By Paul Sheerin

I’m a bit worried, and I think you should be too.

In the testing times we live in, you might guess I am talking about the people of Ukraine, the value of UK sterling, interest rates, maybe my usual gripe about engineering skills – and I am deeply worried for all of these, but it’s not the topic I have in mind.

With winter only six weeks away, this disquiet is the risk to continuous supply of a commodity the UK has taken for granted for decades: our electrical energy supply.

Why the concern? In essence it’s the stacking of multiple risks, but the stand outs are our dependency on gas for electricity generation, a system safety margin that’s too thin even for this optimistic engineer, and a reliance that this contingency consists of energy imported via interconnectors from Europe.

The UK Government’s Digest of UK Energy Statistics (DUKES) shows that in 2021 40% of our electricity production came from gas, and whilst we have our own gas production, we remain dependent on imported supplies, and in large part from European partners who, in turn, are struggling with the withdrawal of Russian imports.

For our contingency, the National Grid’s Winter Outlook report outlines a swings and roundabouts capacity (they call it a de-rated generation capacity) of around 59GW (gigawatts), and an estimated average cold spell peak demand just 6.3% below that. The same figure from the equivalent report just a decade ago was 11.5% contingency and assumed no contribution from imports from interconnectors.

In the base case scenario for this winter’s outlook report, 5GW of that assumed electricity supply – more than 8% of the total – comes from interconnectors to Europe, assuming the low water levels for hydro generation in Norway improve, and the issues currently impacting the French nuclear generation fleet capacity are resolved at best and do not deteriorate at worst. Gas shortages in Europe would make their capacity to export power less likely, and the same gas shortage would impact our supplies, and potentially the 40% of power we generate from it.

The broad multiple risks get very granular very quickly: when we assume it’s cold are we modelling that the typical cold and calm combination reduces wind energy output sufficiently? What about when the wind is too windy?

When a closing gap between demand and supply can be forecast ahead, the Electricity Supply Emergency Code kicks in, starting with a public information campaign to reduce usage. If conditions deteriorate, communication becomes increasingly directive, instructing major users to cut demand, through to rota disconnections for all but the most essential users, as the System Operator seeks to maintain system stability. However, major incidents and interruptions on the supply side of the system cannot always be forecast and hence the notice period for moving through these stages could be uncomfortably short.

In the worst case, unforeseen demand surges or unplanned loss of major generation or transmission assets can lower the electrical system frequency to the point where automatic protection devices kick in to protect generating assets. In this case protection shuts down and disconnects that generation, further reducing supply capacity, and now we are in a consequential domino effect that can cause total power loss to parts or even all of the grid. That kind of power loss isn’t something that can be switched back on in minutes or hours: recovery here could be measured in days and, the more widespread the power loss, the greater the impact on functioning society. While still a low risk of occurrence for the UK, common sense says it’s more likely to happen, and more difficult to recover from, given the reduced flexibility and options the System Operator has at its disposal.

Whilst any outage is unwelcome, for industry and consumers a planned outage is infinitely better than unplanned. An aerospace part in mid-manufacture can scrap tens of thousands of pounds of material if supply is lost during machining, and any energy-intensive business flowing, forming or moulding materials at high temperatures could irreparably damage millions of pounds of equipment in an unforeseen loss of power. For that reason, businesses can apply to be exempt from forced electricity supply reductions if they meet one of three criteria: a national or regional critical need, public health and safety issues, or the potential for catastrophic damage to a high-value industrial plant.

One step before that, however, is what action can be taken to help keep the safety margin healthy, and an example is the new Demand Flexibility Service which incentivises businesses to reshape or eliminate their usage profile to avoid times where margins are tight. In fact, discussions with industry have voiced that cooperation with the electricity supply operator to avoid these impacts could go much further, but this is where we hit a bump in the road.

Absent is the leadership and communication from the top of UK Government – to both industry and consumers – that enables a conversation around how we can collectively work to avoid these potential impacts. It may not be a comfortable message to share on top of a few other challenges on their plates, but this conversation falls into the category of “bad news doesn’t get any better with age” and, at the risk of being dramatic, in the worst case there is a risk to public safety that can be reduced by having that conversation soonest.

December, and the start of winter, is only six weeks away: Mind The Gap.

Paul Sheerin is chief executive of Scottish Engineering