Gravity Battery
Gravity Battery
(OP)
I am trying to figure out how the energy density of a gravity battery (Energy Vault) would be calculated ?
I know the formula is energy/unit volume, but with a system that uses cranes or large lifts, would you use the full volume of the height the mass as lifted to ?
Thanks
Scott
I know the formula is energy/unit volume, but with a system that uses cranes or large lifts, would you use the full volume of the height the mass as lifted to ?
Thanks
Scott
RE: Gravity Battery
I think it'd be more meaning to say the maximum energy capacity of the facility.
Then possibly the maximum energy storage per sq.ft ?
another day in paradise, or is paradise one day closer ?
RE: Gravity Battery
RE: Gravity Battery
The 1/2 stack height is the average height of the stack if always going from full stack to full empty.
RE: Gravity Battery
Batteries, of course, stay mostly the same size (but they do swell).
Consider also efficiency -- energy in vs energy out. I'd wager the mechanical system has better returns, but this is before conversion to electricity.
RE: Gravity Battery
https://www.eng-tips.com/viewthread.cfm?qid=476409
Check the item posted on 22 Mar 22 00:35.
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Gravity Battery
I haven't studied the issue, but I suspect wear and tear and maintenance of mechanical equipment of any kind would outweigh the benefit of the storage.
RE: Gravity Battery
RE: Gravity Battery
another day in paradise, or is paradise one day closer ?
RE: Gravity Battery
Think of a pumped water storage system. How can you say the water has any "energy"?
Only thing you could do is calculate total energy stored for the mass of water or concrete used in the store maybe, but really not sure what you could use it for.
What you want to know is how much energy can it store and what is its power output?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gravity Battery
The Energy Vault MBAs have finally hired an engineer !!! (there are hundreds of MBAs already on staff)
Are you the poor b*astard that is supposed to make everything work ?
You seem like a nice polite guy Scott .... but
I strongly suggest that you read all the way through this thread
https://www.eng-tips.com/viewthread.cfm?qid=488786
And please give us more background on what you are trying to accomplish and your overall evaluation of this industry
Best Regards, sir
MJC
MJCronin
Sr. Process Engineer
RE: Gravity Battery
So they have addressed a key issue which was wind and also that the lower blocks stored less energy than the high ones.
So they are a bit coy as to how it works but looks like you store all the blocks in rows at the bottom, push them horizontally to the end, lift them up ~100m? 200m? then store them in a rack at the top. Then the reverse back out. Then cover the steel frame to prevent wind issues.
CAPEX for the building is HUGE and all the blocks, but once the are there in some desert where space is free, running costs are pretty low, don't really need replacing and are inert.
I worked out with 100% efficiency you need 180, 20 tonne blocks to store 1MWhr. Hmmmm
https://www.energyvault.com/gravity and scroll down for the animation. This is a much better design than the crane block thing, but needs a lot of steel. Think it might be a long payback time in carbon terms.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gravity Battery
and some "magical" way of moving the blocks laterally at the top and at the bottom ?
marginally less silly then the original crane. but more complicated ... each row has it's own "charging" and "discharging" electrical sub-system ?
another day in paradise, or is paradise one day closer ?
RE: Gravity Battery
For comparison, the (roughly) 0.1 MWh battery in a modern electric car weighs (roughly) 0.5 tonnes. The whole car weighs (roughly) 2 tonnes.
YES, stationary batteries can afford the use of heavier but cheaper and more available battery chemistries, and they need not have the power density, and they can afford temperature control strategies that an automotive one can't, which opens up some options ... sodium-sulfur, for example. 100 kWh/tonne seems in the ballpark for those. 1 MWh = 10 tonnes of batteries.
Chemistry wins.
RE: Gravity Battery
The bricks move horizontally on rails (kind of by magic on the animation mind) but clearly some small motors moving them along the rails.
So each row will be independent but if you program them so that you always have say 7 out of 10 moving down then the other 3 are moving a lot faster to get back to the top empty to pick up the next one you should have some fairly even power out put.
If you think about something like a robot driven warehouse it shows it can be done and this only has one thing it is moving.
Now how you service it all and fix problems up in the lattice work is another issue.
This version actually seems feasible, but the crane thing is a complete waste of money.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gravity Battery
As for the OP's energy density, it's not unreasonable to calculate it as described, and you can then compare it with, say, a rack of batteries, although you'd have to account for the net mains power to be comparable.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Gravity Battery
They claim of course you can use loads of waste materials for your weights, but it does seem rather extreme, even if the weights should last for 2-3 times longer than the batteries, plus you don't need expensive / in short supply minerals etc.
I'm like you I think in that it doesn't seem to work financially, but at least from an engineering and operation perspective it is at least a lot more feasible than the crane and blocks idea and you get to use the full height first rather than having to build from the bottom up.
So i guess this is why they still want to find investors to build one of these things.
The energy density thing is density of what though? difficult to compare something which uses kinetic and static energy vs stationary batteries.
But I suppose kWh per tonne isn't too bad a way, just you need to assume the height storage ( so maybe use 100m?) So 0.25kwH/tonne versus 100kW/h /tonne for a battery
but if cost of the tonne of battery is 100 times the tonne of ??(insert waste product here) then you're looking at 25 versus 100 in terms of kWh/ $
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gravity Battery
RE: Gravity Battery
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Gravity Battery
another day in paradise, or is paradise one day closer ?
RE: Gravity Battery
The energy contained in a gravity battery is the lifted weight, times the elevation. If I lift a big chunk of (hopefully) depleted uranium, there will be less elevation and less mechanical volume for a given amount of energy. Is this what you mean by energy density?
--
JHG
RE: Gravity Battery
but cables should be relatively cheap. It's how long the motor generators and the switch gear for all this stop start reverse action its getting.
The main structure and weights though should last a long time. not so sure out the wheels on the weights, but again, maybe not a big renewal cost once you've built the thing.
Just needs oodles of space. and money.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Gravity Battery
RE: Gravity Battery
As long as this machine is based on a firmly established, and tested technology, I have no problem investing in it..
It's those half-assed fever dreams of MBAs, Project Management Institute Grads, entrepreneurs and investment bankers that you have to watch out for ....
But I have been told that I am not a "team player" before ..
MJCronin
Sr. Process Engineer
RE: Gravity Battery
unless it's used for carbon trading !? Look, we've created so much Carbon-free power storage that we can offset our other coal burning power stations ??
another day in paradise, or is paradise one day closer ?
RE: Gravity Battery
Keith Cress
kcress - http://www.flaminsystems.com
RE: Gravity Battery
RE: Gravity Battery
- Andrew
RE: Gravity Battery
RE: Gravity Battery
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm