Considering the targets of the Paris agreement, rapid decarbonisation of the power system is needed. In order to study cost-optimal and reliable zero and negative carbon power systems, a power system model of Western Europe for 2050 is developed. Realistic future technology costs, demand levels and generator flexibility constraints are considered. The optimised portfolios are tested for both favourable and unfavourable future weather conditions using results from a global climate model, accounting for the potential impacts of climate change on Europe's weather. The cost optimal mix for zero or negative carbon power systems consists of firm low-carbon capacity, intermittent renewable energy sources and flexibility capacity. In most scenarios, the amount of low-carbon firm capacity is around 75% of peak load, providing roughly 65% of the electricity demand. Furthermore, it is found that with a high penetration of intermittent renewable energy sources, a high dependence on cross border transmission, batteries and a shift to new types of ancillary services is required to maintain a reliable power system. Despite relatively small changes in the total generation from intermittent renewable energy sources between favourable and unfavourable weather years of 6%, emissions differ up to 70 MtCO2 yr−1 and variable systems costs up to 25%. In a highly interconnected power system with significant flexible capacity in the portfolio and minimal curtailment of intermittent renewables, the potential role of green hydrogen as a means of electricity storage appears to be limited.@en

The impact of both climate change and climate variability on the supply of intermittent renewable energy sources (I-RES) in Europe are assessed based on global climate model simulations. The main driver of climate variability over Europe is the North Atlantic Oscillation (NAO) in winter and its equivalent in summer (sNAO) which determine to a large extent the atmospheric circulation in Europe. Four climate scenarios are constructed distinguished by a moderate and strong increase of the average global surface temperature, and a positive and negative phase of the atmospheric variability over the North Atlantic and Europe. This spans a framework which combines the effects of both climate change and climate variability. Using a 2050 distribution of PV panels and wind turbines, we found that although climate change is likely to have significant impact on future I-RES output in Europe, its effects, especially for wind power, are outweighed by the high and strongly variable impact of the NAO/sNAO phases. Variability in the large-scale atmospheric circulation is able to induce median I-RES yield differences of 20–30% for high wind potential regions. Due to the NAO variability also months were identified with persistent calm conditions over Europe linked to the inflow of frigid arctic air resulting in some regions in a decrease in wind power of up to 75%a accompanied with an increase in heating degree days of up to 30%. The results of the study imply that if requirements for the power system including back up capacity take into account the weather variability, the power system can also cope with the climate change impacts.@en