Capacity crunch – can we store our way out of it?

This article originally appeared in the Environmentalist, 4th November 2015

The conventional wisdom for a long time has been that you cannot store electricity – you have to generate it, send it down the wires, and, by the way engage in a lot of complicated balancing arrangements to ensure that, on any one day, anticipated demand meets whatever it is you are sending out. And it is this ‘truth’ that lies behind the forecasts of tightening capacity margins that we are again hearing about for this winter – the capacity of the power stations we have on the system to provide for the highest likely demand at some stages in the coming winter is increasingly marginal. This is not helped by some gas fired power stations being ‘mothballed’ by their owners because they don’t make money generating, and the closure of some coal fired power stations as they wear out and fail to meet important pollution standards.

I don’t think that the lights will go out this winter because of this – National Grid has developed a number of intervention back-up programmes, and we still can access additional power through interconnectors from Holland and France; but if the rate of power station closures without replacements coming on stream continues, then there certainly could be a ‘crunch’ point in a few years’ time.

It is the nature of those replacements, though, that ought to give us pause for thought, because we are no longer in a position nationally, where the ‘mix’ on the grid is that simple. Even after the recent Government announcements curtailing the development of renewable energy, there is already a vast amount of renewables on the system – about 13GW of offshore and onshore wind, and by next year, even after the effective ending of the solar FITs programme, about 10GW of solar of all shapes and sizes. That represents in size, about a quarter of Britain’s overall installed capacity.  The problem is that these installations are scattered across the country, and are all, to a greater or lesser degree, intermittent – they don’t generate all the time.

And this is where I think the storage question comes back at us. It is no longer really true that we cannot store electricity: in fact there have been short term storage schemes, using electricity generated in times of low demand to pump water uphill and release it downhill again to recreate electricity at peak times. But these are essentially ‘day balancing schemes’ and also lose a lot of electricity in the process.

What we can now do, increasingly effectively, is store electricity in batteries. Essentially the domestic rechargeable battery multiplied thousands of times in size, and using fast-developing technology that now really can present storage facilities at scale.  And this technology is particularly suited to the range of dispersed renewables we now have on the system. It is not that renewables do not generate well, but they often do so when the system doesn’t need their power – and it is therefore wasted. Attach battery storage to large windfarms, or solar field installations that are already there, and – hey presto – you have a much more reliable stream of output from the plant, and a substantial increase in overall available power. Do the same for smaller installations, and there is the prospect of a number of homes and buildings effectively taking themselves off the grid because, all in all, they make much lower demands for outside power.

Now I’m not saying that batteries will solve all our problems: we will undoubtedly need to combine new conventional power stations into the energy mix for many years to come, but I do think Government ought to get seriously behind the next stages of battery storage development. Battery power may well turn out to be that additional arm of reliable back up power that fills the gap between sufficient and insufficient capacity for winter demand – and by the way, it potentially flattens that demand if operated smartly in any event. And it may not need subsidies in operation to any great extent, because of the ability it has, at scale, to sell into the system at most advantageous points, and make its investment costs back fairly rapidly. That’s why I think Government ought to get seriously behind the next phase of storage development. It could literally have a very bright future as far as our lights/no lights debate is concerned.


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