Winters in north-western Europe have been becoming milder on average in recent decades, which is consistent with the trend of global warming observed and documented worldwide. Both average as well as extreme temperatures have shifted to higher ranges as a symptom of this warming. Since electricity demand in north-western Europe is well-known to peak during the coldest periods, this warming trend is likely to have important implications for power systems.
In this study, we analysed observed weather data at daily resolution over Belgium (and its neighbouring countries) for the period 1980-2019 to assess the (change in) occurrence of extremely cold days. We compared this temperature information with the occurrence of Loss of Load Expectation (LOLE – moments when power demand exceeds the available capacity) as simulated in power market and adequacy modelling by Belgium’s transmission system operator, based on the country’s expected 2025 power mix and historical (1982-2015) weather conditions. We conclude that (i) there is a high degree of co-occurrence of simulated persistent LOLE events with extremely cold days, and (ii) the probability of such extremely cold days has shown robust decreases across Belgium (and its neighbouring countries) since the 1980s.
Based on this analysis, we advise that whenever simulations on power system adequacy are undertaken to support future peak generating capacity planning, such assessments should account for climate change effects on the meteorological data used for the simulations, for instance through sensitivity tests regarding the choice of time period. Considering the robust warming trend observed in recent decades, simulations based on weather data that is no longer representative of the current (and future) climate may result in unrealistic estimations.
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