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

sciencemag.org

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

#261

Post by lebuffon »

xutopia wrote: post #236
lebuffon wrote: post #158

I think this guy is onto something... Liquid metal batteries will be better than gravity storage IMHO. https://www.youtube.com/watch?v=NiRrvxjrJ1U First commercial scale system is going live in 2021 so we shall see how it works out.

I don't understand how that would be feasible... wouldn't the battery need to be kept at a really hot temperature somehow to function?

Using it causes the heat. It is in an insulated container so the heat stays around for about 4 hrs I think he said.

So applying first charge must heat it to melting temperature but then it's working.

Then when you discharge it, electron flow cause heating again. So if it is constant use it just works.

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

#262

Post by nl »

f6v wrote: post #185
nl wrote: post #30

Earlier quoted context omitted.

> It's crazy how little we understand about gravity if you think about it. We understand most things about it > It's a perpetual energy source right in front of us, No it's not. It's a good way to store energy but in no way is a source. > and can barely offer a basic explanation as to what powers it It's not something that has power. It's a consequence of entropy. > It even impacts time itself You sound surprised by…

> We understand most things about it In a classical mechanics sense - yes. But the waves were detected just couple years ago.

It's true we only recently have been able to built equipment sensitive enough to measure them.

However, they were predicted in 1916 as part of Einstein's Relativity work: https://en.wikipedia.org/wiki/Gravitational_wave

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

#263

Post by nullc »

ephbit wrote: post #239
VLM wrote: post #196

Earlier quoted context omitted.

The cheapest "energy storage" is bandwidth and demand based billing. The required battery storage cost to guarantee my 3 KW electric clothes dryer could theoretically operate 24x7 when needed after three weeks of cloudy windless weather at midnight is staggering. The alternative is demand based billing and program my dryer to never accept a KWh that costs more than say, seven cents. On a minute by minute basis I don'…

Problem is: how are you going to convince great numbers of people to alter their daily routine that might also be quite synchronized across a country's population? Like tea time in the UK where apparently millions of people turn on their kettles (2 kilowatts each) in synchrony to get some hot water. What if they also like to cook something with their stove (another 2 KW) to get a nice dinner, around the same time?

He told you: Dynamic rates and appliances that let you adjust their behavior based on rates. Have people pay based on the demand and the most able to alter their usage will do so.

I'm skeptical-- but probably for different reasons that you.

W/ PG&E and MCE the utility can't even manage to tell me my current rate-- determining from my bills requires solving a linear system in three unknowns, requiring three bills. And the rates change quarterly, so I can only determine the rates at the moment they no longer apply. The rate scheme also has various non-linearities such that my total rate depends on my overall usage over the year and as a result my true marginal rate is unknowable at any given time. I dunno how rates are supposed to incentivize behavior when they're so opaque.

So I like to imagine a future with smart electrical panels and appliances where their behavior can be rate shaped in realtime, ... but then I encounter the actual behavior of the PUC and utilities and a future with demand shaped by economics seems distant indeed.

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

#264

Post by FooHentai »

jodrellblank wrote: post #177
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…

> " a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour " By comparison, a pint of gasoline stores about 4 kilowatt hours.

Yes, but only once. This is energy storage not energy source for the purpose of human utility. The ability to pull that 1kw of potential energy back up (with some renewable source eg wind turbine) to be output over again is where the comparison breaks down.

A fairer comparison is current battery tech, you can pack something like 40kwh in 200kg of batteries (rough guess based on leaf ev battery modules). So vastly more in the same space/weight. But those are complex and energy intensive to manufacture, and have limited lifespans before further energy investment is required to recycle/replace them. The relative simplicity and long lifespan of gravity storage seems like it has potential. Not to mention the potential for owner/operator to self install, which could be great for developing nations.

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

#265

Post by ianai »

martinald wrote: post #154
ianai wrote: post #141

Earlier quoted context omitted.

I’d just build the generation out to that maximal use case. During the off peak times power a desalination, hydrogen, or other energy intensive plant.

The problem is the UK sees maybe 1-2GW of renewable generation sometimes in winter while demand is about 50GW. So you'd have to overbuild 25x to cope with these days. Keep in mind the UK already has about 30GW of solar and wind potential nameplate capacity. Your suggestion would result in a requirement of 700GW of solar and wind to be installed. On windy and sunny days would result in probably 350GW of generation, at…

Seems nuclear would be more optimal there.

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

#266

Post by vanattab »

dahfizz wrote: post #221
mbreese wrote: post #216

Earlier quoted context omitted.

Does that matter though? If it is weak to extract energy with gravity, then it should also be weak to “charge” the system against gravity. The weakness may push these systems to less “instantaneous” loads, but I don’t see why it would necessarily be bad to use gravity storage (as opposed to another mechanical method like pressure). I’d love for someone to explain more though.

It's just impractical. You only need a 21x21 foot square of ground covered in solar panels to generate the same amount of electricity this does. It doesn't make sense to invest so much land, machinery, and labor into something that generates and stores so little energy

While I don't disagree with your general sentiment of the viability of gravity batteries. I don't think its a very good comparison. One is all about electricity generation and the other is all about storage. If gravity batteries ever become used in practice it would probably be in tandem with solar. You would charge the battery during the day off solar and allow it to discharge at night when there is no sun to stabilize the grid.

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

#267

Post by vanattab »

FigmentEngine wrote: post #229
bluGill wrote: post #214

Earlier quoted context omitted.

We should always hold out for some new discovery that is weaker.

Design forces are very weak... btw anyone saying that gravity is weak should try getting of this planet...

anyone saying gravity is strong relative to the other forces should ask themselves why they don't keep sinking or get crushed when gravity pulls there feet back to the ground.

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

#268

Post by masklinn »

mbreese wrote: post #240
zestyping wrote: post #223

Earlier quoted context omitted.

Because gravity is so weak, in order to store a meaningful amount of energy, the lifted object has to be very heavy or very high. Building large tall structures is expensive, and we just don't have objects that are dense enough to make the system small.

Okay, so the question isn’t “can you get out what you put in”, but rather “is the amount of energy you can store worthwhile”?

Yes. The efficiency is OK (nothing amazing), it's really the scale requirements for anything useful which are problematic.

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

#269

Post by kleiba »

throwaway189262 wrote: post #132
kleiba wrote: post #109

Earlier quoted context omitted.

In places with cold winters, it is often forbidden to approach wind turbines because of the risk of falling ice.

The turbines are all in fields, useless scrubland, cattle ranches, and the ocean. Humans don't hang out in these places anyways

So you think it doesn't matter if cattle gets hit by the same ice?

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

#270

Post by 8note »

darawk wrote: post #192
wizzwizz4 wrote: post #137

Earlier quoted context omitted.

Cost functions have an implied ethical system behind them. Using money is just waving your hands over it and going “well, money is objective , so we don't need a value system” – but there's still a value system there. It's like “machine learning” in that regard; there's no magic.

Money is just a fungible unit of comparison for types of value, nothing more.

Is that a meaningful statement?

I can rephrase to say that the comparator function for money has an ideological bent. It rewards the externalization of costs

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