Doesn’t it make sense to use solar to pump sea water into man made reservoirs in hot countries, and in cold/wet countries use wind and natural rain to fill reservoirs?
As a layman it seems infinitely better than nuclear or battery storage.
In: Technology
Cause they destroy ecosystems via taking up an ungodly amount of land.
Produce unstable amounts of methane.
And are abdominally dangerous when in high geologically active areas.
And when everything goes down, it goes down Hard
Also money lol
Using energy to pump water inland for the purposes of generating energy doesn’t make sense. Thats just wasting resources and energy.
As for the dams on existing flowing water, in general we do build them. There’s about 2,400 hydroelectric plants in the US. There are some drawbacks to building the dams (utterly destroys vibrant ecosystems, expensive, etc), but even if we built them on every viable location that’s simply not enough energy to meet our needs.
Pumped storage is brilliant… If you have the geography. You need the ability to create a large reservoir of water high above another large reservoir/the sea. Scotland has loads because they have good geography for this. England, not so much.
They are also “only” 80% efficient, lithium iron batteries are around 99%, other types 80-90%. They make up for it in cost but still.
Then factor in that while some places have dependable solar, those tend to by dry places (no clouds), and often flat. The sort of places you can use pumped storage can’t depend on the sun, so they’d have to massively oversize their solar farms so that in winter when the days are shortest, power demand is highest, they are sufficient. Pumped storage solves the day night cycle, not the weather and seasons at the expense of requiring EVEN MORE solar cells to overcome the efficiency loss. And nowhere has reliable wind.
Funny you mention nuclear, because it works amazingly well with pumped storage. Nuclear is the best power source for baseload, but power demand fluctuates during the day and nuclear can’t do that well. But if you use excess nuclear at night to pump water up, and use this to cover peaks in demand during the day, you get the dependability of nuclear with the ability to adjust supply with demand.
Solar+pumped storage isn’t the perfect energy solution, nuclear+pumped storage is (assuming its wet and you have somewhere high to flood).
(Geothermal also works instead of nuclear here, but good god you need to win a geographic lottery for that combo).
I’ll assume there’s a cost element here too. The cost of building the pump infrastructure will always be used as an argument against it, no matter if it’s cheap/ efficient to run afterwards. Yay conservative politics!
Pumped water storage is a thing that exist.
People build reservoirs up on hills or in the mountains and pump water between lower lying and higher up reservoirs to store energy for later use.
It is a good way to bank electricity from solar or wind for later when the sun is not shining and the wind is not blowing.
The problem with pumped storage and hydro-electricity in general is that you need hills and mountains to build them.
You can’t really create a reservoir on a hill if you don’t have any hills anywhere.
The same goes for damming a river to create a hydro electricity dam. You need rivers that come down from the mountains and carry enough water.
This works great if you are Norway but is more problematic if you are the Netherlands.
Geography is a big limiting factor here.
Another problem is that to build big dams and reservoirs you need flood some valleys and convince the people who live in that valley to move.
This works well in places like China or even the USA from a few generations ago, but not in more modern places where people will sue the government to stop them from forced resettlements and taking their land.
You also have environmentalism as an issue. while hydro electricity is clean energy in theory, building a new reservoir will destroy the parts of the environment that you are flooding and negatively affect the environment (and the people) downstream.
Another problem is lack of rain. Currently the Hoover dam in the US is working at reduced capacity because Lake Mead has so little water in it.
Also keep in mind that filling up a reservoir with water means that there will temporarily be less water downstream. This will make people angry who live downstream and need that water for a living. This is bad enough when those people are your won people, but if the river flows into another country, than you will affect a bunch of foreigners who get upset at you because they can’t grow crops the way they are used to.
This was a big problem with the big new dam in Ethiopia. It was supposed to provide energy for that very poor country, but filling it up would affect Egypt negatively so there were even threats of military strikes against the dam made.
So you have a bunch of issues.
* You need a place with the right geography to build anything like that in the first place.
* You need to be able to evict the people living in the place you are flooding without too much trouble.
* You need to not have conservationist groups cause too much fuss about the environmental impact of flooding part of the place and stopping regular floods downstream.
* You need to be able to pacify people living downstream who depend on the water and get upset about having less of it for a while.
* You also need to be able to deal with people in other states and countries who get affected by your messing with the river. Either with money and diplomacy or by having a big enough military to just get away with it.
Obviously not all points apply to just pumped storage batteries as much as to hydro electric dams. Pumped storage tends to to be smaller and less invasive and less of a downstream impact but it also has less of a benefit since you only store electricity in them not generate more of it. You only make money from arbitrage between the time you bought electricity and the time you sell it back.
