the pumps are shut down. It does seem like an end of life mine already has most of the infrastructure in place for pumped storage.

[@theonly5001]

Most Mines keep a certain area clear of water to make sure the shaft doesn't collapse. And those pumps will run indefinetly.

[@zbarba]

As you said, you need constant pumping to keep the water out. Pumped hydro can't work if the bottom lake keeps filling on it's own

[@chuckoneill2023]

@@zbarba In most cases, the speed it fills at is slow enough to not be a problem. The capacity is generally very, very large. It would likely be much larger than whatever the surface area tank or lake would be.

[@ruukinen]

@@chuckoneill2023 I find that hard to believe. You get a lot of volume from a reservoir since it is roughly cube or cone shaped. Meanwhile a mineshaft is by design narrow and windy.

[@chuckoneill2023]

@@ruukinen Actually, I think you're confusing a mine with a cave or cavern. Mine shafts are generally cut as straight as possible, for ease of removing the ore. In any case, however straight or crooked the shafts are has little impact on the flow of water. I toured an old below ground iron mine a few years ago. The void left behind by mining out a large deposit was basically the size of a cathedral.

[@Voltaic_Fire]

I can't believe that energy vault got as far as it did, at best it was too finicky & the next version isn't much better. The gravitricity mineshaft version looks more promising with a more controlled environment, fewer points of failure, it has a much smaller footprint, regenerative power is proven, and cheaper to implement since the hole is already there.

[@Kiboxxx]

It is also not very convincing that they present their (final) idea and probably pitch for money without having built a reasonable prototype to test their theory. After "working" on whatever and getting told that the idea will not work, they completely change their concept.

[@Voltaic_Fire]

@@Kiboxxx Yes! Their idea crumbled under basic scrutiny (though not before wasting a lot of money) but it's a good idea to never trust a company that only ever presents CGI concepts, proof of concept isn't just important but vital.

[@chuckkottke]

But just wait until the rock monsters see that iron ore coming down. The Enterprise may have to tractor beam the ore up before they nibble on it! 🚀

[@evilotto9200]

discarded minshafts make for unsexy powerpoint when marketing to investors

[@mikedavison3400]

@ Evil Otto I disagree. Discarded mineshaft areas are less likely to draw the protest crowds when a company seeks to do something there.

[@brookestephen]

I don't like the cube towers, since it's a total electrical energy loss to transport blocks laterally. It doesn't affect the potential energy, but it does drain electrical energy to move the blocks anywhere but up and down. This is a drain on stacked block towers too. Moving blocks closer or further from the tower core is a net loss.

[@Hans-gb4mv]

There's a lot more issues with that concept. While the principle is tried and proven as a warehouse system, there has never been a setup like this as far as I am aware with handling weights anywhere near this.

[@robinherrick2177]

There is also the issue of the embedded energy in the construction.

[@patreekotime4578]

Not just lost energy... Wayyy too many potential points of failure. A weight suspended on a hoist could be deployed even if there was no energy in the system... Like during a total outtage. But a giant warehouse of weights stored in computer-controlled conveyances by definition requires inputs to operate, so it could never be used as emergency power during outtages. And is just flat out going to break down at some point.

[@robinherrick2177]

@@patreekotime4578 I can't believe I'm defending this daft design, but all power stations require some power to operate. In this case you would just need to have enough weights ready to drop to ensure there was power to move the weights sideways.

[@MolloRelax]

The engineers should be able to design the system in such a way that the blocks that have to travel laterally do that on a small slope configuration ,to reach their destination; by equipping the blocks with temporary rollers, or design the transport railing system with permanent ones.

[@yorkyone2143]

Energy Vault appear to be building a Borg cube, keep a close eye on them, is all I'm saying.

[@simongross3122]

Resistance is futile...

[@zackperry1594]

😂

[@SX939]

I do believe that pumped hydro is ultimately the answer. It has been a proven technology with far fewer longevity problems than the mechanical wear and tear of wire rope llift systems. Respectfully, Dennis, KV4WM

[@markuslenzing7386]

Yes and it has an impressive effenciency if build big enough.

[@darrennew8211]

And you could probably build hundreds of water towers for the cost of one building full of concrete blocks.

[@douglee7985]

Head loss (friction) in the pipes is the problem with hydro. Pulleys are much more efficient.

[@azzzertyy]

It obviously has geographical issues though, a lot of countries have nowhere else to put any more hydroelectricity, england for one example really, we dont really have anywhere else to put them, an alternate way of doing what hydro can do is absolutely something worth atleast looking into, since were going to need it for a green revolution.

[@mully006]

@@darrennew8211 the problem is you cannot build towers big enough to be very effective. You need a huge amount of water and height to do pimped hydro.

[@thumper1747]

Excellent content delivered in a quiet and understandable manner. Love the fact that Gravitricity is run by engineers too.

[@jimprier326]

Most mine shafts need constant dewatering to remove water ingress. This comes at a high energy cost which has not been factored into levelized-cost callcs

[@janwinders]

Maybe they plan to operate in flooded holes.

[@peterbreis5407]

Good point. That natural inflow of water takes off a slice of the potential energy to be stored.

[@mikedavison3400]

@ Dan Tronics I don’t think energy storage systems of any sort need to be near where demand is. They just need to be somewhere along the grid to take in excess power and feed it back into the grid as needed.

[@jimprier326]

@@janwinders not likely. weight in water is considerably less than in air. Also there will be significant hydraulic drag both lowering and raising the weight

[@johnschneider931]

I don't know, find a spot on a hill in the Western US, pump the water up/out let it run down hill. Recover some electric cost with hydro generation. If there is a gully and Hill at the bottom, you will get the water to return underground away from your project and start to turn the desert into grassland.

[@sephiroth127]

On a delta height of 360 meters, you get 1kWh/ton. To have 1 GWh of storage, you need 1 million tons of weights to move up and down over 360m. If your weights' density is 5 kg/l, you'll have 200'000 cubic meters of volume, which is roughly a parallelepiped of 100x100x20 meters. This is why storing large amounts of energy with gravity is hard (unless you use water reservoirs): because you need a lot of materials and space.

[@solarguy4850]

Yup .. and water flows all by itself so you don’t need to stack it. No question water for long-term storage and batteries for short term is where this is going. Large battery buyers are buying under $150/kWh today, CATL anticipates being under $50/kWh this year for (Sodium batteries if memory serves) .. and we are no where near the limit on battery/performance/price.

[@davidleaman6801]

Don't forget that installation of the weights allows that the gravity battery can start out in the "Fully charged" position. As long as the modular design has enough modules and energy collection equipment, there is a chance that the gravity battery can keep up with demand. I think it's important to think of the gravity battery as a secondary source of energy when demand requires it's use, or more or less a supplement to existing infrastructure.

[@SatanIsTheLord]

@@davidleaman6801 and I think you are and idiot, Sir.

[@saurabhmangal6322]

100x100x20 seems doable...

[@panzervpl9406]

@@solarguy4850 Water is problematic because it's a liquid, it's harder to contain than solids, it can evaporate and couses corrosion, so imo pumped hydro is best built using natural terrain. Good boon for gravity storage is that it doesn't lose capacity over the years, downside being moving parts but pumped hydro has the same problem albiet smaller

[@petersmith2137]

I like the idea of gravity storage, but I can't see this being useful for mass storage, say to get us through a period of gloomy, windless weather. It would appear that its utility will be for grid balancing.

[@bearalohalani]

Yeah, exactly. I see this more as covering overnight demand for a solar farm than holding those weights up waiting for a rainy day.

[@davestagner]

There's more than one kind of storage issue with renewable sources, and wind and solar have different problems. Despite the "OMG WHAT IF THE SUN STOPS SHINING OR THERE'S A VOLCANO OR A METEOR HITS THE EARTH???" nonsense, there's some very regular, quite predictable variation in both output and demand. So if you can compensate for that expected variation, you can turn either wind or solar into a consistent supply that can handle normal day-to-day variations. And those variations don't need nearly as much storage as saving energy so we can not have interruptions while the asteroid dust cloud blots out the Sun for seventeen years or whatever...

[@zenko247]

Used for grid balancing. for over 100 years en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

[@andrasbiro3007]

Calculate how much mass you would need. It's enormous. Think mountains.

[@bartylobethal8089]

That really depends on the amount of mass in storage. With sufficient mass reserves to account for worst-case scenarios it should be OK. It's not as if the blocks are evaporating or chemically degrading while they sit in storage, so other than the requirement for 'excess' storage area there shouldn't be many downsides.

[@johnnytarponds9292]

Thunderfoot did an excellent "debunk" of the tower concept, and did mention hydroelectric as a form of gravity storage. I mean, wasn't very hard to debunk, eh?

[@hg60justice]

i gave this some thought, and imagined it could be used out at sea for offshore wind storage. just a few more appendages hanging off a tied together wind farm. could even be the righting ballast and be as deep as where the farm is situated. could even hang freely in some places without a structure to drop it in.

[@TheReaderOnTheWall]

I love that you addressed "Adam Something" video on gravity storage.

[@RichardRoy2]

It would seem a good plan for the sides of mountains as well. I would point out that we've been using the water cycles for energy for some time with mills that run on river currents. Love your work. You seem to do a much better deep dive into what's going on than others I've seen. Thanks.

[@johnpublicprofile6261]

Great idea. A variation on the funicular railways that have existed since the 1820's.

[@mralistair737]

but water is free, easy to transport and heavy. and the whole thing can be done with one moving part. huge funiculars have millions of moving parts and youd need to find some niche sites with long steep slopes.

[@geoffreycahoon2410]

They have (or had) a project in development in California, utilizing the rails on old mining sites. Traction engines were to be used, with concrete weights on cars, controlled by grid software. Back them up the hill to increase stored energy, let them roll down to collect. I think they had already taken it far enough to determine that response times were fast enough for a lot of grid needs, besides just bulk storage. Since they were using existing tracks, installation costs were low. But even if newly constructed, the transmission line install costs would probably be higher than laying the necessary track and setting up the traction engines/ballast cars. Very old tech, but seemed simple, robust, and cost effective.

