Last February, Europe faced Siberian winter weather, challenging its energy production systems in meeting the unexpected boom in electricity demand. A good opportunity to speak with Dr. Matthias Piot and Dr. Christoph Elsässer, two meteorologists at EnBW, one of the top German energy providers, and S2S4E project partner.
S2S4E. Could a country like Germany (and its current electric system) support extreme cold weather like we faced last February?
Matthias Piot. To this question, the answer is obviously yes! Germany has some 190 GW of installed capacity altogether. According to internal data, the total German power demand did not exceed 85 GW during this past February cold event. Even when adding extra demand from interconnectors (country-to-country power flows), the country remained well below critical thresholds.
Christoph Elsässer. The question whether the German energy supply meets demand is also strongly linked to renewable power production. This can be highlighted by comparing the two different cold spells in February 2018 and January 2017. In January 2017, the German power system underwent a cold spell with daily temperatures averaging -3 to -5°C over several days. This weather pattern combined low wind (less than 5GW on daily average power production), low solar production (daily peak power production below 5GW), and depleted hydro power levels. As a result, we saw German power prices rising up to 85€/MWh: January 2017 has been the most expensive month in five years! Temperatures this past February displayed even colder temperature levels than in January 2017, but the renewable production in Germany was above normal level. German wind power production increased up to 30 GW at the end of the month, while the combination between solar and wind peaked around 48 GW. Power prices in February 2018 did not exceed 50€/MWh on a daily basis.
S2S4E. Did the electricity demand and production reach its highest level? If yes, which level?
Matthias Piot. It is important to note that the cold event in February 2012 remains the reference for record power demand. France recorded 102.1 GW of peak demand, and it was the first time ever over the magic threshold of 100 GW! The cold outbreak in February this year was indeed the coldest event of this winter.
Christoph Elsässer. The absolute level is quite difficult to assess. However, temperature is a crucial parameter affecting the power demand. From a climatologist’s perspective, extremely cold events are rare but certainly do occur from time to time, and they are in no way unprecedented.
S2S4E. Are renewables reliable sources in this case? For instance, how can we use solar energy when it’s snowing and freezing?
Matthias Piot. Basically, freezing has a very limited impact on solar production. For example, the German solar production topped at 16-18 GW during the cold spell, which are high values for this time of the year. Snow has a much deeper impact on solar production. To the best of my knowledge and considering past events, snow may be responsible for a production reduction around 40 to 50% compared to snow-free conditions. Thus, snow is a high-risk factor that may induce direct market reactions.
Christoph Elsässer. Weather theory tells us that cold winter events may be more often accompanied by lower wind power, while solar levels are low either way in December and January. However, this February event shows that this is not always the case.
S2S4E. As an energy provider, how do you think a project like S2S4E can help forecast electricity demand and production during extreme cold events?
Matthias Piot. According to our analyses this cold spell was triggered by the polar vortex split in the stratosphere, also called ‘sudden stratospheric warming’ (SPV-split), which led to a ‘blocking situation’ and to cold north-easterly winds towards Europe. SPV-splits are well-known phenomena and can be modelled. For example, if S2S4E is able to better characterise the risk of SPV-splits on a sub-seasonal scale, it would create a clear added value. The same remains valid for other weather indices like NAO (North Atlantic Oscillation), AO (Arctic Oscillation), MJO (Madden-Julian Oscillation) or ENSO (El Niño Southern Oscillation).
Christoph Elsässer. From my personal perspective, sub-seasonal to seasonal forecasts (S2S) may provide the basic weather direction, but are not suitable to directly forecast extreme events in detail. However, energy markets are quite used to dealing with statistics and S2S decision-making: for example, power and commodity hedging or storage facility management will be definitively improved with enhanced S2S forecasts!
Written by Mathilde Bazin-Retours/ LGI.