A simple model: seasonal storage in perspective

In previous posts, I threw around a bunch of numbers and sometimes mentioned that these are insanely high, but never gave an idea how high. I now will try to put them in perspective in this post. I found a sweet spot where solar and wind both could deliver enough power to meet demand. This happened at 8.57 times the current capacity of solar and wind, supported by seasonal storage of 2,421 GWh. I called that an insane amount of storage. How would this compare to actual demand over the year?

When I compare the storage state graph with demand in the reference year 2018, then I get this:

simple energy model (charts007c) - belgium - solar and wind production x8.57 versus total load - reference year: 2018 - with 2500 GWh storage

Hey where is the demand curve? There is only the storage in that graph!

Well, that is the storage AND the demand of the reference year. That nice and straight orange line at the bottom is not the x-axis … it is the demand curve. This is not hard to understand, 2,421 GWh is a lot of power in storage. The maximum capacity that we needed in 2018 was 13.31 GW, registered on February 7 between 18:15 and 18:30. That is just 3.33 GWh and tiny compared to 2,421 GWh.

To get some idea how big that storage capacity needs to be, when we want to store that amount of energy in super batteries, this means 2,421,000 MWh / 2 MWh = 1,210,500 “super batteries” (which will be only used once a year at full capacity). At €1,500,000 each, this amounts to €1,815,750,000,000. We are now alarmed about a budget deficit of 11 billion euros, well, this will end this particular anxiety because a deficit of 11 billion will be peanuts from then on. 😉

If we want to store that power in Tesla powerwall 2 batteries of 14 kWh, then this means 2,421,000,000 kWh / 14 kWh = 172,928,571 powerwalls. At €7,500 each (only the hardware), then this amounts to €1,296,9642,000,000.

If we want to use stored hydro (for example our biggest installation in Belgium is Coo-Trois Ponts), then we need 2,421 GWh / (1.164 GW x 5h) = 416 of those.

That is only the storage. The capacity in 2018 was 3,369.05 MW solar and 3,157.185 MW wind, so 8.57 times that means 28,872.76 MW for solar and 27,057.08 MW for wind. That is a staggering amount which we will not have available any time soon.

No matter how to turn this, this scenario is clearly highly unrealistic.

But wasn’t there a more realistic scenario with a capacity of 130 GWh?

Well, yes and no. Yes, I ran the scenario of a limited storage of 130 GWh, but no, it wasn’t able to balance the system (it had 86 days of shortage). Anyway, here it is compared with our current demand in GWh:

simple energy model (charts007c) - belgium - solar and wind production x8.57 versus total load - reference year: 2018 - with 130 GWh storage

That orange line start to get the characteristic wobble of demand (only visible at full size, just click to enlarge).

That would still require 65,000 super batteries (€97,500,000,000), 9,285,714 powerwall 2 batteries (€69,642,850,000) or 23 Coo-Trois Ponts facilities. Plus the additional capacity to absorb 86 days of shortages.

That is still a shitload of storing capacity, knowing that by using dispatchable power sources, this demand can be perfectly satisfied with a capacity of let’s say 15 GW…


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