From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

The Telegraph has reported that even NESO are now warning about potential blackouts:

The grid operator has raised concerns that the switch from dependable gas to intermittent wind and solar power would “reduce network stability” and said the cost to taxpayers of funding measures to prevent the system crashing was set to “increase significantly” to £1 billion a year.

https://www.telegraph.co.uk/news/2025/05/10/britain-blackouts-net-zero-ed-miliband

But even now they are still underestimating the size of the problem. Here is what the power engineering expert, Capell Aris, wrote in the Telegraph last week:

Last Monday, the Iberian grid suffered a disturbance in the south-west at 12:33. In 3.5 seconds this worsened and the interconnection to France disconnected. All renewable generation then went off-line, followed by disconnection of all rotating generation plant. The Iberian blackout was complete within a few seconds.

At the time the grid was producing 28.4 GW of power, of which 79 per cent was solar and wind. This was a problematic situation as solar and wind plants have another, not widely known, downside – one quite apart from their intermittency and expense.

This is the fact that they do not supply any inertia to the grid. Thermal powerplants – coal, gas, nuclear, for example – drive large spinning generators which are directly, synchronously connected to the grid. If there are changes which cause a difference between demand and supply, the generators will start to spin faster or slower: but their inertia resists this process, meaning that the frequency of the alternating current in the grid changes only slowly. There is time for the grid managers to act, matching supply to demand and keeping the grid frequency within limits………..

But there are places where things are worse. The UK and Ireland are island grids. They do have undersea power interconnectors to Europe but these are non-synchronous DC links and transmit no grid inertia. There’s little prospect that this will change.

Nowadays, 55 per cent of our generation mix (wind, solar, DC imports) cannot supply inertia to the grid. Are we approaching a system that compares with Spain and Portugal on Monday?

It certainly looks that way. In 2012 the National Grid produced a solar briefing note for the government which is still available online. In that note they imagine a system that has 22 GW of solar power attached to the grid. They demonstrate their concerns based on a sunny summer day when demand is low. The sun rises at 5 o’clock when little or no synchronous plant other than nuclear generation will be on line and at midday, solar is 60 per cent of all generation. The Grid’s engineers then considered that situation “difficult to manage” and concluded that wind+solar power must never exceed 60 per cent of generation.

We now have 17.7 GW of grid-connected solar farms to which we must add all rooftop solar installations. At midday on Tuesday according to Gridwatch the UK’s asynchronous, no-inertia generation was at 66 per cent of total generation.

After nearly 50 years of operation, Dinorwig Power Station is currently shut down for major repairs and there has been no information on when it will re-open. Over the next five years all of our nuclear stations, bar Sizewell, will be closed. Over the same period our combined cycle gas generator fleet will halve from 30 GW to 15 GW. (It takes 5 years to build a new CCGT even using an existing site. The new ones are 66 per cent efficient and cost less than £1 billion to build a 1 GW plant – one third the cost of an offshore windmill.)

We will lose huge amounts of grid inertia. Low-inertia operation will become routine. It is hard to imagine that we won’t start to suffer complete national blackouts like the Iberian one.

One last piece of doom: the recovery of Spain’s grid in just one day is impressive. This speed is certainly due to the assistance of a large, stable grid reconnecting into the Iberian system thus allowing recovery in a series of stable steps as each grid area is recovered. We will not have that facility in the UK with our asynchronous interconnectors.

Read the full story here.

Flywheels

One final comment.

There has been talk that the army of giant flywheels Miliband is planning to instal at a cost of billions will replace the inertial from nuclear and gas plants.

It won’t, not totally anyway.

Flywheels run on electricity, so as soon as this is turned off the flywheels will quickly stop as well. This may allow enough time for grid engineers to react in an emergency, the grid also needs that inertia maintaining, which only the likes of gas and nuclear can provide.