by Lord Toby Harris


On 5th December 2015, Storm Desmond caused the River Lune to flood and to swamp the electrical sub-station serving the city of Lancaster.  As a result, more than 60,000 homes and businesses, and at least 100,000 people, were left without electricity for four days.

Not surprisingly the impact on the city was substantial: transport was disrupted; ATM machines went out of action; garages were unable to dispense fuel as their pumps needed electricity to operate; traffic lights stopped working; the train station had to close; and text messaging, digital radio and the internet ceased to be available.

75 emergency generators had to be brought to Lancaster from as far away as the south-west and across from Northern Ireland in order to restore some electric supplies.

However, as the Royal Academy of Engineering noted in their review of the incident, this was a “comparatively localised area” and one which was “manageable in size”.  In a much larger area or locality with a much bigger population such arrangements would not have worked.

But what would it mean if the outage covered a much wider area – perhaps even the whole country?

The Government view is that such a power failure is a low probability but plausible scenario.  And it is clearly one with a very high impact.

So what might trigger such an event? 

Some potential causes are natural.  The UK is not in an earthquake zone, but in principle a major seismic event could cause this level of disruption (and much more besides).  Similarly, the UK tends not to suffer hurricanes but the severe weather we do get can cause major disruption to power supplies (as Lancaster discovered). 

We should also not ignore extreme space weather: coronal mass ejections do reach the Earth and, when they do, lead to electrical systems burning out and malfunctioning.

Then there are malign attacks on our electricity infrastructure, such as a concerted physical assault (perhaps by terrorists) on key nodes within the electricity grid.

This would be difficult and require substantial hostile manpower, but in July 1996 an IRA plot involving 37 explosive devices designed to destroy the six sub-stations providing London’s electricity was disrupted, and the bombers arrested.

Perhaps worryingly plausible would be a cyber attack.  This has happened to the Ukraine and the US Department of Defense Science Board has reported that the US grid had been so effectively penetrated by Russian and Chinese hackers that either country could switch off US electricity supplies at will (and it would take a decade to secure the system against such an attack).  There is little reason to suppose our systems are more secure than they are in the US.

The Lancaster incident was described – as so many such incidents are - as a once-in-a-hundred-years event.  However, it highlighted the inter-connected nature of our critical systems and our reliance on electric power to make them work and society function.

Of course, much of the critical national infrastructure and many key businesses have some emergency generators available in the event of a power failure.  But is that capacity sufficient?  And will it work when required? 

Emergency generators tend not to be tested as to do so may require that the usual main system be cut off temporarily disrupting day-to-day activities. 

Moreover, even if the emergency generators do work when required, they are often not designed to work for prolonged periods, so the question is how long will they function before they break down?  And all of that assumes that there will be sufficient diesel fuel available to keep them going.

And if the power does go off, some services would of course stop being provided.  Schools, for example, would close which would mean that many parents would have to stay at home to look after their children.

How many hospitals would function if their electricity supply is disrupted?  Presumably only those with functioning emergency generators would be able to continue and even then it will depend on staff continuing to be available for work.

Another critical area is water.  How long could fresh water be guaranteed?  This will depend on proximity to a reservoir and how full that reservoir is.  Buildings over two or three storeys would need pumps to get the water to the higher levels. And for how long would waste water and sewage be removed and treated? 

A city or town without fresh water or where waste water and sewage cannot be removed rapidly becomes uninhabitable.

In a similar vein, how long could communications systems be maintained?  Domestic and business landlines require electric power – the days of low voltage telephony are long passed.  We all use mobile communications devices, but these have to be charged.  And in any event how long will cell-phone masts continue to operate in the absence of power? (Spoiler alert: it is two to four hours.)

Domestic refrigerators and freezers will stop working, as will those in small retailers.  How long will those in major supermarket outlets last?  And in these days of just-in-time deliveries, how well will wholesale supplies hold up assuming that the distribution network itself is still able to function?

In Lancaster the ATMs stopped working, so how long would the financial system continue to function?

MI5 famously reported in 2004 that the UK was “four meals away from anarchy”.  It does not take much to imagine the implications for civil order of the sort of disruption to food supplies that would ensue from the events that we are talking about here.  And we know from riots of 2011 how easily the thin blue line of police can be overwhelmed.

So how well prepared is your own organisation for a power failure?  Do you have a back up power supply?  If you do, when was your emergency generator last tested and what supplies of diesel fuel do you have?

Most organisations will have some sort of contingency plan. However, to what extent do those plans assume that the rest of the infrastructure is functioning: that telephony still works; that internet-based systems can still be accessed; that there will still be water and food; that transportation systems operate; and so on.

While our electricity grid and its distribution system is amongst the most robust in the world, we all still need to plan for the unexpected and to ensure that we and our own organisation is resilient enough that in the event of a power failure we will get through it and be able to recover.


Lord Harris is the UK Coordinator of the Electrical Infrastructure Security Council​​​​​​ and a member of the Joint Committee on National Security Strategy.