Nearly one million homes and businesses were left without power on 9 August after a gas-fired power plant and wind farm both went offline, triggering the UK grid’s fail-safe measures.
Chaos subsequently hit the railways and some airports, as signals and terminal power went down for about two hours.
An in-depth investigation into what truly went wrong is still under way and is expected to last several weeks, with preliminary findings due out this week.
While National Grid called the event “highly unusual” and “without precedent”, in what has been dubbed the worst blackout in a decade, its impact actually goes beyond the UK’s shores.
As part of the European Union’s efforts to guarantee energy supply, reduce reliance on geopolitically toxic imports and decarbonise the bloc’s ecological footprint, an overarching strategy known as the Energy Union was launched in 2015.
That involved increasing the scope of collaboration between countries on power management, reforming energy market rules and rethinking how the EU wants to keep the lights on in the years to come.
Four years later, the outgoing Commission concluded in April that the Union had largely been completed, thanks to a raft of new energy laws that will govern renewables and efficiency measures, as well as new pipelines and cables.
Interconnectors are a big part of the energy plan, as they are supposed to allow clean power to make its way across the EU to where it is needed and help countries make their energy supply more robust.
In an ideal scenario, surplus cheap and clean wind power generated in Portugal would be able to be utilised in Finland, for example.
But the UK blackout has revealed that National Grid has been restricting the use of three of the cross-Channel cables that it co-owns, reportedly to limit the risk of power cuts if any of the interconnectors were to trip.
The company has 4 gigawatts of continental power on its books, which according to a National Grid source, is regularly limited to under 75 per cent of each cable’s capacity when there is an increased risk of failure. UK power needs top the 32GW mark.
Firms are actually paid not to use the continental electricity supplied by the interconnectors and the costs are then passed on to bill payers.
Blackouts can be caused when there is a lack of inertia in the grid provided by the facilities generating electricity, which is particularly true of renewable energy sources like solar and wind, as they lack the large turbines of traditional power plants.
Inertia affects the grid’s frequency, which is supposed to stay as close to a standard 50Hz. A significant deviation away from 50Hz will activate fail-safes.
In early 2018, digital clocks linked to the grid’s frequency were showing an incorrect time after a power dispute between Serbia and Kosovo meant the reading dropped to 49.996Hz, illustrating how delicate the electricity network can be.
Relying too heavily on imported electricity, without a modern grid to handle the worst-case scenario, is a risk that the UK’s electrical network is at least aware of.
The UK’s odd relationship with its partners across the Channel, painfully mirrored by its protracted attempts to sever ties with the EU, looks set to continue in the energy sector too, as more interconnectors are on the way.
Undersea cables are in the works that will increase capacity by more than 3GW, by linking the UK grid to Denmark, Norway and increasing flows to and from France.
If management policy of limiting how much power can actually be used by domestic consumers continues, rather than updating the grid to be better suited to a world of green power and flexible energy needs, a truly interconnected European grid will remain a pipe dream.