If you already have a grid interconnection and a handy energy sink, you can definitely make money just buying excess power for a negative price at certain times. So far, though, it's not quite frequent or extreme enough to justify a bespoke infrastructure investment.
And if you're going to make some kind of investment, better to spend money on some kind of energy storage tech (i.e a chemical or physical battery.) Then you not only take excess power off the system when it isn't wanted, but also help power the evening peak when usage ramps up just as solar is ramping down.
At the beginning of the 20th century we went on a bit of a dam building spree up there (and all over, but heavily up there). Then when WWII broke out and we got a huge demand for airplanes (which require light aluminum), the industry congregated around where there was an excess of cheap hydro. Hence Boeing, Lockheed, and friends all being out of Seattle.
https://www.energy-stats.uk/octopus-agile-london/. I think the all time low was -10p/kWh. Most of the time it's around -3p though when it does go negative. Assuming you had a 20kW (massive) heater you'd only make maybe £1-5/day running it when the prices are negative, which isn't hugely often ATM. So probably not economical, yet.
humans don't desalinate water with their bare hands...
From what I heard they said something like a half-time for the heat in these devices of about 1 to 2 days.
And boost those with phase-change materials at the right thaw points.
* Too cold: Legionnaire's disease. Presumably not right away, so maybe there's some wiggle room if you're careful about timing.
* Too hot: scalding, particularly if you have kids. Maybe a new design could have a thermostatic valve on the output to give more flexibility.
There are also quite a few people who use thermal storage with wood fired boilers. The boilers burn the most efficient and cleanest when they are near full output, then hot water is stored in an insulated tank to intermittently supply the house with heat.
Description of one such system:
Edit: Found it, Cryobox. Seems like a great way to monetize abandoned wells that are emitting methane.
Kinda, sorta. The whole conceit behind wholesale energy markets is balancing congestion on the system by changing the locational marginal prices (LMPs). If you have a very congested line, a generator with a negative shift factor (their generation will reduce flow on the line relative to the constraint) will see high prices to turn up, while generators on the other side with positive shift factors (will put more flow on the line and exacerbate congestion), will see low-to-negative prices to turn off.
There is a lot of development in these markets (in terms of energy, capacity, and ancillary services) with respect to energy storage resources, and co-located (solar+storage) facilities. If you want to know more about that, reading up on FERC Order 841, and the various RTO/ISO implementations to date is a good place to start.
I mean, by all means power everything from your car and stop using the mains supply to your house - but that sounds pretty inconvenient to me - you can't interfere with the supply as a DIYer, and I doubt there's any way to do it in a regulator-approved way short of completely disconnecting from the grid, not off and on based on price.
Extending out the time to profitability (equivalently, reducing ROI; because the plants are idle in summer) means many proposals for generation in winter won't rise above the hurdle rate of ROI and won't get built.
Some regulation might be necessary. Maybe it should be that an energy provider must commit to a guaranteed minimum power output that applies year-round (of course excepting well notified planned maintenance and small outages for equipment failure).
IOW, a provider uses PV (perhaps) as one of a portfolio of generation methods, whatever works cheapest for reliable supply year round in the particular circumstances of the provider and market.
Allowing point of use (rooftop) installs of PV will make seasonal demand on the grid peakier too.
People will say, all those EVs are a distributed energy source. For seasonal variations, they're not.
Let's say A is running a desalinated water giveaway and B is storing the excess electricity as potential energy, which can be sold as electricity when the price goes positive.
B can afford to take the energy for a less-negative price, so outbids A by accepting less money with the juice.
Sure, if things get ridiculous enough, it might be a race to see who can afford to give away the most water / aluminium / nighttime power / Funko Pops.
But, it won't.
However, what's quite common is that renewable energy is not sold at the spot price but instead at a "strike price" agreed at time of construction, which gives the stability to finance the project. So asking a plant to turn off their grid input will invoke a penalty clause for "curtailment". This is more common with wind turbines.
But long and short is if you interrupt the power going out from a nuclear power station it will not be producing useful power for a while! (it won't damage anything but it'll take some time to get it back up to normal operation).
At some point you hit a case where you can't go lower without shutting down completely, and that involves all parts of the system - just spinning up or down a steam turbine can be a harrowing moment as depending on the whole setup there could be an RPM range where the harmonic oscillation might destroy the whole thing (as my grandfather, who was working as engineer on steam turbines for electricity generation, described it: "we would slowly spin the turbine to the critical RPM range, then open the throttle to cross the critical range in as short time as possible, then do slow and steady to the rated RPM")
Again, predicting the future is notoriously hard.
Current rate of progress cannot be extrapolated to infinity.
Most exponentials are S-curves in disguise.
Take a look at Moore's Law.
There are other ways to store electricity. You can store it into electrical heavy processes, such as making aluminum or steel from scrap. (Something that half researched blog post did not even mention).
May I suggest “Hindenburg” as a brand name?
I can assure you that hydrogen can be stored just as safely as other fuel sources. In many ways it is actually safer because it's escape velocity and the fact that it doesn't pool. Not compressing hydrogen would add to it's safety as there wouldn't be any stored forces to counteract, small leaks can be detected and don't cause turbulent ruptures.
Lithium ion batteries == spicy pillows
Not very efficient, but that would be an incredibly flexible green energy storage system.
edit: e.g. https://gravitricity.com/
With large enough tanks, it's not unrealistic to imagine storing 5MW-10MW for several days worth.... so about 50-100 MW-hour.
Here's another possibility: Bitcoin mining.
It's been discussed a lot - mostly hypothetically, but has a fraction of the distribution cost. There is a non-negligible capital cost that will turn over periodically. But there's nothing to ship at the end of it all. And if you're getting paid to use power, then it might be possible to come out ahead.
And then there's the non-negligible cost of locating a desalination plant next to the ocean, where the effluent pollutes the environment.
Putting a generator in place to convert the methane to electricity, then crunching the value into bits on-site, might add up. I agree that it isn't going to be useful for periodic cheap energy, however; there's no scenario where intermittently running your ASICs is going to add up.
Did anyone else think of Crypto mining, where there #1 cost is electricity?