Gravity batteries in abandoned mines could power the whole planet - Techspot - Page 1
Forum section: electronics / general

author: Black Phoenix
author_rank: Super Contributor
timestamp: January 23, 2023, 03:00:37 pm
content: https://www.techspot.com/news/97306-gravity-batteries-abandoned-mines-could-power-whole-planet.htmlQuote

author: berke
author_rank: Frequent Contributor
timestamp: January 23, 2023, 03:10:57 pm
content: Quote from: Black Phoenix on January 23, 2023, 03:00:37 pmYour link is broken, but here is the actual study:https://www.mdpi.com/1996-1073/16/2/825

author: Black Phoenix
author_rank: Super Contributor
timestamp: January 23, 2023, 03:43:05 pm
content: Thanks for the study link.Yes I mistakenly pasted the link to the title and then realized it was wrong and when copied back, since the titles have a limit of characters, it broke the link.It had been correctly updated this time.

author: mfro
author_rank: Regular Contributor
timestamp: January 23, 2023, 04:09:24 pm
content: Hmmm. How many mine shafts would you estimate required to reach any significant power output (e.g. that of theThree Gorges Damthat qualifies as a gravity battery as well)?Don't get me wrong, every little helps, but that seems like a curious idea to me. You might as well propose building a giant clockwork.

author: tszaboo
author_rank: Super Contributor
timestamp: January 23, 2023, 04:32:37 pm
content: So they propose a total of 7 TWh of storage, if it's installed everywhere?This is how much LNG was transported through 1 cargo terminal in Spain in 1 week. So far I haven't seen a real contender to P2G.

author: Marco
author_rank: Super Contributor
timestamp: January 23, 2023, 04:34:26 pm
content: Globally you need PWh storage, not TWh storage and the overhead and wear and tear for this method is ridiculous.To me the most promising gravity method which is in theory scalable to PWh (at enormous resource cost) would be deep sea vacuum domes (you pump fresh water from a concrete dome to a bladder, the pumps don't see salt water). Pumping water causes far less wear and tear than transporting buckets of sand.If Hydrogen storage in old gasfields works, hydrogen is still the most likely seasonal storage medium for renewable energy though.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 23, 2023, 05:03:52 pm
content: You can power the whole planet with the energy stored in a single 100nF 0402 capacitor!(Just not for very long.)

author: ejeffrey
author_rank: Super Contributor
timestamp: January 23, 2023, 05:57:09 pm
content: Quote from: Siwastaja on January 23, 2023, 05:03:52 pmNo problem! Just charge it to a 10 teravolts. That V^2 really pays off. The necessary insulation is an area for future development.

author: AlbertL
author_rank: Regular Contributor
timestamp: January 23, 2023, 06:54:40 pm
content: Gravity energy storage by raising and lowering concrete blocks:https://www.energyvault.com/ldes

author: Marco
author_rank: Super Contributor
timestamp: January 23, 2023, 07:09:04 pm
content: Quote from: AlbertL on January 23, 2023, 06:54:40 pmThat seems to want to compete with batteries, for short term smoothing and/or overnight storage. Not that I give it much chance, but at least it gives you more money to play around with.

author: TimFox
author_rank: Super Contributor
timestamp: January 23, 2023, 07:45:28 pm
content: Does anybody remember the fear of a "mineshaft gap" in the 1964 film "Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb"?General Buck Turgidson (George C Scott): "It'd be naive of us, Mr. President, to imagine that these new developments would cause a change in Soviet expansionist policy. I mean, we must be increasingly on the alert to prevent them taking over other mine shafts space, in order to breed more prodigiously than we do. Thus, knocking us out of these superior numbers when we emerge! Mr. President, we must not allow a mine-shaft gap!"

author: factory
author_rank: Super Contributor
timestamp: January 23, 2023, 09:48:37 pm
content: Quote from: mfro on January 23, 2023, 04:09:24 pmSounds like a bad idea, do they have any idea what a terrible state most abandoned mines are in, the shafts are often in very poor condition, or the sides are collapsing in, or flooded, many have also been sealed/blasted shut for our protection. Not to mention many are in very remote locations with little or no power infrastructure, or usable roads.David

author: TimFox
author_rank: Super Contributor
timestamp: January 23, 2023, 09:50:48 pm
content: If there is a suitable location already drilled, what would be the cheapest bulk material, in kg/$, to use for the weight?My guess is concrete, since steel is denser yet more expensive.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 24, 2023, 12:30:34 am
content: Quote from: TimFox on January 23, 2023, 09:50:48 pmWater, by at least two orders of magnitude. Also, pumps are way cheaper than cranes and robots to move and stack concrete blocks (which will need to be reinforced to be used in this way).