[@mralistair737]

​@@geoffreycahoon2410 but running railways is really expensive. you'd have to have qualified drivers in each of the trains, (sitting around waiting for peak demand) all the maintenance and checks etc. and old railways are really not that steep.. a traction engine is about 2 megawatts, power output, so call it 1.5mw electricity. Absolute peanuts. that's like $200 an hour, at peak times. if you compare it to wind generation that would be $60/h for that much power. '

[@RichardRoy2]

@@mralistair737 These rail systems aren't generation systems, they're storage systems. Think of a weight at the end of a tether on a cuckoo clock. You use a generation system to raise the weight, and when the generation system isn't raising the weight, you use gravity to generate electricity. Saying you need a driver to run the weight is like saying you need an elevator operator to run an elevator. It's not complicated. And you can assemble a lot of peanuts, plus improve the efficiency of those individual peanuts.

[@CeresKLee]

The thing I like that after 50 years, the Gravitricity storage maybe worn out and need replacing but the hole may need just a new lining to stop water intrusion and the new one may be a fraction of the cost of the first!

[@DonHusum]

I can see how Gravitricity's system can be adapted well to decommissioned powerplants, but in the case of mineshaft would it not just be easier to use Hydro, pumping water in and out of the mine? Love these videos by the way. It is nice to see how these technological concepts progresses

[@mralistair737]

Where do you put the water you pump out of the mine?. and how do you stop the empty mine filling with water naturally? if you can solve these then you've invended pumped storage.

[@richardbloemenkamp8532]

@@mralistair737 Creating surface water basins is not expensive per volume at all. In most mine shaft solutions you need solutions to prevent the mines from filling up naturally, through additional pumping of good sealing measures. With heavy block you could indeed have the blocks sink into partially water filled mines, but that would result in complex engineering as well. lifting and lowering a single 50 ton block in a 300 m mine shaft does not give a lot of energy: E=mass*gravity*height=50000*10*300 J = 150 MJ = about = 40 kitchen kettles during 1 hour.

[@redtreemouse]

This might be great in a few locations that have pre-existing mine shafts, but not many places do, so it’s like pumped hydro in that regard.

[@snowtaku1]

Thanks, I love the concept of revisiting previous video subjects to track the progress :)

[@JustHaveaThink]

Thank you. I appreciate that.

[@TuttleScott]

I had a memory of doing energy storage using train cars on a slope so did some googling and found "ADVANCED RAIL ENERGY STORAGE". seems like you could do that in more places without the need for an existing mine shaft.

[@gasdive]

Yes, and you could store more if the mass was stored at the top and bottom, so one rail car could carry multiple lots of rock, rather than a single lot as in this design. However both pale when compared to pumped hydro. Snowy 2 for instance stores 350 GWh. With cheap UHVDC the location of the pumped hydro isn't as critical. Any old mountain by the sea could be pressed into service.

[@awdrifter3394]

They are building the train cart.energy storage in Nevada. We might see it in 2035.

[@ArroEL922]

Remembered seeing that video also. Seems to be easier to install and maintain than either of the two mentioned in this video. And easily scalable also.

[@suit1337]

In Australia the Fortescue Metals Group is planing a system like that near Port Hedland

[@poneill65]

Being Scottish Engineers I wouldn't bet against them. They don't tend to be bs merchants. A large part of the Industrial and Scientific revolutions of the 1800's and the British empire is based on the brilliance of Scottish scientists and engineers (and I say that as a wretched Sassenach)

[@eaglechawks3933]

Read "How the Scots Invented the Modern World".

[@mralistair737]

As a scotsman I can assure you there are plenty of BS merchants north of the border, especially when there's a bit of free cash going for research. the fact that someone did something 150 years ago is no predictor of current performance.

[@piccalillipit9211]

I believe Scotland has the highest ratio of patents per capita anywhere in the world.

[@bknesheim]

They could just use Loch Ness (221 m), Loch Morar (310) or other lakes. The north sea could be used (even if water with salt are nasty stuff for any equipment).

[@mralistair737]

@@bknesheim use it for what? Loch ness is 15m above sea level.

[@psyeseease2649]

I would've liked to hear more about the energy capacity of such a system. Even if the results are positive it would have a very limited impact given that it has a ceiling already in the amount of existing mines. Even if the weights are heavier they can't possibly compete with the capacity of pumped-hydro.

[@ratgr]

Also concrete is only twice as dense as water so I bet you could store almost the same energy without all that equipment in plain water... maybe salty water, water isn't scarse, drinkable water is, if you keep it close mantainance would be minimal, you will only need to fill it once, keeping it close avoids evaporation

[@lenrichardson7349]

@@ratgr Water is scarse in some places around the world but not having to transport rock to a location where it is avalible seems a logical option. The perfect combination in my view would be desert based solar panel farm and sand filled weights. Why make concrete if it does not have to be structual.

[@ratgr]

@@lenrichardson7349 The problem with sand is its corrosiveness, its not a fluid so you cant really pump it normally but you could use a screw pump, It will need more manteinance, and some other mechanical help to avoid dunes, before you recomend sand bags that makes it worse, you'll need some kind of computerized complex mechanical mechanism and wouldn't be able to use the mine in its entirety. Water can be transported from the closest source, either pumped or water trucks, its mostly a one time cost, you only have to make the walls impermiable and the loses should be small, you dont even need this water to be fresh water, you could use salty water, very few places in the world are both far away from a water source and close to a population.

[@petitio_principii]

@@aaronlockey6429 the crane-managed block tower idea also had an expensive working prototype, although not to full scale. They had some multi crane tower and some barrels filled with concrete. The new design/3D-animation-concept doesn't have anything real AFAIK, although apparently they have a contract with China somehow. Ironically the closest thing to a prototype for that would be the prototype for gravitricity, specially if they gave up the nonsense of horizontal transport of the weights for no reason. Then it would at least look somewhat credible, although to me it wouldn't be clear whether the return on investment is really superior to just pump-hydro even if in ridiculously small sizes for pump hydro. Like filling the mines themselves with water and pumping it to a ground-level pool. Maybe one could hybridize the water supply system with something like that to some degree, as it has to be pumped up at some point, and has to go down.

[@coolioso808]

I think it's fair to say the energy storage, just like energy production for a sustainable future has to be a multi-faceted approach, often depending on geography and facilities. Just like you wouldn't put solar farms in the high arctic or antarctic or wind farms in a calm area, you'd look at the geography of an area to see what energy storage would be most efficient in each case. If we did things based on studies, data, scientific approach to problem solving for maximum efficiency we could crack the code for 100% renewable energy worldwide, with adequate storage.

[@attilaszilard4210]

Köszönjük!

[@JustHaveaThink]

Thanks for your support. Much appreciated 😀

[@herrvonBrausen]

For sure gravitricity is more promising, the only problem - they using old mines. And here we have a problem, because from my knowledge they have a tendency to be flooded by ground water hence changing this ideal system. For safety reasons quite often water is pumped out, but the point is, part of stored electricity will be used to pump out the water, so hopefully balance would be still positive.

[@erininstereo47]

You know, that sounds like mines would make a good candidate for pumped hydro... pump the groundwater to the surface on off-peak hours (with a small amount of power used to re-circulate water the seeps back in), then release it through the pumps to and release the water back into the mine and generate power on demand.

[@herrvonBrausen]

@@erininstereo47 well, then you need to store it somewhere, and in a meantime new water come from the ground. So basically more water you have to pump out vs what you could possibly use. I'm not an engineer in this area, it just what come to my mind, probably this company have someone from this area in the team.

[@Whyoakdbi]

Make a video about energy storage in sand. I am sure you've read about the Finnish company that started to use it to warm homes.

[@sailaway8244]

Have you been watching "Robert Murray-Smith" latest video no. 1604?

[@Whyoakdbi]

@@sailaway8244 no. I saw a video about it on BBC

[@sailaway8244]

@@Whyoakdbi kzbin.info/www/bejne/b3O6ZnqOZZp5odE

[@dantronics1682]

I think he did a video on it 2-3 months ago

[@shawnr771]

I recently saw an article on this. Interesting idea. Like this one, I hope it is viable and pans out.

[@haxi52]

Thanks for this! I like the update videos, please keep them coming.

[@JustHaveaThink]

Thanks, will do!

[@jansmit4628]

Many mines in the Netherlands have been decommissioned already and most of them are flooded. To lower weights in them seriously pumping is continuously needed. Some of the mines are now in use for diving instructions.

[@josepeixoto3715]

Just ANOTHER problem with deep storage,THANKS for pointing out, VERY important!

[@anngodfrey612]

Great work, - (older woman from down under, who learnt to drive in a 1952 Ford Prefect that you had to hold in 2nd gear to keep it engaged)

[@pauldenney7908]

No one system is going to cover all our needs but this does sound like a very simple (relatively) solution which will be one of the many we will require. It's only going to work in shafts that aren't flooded though and that may be a limiting factor.

[@pauldenney7908]

@@goodcat1982 cost, time and waste, we are facing a £120bn and climbing bill to sort out Sellafield. The French have had to Nationalise EDF because the economics don't stack up. I am not against Nuclear but it has some serious issues that need sorting

[@jameshegedus5566]

After reviewing several hundred comments, it seems clear that gravity storage just does not have the necessary energy density. The exception of Pumped Hydro does not change this fact. Engineering expertise, time and money, should not be wasted on anything below a certain level of energy density. It will never scale.

[@SirCutRy]

What kind of energy density do you mean? Weight based, volume based, or something else?

[@barrygiles9149]

@@SirCutRy I was wondering sort of the same thing. The deepest mine shaft is 1.6 miles down. There must be a theoretical limit to the maximum depth (weight of cables, etc)

[@FLPhotoCatcher]

If water is the exception, then I think the "exception" is not really *the exception.* Heavier materials certainly would work also. And there is something to be said in support for an elegant, interesting and even beautiful energy storage system. Huge amounts of extra money is spent on *buildings* to make them look beautiful and interesting, after all. One *interesting* idea I had was using lava from, for example, the volcano in Hawaii, funneling the lava into rail car "molds" maybe 4ft x 4ft x 6ft, and generating electricity as they rolled downhill to the ocean. Once they hit the ocean, they could heat sea water to turn a turbine to make electricity. The empty rail cars would be pulled uphill by the cars coming down. The cooled lava blocks could maybe even be sold as retaining wall blocks.

