Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Gravity batteries try to beat chemical ones with winches, weights, mine shafts

sciencemag.org

Post reply on HN
Print view View original

91–100 of 278 posts

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#91

Post by berkes »

FooHentai wrote: post #73
rakoo wrote: post #48

As usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land…

I did a bit of scratch math with the notion this might be more suited for individual, home power storage rather than grid supply - You need something in the order of a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour (even then, ignoring conversion losses). So that's the weight of ~ten class-4 fully laden heavy trucks. Once you can get it up in the air then the higher you can go you're doubling your storage i…

I can imagine this tech all packed up in a standard 40ft shipping container and dropped on premise.

This would be rather simple tech, that can supplement solar and wind on your farm, lodge, campsite or island. Another piece in the puzzle for smaller scale independence.

Not to replace metropolis-scale energy demands, as grandparent implies, but to smooth out fluctuations on hourly, household scale.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#92

Post by thirdlamp »

runeks wrote: post #76

Here's an idea: what if -- instead of digging a deep hole into the ground -- we use the tower of a wind turbine as the vertical space in which the weight is raised/lowered? A wind turbine is already equipped with a generator, so it'd be a matter of building some sort of "switch" which would make it either: (a) generate electricity using the turbine, as per usual; (b) raise the weight using the turbine, thus not produ…

This could be something more like a planetary gearbox or a differential that can connect 3 systems (e.g. gas engine, electric motor, wheels in a hybrid car). But if requirements are too different 2 generators may be the better option.

The tower would probably need reinforcements for the additional weight, but I have no idea about the magnitude required.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#93

Post by rsa25519 »

chris_engel wrote: post #85
FooHentai wrote: post #73

Earlier quoted context omitted.

I did a bit of scratch math with the notion this might be more suited for individual, home power storage rather than grid supply - You need something in the order of a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour (even then, ignoring conversion losses). So that's the weight of ~ten class-4 fully laden heavy trucks. Once you can get it up in the air then the higher you can go you're doubling your storage i…

Hm, you also need to consider that 5 trucks can have a much higher combined output than the 1 truck 5 times as high. The storage might scale this way but not the output when demand is high.

> Hm, you also need to consider that 5 trucks can have a much higher combined output than the 1 truck 5 times as high.

How so?

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#94

Post by thirdlamp »

masklinn wrote: post #89
runeks wrote: post #76

Here's an idea: what if -- instead of digging a deep hole into the ground -- we use the tower of a wind turbine as the vertical space in which the weight is raised/lowered? A wind turbine is already equipped with a generator, so it'd be a matter of building some sort of "switch" which would make it either: (a) generate electricity using the turbine, as per usual; (b) raise the weight using the turbine, thus not produ…

> Here's an idea: what if -- instead of digging a deep hole into the ground -- we use the tower of a wind turbine as the vertical space in which the weight is raised/lowered? First, there's not really any room in there, wind towers are built for the job, we don't add twice the amount of steel and an elevator shaft for funsies. Second, even if there were some room it would be inconsequential, you need a lot of crap ve…

What if we used load bearing batteries as part of the tower structure?

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#95

Post by berkes »

jillesvangurp wrote: post #77
rakoo wrote: post #48

As usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land…

Your assumption that we need that much storage is simply wrong. This pops up in just about any article on HN mentioning batteries. Somebody will jump to the wrong conclusion that we need to provide massive amounts of battery storage and that therefore we need coal/nuclear/etc. (i.e. really expensive ways to generate energy) because buying so many batteries is obviously stupendously expensive. It's a popular argument…

Thanks for the clear explanation.

I'd like to add that with the rapid electrification of car- and soon truck and ships- fleets, we are already rolling out that giant battery-pack, as we speak.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#96

Post by DavidPeiffer »

runeks wrote: post #76

Here's an idea: what if -- instead of digging a deep hole into the ground -- we use the tower of a wind turbine as the vertical space in which the weight is raised/lowered? A wind turbine is already equipped with a generator, so it'd be a matter of building some sort of "switch" which would make it either: (a) generate electricity using the turbine, as per usual; (b) raise the weight using the turbine, thus not produ…

Wind turbines use the tower to take parts to the top for maintenance. Regardless, you'd need to dramatically increase the wall thickness of the tower along with the foundation for the additional load, to the point it probably wouldn't be worth it.