author: ahbushnell
author_rank: Frequent Contributor
timestamp: January 24, 2023, 02:44:15 am
content: Assume a 3000 ft hole in the ground. A block of lead 10 ft x 10ft by 12 feet high. That's 422 tons. That's would store 955 kW-hrs of energy. If the block drops into the hole by cable in The power is 955 kW. I looked up the working load for steel cable 2" in diameter. 13 cables would do it. But of course you would want an even number. The cable weight is 133 tons. That's 32% of the pay load. But that will contribute to stored energy. Also means you need more cable.It's not impossible.

author: max_torque
author_rank: Super Contributor
timestamp: January 24, 2023, 09:10:26 pm
content: Quote from: ahbushnell on January 24, 2023, 02:44:15 amSure it's not impossible, mearly impactical.Cranes need maintainence, lots of it. Cables wear and break, pulleys wear and break, bearings, motors, shafts, gears and couplings all wear and break, even brakes, er break.Look at a typical pumped hydro scheme for reference. Even here with a very robust system with just a couple of moving parts (motor/generator, pump and valve block) and using a working fluid that is effectively free, these schemes "generate" electricity (they are of course net consumers of electricity....) that is very very expensive, and even with a huge lake of millions of tonnes of water, 1,000's of feet up a mountain the energy they can store is actually quite limited......

author: Fred_47
author_rank: Contributor
timestamp: January 25, 2023, 12:57:50 am
content: Quote from: ahbushnell on January 24, 2023, 02:44:15 amAbout 50 years ago I was the junior startup engineer for a pumped storage plant. We had 2 machines doing double duty as pump/motor or turbine/generator that were rated 220MVA as generators and 261,000HP as motors.The storage capacity was about 4200MWH. Compare that to the 0.995MWH for this contraption. You would need 4200 of them to equal 1 mid-sized pumped storage plant.The pumped storage plant is still in service.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: January 25, 2023, 10:25:36 pm
content: Quote from: Fred_47 on January 25, 2023, 12:57:50 amClearly pumped hydro is a better option. The problem is a limited number of locations that are available.

author: tszaboo
author_rank: Super Contributor
timestamp: January 27, 2023, 03:20:29 pm
content: Quote from: ahbushnell on January 25, 2023, 10:25:36 pmIs there any reason you cannot let water into an abandoned mine? I mean it could dissolve toxic stuff, but let's say we build a big tank on the bottom of the mine and pump it there, and make it a closed system. Ho is this not better? Less moving parts for starters.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 27, 2023, 08:48:18 pm
content: Yeah, pumped hydro is abandoned mines seem... at least feasible in some situations. There are a few bit limitations: suitable mines are not super common. The storage capacity is pretty limited in most cases, and often you will have to build both the top and bottom reservoir, which is expensive. Finally, the pumps/generators need to be at the bottom of the mine where it is hard to build and service.It's still a better option that moving blocks of concrete around in most cases, but I wouldn't be surprised if it almost never ended up being competitive with batteries.

author: TimFox
author_rank: Super Contributor
timestamp: January 27, 2023, 08:52:26 pm
content: For hydro, normally you want to pumpupinto a reservoir, then allow it to falldownon demand to generate power.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: January 28, 2023, 02:31:17 am
content: Quote from: tszaboo on January 27, 2023, 03:20:29 pmSure pumping water is possible.

author: Psi
author_rank: Super Contributor
timestamp: January 28, 2023, 03:24:51 am
content: Creating a hydro station by pumping water to some already existing higher area is potentially a good option but the problem is that it's not energy generation it's just energy storage, so it's tricky to build the system at a price which makes sense. There needs to be a large enough price difference between off and on peak power to make it worthwhile and pay back the investment within a short enough time.