[@xenocampanoli815]

I don't want to diminish the cogency of this assertion. I don't know enough about the engineering stuff to make a good critical statement anyway. However, keep in mind, like in anything connected to economics, there are in diverse investments the cigar store model, where the return on investment may be low, or even below par, but its value comes in downturns of various kinds. These gravity projects have the nice side effect of being potentially more available for lower maintenance given the very likely potential loss of trained personnel after a population crash, in particular, which, for good or bad, seems very likely, and to a very great extent, and likely multiple times, in the next 100 years. We should, I think, be making such investments, and learning more about them, therefore, as they may end up being the only thing remaining humans can do some day.

[@SweBeach2023]

@@SirCutRy Let's imagine a 100 ton weight 1000 meter above the surface (or along the edge of a 1000 meter deep hole. It really doesn't matter). The potential energy of said weight is roughly 250 kWh. 250 kWh is roughly how much energy a home is using every few days. So let's recap - a 100 million dollar 1000 meter tall building capable of accepting a 100 ton weight at its very top is able to power a home for a few days. Does this seem like a realistic solution?

[@miroslavhoudek7085]

I think this "update" and "progress" answers some of the questions raised (e.g. the "wind" problem), but possibly only by moving to different problems. It's easy to say that building a 300 meter shaft would cost such and such moneys and produce such and such energy. So first you reuse existing mining shaft, well done, that could be cheap, they are already there. But can you scale this in any way that would have an impact on our needs? How many holes in the ground can you make without destroying water bed? I mean, speaking of which, in how many places you can make holes without it being flooded by the aquifer? Or outgasing, or shifting local weight distribution enough to cause minor earthquakes that crack house walls, like fracking or geotermal sometimes does. I think a geologist can have a field day with this one. Also, there really isn't that much energy stored in the weights, so the output (especially sustained output) numbers always look a bit meh. And I would also like to ask a mechanical engineer how realistic it is to build a resilitient system that works without constant cost in maintenance. I can get that we can build a good cable. Cool. But there's always the moving parts, jugling blocks, constant cycling of stresses.

[@Skoda130]

There is no way to generate of store energy without adverse effects. In the end, our need for energy will outweigh those effects, or we'd need d to do without.

[@timjarrett8777]

From my basic understanding, we shouldn't be looking at this in isolation. This is just one way of storing energy that will fill some use cases but not all of them. I believe the future will be a large mix of renewable energy sources and storage (gravity based, flow batteries, thermal salt etc). Combining all of the options will then provide a lot of resilience which will significantly reduce the 'baseload' electricity required from nuclear and gas.

[@miroslavhoudek7085]

@@timjarrett8777 I agree. But will this cover at least like a bilionth of our storage needs? If not and this is like a humorous curiousity, it's maybe not worth the attention.

[@timjarrett8777]

@@miroslavhoudek7085 absolutely, but we need to look at scale. BBC report states there are approximately 150000 old mine shafts in the UK. If we assume even 10% of these are appropriate for Gravitricity then that is 15 thousand of these small scale storage options. If we assume 2 MwH per location (which is half of the first storage system they are implementing in North Yorkshire) then that means 2 x 15000 storage, which is 30 gigawatts. I personally would call that a substantial contribution to our energy storage needs.

[@timjarrett8777]

"UK needs 80GW of solar and up to 30GW of energy storage to meet net zero targets - Energy Storage News" www.energy-storage.news/uk-needs-80gw-of-solar-and-up-to-30gw-of-energy-storage-to-meet-net-zero-targets/

[@nathanhaskell1743]

Really enjoyed the revisit! I see to many videos that talks about “”cutting edge tech”” but only talk about it once.

[@littlerick3458]

10/10 to review past videos and current developments, most videos are lineal and this really gives a more dedicated insight on any new technologies.

[@JGG3345]

Making concrete adds a lot of carbon to the atmosphere. I wonder how long it would take a gravity/concrete method to make up for for all the carbon created during construction?

[@Laeshen]

remember these are batteries not generators so the answer is never these work on the ends of coal plants too (they would just waste power that way though) the main benefit of batteries is to make up for lulls caused by lacks in the system (renewables not always being actively useful for generating power)

[@zarthemad8386]

its all cheap cgi to grift taxpayer and AGW cultist money away.

[@hynot9175]

A vessel full of sand etc sounds better imo, even rocks.

[@JohnDunne001]

@@hynot9175 I think that's the plan. Build the inital concept prooving plant with concrete, and if the physics/effeciency works out, then use more environmentally friendly heavy loads.

[@rubenayla]

That seems the best possible implementation of this idea. Use any cheap sand or rocks you got, the one with highest density to price ratio, put it into a huge strong steel bucket and move it up and down along a vertical hole. The main cost would be the construction of the hole, since they would need many close together for significant storage capacity. They could build the crane + generator first and use it to get all the dirt out with a different bucket for construction, make ridiculously long holes, and then reinstall the crane over the compacted dirt dug out of the hole, to gain extra length. The energy is mass * gravity * length of tunnel. The section of the cables is proportional to the mass, and its length equal to the length of the tunnel, so the amount of cable is proportional to the energy stored, and there's no way to reduce it by making it light but deep or heavy but shallow. So assuming a tunnel 4 meters in diameter with a weight 12 meters long, it's pi*2**2 * 12 = 150m^3 Filled with water: 150 tons of weight (less weight and more problems, not a good option) Filled with dry sand: 1.6*150 = 240 tons Filled with rocks (100% compacted granite or basalt, 2.6-3 t/m**3): about 400 tons Filled with magnetite: 5*150 = 900 tons A tunnel 1km long with magnetite would store E = m*g*l = 8.8GJ = 2450kWh With a low-discharge high capacity liion battery of $100/kWh, that same storage capacity would cost $245 000 It seems quite hard to me to imagine such a tunnel for such a low cost, knowing that The Boring Company was able to make their tunnels for 4M$/km A 100 meter tunnel for $24 500 seems also quite hard to do. Maybe with many close tunnels reusing the same machinery it could be achieved, but it seems hard to me. Like energy, if tunnel boring became cheaper, many many opportunities would arise.

[@aaaaaa-lt2tl]

Based

[@franklins6694]

Comparing the costs of energy storage by the two batteries in question, for the energy measured in kWh, is wrong. Are you referring to a metric ton, when you write, for example, 150 tons?

[@rubenayla]

@@franklins6694 Cost of energy storage has units of money / energy. I chose $ / kWh When I write 1ton I mean 1000kg of mass of material

[@josepeixoto3715]

What was the tunnel for? You mean, a hole?

[@anthonycarbone3826]

I think all these systems need to be balanced with the growth in electricity demand. If a system works according to plan it will only increase demand for that resource until the price equalizes itself with other energy storage alternatives. There is no static market commodity as each part of each energy component is seeking a dynamic equilibrium with other energy components.

[@nathanielstephenson7932]

There is quite a bit of flexibility in this particular system that could keep costs down. Motors could be of various designs, and with a gear box would not have to be optimized for a particular speed or wide band efficiency (with the exception of very high gear ratios). Gang style cabling could allow for use of a wide range of cable diameters and grades. The ballast could be substituted with anything "heavy," even free material from around the job site (sacrificing a bit of energy density depending on specific gravity). Support structures need to be sufficient, but not standardized. Etc... There isn't a "lithium" equivalent commodity to this system that necessarily creates a choke point. That said, you are 100% correct if this system is deployed as a specific product instead of a general machine concept.

[@zapfanzapfan]

That tower looked like the inventors had played Jenga while drinking the night before... :-)

[@markhamer5112]

I watched to the end and I still have no idea “who’s right and who’s wrong”

[@NightRunner417]

The truly interesting point of lowering a weight into a very deep shaft is that you don't need resets, which are a waste of efficiency. All you need to do is a lot of separate weights on cables, and take turns raising some weights on condition of surplus... whoever is closer to the end of their descent can get re-raised while others higher up descend if energy extraction is needed at the time. If no energy extraction is needed, raise them all. A matrix system like this will be immune to outside weather and can have a much farther travel length than any above ground suspended weight system. Multiple weights also gives redundancy to mitigate failures. Mind you I'm just talking out loud and I'm not an engineer so feel free to take a hot s**t on my point of view if it's needed.

[@janwinders]

More parallel weights mean more (or bigger) holes more cables and more generator. How could that increase efficiency? You can see in the animation that they plan to have one hole and one lifting/lowering system but multiple weights.

[@dantronics1682]

replace the weight with water, since its a mine shaft you can just dump the water so it takes less energy for winding /raising

[@petersmith2137]

@@dantronics1682 - that is hydro electricity.

[@dougaltolan3017]

@@dantronics1682 mines need pumps to drain them, else they flood

[@zenko247]

ERR why not just use water like for the last 100 years en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

[@jamesmulvihill6856]

Just throwing out an idea here. Why not build a small scale gravity storage system within the hollow steel tower of every wind turbine that you construct?

[@fedwa4148]

This possibly will make tower unstable and prone to collapse during high wind, a special tower need to be built

[@jameshamilton2480]

Something goes wrong with either system and you have to shut both down for repair

[@rickbackous1041]

People looking to $hit on your idea. I think it's brilliant.

[@SoleSur5er]

Even through in theory this would work, the amount of energy that you can store in the very narrow shaft will be so little it will not weigh up to the CAPEX and OPEX. There is simply no room for a large, heavy object and the travel is limited as well (compared to mine shafts).

[@Mothball_man]

Because once the weight is lifted in that one tower the wind turbine would then be useless… sitting still with blades feathered for possibly days. Not to mention how top-heavy the tower would then be. Of course they could probably disengage and bypass the weight and gear system but gosh all that would be so complex and require so much upkeep.

[@thesilentone4024]

Thats unique. Question can you talk about thirsty cement please 🙂.

[@jamesgrover2005]

Do you mean after it's been poured? I've got thin concrete foundation around the edge of my greenhouse, I get the feeling they draw quite a lot of water up out of the nearby ground through wicking which then evaporates, I've been considering removing the soil and painting the concrete to avoid this happening.

