Grid demand is also significantly higher in the daytime so that 4h of battery allows you to very closely match users demands over 24 hours or ramp up during peak demand and fall back on other sources at night.
Furthermore, cost of storage is falling even faster than wind or solar ever did. Wait until next year, and you get lots more storage for your money.
Finally, batteries are good for very short-term storage -- their round-trip efficiency and fast response are unbeatable -- but they cost more than alternatives. For storage that you don't need to draw down every night, something you can fill cheap tanks with is better even if round-trip efficiency is low. Something you can also sell when your local tanks are full, and buy if they seem likely to go dry, is better yet.
So, expect to see a lot of anhydrous ammonia long-term storage. Also, hydrogen, and liquid nitrogen. And, lots of tropical sites synthesizing for export to higher latitudes in winter, and lots of higher-latitude cities importing it, via ship, in place of LNG and oil.
It is kind of surprising to see the batteries set up in Morocco, not in UK. That might be politics. Typically, storage is best sited near point-of-use. Maybe part of the deal is Morocco gets to use a share of the energy.
As to location. All the equipment you need for moving solar power around the grid like long distance power lines is exactly the same equipment you need for moving battery power at that location around the grid. Even better batteries charged with solar power get to avoid DC>AC inefficiency selling solar to the grid and AC>DC inefficiency charging the batteries. They get to skip out on equipment like redundant DC>AC inverters etc. You are even moving power through cooler power lines that therefore have less resistance.
And, storage adjacent to the point of use is less at risk of being wholly unavailable, e.g. if there is a problem with the cable. So, you need good reasons to put it somewhere else. That is not to say there cannot be such reasons, but what they are is of interest.
This is wishful thinking. These are very much research projects at present.
> Also, hydrogen, and liquid nitrogen.
Hydrogen makes no sense as energy storage. The energy costs of compression (and liquefaction, if you do that), and the risks, are just silly. Liquifying and regasifiying nitrogen are energy-expensive too.
It'd be better to combine hydrogen with air-captured carbon to make medium-chain hydrocarbons. We can store those at room temperature and pressure safely for season-long periods of time, as demonstrated by hundreds of millions of motor vehicles and tens of thousands of fuel depots.
Leaks of liquid hydrocarbons are much less likely to kill people than leaks of ammonia.
Hydrogen storage will be mostly underground, at low pressure. So, no compression or liquification needed. But, for transport it will be liquified and shipped just like LNG is today.
Liquifying nitrogen is extremely mature technology. A 100MW LN2 storage plant is under construction in Chile. Little hint, again: [ ... ]
"Re-gasifying" liquid nitrogen needs only ambient air, which (little hint) is all well above the boiling point of nitrogen.
If you think liquifying hydrogen takes a lot of energy, wait until you find out how much you need to synthesize hydrocarbons. Little hint: you will need a lot of hydrogen stockpiled. And, a lot of carbon with all the oxygen picked off.
