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VIEWPOINT | ada gazette SPRING 2014


Engineering resilience into our infrastructure DAVID SMITH,CHIEF EXECUTIVE, ENERGY NETWORKSASSOCIATION (ENA)


Resilience is a priority for the energy networks and along with safety there is nothing that matters more to the companies that operate them than customers being able to rely on the supply of these vital services. Ten years ago, just as the Energy


Networks Association was being formed, the UK experienced its last major outage caused by a system failure. It was a rainy August rush hour and a fault on the network, followed by a second on the backup


resulted in widespread damage to the electricity distribution network across the country and meant that engineering works to reconnect some customers took many days. The Met Office has concluded


David Smith Chief Executive, ENA


system, caused parts of South London and North West Kent to be without power for half an hour. This is still the last time such an incident


occurred because the system itself failed. Preparedness for the energy networks is the bread and butter. Contingency and protections are built in and the day-to-day security of the network is paramount. We are fortunate to have a system that is


incredibly reliable and incidents such as the one in 2003 are not a regular occurrence. This is not something we should take for granted but it is also not something that some advanced Western countries could say with confidence.





Contingency and protections are built in and day-to-day security of the [electricity] network is paramount.


In recent months that resilience has been tested


and the affect of severe weather has been the focus of media and political attention. For the industry, it is always a terrible situation to have customers off supply and this is felt even more when the impact leaves people struggling without electricity for days. The severe weather experienced in December


2013 caused some of most significant and widespread damage to the electricity network in decades. The high winds coupled with heavy rainfall and flooding resulted in the loss of supply to hundreds of thousands of customers over the course of a 5-day incident. The frustration and difficulty this posed customers was further compounded by the storm hitting over the Christmas period. The severe weather seen in October and


December was some of the worst experienced in the UK in decades. A combination of storm force winds, heavy rainfall and significant flooding


that St Jude's Day storm, which hit on 28 October, was one of the top 10 storms in the last 40 years but lasted a relatively short period of time compared with those of December. What was unusual about it was the time of year and


its geographic position. Winds of those strengths are not uncommon on the West coast of Scotland or Northern Ireland but are rarely seen of this significance in Southern England. Furthermore, at that time of year many trees are in full leaf and are therefore more susceptible to being blown over than would usually be the case. This storm was


of this context. A huge amount of work went into getting people back on supply as quickly as possible. More than 90% of people being reconnected within 24 hours is a significant achievement and a tribute to the tireless work of the distribution networks staff over Christmas. Add to that, this was done without any injuries to either the workforce or the public, which shows you how far we have progressed in recent decades. Serious flooding in 2005 and 2007 showed that


more was needed to protect networks infrastructure. ENA set up a task group to look at this bringing in





What is clear from recent events is that no sector can rely on these rare and extreme events to be as uncommon as previously thought... Resilience and adaptation in the future are going to be as critical if not more so than our ability to deal with the incidents when they affect us.


geographically focused and the weather system moved on allowing engineering work to begin to reconnect people and mutual aid to be provided by other Distribution Network Operators (DNOs). There were three significant storm events over


the Christmas period on the 23-24, 27 and 29-30 December. Each of these events caused damage to the network and brought further wet conditions and flooding which hampered restoration efforts. The relentless and sustained bad weather throughout,





...more than 90% of people were reconnected within 24 hours is a significant achievement and a tribute to the tireless work of the distribution networks staff over Christmas.


coupled with multiple storm events and the continually flooded and blocked roads, meant that engineers had to battle extremely challenging conditions to make repairs and jobs will have taken longer to complete and move between. The Met Office data also shows that the


weather seen over Christmas made it the stormiest December since 1969, the wettest since 1910, and the windiest calendar month since January 1993. This context helps us to appreciate why the weather resulted in some of the most extensive and widespread damage to distribution infrastructure since the storm in October 1987, when over 2 million customers lost power with repairs running over two and a half weeks. There are clearly lessons to be learned from the recent experiences but we must also not lose sight


34 What is clear from recent events is that no sector


can rely on these rare and extreme events to be as uncommon as previously thought. Whether it is crumbling sea walls, river capacity, fallen power lines or train tracks washed into the sea, nature is laying a clear challenge to our infrastructure. Resilience and adaptation in the future are going to be as critical if not more so than our ability to deal with the incidents when they affect us.


Government, Ofgem, the Met Office and the various Environment Agencies around the UK as well as the team responsible for the Pitt Review. The Report was held up as exemplar by Defra. Work continues on this with further analysis of flood levels as part of climate change adaptation. The current price review period for the


electricity distribution networks earmarked specific investment for flood defences for substations and the outcome was a programme of works to protect from surface water flooding. Despite this having been the wettest December since 1910, with significant flooding risk where parts of the UK saw between 80-100mm of rainfall, no substations were adversely affected. However, the extreme weather has continued into January and February of this year, and that investment will once again be put the test.











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