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Grid-scale electricity storage

Mike Woolgar | 01 Jun 2015 | Comments

I read an article recently that said the UK could cut the cost of decarbonising its electricity supply by more than £3.5bn if it can create a grid-scale electricity storage system to balance the variable output of renewables.

It is clear that the benefits – both carbon and economic – of non-base load generation through wind, solar or other intermittent renewables can be optimised if excess generation from these sources can be stored for later use. In the absence of such storage, any excess energy generated at any point in time will be wasted and the need for sufficient base load when the intermittent supplies are not working remains, suggesting that more capital will be spent on systems backing each other up than would be the case in the absence of intermittent supplies.

The existence of significant interlinks with other major generation/transmission systems in Europe acts to some extent to even out supply and demand but as we increase the capacity of wind energy installations in particular there will come a time when such balancing will not work. Hence the need for some form of storage.

The use of pumped storage linked to wind farms is an obvious potential match and several schemes have been mooted, looking to take advantage of the potential peak prices available to offset the cost of the capital required for the joint system. The fact that in this country to date none has reached financial close is indicative of the probable mismatch currently between the costs plus risks and the revenues. Probably also indicative of the historical mismatch in incentives between wind/solar and “conventional” sources of energy. Unless the policy aspects of incentives are resolved appropriately, storage – whether by pumped storage systems, compressed hydrogen, the Dutch energy train system or any other storage – will probably continue to lag renewables installation leading to a likely over investment compared to a nominal optimum.