How do we store solar and wind energy?

23 February 2016



How do we store solar and wind energy?


Kat Arney asked Peter for a solution to this question...

Peter - Yes, well I assume the question means how do you store them, not in it's current form, so the concept of storing photons.

Kat - Yes, the sun: that's a good storage device.

Peter - Of course, there are all different kinds of ways of doing that. There are three main ones which are: chemical - so you charge a battery and discharge a battery - so you're storing the energy from solar or wind and you can use it again at other times, particularly that moves the energy production from say daytime to nightime. Kinetic - so fly wheels. Things where you're changing the energy into somethings that's kinetic which can then be run down again.

Kat - So like winding up a spring effectively and then like "poing".

Peter - Yes, there's some work done here in Cambridge on superconducting high temperature magnets for for flywheels for storing energy in Saudi Arabia, specifically. Or, of course, potential energy and that's been done for many years in North Wales actually. There's a power station called Dinorwig (I hope I've pronounced that correctly), which is about 2 gw, which is done by pumping water up when you've got spare energy capacity in the grid and letting it come back down again and generating power when the need's high because we're getting close to to our peak production.

Kat - And where are the innovations coming from because I know people like Tesla in the States, they're very excited about trying to get better batteries. But it does feel that, although there's been a lot of emphasis on more efficient solar panels and stuff, it doesn't really seem to be a lot of emphasis on making better storage techniques or better batteries.

Peter - Well actually the battery's a different issue altogether. That's to do with the chemistry of the battery and that's not satisfying us. Our mobile phones don't last long enough, etc., or our smart watches which we'll talk about in a few minutes no doubt. It's not that, it's how this energy is being stored. Now, if the amount of energy that can be produced by everything say in the U.K. is limited of course - in any country it is. But if you can move the usage away from the peak times to other times by storing energy, then you don't need to build new power stations. And that's being done either at the edges of the grid with big containers full of batteries or actually being done in the home which is where the Tesla thing comes from. So the Tesla Box which is quite expensive, but there are UK versions of it, where you're actually storing the energy in the home from solar or from cheap energy overnight and then distributing it out, possibly as DC because more and more devices, your USB devices, you LED lighting is DC, so yes, there is lots going on.

Ginny - Are there issues not just with storing the energy but also then connecting everybody up. Because say if we all put solar panels on our house, we wouldn't necessarily only be using the amount of power made from them. So how do you connect up all the different power stations?

Peter - Well that's been done for several years now because you can sell your solar energy back into the grid. So there is something called the feed-in tariff which allows you make money out of the solar panels so actually, with electricity, it's pretty well connected in the U.K. anyway. If you were to connect other things like water - is not nearly as well connected.

Stuart - It's really interesting is the other side of that as well which is the usage. So there's a lot of research into smart grids which is the idea of can you do clever things with all these connected electrical devices. So there's a company in London that's looking at you know, can they shut down the air conditioning in a particular hotel for a few hours that would reduce demand, learn to moderate the flow of energy coming out of the system to try and meet some of those demands and actually do things on the other side, on the consumption side as well.

Chris - Yes, sort of knowing what are priority things. Like you wouldn't want to turn off someone's life support machine, for example, in order to meet the demands of the grid, but my fridge really won't care if it's interrupted for five minutes when everyone's turning their kettle on because their favourite tele programme has gone to adverts. And so you can dynamically shift power around the grid to make it more efficient so we don't have to keep loads of power stations sort of running on standby to mop up the shortfall.

Peter - That is going to be happening. The smart meters and all our devices, in time, so we won't actually have control over when the fridge is or the freezer is on or off. Of course, if we want lights on we're allowed to switch those on.


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