Mechanical battery/energy storage

[BUDFORCE]

Something I have been thinking about for a while.

I am sure there are lots of these, but there is a place called Power Mountain in North Wales. Its basically a lake/reservoir at the top of a mountain, with another at the bottom. Where there is an excess in the grid/low demand the water is pumped to the top, and then the opposite when the energy is required.

It got me thinking, would this be possible in other ways?

The downside with many froms of renewable energy is it isnt always reliable, clouldy, still day, lack of rainfall etc. And on a smaller scale, with people having solar panels on their homes. Energy can be stored with chemical batteries, but these have a limited lifespan plus I am not sure how environmentally friendly constantly producing chemical batteries is.

Now, I am certain almost the very first post to reply will point out something completely obvious I have missed here, but I was wondering about other forms of mechanical storage? So for example, a very heavy weight. When there is an excess of energy, a motor pulls up the weight. Then when the energy is needed back, mavity pulls the weight down spinning a dynamo/alternator. But I am guessing there are tons of ways this could be done?

 

[sovietspybob]

The most efficient way is to do it with water as you say they do up here in Llanberis, anything else just adds a lot of complexity and less efficiency to do it in a scale that is in any way meaningful.

You will see some small scale trials of weird and wonderful ideas of small automated trains taking concrete blocks up to the top of a hill and then coming down to generate energy but it's hugely complex when you could just do with same with 2 lakes..

 

[Mercenary Keyboard Warrior]

Some trials on hot sand are taking place
for smaller scale, heating a static volume of sand via an electric coil. when needed the energy is released back as hot water, just pump colder water round a water loop inside the sand "bunker"
For commercial its a bit more involved. They are proposing large silos with conveyors. Again a coil is inside the silo.
When needed the sand is released which drops and drives a turbine from mavity plus then the heat is harvested and the cold(er) sand is moved back up into the top of the silo ready to be reheated when excess energy is available.

There is talk of using old mines as well as some kind of water storage or allowing for large weights to be lowered driving turbines, and hoisted back up with excess energy later.
I am not sure the old mines one works that well but maybe
If they actually scaled it up then I can sort of see the weight working. Ie they stack them a bit like one of them gyms where you can select the number of weights that move. So you have a lot of weights stacked up.
problem will be when it goes wrong its going to be quite mega engineering so not a quick fix.

 

[Finners]

Another way it can be done is compressing air, use excess energy to compress air then release it to spin a generator when needed. Water and air in my head seem the easiest as its all known proven technology. Just don't think the efficiency is terribly great.