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Scientists Propose Turning Abandoned Mines Into Super-Efficient Gravity Batteries:
As the world comes to terms with the realities of climate change, the pressure to adopt more renewable energy is unavoidable. However, the sun isn't always shining, and the wind isn't always blowing. Worst of all, our ability to store that energy for the cold, still nights is still woefully inadequate. There may be a solution, and it's not a fancy new technology—it's a new take on something decades old. A team from the International Institute for Applied Systems Analysis (IIASA) has developed a plan to create a network of super-efficient gravity batteries that could store tens of terawatt-hours of power.
Humanity has been harnessing small amounts of energy from gravity for centuries—technically, the pendulum clock is a primitive gravity battery. In the 20th century, scientists developed pumped-storage hydroelectricity, which uses elevated water reservoirs to store gravitational potential energy. Several of these facilities exist around the world now, but most areas don't have enough water or the right terrain to make it work. The IIASA proposal for Underground Gravity Energy Storage (UGES) would use something we already have in spades: abandoned mine shafts.
A UGES stores energy when it's plentiful—for example, when the sun is shining on a solar power plant. A heavy container of sand or rocks would be suspended in the previously abandoned mine shaft with an electric motor raising it to the top. As long as the bucket remains at the top of the shaft, the energy isn't going anywhere. When power generation drops, the grid can harvest power from the UGES by letting the vessel drop back down. The UGES would use regenerative brakes on the cabling, similar to the way electric cars extend their range when you apply the brakes. Unlike batteries, all of which lose power via self-discharge over long periods, sand always has the same mass, and we're not going to run out of gravity.
(Score: 4, Informative) by Barenflimski on Saturday January 28 2023, @03:13AM (8 children)
I think its fairly clear that these scientists have never seen the inside of a mine.
They're not a vacuum. They're straight, only in the most modern of modern, very few that are deep enough, mines.
The reality is that mines follow the ore. You're typically following a slope of X degrees. The lucky miners found ore streaks less than vertical.
I'm all for them proving this out without drilling new mine shafts.
(Score: 2, Insightful) by Anonymous Coward on Saturday January 28 2023, @03:31AM (2 children)
A deep mine I heard about did have a vertical shaft to get down to ore level...but it was very small, just big enough for the escape ladder. The main entrance to the mine was a spiral tunnel that was big enough for vehicles to drive in, the spiral surrounded that central shaft.
(Score: 2) by istartedi on Sunday January 29 2023, @01:44AM (1 child)
Anybody remember the Chilean mine rescue? It was a huge news story in 2010. The mine was a spiral [wikipedia.org] as you describe, with no central shaft AFAIK. Even though they had the spiral road in the mine, they couldn't get drilling equipment down there so they had to drill new shafts straight down to rescue the miners. All 33 got out but I'm sure there was some PTSD.
Appended to the end of comments you post. Max: 120 chars.
(Score: 0) by Anonymous Coward on Sunday January 29 2023, @02:30AM
Continuing OT:
Guessing the reason the US spiral mine had the central shaft with ladder was OSHA, or similar regulation. Sounds like Chile doesn't have that safety regulation?
The mine I heard about (I'm the GP) was pretty deep, perhaps a mile (1.6km). While it might be reassuring to have the central escape route, I'm not sure that I'm able to climb that far on a ladder. I probably average 0.1 hp (75 watts) for a long time on a bicycle (some sort of average fitness for a boomer). If all the power went into lifting myself that would be 3300 ft-lbs/min. Over my weight of 180 lbs = 18.3 ft/min average. If there was 5000 feet to climb that would take nearly 300 minutes or 5 hours.
Better carry some water, even if the extra weight will slow me down. Or, hope that rescuers drop a harness and hoist me out.
(Score: 3, Interesting) by khallow on Saturday January 28 2023, @04:36AM (2 children)
I'd say that the vast majority of those mines would be so unsafe, they couldn't be made into viable gravity storage. You'd probably have better luck digging your own holes.
(Score: 3, Funny) by acid andy on Saturday January 28 2023, @06:36AM
...with a solar powered digger while the sun in shining. Then you drop all the earth you dug out back into the hole (using the generation vessel) when it's dark and you've got your electricity supply! Repeat. :)
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 3, Touché) by Runaway1956 on Saturday January 28 2023, @09:21AM
If only there were a substance which could be induced to fall in whichever direction we wanted . . . you know, kinda like water in pipes. Plumbers and pipefitters are all the time forcing water to flow whichever way they want it to flow. Alas, there is no such substance, so we'll have to wait for straight mines to evolve.
(Score: 2) by quietus on Saturday January 28 2023, @08:12AM
Just checked: the local, now abandoned, mine here had/has 2 straight shafts of 800+ meters deep, with a diameter of 5-6 meters. It has to be said though, in line with khallow's comment, that *maintaining* these shafts doesn't come for free. (These shafts were freeze-drilled i.e. the surrounding material was frozen, then cut away. What I can gather is that the shaft was maintained that way too: by keeping the surrounding meters frozen.)
(Score: 1, Funny) by Anonymous Coward on Sunday January 29 2023, @08:48AM
Are they also assuming a spherical mass of sand? 😉
Seriously, it should be obvious the amount of energy stored isn't going to be enough for anything other than niche purposes. After all, the mines don't need to use that much electricity[1] to lift tons of ore out.
Maybe the scientists used ChatGPT for this proposal.
[1] See also: https://www.omnicalculator.com/physics/potential-energy [omnicalculator.com]