Due to technological trajectories set in motion by past policy, a global irreversible solar tipping point may have passed where solar energy gradually comes to dominate global electricity markets, without any further climate policies
this post was submitted on 17 Oct 2023
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For 1. grid size matters a lot. It is always sunny and/or windy somewhwere, so if you can transport the electricity with a good enough grid you can cut down on storage. In the EU the lowest share of renewables on a single day was 23% of electricity production of what over the entire year was 37.6%. 8.3% of total production on the worst day was from solar and wind the rest mainly hydro and biomass. Btw that was 06/12/2022.
Point is that seasonal electricty storage for renewables grid is absolutly not needed and for a continetal sized grid you mostly run to about a days worth of storage and some smart grid management. We also already have hydro power reservoirs, which have some truely massive storage capacity, if used not for baseload, but for dispatch.
Hydrostorage is absolutely nothing and can not be significantly increased, just like hydro power. Take a calculator and see how long it lasts. World wide it's 180 GW of power and 1.6 TWh energy, as per wiki. The USA need over 4000 TWh yearly, they empty the whole world capacity of hydro storage from 100 to 0% in 3 hours. Just the USA alone.
That was exactly my point, you do not need a global grid for this to work a continent sized one already does a great job. That was why I used the EU as an example. As for seasonal storage the worst month last year had 42.8% renewables, which was March, the best was February so a month earlier with 60.0%. The average was 49.7%. So we are talking 20% up or down. That is also true when you just look at wind and solar. Average was 47.15GWh and the worst month was 40.97GWh and the best 59.00GWh. So again fairly even distribution over the entire year. So no need for seasonal storage, unless you have something super cheap.
That is real world data and not some crazy stuff. You basicly just have to overbuilt by 50% and add a days worth of storage to the EU grid to work and the ability to move around electricity.
Also I am talking about hydro power, which per wiki only makes up 16% of global generation. That has storage capabilities built in current reservoir power plants. https://en.wikipedia.org/wiki/Hydroelectricity#Properties
You need enough storage to get over a Dunkelflaute . How much is that for Europe? How much do we have now?
Right now Sweden and Norway have 118GWh of hydro storage and there is more in other EU countries. That alone is enough to power the EU for two weeks or so. But even that is not entirly needed as Europe is large and diverse enough geographically to have different weather in different countries. So power can still be moved. Even on the worst day of last year wind and solar were still able to produce 8.5% of the EUs electricity production so 37% of average levels.
At 2800 TWh of annual electricity demand/production in Europe, 118 GWh lasts for about 22 minutes. 2 weeks would take 1000x the storage capacity, about 100 TWh.
Sorry, I mean TWh and not GWh. For Norway it is 87TWh as here: https://energifaktanorge.no/en/norsk-energiforsyning/kraftproduksjon/
and for Sweden as well: https://www.researchgate.net/publication/228782162_A_Nordic_energy_market_under_stress#pf2
So yes it is a thousand times more, my bad for mixing up units.
Thank you. However, that is the yearly amount of energy. Not the maximum storage capacity at one point. Like (dis)charging a battery once <-> discharging it many times over the year. So over the whole year this massive storage was able to produce the energy needed in 2 weeks.
It is absolutly the storage capacity at one point. . As in the first link:
That is not that crazy. It just means that less then 10% of global hydro reservoir storage is in two European countries, with a lot of water and mountains. Hydro is by far the biggest storage capacity we have. To put it in the words of the iea and globally speaking:
Source: https://www.iea.org/reports/hydropower-special-market-report/executive-summary
So that are the numbers for dams (since pumped storage is extra and much smaller). That is not (electrically) rechargable storage. It is storage, but bound to the influx of water and with many constraints about how much water can be released at what point, how much it has to have at least or at most at which point in year to prevent floods or droughts etc. That is not the kind of storage we need for solar and wind. And while the storage capacity is high, the available power output is not. Since they maximum anyone would install is going to be correlated to the influx of water, not to the fastest possible draining of the reservoir - which nobody would ever want to do.
Also, thank you for the interesting discussion.
Most of that is fine during a dunkelflaute. The only really big issue is not having enough generating capacity, but even that likely works out. The most fuel generation during a single week last year was 24,302GWh so 144GW running throu. Sweden and Norway can generate 49GW in hydro at full power. Even the best weeks still have over 12TWh of fossil fuele generation in the EU, so that certainly goes a long way to solving the problem of dunkelflaute.
But you are right, most of the year smaller storages to cover a night or so, is all you need. So you still want some TWh of battery and pumped hydro storage. That preserves hydro storage and is needed to balance the grid. Biomass is also worth a look for long term storage.