"bigger than an Olympic-size swimming pool" - not helpful but I'll assume not much bigger, or they'd compare it to something bigger - so 2.5 ML (million litres), pumped 200 m against gravity with 2.5 x the density of water, in MWh:
(2.5e6 * 2.5 * 9.81 * 200) / (3600e6) = 3.4 MWh. That's:
- about 5 minutes feeding the 50 MW turbine, - most of an hour replacing the output of a large (10 MW) wind turbine at typical capacity factors, - about 0.03 % the capacity of Dinorwig (I believe the UK's largest hydro plant), - 1 - 2 tonnes CO2 emissions from a natural gas peaker plant, - the usage of about 3 - 5 g of typical nuclear fuels. - don't know or care about coal, sorry.
If you really want to avoid using gas or nuclear in the UK, and not freezing pensioners, I'd be looking at storing the order of 1-2 TWh. I'll bet that the best competition for water is just building more wind turbines than you need. Any working fluid that doesn't literally fall from the sky just won't scale, and is at best a distraction. Yes, fluid.
I'll note an interesting relation between global nuclear deaths and global hydro storage deaths.
I did a back of the napkin calculation on this, assuming the article meant 7 GWh. That'd require roughly 4 pools per installation (assuming 50m x 20m x 2m for one). However the article is constantly mixing up energy and power.
I think it has debunked many times that gravity storage may solve our energy storage needs. Gravity is just to weak for that. You literally would need to move mountains for that.
I'll let you do the maths regarding the required storage capacity :)
> I'd be looking at storing the order of 1-2 TWh
Maybe not that much, but in any case that'll probably require looking at a number of different solutions and to combine them all. This one could be part of the mix.
Look at the diagram. The water reservoir is way bigger than 2.5 times the size, it's also way higher (So more energy). And it doesn't have to be buried.
Working in mines is a nightmare for safety, working in confined spaces is dangerous. Burying things underground is expensive.
Ponds look beautiful if done properly. They can be used by the public. You can use them as nature reserves. They are cheap, just holes in the ground.
They would be 'tidal' and you couldn't drain all the water, but to me this is the way to go. But because the project costs are simple, people won't fund them.