[@TheKennethConner]

@@jamesgrover2005 Do you think that's what was meant? I thought perhaps they were referring to Permeable Pavement. 🤔

[@frankyjayhay]

How about a huge floating block driving a generator as it went up and down with the tide? Some tidal ranges are about 40 foot so a few hundred tons continually going up and down should produce useful amounts of electricity.

[@paultrauzzi5360]

I thought of using my dried up well, of 25' depth, to drop a concrete block up and down, UNTIL I did the calculations. I'd need a huge block and much greater depth just to boil water for a cup of tea.

[@NickPiers]

I love the idea of using this system in decommissioned mine shafts. That's a great re-using of space that's just sitting there unused. I wonder if that would work in, say, old abandoned oil wells? You could set up some renewable energy infrastructure around it, like solar panels or wind turbines, and use the old mine shafts to store any excess energy.

[@brianzmek7272]

Probably not as oil wells tend to max out at around 3ft diameter and usually more like 18 inch diameter or less and the system seems to expect a 10 ft ish shaft at the small end

[@NickPiers]

@@brianzmek7272 Ah, I didn't know that. Thank you. I'll be honest, science isn't my strong suit. I love learning about it, though.

[@Sp4mMe]

There's alternatives that use pressurized water; that might be an option. Sorta like pump-storage but in reverse. There might be other reasons why abandoned oil wells don't work though (could be as simple as no useful location).

[@bknesheim]

One problem when using mine shafts is that they fill up with water (often with toxic elements). The pumping of water to keep the mines dry is often a major part of the operational cost and cleaning the water is also a major cost.

[@jackflack66]

@@bknesheim Exactly, plus pumping out the water will cause the water table in that area to drop. The video shows farms surrounding it, I'm sure they wouldn't like their water table dropping and rending their current wells unusable.

[@BMWHP2]

I wonder if old mine coal shafts could be used for this system? In Netherlands there still are several up to 1000 meters deep.

[@jasonleahy5543]

Gravitricity is designed to use old coal mine shafts that's the whole point.

[@BMWHP2]

@@jasonleahy5543 ah thanks, i tink i lost that in translation. ( i am Dutch) I thought they had to dig special size holes to specific depts

[@aeonturnip2]

The Gravitricity system sounded great last year and I'm glad they're making progress. Shame that the government doesn't help and get things like this pushed along. I can see this working really well to balance the over and undersupply of wind and solar.

[@janklaas6885]

🤣

[@sarikajain1606]

Jan klaas, i dont understand your emoji. What is the joke?

[@dantronics1682]

why should the govt gets involve?

[@dama9150]

@@dantronics1682 Because they have the funds to develop key infrastructure that helps society... Much of what we enjoy now was funded by governments.

[@dougaltolan3017]

500 tonnes at 500m is 680kWh. Peanuts

[@stephenacb]

I seems like the best solution would be to use the deep oceans. placing a floating station that lowers weights and then takes advantage of the bouyancy of the water to lift the containers back up and control the lowering of the weights, this will allow many parallel operations any where there is deep water. The floation platforms can then be used for equipment or solar panels etc. which will allow them to be more cos effective.

[@james3876]

Corrosion, barnacles, and accessibility for the communities that need the power all come to mind

[@ryancwiese]

The problem with your analysis of NRGV is that their concrete blocks are a new patented compound that utilizes ash from burned waste in landfills, which the company is actually getting paid by the federal government for cleaning up landfill waste. Secondly, the new mixture is stronger than any concrete we’ve ever even dreamt of, it will be roughly 20-30 times stronger than normal concrete. So continual maintenance and upkeep is in fact not a reality whatsoever. They’ve also already built their concept that absolutely proves the setup works flawlessly. The entire point of is to be able to store all of the solar and wind energy we can harness during the day, but until now lacked the ability to store long enough to be available in the evenings when the grid requires the most energy. And the amount of potential energy storage/output possible blows away anything Tesla battery storage systems could ever hope to provide, oh yea and at a fraction of the cost compared to the large battery farm storage solution.

[@ryancwiese]

Now the issue with Gravitricity is that the scale their solution can provide simply falls flat on its face when it comes to its ability to provide enough storage to actually service an entire electrical grid. Also, mine shafts are limited in size, so this issue cannot be made up for like NRGV’s Sustainability Center’s modular build scale capabilities. Not to mention, much like pumped hydro, the locations you can build such a design are few and far between, and likely exist far away from the grids they’re intended to service, almost guaranteeing their solution will not be able to be profitable and the company will never fully materialize. NRGV on the other hand will be using 100% recycled materials for its entire structure, essentially costing them $0 for raw materials while also helping to recycle and clean up the earth at the same time. NRGV is superior in every way

[@markpashia7067]

It seems to me that the gravitricity process has endless variations. How many old closed mines are in the western US where you would only need a headframe built to use them? And that same principle could be used on steep inclines with rail systems and cables. I have seen many slopes in Colorado that could be utilized to great effect. But the best solutions would be very close to the power source to keep down transmission costs. Where are the good solar and wind opportunities and how many storage sites are available nearby? Pair them up near an end user and you have renewable power 24/7 which is the stumbling block. Smaller more localized grids that can interlock is the real solution. I really like their answer for using gravel instead of solid weights as it could extend the life by reducing weight as they approach end of life means a gradual degradation instead of a sudden shut down as metal fatigues and cables weaken. Just lower the weight by removing gravel to get more years of use. Lower output is better than no output. And just think if ski slopes would build such systems large enough to provide their own power plus enough to power the towns that are nearby. In the off season they would have a source of income as all of the power could be sold on the grid. Just put them in pipelines with tracks inside and avoid the weather issues. No reason they must be totally vertical.

[@mikedavison3400]

@ Mark I thought of the ski hill idea as well. I’m wondering about the necessity of rails though. Given enough compacting and a ‘sled’ type design at the top and bottom ends of the weights you could simply slide them up and down the hill. Miners use to ‘rawhide’ loads of ore downhill.

[@shawnr771]

Most mines have a significant power requirement to run machinery, lifts, lights etc. Most of the basic infrastructure is already there. Might need some upgrades.

[@baronvonlimbourgh1716]

The problem is that people are still thinking about a grid providing energy to customers and talking about grid scale solutions. That makes these problems seem far more complicated and challenging then they will be. Decentralisation is key here. Of both generation and storage. The economics are turning against grid based solutions. The grid has to become a management system instead of a delivery system.

[@eclecticcyclist]

As the system offers long term storage with term independent losses, the tech could offer a tool for the box to cater for seasonal dips.

[@jonathanedelson6733]

500 tons moving 500m vertically stores kWh. The weights need to be very cheap and you need lots of storage room if you want to cover seasonal dips

[@janwinders]

As mentioned in the video it is a short term energy storage system only. That's why they compare it with battery storage systems. Just imagine it would be lifted just once in summer and then lowered in winter again. So you earn money for just 10 minutes per year. But you still have the whole investment and maintenance cost of the facility. Of course you would want to lower your weight as often as possible. Preferably multiple times per day. And that is how they calculate these low LCOE. As seasonal storage you can multiply the LCOE with a factor of at least 300 (depending on their actual assumptions).

[@eclecticcyclist]

@@jonathanedelson6733 I didn't suggest that this technology be solely responsible for covering dips, just that it could help as can hydropower and flow batteries.

[@jasonleahy5543]

@@jonathanedelson6733 Graviticity plans to use scrap iron.

[@jonathanedelson6733]

@@eclecticcyclist I was not saying it couldn't work. I was trying to describe the costs involved in making it work. Say you already have the shaft and regen lifting/lowering system, and assume that this system already makes sense for short term cycling. Now you ask 'what is necessary to get 'seasonal energy storage'. Say 'seasonal' storage means charging and discharging 2x per year. Say your shaft is 500m tall, and you use 500 tonne masses. Each mass stores 680kWh. Over the life of the system each mass cycles perhaps 100 times for this 'seasonal' usage, and thus stores 68MWh. The cost of the 500 tonne mass plus the space to store it top and bottom has to be really cheap (my guess, $5-20K) to be worth it for seasonal storage. You are welcome to do more accurate math. Keep in mind that if your 'seasonal energy storage ' is too expensive, then you are probably better off with things like larger solar arrays to provide sufficient off season production. Jon

[@NirvanaFan5000]

an idea I had that I was happy to see some scientists also looked at is the possibility of using skyscrapers as gravity storage. basically, lots of elevators already have energy-recovery systems built in, so use some section of the elevator and building to carry and store loads. almost all the infrastructure is already in place. may only need something like a kiva robot to move the loads. this would be ideal for big buildings that have multiple elevators, esp office buildings, since one or more of the elevators can be sectioned off (esp at night) to move the loads. (Another option is a two-story elevator, where one booth is just for loads and inaccessable to the public.) truth be told, like most gravity storage systems, I don't know if the economics of this work out, but it does seem really enticing to have energy storage built into local structures by making dual use of capital.

[@thomasreese2816]

Skyscrapers already have enough physics working against them that adding extra strain and liability is not worth the minimum energy gain

[@onebylandtwoifbysearunifby5475]

@@thomasreese2816 It's an idea, even if they only used the energy within their own building to power computer banks and energy load. Dump an overpower to the building, and have it ballance its own power needs.

[@sammason2300]

@@onebylandtwoifbysearunifby5475 The maths for this is very easy. Let's say the elevator has a rated capacity of one tonne and the building is 100m high. That equates to 0.28KWh of stored energy. By the time you've overcome frictional losses I'd be surprised if you get 0.1KWh of electricity, which will make about one cup of tea and has a commercial value of about 5 pence. Deduct the cost of all the extra machinery and you rapidly conclude it's a non-starter

[@onebylandtwoifbysearunifby5475]

@@sammason2300 Frictional losses could be replaced with magnetic forces, so could be analogous to mag-lev trains or regenerative AC motors. New buildings are being built all the time, and such ideas as energy recovery seem a good idea. Maybe a retrofit wouldn't be efficient in this case, but a central tower with a mass suspended as a counterweight to locomotion may be feasible. This tower could also be subsurface, and part of the building's cantilever foundation. The first aeroplane sucked too; i mean 12 seconds? That will never take off.

