Signe Klange asked:
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 itís current form, so the concept of storing photonsÖ
Kat - Yes, the sun: thatís 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 youíre 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 youíre changing the energy into somethings thatís kinetic which can then be run down againÖ
Kat - So like winding up a spring effectively and then like "poing"Ö
Peter - Yes, thereís 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 thatís been done for many years in North Wales actually. Thereís a power station called Dinorwig (I hope Iíve pronounced that correctly), which is about 2 gw, which is done by pumping water up when youíve got spare energy capacity in the grid and letting it come back down again and generating power when the needís high because weíre 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 thereís been a lot of emphasis on more efficient solar panels and stuff, it doesnít really seem to be a lot of emphasis on making better storage techniques or better batteries.
Peter - Well actually the batteryís a different issue altogether. Thatís to do with the chemistry of the battery and thatís not satisfying us. Our mobile phones donít last long enough, etc., or our smart watches which weíll talk about in a few minutes no doubt. Itís not that, itís 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 donít need to build new power stations. And thatís 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 youíre 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 wouldnít necessarily only be using the amount of power made from them. So how do you connect up all the different power stations?
Peter - Well thatís 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, itís pretty well connected in the U.K. anyway. If you were to connect other things like water - is not nearly as well connected.
Stuart - Itís really interesting is the other side of that as well which is the usage. So thereís a lot of research into smart grids which is the idea of can you do clever things with all these connected electrical devices. So thereís a company in London thatís 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 wouldnít want to turn off someoneís life support machine, for example, in order to meet the demands of the grid, but my fridge really wonít care if itís interrupted for five minutes when everyoneís 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 donít 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 wonít actually have control over when the fridge is or the freezer is on or off. Of course, if we want lights on weíre allowed to switch those on.
I've always advocated using spare electricity to electrolyse water. The existing gas grid can store and distribute hydrogen either by itself or mixed with methane (old fashioned town gas was 50% hydrogen) and already has sufficient capacity and distribution reach to supply about half of all industrial and domestic power requirements, with existing storage capacity for several weeks' supply. Why invent anything else? alancalverd, Tue, 23rd Feb 2016
The problem with gravitational storage is its very low energy density.
But what about the energy cost in storage of the gas; high pressure needed, embodied energy in infrastructure etc...? chris, Wed, 24th Feb 2016
We already have a gas grid - it feeds factories, hospitals, your cooker and boiler, and about 60% of the UK electricity generating industry!
I agree with alan regarding the storage of energy in the form of hydrogen gas. Not only can it be mixed with methane for use in home and industrial heating purposes, it can be used in the hydrogen cell and become an efficient form of electrical energy for use in transportation as well. Ethos_, Fri, 26th Feb 2016