Despite claims to the contrary, the first task of the agencies involved in the UK power outage yesterday will have been to cover their backs and, if necessary, lay blame somewhere else. So it is that a story emerged that it was a freak accident coincidentally affecting two separate generators. As the BBC reported:

“The power outage happened at about 17:00 BST on Friday, National Grid said, with blackouts across the Midlands, the South East, South West, North West and north east of England, and Wales.

“Industry experts said that a gas-fired power station at Little Barford, Bedfordshire, failed at 16.58, followed two minutes later by the Hornsea offshore wind farm disconnecting from the grid.”

The almost simultaneous failure of two power generators, which took nearly 2GW offline, was presented by National Grid as so unusual an event that it triggered automated emergency shutdowns to balance supply and demand:

“Speaking to BBC Radio 4’s Today programme, Mr Burt acknowledged the ‘immense disruption’ the blackout had caused.

“He said the near-simultaneous loss of two generators was more than the grid was routinely prepared for, prompting automatic safety systems to shut off power to some places.

“’We think that worked well, we think the safety protection systems across the industry on generators and on the network worked well to secure and keep the grid safe, to make sure that we preserved power to the vast proportion of the country,’ he said.

“But he said the industry needed to examine whether these safety systems were set up correctly to have “minimal impact” on people’s daily lives.”

The safety protection systems referred to here, include a national scheme to disconnect large industrial power consumers during periods when demand outstrips supply. The aim of the scheme is to prevent power outages from spilling over to ordinary households. Clearly on this was insufficient, since several million households across England and Wales were left without electricity in the busy rush hour/tea time period.

As neat official stories go, it is good. Extreme circumstances that nobody could reasonably be expected to anticipate temporarily halted normal operations; but the safety systems worked; albeit at the cost of inconveniencing people… something from which lessons will be learned.

The problem with the official story, though, is that the timings simply do not match what actually happened. Evidence for this was originally included in the BBC reporting (which is where I obtained it) but has since been dropped. It tells a somewhat different story.

The BBC originally linked to this graph from EnAppSys – a company that provides real time data to the UK electricity market:

The original cause of the power outage is clearly visible. Just before 17:00 there was a massive drop in grid frequency. In the UK, electrical frequency is maintained at or very near 50 Hz – the output of a two pole generator running at 3,000 RPM. It is this consistency of supply that provides us with safe electricity. Too big a deviation from 50 Hz would result in electrical devices being fried. So when frequency drops (or rises) suddenly, the Grid operators have to act fast to restore it.

When frequency drops in the way the EnAppSys graph shows, it is either because there has been a sudden and unusually high increase in demand or – more likely in this case – a sudden and unexpected loss of supply. This would be consistent with the official story except for one key detail that is not immediately obvious in the EnAppSys chart:

Remember that electricity transmission is almost instantaneous. The electrons that allow me to type this article were generated less than a second ago. A massive drop in frequency at 16:54 simply cannot be explained by two power stations going offline at 16:58.

One obvious answer is that EnAppSys have their timings wrong. What they are actually showing is the sudden loss of power from the two power stations, but the timings on their graph are four minutes out. This would be a reasonable explanation if this was the only chart of its kind. However, Devrim Celal, Chief Executive Officer at Upside Energy, has posted similar charts with identical timings:

Indeed, because Celal’s charts cover the much shorter time period 16:45 to 17:15, not only do we see the initial collapse in both power and frequency at 16:54, but also the much smaller drop corresponding to the official story at 16:58:

We are left with two options here. First, some yet-to-be-explained massive drop in power supply occurred at 16:53, resulting in a collapse in frequency across the Grid at 16:54; but this had no impact on the operation of the Grid. However, four minutes later the entirely coincidental loss of nearly 2GW of power, which resulted in a much smaller loss of frequency was sufficient to trigger the Grid’s automatic safety system; causing a widespread blackout across England and Wales.

Alternatively (and I accept, this is speculation) might it be that the Hornsea offshore wind farm was taken offline due to bad weather conditions in the North Sea at 16:53? If so, that would explain both the power and frequency loss. Not only would the loss of Hornsea result in the loss of 1.2GW of power; but the lack of inertia (i.e. tons of spinning turbines) would explain the cliff edge drop in frequency. Ordinarily, this situation would be compensated by ramping up production from one or more of the UK’s combined cycle gas turbine power plants (which are able designed to rapidly respond to changes in supply and demand). Could it be that one of the CCGT stations that was meant to compensate for the loss of Hornsea – Little Barford – failed either coincidentally or as a result of the additional load at 16:58?

This might explain the somewhat cryptic statements – also in the BBC article – by the Little Barford owner RWE and Hornsea owner Orsted:

“RWE, owner of the Little Barford power station, said it shut down temporarily as a routine response to a technical issue, and called for National Grid and Ofgem to investigate the ‘wider system issues’.

And Orsted, the owner of the Hornsea offshore wind farm, said automatic systems on Hornsea One ‘significantly reduced’ power around the same time others failed.”

Note the precise wording “around the same time” is not the same as “at the same time” or “just after.” And what, exactly, are those “wider system issues” that RWE – which is currently shutting down fossil fuel plants because of their high costs in a system that prioritises wind power – is referring to?

Certainly one reason why the various players involved would want to gloss over an earlier (16:53) failure of the Hornsea offshore wind farm – which is merely the first of a multi-billion pound three-stage development which will eventually supply 4GW to the Grid – is that it would be devastating for an offshore wind industry that the UK is gambling much of its future on. Relatively concentrated wind generation can certainly provide a lot of power, but it also leaves the grid highly vulnerable if it unexpectedly fails or is taken offline too rapidly. As David Hunter, an energy analyst at Schneider Electric told the Independent:

“… the scale of disruption should act as a ‘wake-up call’ for National Grid, as well as for businesses, hospitals and critical national infrastructure to ensure they have fail-safes in place…

“National Grid must ensure that its processes for very quick frequency response and backup power generation are being operated exactly as they should.

“He said there was a ‘very high percentage’ of wind generation on Friday, and that it was not as effective at absorbing sudden fluctuations in frequency as gas, coal and nuclear power.

“Mr Hunter added: ‘The growing wind part of the energy mix creates challenges that the National Grid must demonstrate it can meet’.”

In the absence of widespread storage options – which themselves come at a huge cost in both money and resources – so-called “Demand Side Reduction” (DSR) is the only option available to the Grid operators. The problem, however, for a non-manufacturing economy like the UK, is that there are only a handful of major industrial consumers who can be taken out in a managed shutdown before chaos begins to spread.

One question the media has so far failed to ask of National Grid is whether Network Rail (the UK’s rail infrastructure operator) is one of the large industrial users in the DSR scheme. If so, that would explain why a large part of Britain’s railway system was still without power several hours after National Grid claimed to have resolved the problem. Note also that even with the railways shutdown, millions of households, public services and small businesses were also affected.

Earlier yesterday, green energy enthusiasts had pointed gleefully to the 58 percent of UK electricity that was being generated with “renewables”. We will, of course, have to wait for the technical appendices to the Ofgem/National Grid investigation report to see whether it was this excess wind power that triggered yesterday’s event. Nevertheless, the event was in line with the many warnings that have been made about deploying too many wind farms before the Grid has been upgraded to accommodate them. What happened in the minutes and hours after 16:53 yesterday afternoon is an indication of what we can expect if even more wind turbines and solar panels are deployed unless and until Grid scale storage can be deployed to prevent a sudden loss of power and frequency taking a large part of the Grid – and the wider economy – down.

As you made it to the end…

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