[@sammason2300]

@@onebylandtwoifbysearunifby5475 Low speed generators are very big and expensive, whilst high speed generators require lossy step-up gearboxes. But my main gripe is the exceptionally low power density. My view is that gravitational storage only makes sense for pumped hydro, and only then if the natural geography already exists. This idea has been around forever. It wasn't commercially viable before so why would it be now?

[@themeantuber]

Harnessing gravity energy storage system... They make it sound so scientific when it's nothing more than a dumb weight on a stupid rope. Even in ancient Greece they had gravity harnessing energy storage system.

[@mweskamppp]

I read about a gravity energy storage project in Saudi Arabia. A big stone cylinder cut out from the ground, sealed to the walls and pumped up high with water regaining the energy by running the water back through the pumps by the weight of the stone cylinder. I do have some doubts about the seals between cylinder and walls.

[@josepeixoto3715]

me too, someone sold that well to the arabs lol

[@physiqueDrummond]

in a physically constrained world (like, planet earth?) cost of a system SHOULD be evaluated in Joules, not in USD! Storage tech should be evaluated on: #1 ratio of embodied energy over stored energy #2 efficiency: Eout/Ein and #3 max power output

[@bearalohalani]

I think it might be easier to convert between currencies than from joules to money.

[@Jimmy4video]

The mine shaft version looks nice. I wonder if you could use one lift system to make use of multiple shafts to save on overheads. Assuming a site has multiple shafts in close proximity.

[@johndododoe1411]

Mechanically switching the mechanical system between shafts while holding up the weights at the top will add extra complexity that would be avoided by simply replicating the equipment to provide complete failure redundancy.

[@martincotterill823]

Great video, Dave, and a great idea, to see how projects are getting on. Here in Saarland, Germany, there are many disused deep mines, so perfect location for energy storage. I'm sure the tech. won't cause earthquakes, all nice and smooth. However, the shafts are all full of water, sure the weights aren't bouyant, but would act like plungers. I wonder what the consequences would be? Loss of energy, fountains...

[@ericmgodfrey]

If the shafts are full of water, I wonder if they can be pumped out and used as the lower reservoir for pumped hydro?

[@netional5154]

@@ericmgodfrey Quidnet Energy wants to use such shafts to pump them full with water under pressure as an alternative energy storage system.

[@LesNewell]

It's noticeable that Gravitricity don't compare their LCOS with the nearest equivalent actually in use, pumped hydro. I don't know the LCOS of pumped hydro but I bet it's considerably lower. They both have a limited number of suitable sites but hydro has far greater capacity.

[@JohnR31415]

Depends on the depth of your mine, and how much rail you want to put at the bottom/top to store rocks to the side.

[@LesNewell]

@@JohnR31415 To give an idea of the amount of mass involved in grid scale energy storage, the Dinorwig pumped hydro station in Wales can use up to 390 tonnes of water per second at 1,800 MW output (source: en.wikipedia.org/wiki/Dinorwig_Power_Station). It has a 536m fall. Let's assume the mine is twice as deep (pretty deep for a mine). Assuming roughly similar efficiency, for the equivalent output you'd still need to move somewhere around 195 tonnes from top to bottom per second. That's a lot of rocks!

[@maxtorque2277]

The biggest issue is that mostly mines are horizontal shafts with only one (or a few) vertical shafts. This is because the mine is accessing material laid down in rock strata so once you dig down the drop shaft, most of the work of the mine is then digging out sideways at constant gravitational potential. As such, lowering a single weight looks very limiting. Better in terms of total energy storage to either lower and raise lots of weights (using some sort of train track to shift carriages of weights sideways at top and bottom of shaft, or much simpler and more reliable, simpyl pump a suitably dense fluid (ie water...) up and down. Whilst the water is probably 6 times less dense than a physical mass, it would seem to be trivially simple to move well over 6x more water by volume than individual physical masses, and that's before you include the complex arrangements required to handle those masses, the inability modify how much mass is moved at any given time, the likely mechanical friction and of course the maintaince and installation of all those systems. concrete spraying the mine walls to seal them, and building a resevoir at the top of the mine, then using water sounds far easier to me.......

[@papparocket]

One factor I didn't hear you mention is the round trip efficiency. Even though round trip efficiency is included in the levelized cost of storage capacity (LCOSC), I think it merits individual mention since it makes no sense to use a storage system that only returns only half or less of the energy input into the storage system. In this regard gravity storage systems have a very good round trip efficiency. The only points of energy loss is from electricity to rotation of the motor/generator to store energy and then back again to electricity along with some friction losses in the gearbox and pully system. Substantial improvements in efficiency of motor/generators larger than 500 kilowatt and the power electronics to control the motor/generator thanks to the NASA Electrified Aircraft Propulsion program to electrify aircraft from fully electric for very small aircraft of around 10 seats to a turbine/electric hybrid for aircraft for larger aircraft. Motors and power electronics currently in testing at the 1 MW size are able to achieve efficiencies of 96% and 99% respectively. That means that round trip efficiency is in the range of (0.96*0.99*0.96*0.99 = 0.903) 90.3%. Knock another percent or two off for friction in the system and you get round-trip efficiencies of 88%-89%. This is less than the 95% round trip efficiency of lithium-ion batteries, but better than the 80% for both pumped hydro or 70% for compressed air storage (assuming that heat removed during compression stored elsewhere such as in phase-change salts where it can be added back to the high pressure air before being expanded through the turbine.CAES systems without heat storage have such poor round-trip efficiency as to not be a viable large scale energy storage). And an alternative to vertical pits is to take advantage of long slopes where rail lines can be laid and electric trains with cars full of rocks or other high density material (slag?) that take power from or return power to power cables as the train is run up and down the slopes to store and release energy respectively. The advantage of course is that it doesn't need a 500 meter deep hole to exist or to be dug. This can be done with conventional trains with a locomotive with electric motor/generators providing the input power going up the slope and extracts power to "brake" the train going down the hill and a train of railcars filled with heavy stuff. This system has the advantage that it can follow a winding path to adapt to the contours of the slope in order to keep the grade within the friction limits of the wheels of the locomotive on the track. If all cars in the train had traction motors, that slope could be steeper. Alternately a cog railway or a cable system with stationary motor/generators at the top of the slope can allow the slope to be very steep. Such a cable system has been proposed by Advanced Rail Energy Storage (aresnorthamerica.com/). The system consist of a number of individual bins containing "heavy stuff" that travel up and down the slope to store and release energy. A set of motor/generators at the top of the slope drives a cable that runs in a loop along the slope. The individual bins clamp to the cable to go or down the slope. A flat area at the top and bottom allow a number of bins to be queued up on either end. The amount of energy that can be stored is determined by the total number of bins that can be parked at the top of the slope. The total power of a single rail system is determined by the maximum power of the motor/generators with the limit being the number of bins that can fit on the slope at one time. So as to keep the speed of the motor/generators constant at their highest efficiency speed, the number bins that are on the slope at a given time would likely be how the power is adjusted rather than the speed of the bins. The input and output power of the total system can be increase by putting additional tracks on a given slope. With parallel tracks, the flat sections at the top and bottom can be shorter for a given amount of energy storage for the total system. Also note that the maximum power and the total system storage capacity is somewhat decoupled and so can be tuned to a given situation.

[@richardstubbs6484]

I was also thinking of rails on a mountain slope . Probably more efficient than pumped hydro ...

[@anthonypape6862]

@@richardstubbs6484 Exactly. Why lower cement blocks, roll the fucker. And to the marathon answer above, A simpler way to say it is every energy storage system is 100% efficient. Because the energy you are putting in is excess energy that the grid doesn't want, so currently it all goes to ground.

[@erichawthorne2519]

I think Energy Vault is claiming in the range of 75 to 80% round-trip energy efficiency, so somewhat comparable to lithium-ion battery systems. However, low round-trip efficiency may not be as bad for an energy storage concept as you are saying. As an example, a large-scale hydrogen electrolysis, storage, and fuel-cell facility e.g. in the middle of Europe could make sense, even though RTEE may only be 35%-40% or thereabouts. Here's the thinking. Wind power and PV power are becoming dirt cheap in capital cost. However they need cheaply scalable energy storage, capable of long storage time periods, to cope with intermittency and long periods of unlucky weather. So a centralized large-scale hydrogen facility could absorb excess power capacity and give 35% of it back potentially much later on. Scaling just involves more hydrogen storage tanks. So you build twice or three times as much wind and solar capacity as you need since it is dirt cheap, and rather than wasting the output as is frequently done now by disconnecting turbines from the grid or idling them, you get 35% of the excess energy back to use later. May very well make economic sense, since there would then never be times when wind farms etc are being paid not to generate.

[@papparocket]

@@erichawthorne2519 Yes, if you are going to otherwise have to divert power to a shunt and turn it into heat or shut down wind or tidal turbines to reduce supply to match demand, any round trip efficiency is better than nothing. And while the cost of wind and solar is dropping, it isn't nothing. Also different storage systems have different costs per kWh of output power. So as long as the extra generating capacity cost something, and the cost per kWh of storage capacity also varies, the round trip efficiency will always be a key factor in determining the optimum combination of energy storage methods to minimize the total cost per kWh of the system when averaged over an entire year. Another factor is the response rate and duration required of the stored energy system. In systems in the US southwest, Australia and other desert climates where solar is going to provide a large percentage of the total renewable power capacity. The energy storage system is going to need to supply 8-14 hours of power with a daily cycle. This would tend to favor systems with moderate storage capacity and fast response rate to keep the grid stable. This is likely where systems with higher round trip efficiency and power response rates in the 1 second range would likely have the advantage. This could be batteries (which don't have to be lithium-ion regardless of what Elon Musk thinks). This is also where potential energy storage would have an advantage. Potential energy storage is nowhere nearly as energy dense as batteries, thus they will have a much bigger footprint to store the same amount of energy. But they make up for that by having the energy storage medium be dirt cheap because it is literally dirt (well rock, but same difference) and an extremely long cycle life. However, for system like solar energy systems at higher latitudes where there is considerable seasonal variation in the length of the day and solar intensity, some form of long duration storage that can bank some of the summer energy for use during the winter will probably improve the cost per kWh of the system when integrated over a full year. Long term storage for seasonal shifting is where systems like power-to-fuel can be the better solution since the net kWh/m3 density is much higher and thus the very large amount of stored energy required for seasonal energy shifting will fit in a much more reasonable volume, even considering the much lower round-trip-efficiency. Hydrogen could be a good storage medium, but methanol might be better since it is a liquid at ambient conditions and so can be stored in simple tanks rather than requiring the expensive high pressure tanks for gaseous storage or complicated and expensive zero-boil off system for long term liquid hydrogen storage. Bottom line is that to optimize an electrical power system where the majority of the power is coming from intermittent sources like wind, solar, tidal, and wave will require a number of different energy storage types working together to meet the demand power on the grid that varies on time scales from seconds to months to energy generation types which also vary in output from seconds to months.

