## Highlights
- Climate change shows impacts on large-scale metrics of a European electricity system
- Largest climate impacts are observed within fully wind-dominated electricity systems
- 6 high-resolution CMIP5 GCMs under the forcing of three IPCC RCPs have been used
- State-of-the-art wind and solar capacity factors and electricity demand data were used
> ### Context & Scale
> Globally, electricity production from wind and solar sources is increasing significantly. The increase is primarily driven by lower costs and by political efforts to mitigate climate change. Climate change, however, may radically change the weather that drives these sources of renewable energy. We find that the impact of climate change on a future highly renewable European electricity system is up to 20% for a few key metrics when compared to corresponding numbers for a historical climate scenario. In most cases, however, the relative impact is an order of magnitude smaller. The level of impact is, in general, smaller than corresponding differences from one weather year to another and also compared to differences between system designs, e.g., with different levels of international power transmission lines or different mixes of wind and solar generators.
## Summary
Falling prices and significant technology developments currently drive an increased weather-dependent electricity production from renewables. In light of the changing climate^[https://www.sciencedirect.com/topics/engineering/changing-climate], it is relevant to investigate to what extent climate change directly impacts future highly weather-dependent electricity systems. Here, we use three IPCC CO2 concentration pathways for the period 2006–2100 with six high-resolution climate experiments for the European domain. Climate data are used to calculate bias-adjusted 3-hourly time series of wind and solar generation and temperature-corrected demand time series for 30 European countries using a state-of-the-art methodology. Weather-driven electricity system analysis is then applied to compare five key metrics of highly renewable electricity systems. We find that climate change changes the need for dispatchable electricity by up to 20%. The remaining key metrics, such as the benefit of transmission and storage as well as requirements for balancing capacity and reserves, change by up to 5%.
## Keywords
`climate projections`, `renewable electricity systems`, `climate change mitigation`, `dispatchable electricity`, `regional climate models`, `global climate models`, `wind power projection`, `solar power projection`, `electricity demand projection`
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## Results and Discussion
#### Table 1.
20-Year Average Values of the Normalized Wind 〈W〉~20yr~ and Solar 〈S〉~20yr~ Power and Electricity Consumption〈L〉~20yr~ for the European Domain
| | Historical | RCP2.6 | RCP4.5 | RCP8.5 |
|:-----------:|:-------------:|:-------------:|:-------------:|:-------------:|
| 〈W〉~20yr~ | 1.00 ± 0.03 | 0.98 ± 0.02 | 0.99 ± 0.04 | 0.96 ± 0.03 |
| 〈S〉~20yr~ | 1.00 ± 0.01 | 0.99 ± 0.02 | 0.98 ± 0.02 | 0.96 ± 0.03 |
| 〈L〉~20yr~ | 1.000 ± 0.005 | 0.995 ± 0.003 | 0.992 ± 0.005 | 0.986 ± 0.003 |
_One sigma standard deviations are shown after each value. All values have been normalized to the corresponding values calculated for the historical period._
## Conclusion
The different climate change scenarios show a modest impact on the key metrics that are representing the gross properties of a highly renewable European electricity system. On the supply side, both wind and solar power generation^[https://www.sciencedirect.com/topics/engineering/solar-power-generation] are affected in a way that generally reduces performance slightly as their average electricity output decreases and their variability increases with an increasing effect of climate change. Consequently, the most extreme impacts of climate change are observed within fully wind-dominated electricity systems. In this regime, the dispatchable electricity changes up to 20% of the historical values. Changes in the benefit of transmission and benefit of storage stay below 5% of historical values. Changes in the short-term variability stay below 3%.
An important consequence of these findings is that for most of the key metrics that are studied in this work, it is not required to take into account the effect of climate change on the VREs wind and solar when designing gross properties of future highly renewable electricity systems. However, other properties, e.g., siting of renewable generators and selection of conventional generators, are not studied in this work, and the impact of climate change remains inconclusive. The need for dispatchable electricity is influenced by climate change, in some cases, depending on the VRE composition in the electricity system.
In designing a future highly renewable electricity system that is robust against climate change, it is most important to focus on reaching a mixture of wind and solar power generation that minimizes the need for dispatchable electricity as the effect of climate change simulated by typical GCMs has a modest impact on the gross design properties of future highly renewable electricity systems. This suggests that, to first order, the gross character of highly renewable power system design solutions is not strongly affected by differences in climate produced by the current generation of GCMs under different IPCC RCP scenarios. Further investigations, however, are required to understand the quality of GCM representation of climate change in key meteorological properties and their impact on power system design in more sophisticated modeling frameworks.
> This modeling approach is easily adaptable to model large-scale features of highly renewable electricity systems in other parts of the world. Should a stronger sector coupling, in particular between the heating, cooling, and electricity sectors, become a reality, the demand-side impact of climate change would increase beyond what has been discussed in this study.
## Acknowledgments
The authors wish to express their gratitude to O.B. Christensen and F. Boberg from the Danish Meteorological Institute for their contribution to understanding the climate outcomes, for proofreading the final manuscript, and for supplying data from the regional climate model HIRHAM5. G. Nikulin from the Swedish Meteorological and Hydrological Institute is thanked for supplying data from the regional climate model RCA4. E. van Meijgaard from the Royal Netherlands Meteorological Institute is thanked for his thorough reading of the final manuscript on climate information and for supplying data from the regional climate model RACMO22E. P. Lenzen from the German Climate Computing Center is thanked for supplying data from the regional climate model CCLM4. Parts of the EURO-CORDEX climate data have been acquired via ESGF data nodes. Thanks to M. Victoria for a thorough proof reading. Thanks to Dr. I. Staffell for fruitful discussions. Thanks to Professor M. Greiner for fruitful discussions. Sincere thanks to M. Zvonic for providing valuable graphical inputs to the graphical abstract. Thanks to M.S. Hansen for her diligent proofreading of this paper. Thanks to H. Søndergaard for giving graphical inputs to supplemental figures. Finally, thanks to Aarhus University Research Foundation (AUFF) for funding S.K. with funding number AUFF-E-2015-FLS-7-26^[https://www.sciencedirect.com/science/article/pii/S2542435119300509#gs1]. H.L. acknowledges support from China Scholarship Council with grant number 201607940005^[https://www.sciencedirect.com/science/article/pii/S2542435119300509#gs2] and Idella Foundation Denmark with grant number 29392^[https://www.sciencedirect.com/science/article/pii/S2542435119300509#gs3]. G.B.A. was funded by the RE-INVEST project, which is supported by the Innovation Fund Denmark under grant number 6154-00022B^[https://www.sciencedirect.com/science/article/pii/S2542435119300509#gs4].
### Authors
1. Smail Kozarcanin
2. Hailiang Liu
3. Gorm Bruun Andresen
_Department of Engineering, Aarhus University, Aarhus 8000, Denmark_
### Declaration of Interests
The authors declare no competing interests.