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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

#171

Post by im3w1l »

eloff wrote: post #169
martinald wrote: post #127

Earlier quoted context omitted.

Not true in northern European countries. The problem isn't day to day regulation, it's the massive demand in cold snaps in winter (when there is very little wind generation - cold weather tends to have little wind). You're talking balancing 20-30GW of additional demand with little solar/wind generation for weeks/months - probably at least 1TWh of storage required for the UK alone. Keep in mind this will only get wors…

All the while the north sea with it's wind is right there, and the Sahara with it's sun nearby too. Some investment in long distance power transmission would go a long way towards smoothing out the grid.

Importing energy from Sahara comes with serious geopolitical issues. Do you really want to commit to peacekeeping in a huge area of Africa? Keep in mind that oil can be stockpiled much more easily than electricity, stockpiles that let you weather small storms. Importing electricity means being on top of every hint of a blip.

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

#172

Post by tshaddox »

Xylakant wrote: post #61
eraserj wrote: post #52

Earlier quoted context omitted.

But again, slowing tidal currents must be drawing energy from somewhere until there is none left.

It basically draws energy from the moon orbiting earth. It could theoretically alter that orbit, but given that the moon/earth system has a lot of mass, the timescale for that to happen is extraordinarily large.

That’s exactly what it’s doing. It’s slowing down Earth’s rotation and speeding up the Moon’s orbit (i.e. moving the Moon further from the Earth).

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

#173

Post by silon42 »

f6v wrote: post #160
cogman10 wrote: post #136

Earlier quoted context omitted.

This seems like a "running before we can walk" statement. Until we can handle day to day problems, it seems weird to worry about edge cases. I imagine as we transition to renewables and storage we will still have fossil fuel peeker plants to handle these sorts of snaps. It won't be until our power storage is far more beefed up that we'll shut those down, and that will take years.

> This seems like a "running before we can walk" statement. Europe tries to be at a forefront of green energy. No sun/wind is a real issue there, not just an edge case.

Yup, where I live there can be 3 months of fog/clouds... meaning minimal wind / sun.

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

#174

Post by after_care »

eloff wrote: post #169
martinald wrote: post #127

Earlier quoted context omitted.

Not true in northern European countries. The problem isn't day to day regulation, it's the massive demand in cold snaps in winter (when there is very little wind generation - cold weather tends to have little wind). You're talking balancing 20-30GW of additional demand with little solar/wind generation for weeks/months - probably at least 1TWh of storage required for the UK alone. Keep in mind this will only get wors…

All the while the north sea with it's wind is right there, and the Sahara with it's sun nearby too. Some investment in long distance power transmission would go a long way towards smoothing out the grid.

Long distance power transmission is a significant political and military liability, not to mention a fantastic terrorist target.

We cannot guarantee that the UK will be at peace with every county between them and the Sahara forever. Hosting the power line would grant significant political or military leverage.

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

#175

Post by PeterisP »

jdmichal wrote: post #161
dopidopHN wrote: post #138

Earlier quoted context omitted.

Side note on what is currently existing with gravity. The suiss folks are gaming the west European energy market this way. When the French produce too much nuclear energy, the German have leftover and stop buying it 100%w Price go down. Swiss buy it cheap and pump water in their dam system with it. Inevitably, the french grid align and produce a bit less. Price goes up slightly. That when the suiss comes out, release…

> Price goes up slightly. How much of a swing in pricing are we talking about here? Because that storage mechanism is maybe 80% efficient. So the price swing would have to be at least that big to break even. And in that case, if they are helping to smooth out swings in demand that are that large... Sounds like they're providing a valuable service. https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... EDIT:…

> it would probably be too expensive to have a power plant just sitting there idle when the price isn't "high enough"

This is exactly what is done, and pretty much inevitably must be done - grids need spare capacity that can be relied on to spin up rapidly when demanded, that's usually done by gas turbine plants.

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

#176

Post by nixpulvis »

joss82 wrote: post #72

The system bring talked about here can deliver 250kW during 11 seconds max. That is LESS than 1 kWh of energy storage. I hope it's not the one on the picture otherwise their cost estimates are way off and two orders of magnitude larger than current lithium batteries, even taking into account battery replacement. Another problem would be the ever-lowering price of batteries comparing unfavorably against this good old…

I had the same thought. They do make it clear that this is a demonstration, but I'm curious how this scales with larger weights and heights; both in capital cost, and efficiency.

I'm also curious if anyone's seen a good comparison to hydro/dam based gravity batteries? Or even to the gimmicky sounding electric train based ones I've read about before?

My understanding is that anything near or past 90% efficiency gets very hard to achieve, but perhaps there are special cases where this isn't true?

Finally, I'm also curious how these compare to flywheels, which offer a similar style of energy storage, but with rotational potential instead of gravitational.

Storage is clearly one of the largest barriers to large scale adoption of many renewable sources of power we have. And, chemical batteries raise a lot of valid concerns in terms of safety and environmental impact.

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

#177

Post by jodrellblank »

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…

> "a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour"

By comparison, a pint of gasoline stores about 4 kilowatt hours.

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

#178

Post by kstenerud »

kortex wrote: post #170
kstenerud wrote: post #146

Earlier quoted context omitted.

Actually, almost none of our trash is recyclable (despite what you've heard). Plastic is particularly bad, and it's only now, with China banning import of "recyclable" materials, that we're finally seeing just how much of a farce it is. Burying it is a form of CO2 sequestration. Burning it just releases it into the atmosphere.

But it's already out of the ground. I'd rather burn 1T CO2 worth of plastic trash made from oil and prevent 1T CO2 worth of coal or heavy oil being extracted and burnt. Not that it's 1-to-1, point is burying plastic is probably less net carbon vs burning.

Sure, provided that the burn efficiency is high enough.

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

#179

Post by f6v »

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…

> That's the issue with gravity: it's really not that strong

The weakest of all forces, isn’t it?

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

#180

Post by xboxnolifes »

bjourne wrote: post #168
hutzlibu wrote: post #145

Earlier quoted context omitted.

Maybe I do not understand it fully (ne pas parle de francais), but where do they game the system? You buy cheap when you have storage and sell expensive when demand goes up. Pretty much how the market should work? This way there is incentive to balance it out (by creating storage) - and in this case stabilize the grid. When the grid would become more flexible, so even homeowners can do this with their solar panels an…

It's not gaming the system, it is arbitrage. However, it is pretty terrible for producers unable to exploit price swings. E.g a nuclear plant produces electricity at a fixed cost and may sell it at a loss when the price is low, but recoups the losses when the price is high. Since arbitrage smooth out the price peaks, it damages nuclear's profitability. One could say that's too bad for nuclear, others (nuclear lobbyis…

If the fixed price nuclear uses is too low to be profitable, then it must be raised.
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