Balancing seasonality in decarbonising electricity systems worldwide

Decarbonizing electricity grids across the world will be increasingly impacted  by systematic seasonal variation in wind speed and solar irradiance as well as seasonally varying patterns of demand, more so in the context of progressive decarbonization of energy services such as winter heating. These seasonal variations are governed by local meteorology which also has large-scale manifestations impacting entire electricity grid systems. Using ERA5 reanalysis, we quantify the amplitude of seasonality in wind speed and solar insolation across the world and consider the impacts on grid scale generation. Owing to effects of seasonal evolution of solar insolation as well as the seasonal cycle of cloudiness, the seasonal cycle amplitude for solar insolation at the surface is much larger in higher latitudes. For horizontal winds, high seasonal amplitudes are experienced in global tropical monsoon regions and higher latitudes associated with meridional shifts in mid-latitude zonal winds. In general, wind power availability is much higher in high-latitude winters.

Seasonal weather variation also drives electricity demand for heating and cooling, which is a major part of the total electricity consumption of many regions. While many large electricity consumers including China, US, India, and Brazil experience peak electricity consumption during summer, most European countries have higher demand during winter, giving a double peak structure for global monthly electricity demand. Many large electricity consuming countries experience nearly 40 percent variation in electricity demand between seasons. Solutions to bridge large seasonal variations in demand and generation, e.g. bulk energy storage, excess of wind and solar capacity, renewable portfolio design, and demand-side management present critical challenges.

This paper will consider whether a portfolio of such solutions is adequate to balance seasonal variability in supply and demand. We will characterize the main patterns of seasonal load variability across countries, explore whether within-country wind and solar variability are well matched with these patterns, and consider the role of excess capacity and storage in bridging the gaps, in context of limitations of seasonal-scale demand side management. Bridging seasonal-scale gaps and mitigating the impacts of various manifestations of seasonality remains an important roadblock towards net zero electricity systems worldwide, and we will survey the most promising solutions to this challenge.