Comment by bryanlarsen
19 hours ago
You could use the ocean for the bottom level and an artificial reservoir for the top level. You're not going to noticeably affect ocean levels.
Or just use a large lake. You're not going to noticeably affect the water levels of a large lake. You might pump 10 billion litres of water, which is .02% of the volume of Mjøsa.
The problem is where to store it.
10 billion liters of water is 1,000 m^2 * 10m deep. There is no suitable location for that that is both elevated enough and near enough to Mjøsa to be financially viable.
Norway also existing hydro reservoirs with a capacity equivalent to around 6-8 months electricity supply, so it's not really a major need for Norway, anyway, but this is a fairly general problem: Finding suitable locations that are close enough to a water source, and provides a large enough potential reservoir is hard.
> Finding suitable locations ... is hard.
No it's not. Here's almost a million of them: https://re100.eng.anu.edu.au/global/
If big ones are hard, you can make a bunch of smaller ones.
Looking at a few of them, a few obvious problems are apparent.
Firstly, it takes a rather liberal idea of how close the basins need to be to each other to be viable.
Secondly, most of the ones I looked at would require extensive relocation of existing populations and/or large-scale infrastructure changes, such as re-routing important roads.
The first few I looked at also do not have a sufficient water supply nearby - you'd face either covering them or you'd quickly run into problems of evaporation that you have little ability to replenish/replace.
A lot of the ones I quickly looked at would also face "fun" issues such as no nearby infrastructure such as roads to bring in construction materials.
I have no idea how many suitable locations there are on that map, but it seems pretty apparent it is a small fraction of the ones marked before you even consider how many would be politically unviable because of public resistance to the environmental destruction.
To be clear, I'm not at all opposed to investigating pumped storage, but it's also not nearly that simple.
> You could use the ocean for the bottom level and an artificial reservoir for the top level. You're not going to noticeably affect ocean levels.
Then you have to deal with the problem of sea water corroding everything it touches.
> You might pump 10 billion litres of water, which is .02% of the volume of Mjøsa.
It's not the amount of water that you pump, it's the amount * the elevation delta. Where are you planning on getting the elevation delta from?
Neither of these challenges is technically insurmountable, but this is a field where capex + opex/KWH is everything.
> Where are you planning on getting the elevation delta from?
Elevation delta is not hard to find in Norway! A typical pumped storage facility uses 100m of delta; I imagine Norwegian ones would use more.
> but this is a field where capex + opex/KWH is everything.
And pumped storage is significantly cheaper for seasonal storage than any proposed alternatives.
The original post is efficient for heat storage, but converting low grade heat to electricity is not efficient.
> And pumped storage is significantly cheaper for seasonal storage than any proposed alternatives.
This is incorrect. There is currently not a single pumped hydro station that is suitable for seasonal storage. They're all designed to drain their upper reservoir in 4-16 hours.
It's the only thing that's half economical. Do the math: Even a modest power plant - 1 GW output - that can run for 1000 hours means you need a 1 TWh (even typing it feels ridiculous) storage reservoir. If you only have 100m of head, that's 3 cubic kilometers of water. That would mean building an artificial lake that immediately would be Norway's 6th largest body of fresh water, and draining it completely every winter.
And effectively, you'd have to build it twice - you also need a lower reservoir. Because there's nowhere to get 3 cubic kilometers of fresh water to fill it otherwise, and you really don't want to do pumped hydro with seawater.
2 replies →
For some applications, you don't actually convert the heat to electricity.
This sounds pretty cheap if it works out:
https://austinvernon.site/blog/standardthermal.html
> A typical pumped storage facility uses 100m of delta
Most projects seek 200-600m. This map doesn't even consider pumped hydro <200m: https://maps.nrel.gov/psh
> And pumped storage is significantly cheaper for seasonal storage than any proposed alternatives.
Based on what? Cost is particularly variable for pumped hydro. It can be one of the cheaper options when stars align. But you need 1) a suitable geography that minimizes the cost of damming or digging a resivoir with sufficient head 2) available for development without too much backlash 3) Near enough grid resources to minimize infrastructure and line losses. I'm surely leaving pieces out.
It can be cheap, but it has far more hoops to jump than alternatives like batteries, hot sand and other "storage-in-a-building" designs which can be built where needed and using fairly standard industrial construction.