The big problem there is you have these intensely capital expensive capture plants sitting idle around 75% of the time. Also the processes may not gracefully start and stop though maybe you could smooth that out by building a huge battery bank along with the CC plant to effectively run a full duty cycle with 'free' energy. That bumps the capital costs up again though so the economics get tricky.
Yeah. Anything that's designed to use nearly-free or negative-priced energy from the grid needs to be cheap to build and easy to start and stop (The former being one of the main issues with the 'bitcoin mining as grid management' idea).
In theory if you run it using negative priced energy you could maybe run with older less efficient hardware that's not viable for current mining that would be much cheaper, if you can source it. I'm thinking older ASICs for BTC for example where the best in class kHash/W has moved on and the price doesn't support running the older devices but the negative price would offset that by giving a reliable return on time to offset the extra energy burned.
It'd take a far amount of math to figure out if that tips it over though I don't feel like tackling haha.
Electric heating elements aren't free nor infinite in capacity. You'd pay a lot of money for a rarely used asset that has to be replaced by something else most of the time because people want their heating to be reliable.
But it is not horrible. A lot of people have resistive water heating for their solar setup because grid sell prices are super low and a 2kw water heater cost basically nothing.
Which they use all the time. If you did this at a district heating level, you'd just be running an electric district heating system, resistively, which you run all the time - it wouldn't be a dump load, it would just be the load and a very inefficient one at that (compared to a heat pump).
The point is all this stuff costs money to build, money to maintain, so if you don't use it most of the time the time you do needs to be incredibly valuable.
A 10kw heating element costs 250 euros, lets double that to make it able to switch off by the smart meter. Now if you used it 1% of the year and saved 5ct per kWh you would gain 43 eur a year. Not a super convincing ROI but compared to your 10kw peak solar array a very small investment. If you used it just 2% of the year it would already be pretty good and the switch might become very cheap in the future if most houses use load steering for all kinds of things
> Electric heating elements aren't free nor infinite in capacity.
They are about as close to an ideal load as one could imagine.
And capacity is easily expanded with a water tower. You can scale the total thermal energy stored and the efficiency of that storage by simply building a very large water tower. You don't even need special insulation because the water insulates itself.
> You'd pay a lot of money for a rarely used asset
Assuming you've converted over to district heating and cooling, it'd be frequently used as climate control for surrounding buildings.
> that has to be replaced by something else most of the time
What? No. District heating is the most efficient way to provide climate control, bar none. The only thing that needs to happen is setting minimum and maximum temps. Maintain the minimum temp and when negative power price events hit heat to the maximum or cool to the minimum.
And if you want to get super clever, part of your storage can be sand which can store huge amounts of energy.
> because people want their heating to be reliable.
District heating/cooling is as reliable as plumbing. That's because that's effectively all that it is. It's super reliable. If the incoming water is 60C or 90C, it doesn't make too much of a difference in terms of heating a home.
It's a proven tech. Many universities use it because it significantly reduces the heating and cooling cost for their buildings. My own city uses district heating in the downtown to great effect.
The problem is desalination plants cost billions. You're not going to make money building one then running it the 1% of the time the price of electricity is negative.
