Climate change influencing the electricity network

Extreme weather conditions might increase failure rate

How will higher temperatures due to climate change influence the efficiency of electricity transmission and distribution? Last April, Nastaran Rahimi posed this interesting question in the Leonardo Energy forum. Stefan Fassbinder replied by making the rough estimate that a temperature rise of 2°C would increase network losses by 0.04% of the total throughput. This conclusion, if correct, is a fairly negligible effect compared to other network losses. The idea that ‘climate change increases network losses, increasing climate change in their turn’ does not hold.

This conclusion does not mean that climate change will have no influence on the electrical system. The main negative consequence will be operation and maintenance issues due to extreme weather conditions. A relatively small global temperature increase can change local climates, leading to a significant increase of days with potentially harmful extreme weather.

One such extreme condition is summer drought. Sergio Ferreira has already reported that in the summer of 2007, ‘several nuclear and other power plants had to be shut down due to very hot ambient and river water temperatures in Western Europe (particularly in France)’. A study in 2007 by the Finnish research institute VTT shows that many other climate issues could affect the reliability of the electrical system.

Extreme weather conditions affecting Finnish network

The study 'Recognizing climate change in electricity network design and construction' by VTT compares statistical data from the period 1961-1990 with projections by various climate models of the period 2016-2045 and examines the influence on the operation and maintenance of the electrical system in Finland.

The predicted average temperature increase in Finland of 0.5°C to 1.5°C would not have a significant influence on the electrical system. However, the resulting effect on the frequency of extreme weather conditions in the region should certainly be taken into account. Those extreme weather conditions would increase the failure rate of power lines, affecting the reliability of supply, in particular in remote regions where backup lines are few and the time-to-repair is long.

Four main negative influences

The paper described the following main influences for Finland:

1) Temperature rise will increase precipitation in Finland. In winter, an increase in ‘maximum snow precipitation’ (quantity of snow in a period of 6 hours) is to be expected. This would lead to more severe snow and ice accretion on power line structures.

2) Temperature rise results in an increase in thunder storms and consequently lighting strikes on power lines.

3) Periods with unfrozen ground will increase. This has the positive effect that it facilitates working at underground lines during a longer period of the year. However, it will increase the frequency of weather conditions combining high wind speeds, snow, and unfrozen ground. Such a combination bears a high risk of falling trees, possibly damaging power lines.

4) An increase of days with temperatures of 30°C and more. Distribution transformers in Finland are calculated for an ambient temperature of 20°C corresponding with a transformer hot spot of 98°C. Ambient temperatures of above 30°C leading to hot spots of more than 110°C would seriously affect the life expectancy of those transformers.

Vital information for design and maintenance plans

The combination of the four main negative influences as well as a few other minor effects could increase the failure rate of overhead lines in Finland. These influences should consequently be taken into account when drawing maintenance and development plans for the electrical network in Finland for the period covering the next 30 years. Fortunately enough, all four of those influences can be minimised by measures in the design and maintenance of the network, though it indeed comes with an investment cost.

Those conclusions of the VTT research study do, of course, only count for the regional situation in Finland. However, it is not difficult to imagine that other countries will also be subject to an increase in extreme weather situations influencing the reliability of the electrical system.

References

• Paper 'Recognizing climate change in electricity network design and construction' by VTT, Finland 2007
• Post 'Global warming effects on electricity transmission and distribution losses' + comments