The UK's electricity network is affected by faults caused by weather such as lightning, snow and high winds. In this study, we looked at the present-day resilience of the network to weather and, using projections of regional climate change, estimated how the frequency of these faults may change in the future. Lynsey McColl, Climate Change Consultant at the Met Office explains:
Over the last few years, the Met Office has worked closely with leading energy companies to explore the potential impacts of climate change on the UK's energy industry.In this latest study, we investigated how climate change could affect the frequency of weather-related faults on both the transmission and distribution networks.
The first step was to understand the sensitivity of the networks to weather, which we analysed using historical weather-related faults and weather records. We then used projections from the Met Office Hadley Centre Regional Climate Model to assess how the frequency of these faults may change in the future (assuming no adaptation policy and no change in the weather-to-fault relationship).
By combining the knowledge of our climate scientists with industry experts' understanding of thresholds and procedures in this way, the UK is in a better position to manage the impact of the weather and climate on the electricity network - now and in the future.
There are two stages in transferring electrical energy from generating power plants to individual consumers:
The electricity is first transferred on a high-voltage transmission network from the power plants to substations near to population centres. Then, the distribution network transforms the electricity to a lower voltage and transfers it between the substations and consumers.
Both networks are largely made up of overhead power lines, underground cables,substations and transformers. Both are affected by faults which can be attributed to a variety of causes such as age or deterioration of equipment, fire, interference by third parties, and the weather.
Our study showed there were five major weather-related faults on the UK's electricity network: wind and gale, snow, sleet and blizzard (SSB), lightning, solar heat, and flooding.
For the transmission network, our study found that the type of weather-related fault which caused the greatest problems varied from year to year. But when we looked at the distribution network, more of a pattern emerged. Wind and gale faults tended to occur most frequently, followed by lightning faults, then SSB faults.
The three main faults also exhibited seasonality, with lightning faults dominating in the summer months (June, July, August); and SSB along with wind and gale faults occurring more frequently in the winter months (December, January, February).
In addition, we found that flooding faults could occur at any time of the year, while solar heat faults only occurred in the months of April to September.
Our main objective was to understand how these faults may change in the future. The key findings are summarised below:
Wind and gale - these faults are caused by high winds or gusts and predominantly affect overhead power lines. Faults can be exacerbated by trees and debris being blown on to the lines which, in turn, is affected by the length of the growing season and the schedule of maintenance work carried out on the trees. In coastal areas, wind and a lack of rain can lead to salt accretion on lines and faults occurring, while in other areas the speed of the wind and consequent damage to power lines is greatly affected by the landscape and height above sea level. Future projections of wind and gale faults indicate that they may remain the same, increase, or decrease in the future, due to uncertainty in wind gust projections.
Snow, sleet and blizzard (SSB) - these faults are caused by a combination of snow and high-wind gusts which can cause ice to accrete on the lines. SSB faults may decrease in the future due to less days of snow, but when it does snow the intensity of the event may be the same or increase.
Lightning - these faults are usually caused by cloud-to-ground lightning. They are projected to occur more often in future due to an increase in days with stronger convection.
Solar heat - these faults are rare as network equipment is built to be resilient to high temperatures. They occur when the temperature is high and the wind speed is low and can be exacerbated by the urban heat island effect - when a town or city is significantly warmer than its surroundings. The incidence of solar heat faults is projected to increase throughout the UK, due to projected increases in maximum temperatures.
By transforming climate projections into weather-related fault information, we aimed to provide the industry with information that can be used to help prioritise which adaptation measures to implement and when.
For example, given the projected increase in lightning faults, one possible adaptation option would be to increase the number of lightning arrestors on the electricity network. Arrestors protect the insulations on the network by diverting the current from a lightning strike or surge around the insulation to the ground.
Although applied specifically to the UK electricity network, these techniques are transferable and could be applied to networks in other countries (if sufficient data were available) and potentially different types of infrastructure that suffer from weather-related faults.