Electronics > Power/Renewable Energy/EV's

EnergyVault gravitational energy storage

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rob77:

--- Quote from: voltsandjolts on February 04, 2022, 05:18:33 pm ---
--- Quote from: rob77 on February 04, 2022, 04:24:55 am ---you somehow ignored the point related to buoyancy of a 25000 ton  sphere with a 12200 cubic meter cavity... how exactly will you make it buoyant ?

--- End quote ---

Be sensible sir, of course you would not raise the concrete sphere for maintenance.

--- End quote ---

yes exactly that was my point ! you can't lift the concrete sphere for maintenance and you can't dive to 750m for maintenance either ! but the tech submerged to 750 meters needs to be maintained to keep it running.

rob77:

--- Quote from: Marco on February 04, 2022, 11:07:11 am ---Why would you leave it vacuum to lift the pump assembly? Just let it flood through a bypass.

--- End quote ---

either you don't understand or trolling....
you have assembly which must withstand vacuum against the pressure of 750m water column. it means it must be sealed and fastened well... all clear right ? hope you follow me.

now imagine how would you remove such a assembly from the concrete ball in a depth of 750m.

a) you can't fish it out with a hook... "plop" and it's out like cork from a bottle... doesn't work like that , it's has those seals and fasteners.
b) you can't dangle a wrench on a 750m rope and release the fasteners with your tongue at the right angle... doesn't work that way.
c) you could send down saturation divers - it takes roughly a week do to down and week to come back up, probably even longer. divers live in a steel tank/submarine in the depth and breathing helium-oxygen... expensive as hell to have anything done by saturation divers. and as far as i know 700m is the current depth record for such a work.
d) you could develop and build some specialized robot submarines controlled through cables from barges/ships above (wireless doesn't work under water except very long waves) - also expensive as hell and doable only during calm seas.

i know that you have a solution for every impractical idea some startup comes up with , but real life is a bit more complicated ;)

 

Marco:
The pump assembly will weigh a couple tons and the moment you pull vacuum a 10 m2 lid will get forced down with around 10 extra ton. I don't think it's all that natural to assume you need pre-strain on the seal to hold back the water, I assumed simple guide pins would be enough. With some robot to clean the seal seat.

voltsandjolts:

--- Quote from: rob77 on February 05, 2022, 05:16:54 pm ---
--- Quote from: Marco on February 04, 2022, 11:07:11 am ---Why would you leave it vacuum to lift the pump assembly? Just let it flood through a bypass.

--- End quote ---

either you don't understand or trolling....
you have assembly which must withstand vacuum against the pressure of 750m water column. it means it must be sealed and fastened well... all clear right ? hope you follow me.

now imagine how would you remove such a assembly from the concrete ball in a depth of 750m.

a) you can't fish it out with a hook... "plop" and it's out like cork from a bottle... doesn't work like that , it's has those seals and fasteners.
b) you can't dangle a wrench on a 750m rope and release the fasteners with your tongue at the right angle... doesn't work that way.
c) you could send down saturation divers - it takes roughly a week do to down and week to come back up, probably even longer. divers live in a steel tank/submarine in the depth and breathing helium-oxygen... expensive as hell to have anything done by saturation divers. and as far as i know 700m is the current depth record for such a work.
d) you could develop and build some specialized robot submarines controlled through cables from barges/ships above (wireless doesn't work under water except very long waves) - also expensive as hell and doable only during calm seas.

i know that you have a solution for every impractical idea some startup comes up with , but real life is a bit more complicated ;)

--- End quote ---

either you don't understand or your trolling....

I played a very small part in a project which placed a multi-megawatt electrically driven turbine compressor at a water depth of >200m and it’s been down there, running since 2016. In comparison, pumping water out of these concrete bell jars is child’s play. Of course, you would not go this route if geology allowed other means of pumped storage. Maybe the volume of concrete is abhorrent. Maybe the numbers won't add up in reality. But to dismiss it out of hand because of these nonsense maintenance issues (which are solvable BTW) is short sighted and lacks the imagination required for creating new technologies.

rob77:

--- Quote from: voltsandjolts on February 05, 2022, 07:58:24 pm ---
--- Quote from: rob77 on February 05, 2022, 05:16:54 pm ---
--- Quote from: Marco on February 04, 2022, 11:07:11 am ---Why would you leave it vacuum to lift the pump assembly? Just let it flood through a bypass.

--- End quote ---

either you don't understand or trolling....
you have assembly which must withstand vacuum against the pressure of 750m water column. it means it must be sealed and fastened well... all clear right ? hope you follow me.

now imagine how would you remove such a assembly from the concrete ball in a depth of 750m.

a) you can't fish it out with a hook... "plop" and it's out like cork from a bottle... doesn't work like that , it's has those seals and fasteners.
b) you can't dangle a wrench on a 750m rope and release the fasteners with your tongue at the right angle... doesn't work that way.
c) you could send down saturation divers - it takes roughly a week do to down and week to come back up, probably even longer. divers live in a steel tank/submarine in the depth and breathing helium-oxygen... expensive as hell to have anything done by saturation divers. and as far as i know 700m is the current depth record for such a work.
d) you could develop and build some specialized robot submarines controlled through cables from barges/ships above (wireless doesn't work under water except very long waves) - also expensive as hell and doable only during calm seas.

i know that you have a solution for every impractical idea some startup comes up with , but real life is a bit more complicated ;)

--- End quote ---

either you don't understand or your trolling....

I played a very small part in a project which placed a multi-megawatt electrically driven turbine compressor at a water depth of >200m and it’s been down there, running since 2016. In comparison, pumping water out of these concrete bell jars is child’s play. Of course, you would not go this route if geology allowed other means of pumped storage. Maybe the volume of concrete is abhorrent. Maybe the numbers won't add up in reality. But to dismiss it out of hand because of these nonsense maintenance issues (which are solvable BTW) is short sighted and lacks the imagination required for creating new technologies.

--- End quote ---

cool project and amazing reliability! , but compressing natural gas can't be compared to pumping sea water at 75atmospheres of pressure.
what was the cost of the pump assembly ? it sure makes economical sense when pumping natural gas, but let's be realistic.. we're talking about 5MW of pumped hydro with similar cost for the pump assembly (of course manufacturing at large scale would bring the cost down a bit).

btw.. the numbers from that reality you linked are terrifying...

lifetime 20 years... what ?? why ? concrete lasts much longer ! why only 20 years then ??? probably the maintenance issues i'm talking about are the reason of the short lifetime ?
so we'll end up with concrete spheres on seabed everywhere ? are we creating "new technology" to be cleaner while leaving crap behind ? manufacturing concrete creates a lots of CO2, abandoning concrete structures is definitely not "green".
furthermore all calculations are based on assumption of having 2 cycles per day ? i don't think we have lows on the grid 12 hours apart long enough to charge a pumped hydro twice a day...  so probably we should double the cost per kWh in their calculations.

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