[@josepeixoto3715]

Interesting; but there will be a HORIZONTAL component there, doing NO WORK; ,how much extra loss,if any, will that be ?

[@Tuxfanturnip]

Are there any comparisons of these systems vs flywheels? There are a few types of non-battery energy storage proposals going around, but it's hard to find comparisons between them, just for each one against pumped hydro and lithium-ion.

[@DieZockerZone1]

i think flywheels would last not very long, i think they would get damage very often, but yah i like the idea too, every house could have one

[@zarthemad8386]

a flywheel of that size would be very very dangerous. ... and always losing energy

[@DieZockerZone1]

@@zarthemad8386 i know, but it could be usefull and is easy to build, for safty reasons you could fill the room with water and it will brake by its self if the normal brake will fail

[@Tuxfanturnip]

@@zarthemad8386 Flywheels are already in use in some limited applications for rapid response to load. These systems tend to use large banks of smaller flywheels, and losses can be minimized with vacuum chambers and magnetic bearings. These complications are exactly why I'm interested in seeing more data on them.

[@manickn6819]

Great where there are abandoned mine shafts. I am not convinced that is very common in the world. Good solution for some places though.

[@jonjohns8145]

Surprisingly there are a LOT of abandoned mines in most areas (I bet there is one within 100 miles of where you live). And even if there isn't, the cost of digging a new shaft is not as expensive as people think. It is certainly less than the cost of putting up a bank of batteries.

[@SeeNickView]

Tons of Cobalt mines in the DRC, Nickel in other parts of Africa, coal in the US and Germany. Honestly, this solution would work better for regions that don't have very much aboveground sea level variation. If aboveground is flat, go underground. The Midwest and Great Plains of the US would be perfect for this, and I'm sure the northern provinces of France/Germany would welcome something like this. The Scandinavian countries would probably love to implement this tech

[@shawnr771]

Electricity can be provided into the grid from anywhere. Even if it is a 1000 miles away.

[@manickn6819]

@@SeeNickView I think the problem will be cost. Using abandoned mines saves a lot. DR is probably not going to be at the front or even middle of the pack with adoption of these technologies. France and Germany definitely have the money and will. I do not know enough about midwest USA with respect to available mines. If they do not have then another storage technology would be more applicable. Scandanavian countries have the terrain for pumped hydro so no need for this more expensive solution.

[@Steve-o5x9g]

The best solution ive seen is a mountain slope with a long rail line. Basically the cars are hooked up to a special track that delivers the electricity similar to a subway car. The wheels have electric generators on them and a huge amount of weight with rocks. During peak energy they push the cars to the top of the mountain where the cars sit. Then at night they slowly roll down hill delivering something like 95% efficiency. Now the nice part about this is that hydro power has the risk of evaoprating meaning anything over a 5% evaporation means its not as efficient. Its also instantly available and can meet the exact energy needs. I also believe that eventually you could have a sytem which allows for energy to be harvested by moving large amounts or rock to the bottom of the track. Basically you could find an ideal location with a huge amount of loose rock which would allow this to be harvested for electric power. Giving the potential to make electricity simply by moving a massive amount of weight onto these rail cars and letting them roll down the hill and then be emptied into a quarry or canyon. Theoretically you could be generating electricity on demand simply by having mining equipment move rocks onto rail cars and letting their weight rolling fown hill produce electricity. I think it offers a great opportunity for old mines to be filled as a way to produce more revenue and be an environmentally friendly way to produce electricity. Its also fascinating to think of electric powered machinery that would make the entire system carbon neutral. There are mines all across the country that have been abandoned. And have massive amounts of removed material sititng outside of them. The potential to use those old rails to produce electricity by refilling the mines is like a second gold rush.

[@jeremyquentin42]

There's news about Energy Vault today: "Energy Vault completes 25 MW/100 MWh gravity-based storage tower in China". Maybe time to revisit that? First thought: 100MWh sounds like peanut for such a giant building. Il y a 1 jour

[@owenanstey436]

The only bad idea is one that isn't voiced. It is very easy to shoot down projects while not suggesting alternatives. Keep up the good work Dave !

[@robinandelizabethhill9450]

Where I live, in Alberta, Canada, there are a lot of unused oil wells. The average depth is about 1.5 km. I wonder if these could be used for gravity energy storage, or is their diameter too small.

[@NightRunner417]

Technically no diameter is too small because for one you can do matrix type applications that use a lot of such wells with small diameter weights. Also, if you use heavy metals for your weights, you can do a lot with a small diameter. Pick up a lead cylinder of 1" diameter and 5" length. Now do the same with a cylinder of 1" diameter and 20' length. I guarantee you you're gonna bust a gut on that 20 footer and embarrass yourself, lol. Mass doesn't care about form factor unless balance is all gnarly or it's too thin and frail to suspend it's own weight. 🙂

[@janami-dharmam]

1 ton dropped by 100m produces about 1MJ of work (0.277 kWh under ideal conditions). Use 10t and 1km and you will get 27 kWh of energy per drop. Actual amount will be determined by losses. You will need lots of unused oil wells.

[@bearalohalani]

Since it's made with containers filled with stuff, I don't see a reason why you couldn't make longer, thinner containers and fill them.

[@NightRunner417]

@@janami-dharmam So are those figures then according to 100% efficiency? Just trying to get educated with all this.

[@erwinmulder1338]

Width might not be the problem, but oil wells are not necessarily nicely vertical shafts. They can be pretty curvy. Unlike mine shafts, oil shafts just need to be able to transport a liquid after all.

[@corujariousa]

This is an interesting model (gravity energy). One part that I do not understand yet is about the energy used to pump water, raise the weighs, etc to allow for the potential energy to exist. Is the energy used for the creation of the potential energy being well calculated in the efficiency numbers we see?

[@melmartinez7002]

The point of the technology is only on the storage side of the equation. It is a given that there is a need for such storage solutions given stochastic energy sources such as wind or solar. In other words, you would deploy such a storage system in coordination with such a source.

[@corujariousa]

@@melmartinez7002 I am aware of that. My question is about the details of the cost/efficiency calculations.

[@ps.2]

For any energy storage mechanism, the ratio of energy output to energy input, or "round-trip efficiency," is one factor to compare technologies. The round-trip efficiency of pumped hydro is something like 80-85%; for lithium ion batteries, it's something like 85-90%. Obviously, you want high round-trip efficiency, but it's only one of many factors in overall cost effectiveness. Think of energy input as a cost and energy output as revenue. If your input energy cost is very very low (because there is excess energy available), say $0.02/kWh, and your output energy revenue is much higher (say $0.05/kWh), then so long as your other costs (materials, land, construction, operation, maintenance, grid connection, etc.) are also very low, you can make money even with a low round-trip efficiency. Whereas, if the difference in input and output energy costs is lower, or your other costs are higher, then you need a better round-trip efficiency for your project to be cost-effective overall. You can see this comparison at 8:24. Pay attention to the "charging" lightest-blue portion of each bar in the graph. That's the cost of energy input. Notice it is much larger for compressed air than for the others. I think that means compressed air storage has significantly lower round-trip efficiency.

[@TimpBizkit]

I'm interested in the power regulation process in gravity power and also spring driven radios. It seems you need some system of charging and discharging capacitors to regulate the speed of the weight because it behaves exactly the opposite of demand. When demand increases, generators feel more resistance to turning. When demand reduces, generators spin more freely. The problem of this is the weight plummets rapidly when you don't need much power, and is slow when you need a lot. This is the exact opposite of what you need. With pumped hydro you can change the flow rate. One way I've thought of for a DC system is to charge a big capacitor that's running your load, then disconnect it and switch a shorting wire across the generator to slow the weight lowering. Then reconnect the capacitor. You'll see the speed of the weight change rhythmically but I think this is similar to the old reel spring radios before they just used a hand crank generator to charge a battery. You'd need a voltage sensor to switch between them.

[@GTsportscar]

I like that revisited the topic again. Nice work!

[@reesewebster9149]

The problem I have with these gravity concept is you cannot control the amount of power you output onto the grid, it’s either running or not, it would also have to re-sync to the grid each time, they are interesting ideas but I see them as more edge cases for helping the grid

[@rot7296]

You can with Pumped-storage hydroelectricity which coincidentally is the best and most importantly viable option. Still, it's an edge case solution as it requires a high difference in elevation and a cheap but unsteady source of power, most prominently wind turbines.

[@reesewebster9149]

@@rot7296 I was referring to these suspended weight systems. They are constant torque, unless they have a complex gear box.

[@rot7296]

@@reesewebster9149 And I was agreeing and also shitting on those systems.

[@maxtorque2277]

er, yes you can! with a suitable inverter driving the load motor you can control both the speed and the torque of the system, where torque x speed = power in either quadrant

[@reesewebster9149]

@@maxtorque2277 are you saying to use a dc motor connected to the weights then use an inverter to connect it to the grid?

[@apoco_lips9957]

That EVRC animation is so frustrating to look at, its literally being animated next to a mountain where a reservoir could be built and water could be pump to at a higher elevation for more energy potential than the building they propose. Its unreal the people making the animation didnt catch such a basic observation

[@SeeNickView]

Agreed, very cringe

[@rockyallen5092]

And the wind turbines in the valley instead of on the ridge

[@shawnr771]

Yes that storage system is horrible. But at this point in the American southwest pumped hydro is probably not a good choice. Being that Lake Powell and Lake Mead are at excessively low levels. 10s of millions of people's water supply is under a serious threat. Should the trends continue it is highly likely that a few cities might cease to be in the coming decades due to lack of water.