Bad math, let's say we can use a lead weight 2 meters in diameter, 3 meters tall (107,000 kg) with 120 meters of drop available.

All of that gets us 35 kWh, or 0.035 megawatt hours of energy. Compared to a 2 MW turbine, it's a negligably small amount of stored energy, even if we scaled every dimension up by a factor of 2 (getting us to 0.28 MWh).

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#97

Post by audunw »

blueblisters wrote: post #23
amanzi wrote: post #4

This is a clever system. I remember reading about a similar system in Australia that used excess solar power to lift giant concrete bricks, and then these bricks were lowered to the ground in the evenings to drive generators. Not sure if this is the same one I read about, but it's the same concept: https://energyvault.com/

Wasn’t Energy Vault debunked as being too impractical? Here: https://youtu.be/NIhCuzxNvv0 These guys “solve” the wind and control problem by digging a 300m deep pipe for the weights.

You should not use Thunderf00t as an authority on this. He has no clue what he's talking about. That seems to be a problem in general, he doesn't actually do much research on the topics he talks about. So unless he already has some understanding of the topic, he doesn't provide much insight.

He seems to think Energy Vault is an alternative to pumped hydro, which it is absolutely not. They're not solving the same problem.

Pumped hydro is best suited for regulating power over days/weeks. You do not want to use it to do frequency regulation or regulate power fluctuations over hours/days. In fact, in Norway, where there's a whole lot of hydropower, and now an increasing amount of wind power, they're considering putting battery storage inside hydro power plants. This may seem really stupid until you understand that constantly regulating the output of a hydro power plant up and down wears down all the parts of the power plant much faster, and can cause issues for life in the river downstream. So it actually makes a lot of sense, since the hydro power plant has a good grid connection and may have some spare areas for batteries.

Batteries and solutions like Energy Vault are primarily intended for frequency regulation and short term storage, and that covers most of what's needed to help balance renewables in most areas.

There's a bunch of other serious flaws in his reasoning too, such as thinking that a marketing-material picture of Energy Vault next to wind turbines means that they actually propose putting Energy Vault towers right next to wind turbines, rather than just an illustration that the Energy Vault helps regulate output from renewables.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#98

Post by tralarpa »

guerby wrote: post #21

"But Schmidt’s calculation of the lifetime cost per megawatt-hour for lithium-ion batteries, $367, is more than twice as much" This is ridiculous. I'm charging right now my EV from a 14 kWh 16S LFP pack which costed me $1400 tax paid and delivered. LFP properly managed will do minimum 3000 cycles, so that's 42 MWh for $1400 which gives $34 per MWh out of the battery. Note: 5kW 48V inverter cost $500.

> 14 kWh 16S LFP pack which costed me $1400

Wow, that's amazing. But why are home battery systems still so expensive? I see system prices in the range of $700 to $1200 per kWh. Even on aliexpress, it's minimum $550/kWh. Is the inverter so expensive?

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#99

Post by SagelyGuru »

chris_engel wrote: post #85
FooHentai wrote: post #73

Earlier quoted context omitted.

I did a bit of scratch math with the notion this might be more suited for individual, home power storage rather than grid supply - You need something in the order of a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour (even then, ignoring conversion losses). So that's the weight of ~ten class-4 fully laden heavy trucks. Once you can get it up in the air then the higher you can go you're doubling your storage i…

Hm, you also need to consider that 5 trucks can have a much higher combined output than the 1 truck 5 times as high. The storage might scale this way but not the output when demand is high.

You can make that one truck descend five times faster, giving the same output.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#100

Post by throwaway189262 »

rakoo wrote: post #48

As usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land…

> as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land use.

This is just false. Every wind turbine I've ever seen uses 50 square feet on a farm or cattle ranch.

Not once have I seen a wind farm where the land underneath isn't still used for it's previous purpose.

And at least in US we have enough farmland to power entire US with wind.

And that's not counting rapidly growing offshore wind power. Which uses no land at all

Post reply on HN