Concrete teapot?

[Mart]

Some info on Energy Vault in this weekends Carbon Commentary newsletter from Chris Goodall:

1, Energy storage using gravity. Energy Vault uses an unusual technology for energy storage, lifting heavy objects at times of grid surplus and then letting the weight drop when power is needed to drive a turbine. According to the company, using gravity in this way can provide 12 hours or more of daily storage, which is ideal for balancing solar power in low latitudes with reliable sun. The company went public in the US a month ago, stating that it expected the levelised cost of its technology to be half that of lithium ion batteries in 2025. (More useful material on energy storage costs in the presentation). It also claims that it will reach more than 87% round-trip efficiency, a number only marginally below batteries. Energy Vault announced last week a prospective order from DG Fuels to provide up to 1.6 GWh of storage at its sites. DG Fuels will make aviation fuel from waste cellulosic biomass, such as corn stalks/stover, combined with green hydrogen. All preceding ventures hoping to use cellulosic wastes from the production of renewable fuels have struggled to achieve commercial success. DG Fuels says that its prospects are better, with patents that make the Fischer Tropsch conversion process more efficient.

[spread-tee]

Well, "never say never" as they say, I will be interested to see how they get on.

Desp

[Paul_F]

Not all the blocks will be raised to 100m, so you’ll need double the mass assuming a mean height raise of 50m. A cubic m of concrete is c. 2.5tonnes, so 4million tonnes is 1.6million cubic m, given the 100m height, gives a base for the tower of 126x126m.

Maybe the promoter of the project owns a concrete company? Maybe his brother owns a crane company?

Embodied carbon in the system anyone? Cement is 0.73 kg CO₂/kg, and assume that makes up 1/7th of the mix so even if the sand and aggregates are available on site (they won't be) it's half a million tonnes of CO2 for storage of 500 MWh - 1kg of CO₂ per kWh of storage available.

[nowty]

Not all the blocks will be raised to 100m, so you’ll need double the mass assuming a mean height raise of 50m. A cubic m of concrete is c. 2.5tonnes, so 4million tonnes is 1.6million cubic m, given the 100m height, gives a base for the tower of 126x126m.

Maybe the promoter of the project owns a concrete company? Maybe his brother owns a crane company?

Embodied carbon in the system anyone? Cement is 0.73 kg CO₂/kg, and assume that makes up 1/7th of the mix so even if the sand and aggregates are available on site (they won't be) it's half a million tonnes of CO2 for storage of 500 MWh - 1kg of CO₂ per kWh of storage available.

That's looks very good compared with lithium batteries, I've seen figures ranging from 40kg to 200kg of CO2 per kWh.

[Stinsy]

Not all the blocks will be raised to 100m, so you’ll need double the mass assuming a mean height raise of 50m. A cubic m of concrete is c. 2.5tonnes, so 4million tonnes is 1.6million cubic m, given the 100m height, gives a base for the tower of 126x126m.

Maybe the promoter of the project owns a concrete company? Maybe his brother owns a crane company?

Embodied carbon in the system anyone? Cement is 0.73 kg CO₂/kg, and assume that makes up 1/7th of the mix so even if the sand and aggregates are available on site (they won't be) it's half a million tonnes of CO2 for storage of 500 MWh - 1kg of CO₂ per kWh of storage available.

Yep if you scroll to the very top of this thread:

I’ve been watching this system of cranes and concrete blocks as a means of energy storage for years. I like the idea. And the “self discharge” is zero!

Unresolved problems as of last time I looked at this idea were: the cost of the concrete blocks and the CO2 produced in the production of the concrete blocks. Round trip efficiency claims seemed to be as fanciful as they always are…

[Oliver90owner]

6:1 concrete mixes are for structural concrete. Not necessary for a duty like this - the concrete will be lifted by the embedded steelwork - reinforcement is the usual term.

Still seems like a lot required for not so much real energy storage. We are needing multiple GigaWatt hours as storage. Most Lithium batteries are fairly short term MWh devices.

Storage for just one day @20GW is nearly 500GWh. Short term storage for frequency control is much faster with electronic devices (battery power). Dinorwig, with 30TJ of energy storage, can only provide less than a couple of GW for about 4 hours. What weight of water falling, by near 250m, is needed for that?

[Paul_F]

That's looks very good compared with lithium batteries, I've seen figures ranging from 40kg to 200kg of CO2 per kWh.

Depends what you're using it for - for most applications of batteries it's the kWp value that counts, not kWh. No way this could discharge at 0.5 or even 1C!