[@chrisb508]

I know that the devil is in the details, but this seems to be a really good solution since it doesn't require any of the raw materials needed for grid scale battery storage so both systems could be employed simultaneously without competing for the same resources. Love it! So much better than a coal fired peaker plant. :-)

[@fritzstauff]

Yup got to say this one seems logical. It won’t handle all energy storage. But I imagine any one sitting on old mines will be installing these.

[@Techmagus76]

@@fritzstauff Well if you already have a cavern down there that you need to stabilize anyhow then it is really about running the numbers if you go for this solution or a more classical approach with water or compressed air as media.

[@zvezdaster]

well it does seem a great use for these old mineshafts. however, most mines, once decommisioned will flood when the pumps are turned off, greatly reducing the droplength of the weights... and keeping the pums running isnt really viable...even if somehow they manage to isolate the shaft from rest of the mine...

[@fritzstauff]

@@zvezdaster Great point. Any clue how much energy to run the pumps? Also I assume they only run when water is detected. Maybe a decent solar array can neutralize that energy.

[@zvezdaster]

@@fritzstauff well that would depend on the geological circumstances, but its safe to say that extraction has to be continuous and at a near fixed rate or level. alternating the pressure on the shaft walls is the surrest way to make it collapse. However when the shaft starts an elevated level, lets say halfway up a mountain you might get the advantage of "dry hight" that you will be able to exploit. also some of such shaft could be sunk on purpose with exit openings at the bottom in mountainous locations. Which was common in old mines in such locations to keep em viable. with modern tech this should be much easier to do..

[@rschmidt123]

The mine shaft idea as presented is only partially mature. Rather than having a single block suspended above the shaft, it should instead have dozens of blocks at ground level on a rail that can sequentially be moved above the shaft and lowered, thus greatly increasing the potential at a low additional cost. At the bottom the block can stack or be placed on another rail and moved down a mine corridor out of the way until excess energy became available to lift them to the top once again

[@geraldbull9272]

Nice chap, like listening to him, he talks down to earth with no hype which so many seem to do.

[@carlinglin7289]

Seems like a very promising idea. You would think that US coal mining states like West Virginia, Pennsylvania and Kentucky, with numerous old mine shafts, would be all over this.

[@tschorsch]

Coal states are owned by coal companies who don't want renewables as it cuts into their business. Even if, in economic terms, this is better for the state's economy, the politicians are already owned by the fossil fuel industry.

[@mm-qd1ho]

I agree. The Appalachian mountains now have lots of wind turbines harnessing the wind through the mountain passes and over the ridges, with many coal mines nearby. I think it would be a great area to test this out.

[@phhowe17]

Most coal is removed on horizontal galleries there are not all that many tal vertical shafts compared to the mine area. Also, mines don't stay empty. Ground water eventually getsmin and needs to be pumped.

[@eaglechawks3933]

@@phhowe17 Which would make me think that pumped hydro storage on the surface FROM the old mine shafts would be a good way to go.

[@mm-qd1ho]

@@eaglechawks3933 Yes - Rye Development is working on the 200-MW Lewis Ridge Pumped Hydropower project in a former coal mine in Kentucky

[@donchaput8278]

I'd like to see the idea explored of pumping air under sea/underwater into storage/balloons that pull tethers to the surface and then are deflated and retracted.

[@Frag-ile]

I suspect such a system would be very hard to maintain. It would also suffer worse from weather and currents than the crane tower does from wind. Salt water being very good at dissolving stuff would make material requirements strict and maintenance underwater is far trickier and expensive. It's a fun idea though.

[@oliverh.1694]

It's not quite what you are describing, but you might find this video interesteing. It explores 4 concepts of underwater storage: kzbin.info/www/bejne/nZWUl4eAYsimn9E The first one pulls gas filled containers under water to store energie, the others pump water in/out of a container and utilize the pressure difference to strore energie. Especially the last two concepts look interesting, as the capacity would go up with higher depth (higher pressure).

[@donchaput8278]

I know it would be a Challange, so is space. Plastics work well in the ocean, we have years of data confirming that. Lol Thanks for the video Oliver! I love outside of the box ideas

[@TheAnnoyingBoss]

The submarines gonna crash right unto that and itll gum up from ocean barnicles etc

[@donchaput8278]

@@TheAnnoyingBoss yeah seems impossible for them to be able to avoid something like that with the ocean being so small and having no way to navigate or see anything underwater

[@chase-2-2]

It just feels like Gravitricity is the more reasonable concept. Taking existing unused shafts, smaller container based weights and existing technology makes it seems like a viable prototype. It will have to be proven to actually work and give the expected outputs, but it at least isn't a huge tower of concrete blocks

[@JasperJanssen]

Mineshafts are a) small and b) few and far between, relatively speaking. This would be a very small scale setup.

[@history8192]

Leveling out grid demand with rapid response is also a good idea. It’s not trying to compete with pumped hydro, it’s dealing with brief shortages.

[@JasperJanssen]

@@history8192 but batteries are much better at that. Bigger capacity and much faster.

[@prich0382]

"Here in Switzerland, where Energy Vault is situated, we have a particular high knowledge of pumpstorage optimisation. Our pumpstorage lakes in the alps typically contain tens to hundreds of millions of cubic meters and will exploit a hight difference of 500 to 1'500 m, thus storing the same amount of energy as tens of millions (!) of 20 tons concrete blocs. I am happy to see that none of the major Swiss power companies or any of its leading employees support this project."

[@obiwanbenobi4943]

I like the ones on rails on the sides of mountains too. Not sure anyone has finished a major system yet or not.

[@trialsted]

Having worked for a couple of engineering startups, the word 'modular' is one of those engineering red flags that investors haven't caught on to yet

[@sqrt3101]

You mean small modular reactors won't be a THING?

[@trialsted]

@@sqrt3101 ha, brilliant, exactly. Managed to fool Boris though didn't it

[@truthurts1692]

Here's an idea, David- Why not have wind turbines gear down to directly lift weights (or pump water for that matter) then let them drop weights to generate electricity when needed? It seems to me that it would cut out one or two efficiency losses in converting the mechanical to electric and electric to mechanical back and forth...

[@tomizatko3138]

good idea

[@MoireFly]

Mechanical "energy" cannot be transferred to a different direction or place without all kinds of conversions either. For example, consider an internal combustion engine's gearboxes. Such systems have considerable losses too. Furthermore, many mechanical systems have fairly specific and narrow efficiency windows. You can't just go hooking up some source to some output and expect great efficiency, usually. Then there's the fact that electric motors and generators have exceptionally high efficiency; the best (large) ones around 99%. There's just not much loss there to win anything. (Generator systems have losses - but usually not in the generator themselves, but precisely in the non-electric bits!) Then there's economies of scale - even if you could come up with a complex mechanical contraption that has even higher efficiency than a generator+motor pair, it's going to be custom for your application. But... you probably can't afford that. You want commercial off the shelf parts _as much as possible._ And that makes the electric route cheaper. But even if you achieve scale, mechanical systems tend to have huge, heavy moving parts to carry all that power. Huge things? Those tend to be expensive. By contrast, copper wire is relatively dirt cheap. (I mean, it's not actually cheap, but compared to gearboxes that don't wear and deal with many kW or even MW of power...) I'd say it's exceedingly unlikely you'll be able to do better than going via an electrical intermediate step. Never say never; there are likely tons of very specific counter examples. But finding each of those counterexamples is basically coming up with a clever invention, and will only be possibly in certain specific, hard to predict situations. As a strategy, this won't work.

[@N0Xa880iUL]

My guess is that the purely mechanical method you are suggesting would be far more inefficient and complex.

[@truthurts1692]

@@MoireFly I'm not an electromechanical engineer who works with these things, but if "that won't work" was the end of every idea where would we be? There are many different configurations of electromechanical systems that involve huge things and clever inventions, and gravity energy storage is all huge things, that's it's nature. I'm not proposing a perpetual energy machine here, it's just a thought...

[@MoireFly]

@@truthurts1692 Just thoughts can be actually damaging, however. Not every idea ends in failure. But it's still expensive to try; and in the chaos of creation there's always the lure of riches; and by contributing to that lure for false leads, we reduce the availability of investment for the actually promising new tech. Some ideas are plain dumb. Now, if there's some subtle interaction, some economic factor, or whatever that we're missing on first glance - OK, but let the companies selling this snake oil explain _why_ theirs is the exception that proves the rule. But more explicitly: not every idea appears idiotic in advance. Many appear outright obvious, and just hard to fund or get quite right. When designs appear to fail to satisfy basic physics constraints or economics, that's a pretty big red flag. TL;DR: we should at least try to use common sense. It's a lot better than nothing.

[@kevinjpluck]

The largest grid battery, Moss Landing in California, can store 1.6GWh. This is the equivalent of 160 Eiffel towers raised to the height of the Eiffel tower.

[@DFPercush]

Yeah I really think batteries just make more sense if you already have the energy in electrical form. Converting it back and forth with mechanical energy has more losses. And they don't involve massive construction projects, just mass manufacturing.

[@kaasmeester5903]

@@DFPercush Losses are not the issue, really. When you'll want to storing energy it will usually be dirt cheap (surplus solar / wind); the grid operator will be glad that you're taking it off their hands. For that reason, hydrogen is becoming a viable option despite the round trip (power grid, hydrogen, compression, and conversion back to electricity) only being around 40% efficient. Fewer losses are obviously better, but construction and operating costs are much more important, not to mention scalability. Fundamentally, Energy vault and Gravitricity suffer from the same problem: it does not scale well.

[@simonmoore8776]

@@kaasmeester5903 Surplus solar is never going to happen, it's during the day most energy is needed so there will always be a demand for solar. Wind has more potential as it can be harnessed during off-peak times.

[@kaasmeester5903]

@@simonmoore8776 If we're going to rely on renewables for most of our power, we'll have to massively overspec it. So far the numbers look good for using mostly wind and solar, balancing with batteries or hydrogen, picking up shortfalls with hydrogen as well, and relying on gas fired plants a few times a year (or hydrogen generated from gas) for the few longer periodds of low production we can't bridge.