Generally hydro power and pumped storage is a good thing if you can have it but building more of them is not going to be easy.
Yes, it makes sense. People do it because it makes sense. But it has a lot of problems and is not the ultimate solution, it’s a question of scale.
But don’t confuse energy production with energy storage. Nuclear power plants, for example, are energy sources, and the only reason they require energy storage is because the consumption of energy via electrical grids is sometimes higher and sometimes lower than the native energy output rate of the nuclear power plant. Natural rain-filling reservoirs, which then empty downhill through turbine generators, are also energy sources, though in that case you can control the flow of water through the turbines, and therefore treat them as a source of stored energy. The energy, however, is moved into the reservoir by an energy production source, namely solar energy driving our climate, and pouring water into the upstream via rain. So you have sources and storage mechanisms, the latter which is necessary solely because people use energy when it isn’t being made (fossil fuels are our gem, however, as they were made a long time ago, and are stable, energy-dense, just sitting there waiting to be used with no timeline, among many other reasons).
So why aren’t there gigantic reservoirs being damned and built all over the world in order to store energy? Well, there are, as you know, but why not more? Because you have to flood something. You have to convince people that you are going to take control of their lands and flood them, not to mention building dams, which are themselves enormous projects, as well as destructive, as well as engineering feats, and risky. Anything you want to flood, you have to convince the people who want that land. In one way of thinking, it’s like asking them to destroy their climate to prevent climate change. It’s an ecosystem, and you’re going to destroy it. You need a different solution.
Batteries aren’t it, not on a large scale, but fear not! There are other technologies developing.
About the situation in Germany / Austria:
Where it makes sense there are mostly already Pumped-storage hydroelectricity. For the geography, you need like two lakes at different heights where you can pump water from one lake to the other. They were neccessary to stabilize the power net when the most contribution came from coal and nuclear power plants.
The problem is that these power plants constantly output the same power while power consumption depends often on the time of the day (and there are cultural effects that why I can only speak for Germany). So normally peak power is used at noon and the least is used over the night. In Germany these pumped-storage plants were used so they would pump the water to the upper lake during the night and generate power during the day.
Today they are not so useful because the power mix includes a lot of solar energy that generates the most while the peak power is needed.
In the future we will need them again because solar energy won’t produce during the night so you can use them to pump water up during the day and produce power during the night.
You need a huge amount of water and/or height to store meaningful amounts of energy.
I have a Li-Ion laptop battery here which contains 73Wh (264kJ) of energy. This would be equivalent to lifting a 1000kg weight by 27m. That’s like 7 bathtubs of water on top of a tall building just to store the same amount of energy contained in this small battery.
Pumped-storage hydroelectricity only makes sense when you have a huge (more or less) natural reservoir at a considerably higher elevation than a similarly sized (or bigger) second reservoir. Sometimes when they build a dam for a river they actually build two dams in a row so they can pump from the lower one to the higher one. For example here in Austria in the [Maltatal](https://de.wikipedia.org/wiki/Maltakraftwerke) there is just perfect geography for hydroelectric power plants:
https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/K%C3%B6lnbreinsperre_from_Arlh%C3%B6he.jpg/1920px-K%C3%B6lnbreinsperre_from_Arlh%C3%B6he.jpg
The lower reservoir contains 175 000 m³ of water (it’s big). It can be pumped into the bigger, higher reservoir which is 198m higher (it’s nausea inducing just to stand on top). And yet that’s “only” 95MWh of energy. It would “only” be enough to power my home town with a population of 200k people for 60 *seconds* (average daily electricity consumption is 5.9GWh). And we haven’t accounted for transmission and generator losses here.
Essentially, by pumping the water into reservoirs, you are using the water and altitude to store the solar generated energy. When you view it this way, you will realize that you cannot store more energy than you generated with the solar power – and while you are doing the pumping, you are losing energy – heat from friction in the pumps, leaks, etc. The result – you would have more energy if you just used the Solar energy directly, in the electrical grid. Storing that energy by pumping water uphill would only make sense if that was the most efficient “battery” you could conceive.
The other thing to consider is how the water in lakes and rivers got there in the first place. The answer is that the energy of the sun heated the ocean, the water evaporated, then the heat of the sun caused the wind to blow the clouds over land and it rained. So what you are proposing to build already exists, and has a solar energy gathering surface using 70% of the surface area of the earth. You would have to be pretty ingenious to outperform just using the rivers and lakes that already exist.
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