Flexible demand: when grid talks to fridge

Ushering in a new era of water cooler conversation...
14 June 2022

Interview with 

Sarah Darby, University of Oxford


A modern kitchen


Apart from just storing energy, another approach is to use it more effectively and in a more timely way. The load on our energy supply rises and falls all the time, meaning there are periods when we have a relative surplus and other times when we face a shortfall that necessitates switching on expensive - and carbon unfriendly - fall back systems. If we can make our energy systems more intelligent and flexible in their consumption patterns, we could make significant savings. But what does this involve, and is it realistic. Speaking with Chris Smith, Sarah Darby is at Oxford University’s Environmental Change Institute where she works on smart energy systems...

Sarah - This is one of the most exciting areas of energy research at the moment, I think. It's what Simon referred to at the beginning. It's about looking at the system as a whole and integrating demand with supply. We already have supermarket freezers helping with the power system by adjusting their demand, according to the available supply, using more when the wind's blowing and the sun shining. So we could see a time in the future when that would happen to domestic freezes and fridges as well. That I think would be quite a way down the road, but it has started already.

Chris - Would it involve then really intelligent devices that are informing the supplier, "this is what I am. This is how I sit in the peckin order of power. I'm a dishwasher I don't really need to run right now; or I'm a fridge. I'm not off my temperature. I'm okay. I don't need to fire up quite yet. I can wait." And then the supplier saying, "great. Could you just wait because, actually, I've got lots of other demand at the moment: there's a big train pulling out of central station, or something; grid's under load. Is that how this will work? It's sort of intelligent devices that feed back almost like a smart meter in everything.

Sarah - Yes, indeed. That's already starting to happen. So, for example, our washing machine, I can set it to, say, I want the wash done in eight hours or seven hours, before I go to bed. And then it will do the wash overnight. And it can do that at a time that suits the network. You can do the same when charging a car. Both these are flexible types of demand. You could do that with your dishwasher or your water heater. What you wouldn't want to do it with, of course, you wouldn't want the network interrupting your TV programmes or your cooking. And when you want to boil a kettle, you want to boil a kettle. So those types of demand aren't flexible, but quite a lot of types of demand. Are

Chris - You forgot about the most important one of course, which is radio programmes, like Naked Scientists that that would be ring fenced by, by definition of course. Sarah!

Sarah - I'm terribly sorry about that! Yeah. <Laugh>

Chris - But do we actually therefore need a rethink as to how our grid distribution systems work? Because at the moment we, we've got a sort of broad system where we just shove some power - if you've got a solar array on your roof or something - we just shove that power out into the ether and it goes somewhere. Is it actually the most efficient way to use it? Because that means potentially that the energy generated in my garden is ending up in Scotland via the grid. Is that the most efficient way to work? It doesn't strike me that it is. Would it not be better to rethink maybe how we've got power kept locally to minimise losses of long distance transmission, for example?

Sarah - Yes, indeed. Yes. You do want to be using power as locally as you, as you can. For the, for the very reason you said, and, and so matching supply and demand locally at the substation level. And if you can do that intelligently, it also means that if, for example, you suddenly get quite a lot of new supply or new demand in a local area, you don't have to dig up the road and put a lot of new copper wiring in the ground. You can match the supply and the demand locally.

Chris - And what sorts of benefits, if you sort of look on the back of an envelope of implementing this, what sort of benefits could we return by doing this?

Sarah - Well, there's the system level benefit. So everybody benefits from having a system that it is changing. It will cost to do it, but as Simon said earlier, keeping those costs as low as you can, but there are also ways in which customers can benefit by going on tariffs. That will mean they pay less. If they are prepared to let the system use their load flexibly at times, as long as it doesn't inconvenience,

Chris - You've done a bit of research on that. What do people make of surrendering control in that way? Are people fairly accepting of that?

Sarah - We came up with five Cs that help people to accept all this: comfort and cost, of course, connectivity - the tech has to work properly - control: they need user-friendly controls, and care. The last one, which people tend to forget, which is they need to have real human beings who understand this stuff and can explain it and can help them come to terms with it.


Add a comment