[@randompatillo4336]

In the states, a company called Ares (advanced rail energy storage) has a good solution for this, but it requires hills with a 7.2% slope.

[@Sam-xd9xt]

Great to renew my optimism a bit regarding these projects

[@martyschrader]

How about just dumping surface mining tailings into abandoned mine shafts? The buckets can be lowered to generate zotz, then the bucket dumped into the shaft and raised back up again empty. The cycle repeats as long as the shaft has room for kaka to be dumped.

[@gingernutpreacher]

Kaka is that the tenical name?

[@janami-dharmam]

It has to be reversible: corresponding to charging and discharging process. In real life, surface mining tailings are leveled off over an extended area and are considered environmental nuisance.

[@jonathanjacobson7012]

Kakatricity!

[@louislesch3878]

Surface mine tailings can also hold a lot of other precious metals that can be chemically removed. So it might be a mistake to just throw them back into the old mines.

[@SeeNickView]

There are already projects in the US looking at using abandoned mines for gravitational energy storage. The code word I've seen used is PSHAUM or Pumped-Storage Hydropower using Abandoned Underground Mines, and the projects I've noticed are in the usual coal states of Kentucky and Indiana, as well as in China. Perk about these systems is that the water bodies are not exposed to the atmosphere, meaning that the system can remain closed loop and allow for little to no water losses. With normal pumped-storage and dam hydropower, evaporation works against you. Looks like the deployment timelines for those projects are similar to those of Gravitricity, so it's hard to say if a vertical shaft-based or an isolated reservoir-based technology is better or worse. As with anything in sustainability and resilience, relying on multiple tools to achieve outcomes can mean that those outcomes come faster. It could be the case that these two types of storage could be stacked in the same mine site to get as much power out as possible, or be deployed at mines that have the right characteristics for the tool. Love these videos Dave. Wouldn't this fall under a Just Have Another Think video? What happened to that project? I think the last one you made was about policy, which probably didn't do as well as say your Perovskite solar or battery videos, but it's still a solid platform. Cheers Edit: grammar

[@AlRoderick]

The problem I think with pumped hydro in mines is that the mines tend to fill in with groundwater once you empty them, meaning no space for the water to go at discharge time. Maybe not a problem if you find a place to put the surplus water that you're generating, you'd need a secondary spillway that goes somewhere else and you'd need to be sure that the water from the mine isn't contaminated.

[@robinherrick2177]

@@AlRoderick if it fills with water then that scuppers the weight lifting/lowering idea too.

[@robinherrick2177]

Thanks for your post about PSHAUM. I had the same idea after watching the video so the fact that someone else is doing it isn't surprising and saves me having to do it myself. 😂

[@robinherrick2177]

Agree it would make a good topic for a video.

[@AlRoderick]

@@robinherrick2177 I don't know if it scuppers it, weights sink in water too, the buoyancy would just affect the total capacity (the weight would store less energy per unit height in water).

[@nagualdesign]

I've always thought that large wind turbines offer the ideal infrastructure for gravitational energy storage; a tall tube, protected from the elements, in which a single large mass can be raised and lowered depending on electricity demand.

[@mikedavison3400]

Wind turbines are ‘top heavy’ enough. Having to engineer in having the energy storage weight at the top of it’s run would add greatly to the cost.

[@JeffBilkins]

But would the required reinforcement to be able to hold a significant mass be economical?

[@GrahamCampbell-kr2gz]

The blades cannot be recycled when they have reached their end of life (About 20 years, due to stress fractures),

[@nagualdesign]

@@mikedavison3400 I don't think that's an insurmountable obstacle. What may be an issue is the variable resonant frequency of the structure as the weight is raised and lowered.

[@mikedavison3400]

@ Bart 🎯

[@chrisking7603]

Promising idea, and wondering about progress on pumped-hydro at coastal locations, with sea as lower reservoir.

[@solarpunkstories]

Really interesting and balanced exploration of this issue. Looking forward to the next update

[@douggray169]

Gravitictity looks like a great idea to me

[@Kiyoone]

HOW? 🤣😂

[@urbiso]

I think that only viable option is to combine both concepts, use mineshafts and weight packs which would be stored in the old tunnels. Because using only one weight would give only 40MJ assuming 800m shaft and 5ton weight, which is not that much.

[@matthewwakeham2206]

I think the plan is to use 500 tonne weights.

[@urbiso]

@@matthewwakeham2206 Even so you will get only roughly 1.1MWh, considering one Tesla Megapack module has 3MWh, it is still not enough.

[@danielgrahamandrews9293]

@@urbiso I don't think it matters. What matters is the LCOS. If it has lower LCOS than the tesla megapack then you can just build 3 of them instead of one and call it a day. Granted this LCOS might need to include the exacavation cost of a 500m borehole, and I haven't done those calculations, but a megapack is over 1million each, and you can dig a good sized hole for $1million.

[@markmcdougal1199]

Sounds really promising, especially considering the simplicity, and lack of need for rare earth elements and such. I do wonder if transmission of energy costs are included in the comparison chart you showed. They might be substantial considering there are a limited number of suitable mines, and they might not tend to be close to populations centers. Nicely presented, sir.

[@bigdaddyof2007]

I would think the other concept of the modular building would be a better solution, as it can be built anywhere, like right inside of a city where it is needed, although there is the cost of building construction to consider.

[@markmcdougal1199]

@@bigdaddyof2007 Indeed. Perhaps, until fusion is perfected, we could make use of all the varied sources; solar where the sun shines aplenty, wind where the wind blows, geothermal where the earths crust is thin, hydro where the water flows, wave power on the coasts, fission where the others aren't appropriate (especially, the new small modular, assembly line built safe fission), and the new solid hydrogen for air transportation. Tied together with the various types of storage, each also appropriate for the area, and transmitted by a new, DC grid.

[@crashtech66]

Most people don't even realize that storage is an essential part of utilizing intermittent renewables. Many activists that do know tend to wave it away as a non-issue, saying the the grid is the battery. So what we need is more publicity for these efforts and more education on their critical nature if intermittent sources continue to be subsidized and installed.

[@Aorta_Research]

Well, here in Klamath Falls, Oregon, we have both lots of old railroad track and lots of very heavy old iron train parts. So the materials to build such a system could be all recycled, except for the motor-generator and transmission lines. That means the LCOE could be very low! and we have high hills around the city. There's old gold mines in the are as well. So I will bring this to the attention of the Oregon Renewable Energy Center.

[@benmcreynolds8581]

I personally think the best way to "use gravity for power" is implementing tidal forces that are so predictable and regular and provide a ton of power always.

[@mikebazil1]

It's storing the power is the issue, though, so to use it when we want

[@johnransom1146]

Every 6 hours the tide turns. Pretty much continuous

[@Dundonian1981]

Tidal Barrage systems are in use doing such a thing, also they wanted to build the Largest system in the world (they still might be) in the UK but I forgot where. The problem with putting in these systems as well as other which use the power of the currents etc, is that they mess up deposition of minerals/sediment etc within the ocean.

[@Joe-lb8qn]

@@Dundonian1981 Cardiff bay IIRC. Also the Severn Estuary is also a contender.

[@dec335]

@@Dundonian1981 they are probably trying to set it up in Scotland. The big problem with underwater turbines is corrosion. It's very hard not to get problems with your turbines and it is very difficult to fix them as they are generally underwater. It's expensive to raise and lower a heavy rig from the seafloor to fix it

[@elifishpaw7509]

Gravity is a great energy storage approach. However, I also wonder how many mind shafts are readily available. This would be a limitation similar to the topographic limits for pump storage. If you dig a shaft into the ground for this application, would not you run into ground water issues? Matt, great series. Keep up the good work.

[@bjorngve]

Also a mine shaft may typically be to narrow. To rebuild the whole thing, making it safe, could be as expansive as digging a new one.

[@johnstarkie9948]

There are very few mind shafts around.

[@johnstarkie9948]

@@bjorngve Both expansive and expensive

[@Cartoonman154]

@@johnstarkie9948 UK Coal Authority record some 150,000 coal mine shafts. Now, it just depends on how deep they are and how practical they are for the system.

[@RichardHorsfield]

Imagine a scaled Gravitricity unit at the centre of every new tower block and high rise, being able to supply power straight to that building... I live in Cornwall and we have a vast network of dis-used mineshafts here (probably one under my house), would be a great place for them to start in the UK.

[@ariscol]

Seems brilliant, right? Until you realize you'd need more than the weight of the ENTIRE tower suspended at more than the height of the tower to be able to power the building overnight, and then you'd need a square mile of solar panels to charge the thing every day. And then you'd STILL have to cross your fingers and pray that you don't have two cloudy days in a row :P

[@williamrbuchanan4153]

If you put cost as a deterrent, it is just what has cost humanity advancing.Think money, a promise? Stops humanity? We can’t switch gravity into reverse, let go, down, dump your weight, rise up. Using energy? Equal and opposite required, just to break even. The system of , people transported uphill, by weight of more than them.By water in a free filled tank. Then people coming down by everfree gravity . Water used, but free only for its weight. Then dumped. It’s all going downhill in the true sense of the gravity for water is always going downhill. Get it use it, wind, get it use it, tides ,by lunar attraction, use it Solar, all free , but money is the big controller. Why is this mindset not dumped?

[@anthonydonnelly4069]

I was completely fooled by the animation. Just thought it was made in Switzerland. You Scientists are so smart! Interesting Channel, Thanks! Just keep it dumbed down a little for people like me.

[@mpetersen6]

One problem I can see with basing such a system in dis-used mine shafts. Your mine shafts are only so large. Plus just how many are there. Another is pumping out water. And if digging new shafts what is the cost per cubic meter for a shaft say 500 meters deep that is ten meters square. Myself I like the idea of a tower based system. Place the motor generator set at ground level. This makes maintenance much easier. Use large steel boxes filled with loose rubble (gravel or sand). The weights are in very large elevator shafts basically. Then wrap the tower with housing, office or retail space that could provide rents. Placing the weights inside eliminates the wind issue. Actually you could place a smaller version that in residential buildings that could act as storage for overnight energy needs of the building residents.