Rephrasing that to be more understandable because I didn't get this as it was: "Making sure no one buys expensive electricity from coal or gas plants when the grid is full of cheap renewable energy and almost-free stored energy."
I'm frankly still not sure what you're trying to say even if I understand the sentence now, e.g.: what free storage?! Isn't germany's projected storage capacity by 2050 somewhere between negligible and tiny?
That's like saying the cost of taking an additional bite from your food is very low once you have already bought it, if I'm understanding the continued use of marginal correctly in context?
When I buy food, the marginal cost of a bite from the food is very close to the average cost of a bite, because if I eat 5% more food this week, I have to buy 5% more food next week.
Contrast this with the case of listening to music on my stereo: if I listen to 5% more music on the stereo, I don't have to buy 5% more music, and I don't have to replace the stereo 5% sooner. The marginal cost is near zero: just the small amount of electricity the stereo uses, plus a tiny amount of wear and tear. Maybe I only listen to music three hours a week and the stereo cost me $313 and lasts for 20 years, so the average cost per hour is $0.10. But the marginal cost of listening for an additional hour this week is much lower than that.
Utility-scale batteries are more like the stereo than the food.
Assuming you have an endless supply of food but can only take one bite per day and it means tomorrows bite will be a bit smaller.
These storage systems are generally warrantied as 5000-10000 cycles with 85% capacity remaining in 20 years time.
Guaranteed money today is better than saving a few cycles to maybe make money in 20 years time. Now also factor in discounting the risk etc. and the calculation is given.
But the business case is of course calculated on having the entire construction cost be amortized with profit over a chosen period. With some days making more money than other.
What batteries do are extending the time renewables flood the grid with cheap electricity and thus force nuclear reactors to throttle down, gas peakers to shut down etc.
Or these thermal plants can bid negative ensuring they don’t have to turn off while hurrying on their own demise.
Okay, I can follow that. I've noticed on electricitymaps.com that, for Germany, the coal component never disappears, no matter if you have optimal wind+solar conditions near the summer solstice and prices are far into the negatives. Apparently it's cheaper to let it run the power plant at negative prices for days, than to make it stop burning coal for those days. That renewables with storage would make that finally go away stands to reason
But that fully relies on storage. The person you were responding to was asking whether small-scale solar panels make sense. As it is, during those hours where your solar panel is most effective, you can sign up to receive money for drawing electricity from the grid (if prices are negative enough that it outbids even the transportation costs and taxes). Having a solar panel at that time... you might as well turn it off and get a price that's better than free. Storage would be what we need much more urgently than an extra 800Wp solar per household, then we could already turn off those coal plants for probably weeks at a time during summer
> 3) (medium term) The world-conquering dream is for our PV-based steam to replace fossil-generated steam at conventional power plants. That will let us feed electricity back into the grid using otherwise stranded generating assets (e.g. a coal plant). You might see this as a way to combine an existing, uncompetitive coal plant with thermal energy storage and captive renewables to give it economics more similar to a natural gas power plant.
See also: "Thermal Energy Storage in Dirt for Repowering Decommissioned Coal Plants" (although I believe this assumes the storage is using power from the grid):
While I think what Standard Thermal is doing is very interesting, and in particular may be very helpful for already-built thermal plants, I don't think they've solved the fundamental problem that large heat engines are really expensive to build compared to solar.
As I understand it, their market is dependent on it. They can't store electrical energy, only thermal energy, and their system is designed to store it at fairly high temperatures (they don't say explicitly, but I'm guessing 800° and up from the problems they report having to solve) which you can avoid doing if you're just targeting the process heat market. So turning their stored heat back into electrical energy is necessary for their process to make sense, and that requires a heat engine, such as a steam turbine.
But utility-scale steam circuits cost more per watt than solar panels, and much more than batteries, the electrochemical kind.
No, their market is not dependent on it. Generation of power from stored thermal energy is significantly different from directly using solar: it is completely dispatchable. As such, it serves a role even in a situation where most solar energy (or most solar + wind) is used directly. It enables solar to be used in places, like at high latitudes, where it is otherwise strongly disadvantaged by seasonality (something batteries cannot fix).
Long term storage of this kind reduces the overall cost of providing steady solar/wind output in Europe by half.
They are also addressing markets where the need is for heat. If you are going to make heat from the solar energy, storing it as heat is much cheaper than storing it beforehand as electrical energy and then converting it to heat later.
Generally speaking, steam circuits have large thermal masses, resulting in ramp-up times measured in hours, so most thermal energy is nowhere close to "completely dispatchable". Completely dispatchable thermal power is internal combustion engines (diesel or Otto) and open-cycle gas turbines, and Standard Thermal is not targeting temperatures high enough to operate those machines. Adding Standard Thermal to a baseload coal plant will not make it dispatchable; you will still have a baseload plant, not a peaker. It just won't consume coal.
I agree that it would make solar usable in situations where it would not otherwise be usable, and high latitudes are a good candidate.
For reasons like these I do not think that they will result in a cost reduction.
Standard Thermal has been bending over backwards to store their heat at the high temperatures I mentioned, resulting in a lot of engineering challenges that a lower-temperature thermal store (say, 400° or below) wouldn't have to deal with.
For the most part, process heat is lower in temperature than 400°, so I think that isn't their market either.
Batteries would handle the higher frequency components of the supply-demand mismatch curve, so steam sources wouldn't have to dispatch faster than on an hours timescale.
Typically ramping a coal plant up or down only takes a day or so, so if the prices stay negative for entire days, probably there's some kind of perverse incentive where the coal plant operator is getting paid to run the plant by someone else who is also having to pay a consumer to consume the energy generated.
