General > General Technical Chat
Germany shutting down last nuclear power plants on April 15th
nctnico:
--- Quote from: Siwastaja on April 15, 2023, 06:21:45 am ---
--- Quote from: nctnico on April 14, 2023, 11:30:12 pm ---All the elasticity needs to come from hydrogen storage (as batteries are too expensive for storage that needs to bridge >8 hours; just google that).
--- End quote ---
I'm saying this again, but a lot of elasticity can and will come from distributed thermal storage of heating/cooling buildings and hot water. This is a truly low-hanging fruit which is still not being fully picked. In many cases, the storage resources exist, and it's only control systems that are lacking (disclosure: we are manufacturing and selling such things.)
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I think you are blinded by wanting your idea to be succesfull. You proposed some interesting numbers but I don't think these systems are usefull for domestic use as they will only make sense if such a system can provide storage over periods that lasts way longer than 6 months. Now calculate the volume of water and thermal insulation you need; the volume required is just too large. I ran some numbers on my own but the water storage is just too bulky and too cumbersome to install even if I would make it underground in the garden.
If you can't span a long period, you'll have to rely on alternate sources being available. Remember that every energy source will need it's own distribution network so having multiple sources increases the cost. Especially if the load on that distribution network is extremely uneven over time (which is what local storage is supposed to solve).
Recently I have put solar panels on my roof and the first thing I noticed is that their output varies a lot per day. If I want to add a meaningfull storage system to it then that storage system should be able to even out electricity use over a time span of at least 2 weeks. I might manage not needing electricity from the grid for 6 months a year during the summer months. But I'll still need an electricity grid connection which costs money even if I don't use it at all. And I'll still need to pay for all the grid & generation upgrades that are needed to supply electricity in the winter.
Siwastaja:
Nah, I'm not saying distributed thermal storage solves every possible problem.
But the gain what you get by storing for just 6-12 hours is pretty significant. We are currently struggling with things like having a lot of excess electricity during nighttime for nearly 0 cost, then consumption increasing at 7:00 and wind getting still at the same time (an interesting natural factor), a huge discrepancy, then at least 2-3 good hours during daytime, again worse in late afternoon, and so on.
This is the low hanging fruit: control loads like hot water tanks, in-floor heating elements (which people already have), EV chargers and heatpumps during the best hours of the day.
It does not solve the need for longer-term storage but it's nevertheless a huge difference for a relatively low cost. It's also not for everyone because if you heat both your house and your domestic hot water by burning gas or oil and drive a gasoline car, there is nothing to control. At the same time, some users have excellent "user stories", like those with direct electric heating of both the house and hot water.
Additionally, we need want longer-term storage, in range of weeks, or even better, annual storage. Hydrogen is a strong candidate here indeed, but you can't just go and buy your personal hydrogen storage box, but you can buy an energy management device which makes clever use of the resources you already have. For those who have them.
Siwastaja:
--- Quote from: nctnico on April 15, 2023, 10:21:34 am ---should be able to even out electricity use over a time span of at least 2 weeks.
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Talking about time constants, I ran the simulation with our current optimization algorithm which just optimizes for spot prices given the limit on time constant, which is basically how much storage you have (explicitly in form of water, or implicitly in the construction materials of the house).
The results are as follows:
TC= 4h AvgOnPrice= 7.96c/kWh ( 82.8%) Money= 62.40EUR -> 51.61EUR(-17.3%)
TC=12h AvgOnPrice= 6.52c/kWh ( 67.7%) Money= 62.40EUR -> 42.23EUR(-32.3%)
TC= 24h AvgOnPrice= 5.59c/kWh ( 58.1%) Money= 62.40EUR -> 36.21EUR(-42.0%)
TC= 3d AvgOnPrice= 4.76c/kWh ( 49.5%) Money= 62.40EUR -> 30.85EUR(-50.6%)
TC= 7d AvgOnPrice= 4.00c/kWh ( 41.5%) Money= 62.40EUR -> 25.89EUR(-58.5%)
(Data is simulated with Finnish weather conditions and spot prices during this year, Money refers to a dimensioning where 0.9*1kW of heating power is needed at -30degC outdoor temperature; scale accordingly.)
The conclusion is, while it would be fancy to have a massive pool of water able to store energy for a week (let alone TWO weeks, which I did not even simulate because my stupid algorithm implementation was never designed for such large time constants and gets computationally slow), savings one gets from even just shuffling the hours within 4-hour window is not meaningless, and this does not require massive constructions.
nctnico:
But this is under the assumption that spot prices stay constantly low. IMHO this is a very poor assumption to make. Especially when the ROI time is long (>5 years). Once there is a significant number of people having their own storage (OR the utility companies decide to implement storage as this is obviously economically worthwhile), the daytime prices will become lower and the night time prices will rise. I have been paying the same price for electricity (day / night) for a very long time already. The NL grid uses pumped storage in Norway.
--- Quote from: Siwastaja on April 15, 2023, 10:47:17 am ---Additionally, we need want longer-term storage, in range of weeks, or even better, annual storage. Hydrogen is a strong candidate here indeed, but you can't just go and buy your personal hydrogen storage box,
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That is a decission I have put on hold for about 10 years. Metal hydrate storage systems are available but their ROI time is like >30 years. I'll just see where it goes. It could be suitable solid state batteries are available in a decade and/or metal hydrate storage systems become available. At this moment the grid is my battery as I get the same amount of money per kWh consument / delivered to the grid but that is going to stop in the next couple of years (but long after the solar panels have paid for themselves).
Siwastaja:
--- Quote from: nctnico on April 15, 2023, 12:21:08 pm ---But this is under the assumption that spot prices stay constantly low. IMHO this is a very poor assumption to make. Especially when the ROI time is long (>5 years). Once there is a significant number of people having their own storage (OR the utility companies decide to implement storage as this is obviously economically worthwhile), the daytime prices will become lower and the night time prices will rise.
--- End quote ---
This is of course true. Solving the problem removes the problem, after which the incentive to keep solving it seemingly disappears. But it's a fallacy - if you remove the solution, the problem reappears.
This pattern is true for any problem, btw., and we are all susceptible to this brainfart. For example let's say vaccinations (not some covid-20%-effective-bullshit but good old true and tested vaccines we all agree on): when you vaccinate, the case numbers go down, and vaccination seemingly becomes redundant and stupid thing to do. Yet if you stop vaccinating in large enough scale, the disease makes a comeback.
We are fully aware that solving the very thing we are solving finally undermines our own market. But at that point, we are still needed and there are many other things we can also do.
BTW, the ROI for our little box, at 349 EUR, is 0.5 years to 2 years, depending on the customer case (and we don't sell to customers who don't need the product). But it's still very early to say anything solid about it since it has been on the market just a few months and we have just handful of customers. We will see how it flies.
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