From Sweden to the world: Analysis of future low-carbon electricity systems

Doktorsavhandling, 2023

The increasing urgency of addressing climate change, along with the sustained cost declines in wind and solar power, has led to a rapid expansion in their deployment to decarbonize the electricity sector. In cost-optimal scenarios for future low-carbon electricity systems, wind and solar often serve as the cornerstone of electricity supply. Although many studies have investigated a future low-carbon electricity system based on wind and solar, there are still several important aspects that are not well understood for such a future system, e.g., uncertainty in future electricity demand patterns, potential for trade in renewable energy, the spatial scope for resource sharing and the role of nuclear power. This thesis investigates these aspects and their potential impacts on developing a low-carbon electricity system.     

This thesis reveals that varied electricity demand patterns affect only slightly the electricity system cost for Europe, except for the case of summer peak, where the system cost may increase by up to 8%. The change in demand pattern is generally more consequential to the electricity supply mix than the system cost. Notably, the increased electric cooling demand may change the demand pattern such that the hourly electricity demand is better correlated with the output of solar PV. Through analyzing seven different regions under various CO2 emission targets, this thesis shows that solar PV is the most cost-optimal generation technology for meeting the cooling demand. In addition, to have a more realistic assessment of renewable energy potential, this thesis introduces a new metric “Renewable levelized cost of electricity available for export”, which incorporates heterogeneous discount rates, electricity demand, and land-use requirements. By applying this metric to most of the countries in the world, this thesis shows that countries with significant potential for renewable energy export include the US, China, and Saudi Arabia. Furthermore, this thesis shows that the benefit of an intercontinental super grid, as suggested by the One Sun One World One Grid initiative, is rather limited. Allowing for long-distance intercontinental electricity trade reduces the electricity system cost by 0-5% compared to the case where the continents are isolated from each other. This thesis also shows that integrating different continents always reduces the integration of solar PV, which indicates that an intercontinental super grid is not a cost-effective variation management strategy for solar power. Finally, this thesis shows that including nuclear power in the electricity system reduces the nodal net average system cost by 4% for Sweden. This implies that the economic rationale for Sweden as a country to invest in nuclear power is limited if there is a transition towards a low-carbon electricity system in Europe.

This thesis provides practical information about demand profile treatment for modeling practice, introduces a useful metric for renewable energy trade potential assessment, and generates valuable insights about deploying solar PV to power cooling, and investment in super grid and nuclear power.