The fading dream of reliable power

  • Date: 21/10/19

Even an expensive reliable grid may now be beyond us

Back in August, a major power cut blacked out something like a million consumers in the south of England for the best part of an hour. The official reports into the power cut (and there have been several) beat around the bush quite a lot, but if you read the appendices and the footnotes you can see that the grid now has a major problem with something called “inertia”. Back in the old days, massive steam turbines, fired with coal, were the backbone of the grid. This had the advantage that if there was a loss of supply because of a fault on the grid, the huge rotating masses of the remaining power stations represented a store of energy large enough to make up the shortfall, at least for a short time. That meant that the impact of faults was felt rather slowly, giving grid managers a bit of time to react. Unfortunately, in the brave (some would say reckless) new world of renewables, much of our electricity comes from wind turbines, solar panels and interconnectors, which provide no inertia at all. We still get a bit from biomass and gas turbines and the remaining nuclear power stations, but not enough, and the net result is that many faults on the grid now cause a loss of power that is so fast that there is no time to react. This means that any fault will tend to cascade across the network, causing a major blackout, of the kind seen in August.

The public comments of grid managers are guarded, but in more specialised fora, they are slightly more forthcoming. Fintan Slye, the head of the system operator, recently told an industry conference that “inertia will become much more important in the years to come”, which is undoubtedly true, with the political establishment ploughing on with their multi-trillion pound project to decarbonise the economy entirely. Whether it is possible to deliver a grid that will support the politicians’ madcap scheme is far from clear, and Slye seems to be hoping that companies in the field can come up with new technologies that will help. But whatever happens, it is going to be expensive. Slye seems to be looking for a mandate to throw cost considerations out of the window, noting that the grid currently makes decisions “based on economics rather than carbon emissions”. There is a balance to be struck between resilience and cost, he notes.

In other words, the days of an electricity supply that is both cheap and reliable are behind us. But it may be worse than that. As a recent report from analysts Cornwall Insight suggests, “It is uncertain whether any of the proposed changes will fundamentally resolve the issues that come with increased renewables on the system”. So even an expensive and reliable electricity may be beyond us.

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