Geophysical constraints on the reliability of solar and wind power worldwide

Solar and wind resources are dependent on geophysical constraints. Here the authors find that solar and wind power resources can satisfy countries' electricity demand of between 72-91% of hours, but hundreds of hours of unmet demand may occur annually. If future net-zero emissions energy systems rely heavily on solar and wind resources, spatial and temporal mismatches between resource availability and electricity demand may challenge system reliability. Using 39 years of hourly reanalysis data (1980-2018), we analyze the ability of solar and wind resources to meet electricity demand in 42 countries, varying the hypothetical scale and mix of renewable generation as well as energy storage capacity. Assuming perfect transmission and annual generation equal to annual demand, but no energy storage, we find the most reliable renewable electricity systems are wind-heavy and satisfy countries' electricity demand in 72-91% of hours (83-94% by adding 12 h of storage). Yet even in systems which meet >90% of demand, hundreds of hours of unmet demand may occur annually. Our analysis helps quantify the power, energy, and utilization rates of additional energy storage, demand management, or curtailment, as well as the benefits of regional aggregation.

Automated summary

Solar and wind resources can satisfy most countries' electricity demand, but hundreds of hours of unmet demand may still occur annually. Even in systems that meet more than 90% of demand, there is still a possibility of unmet demand for hundreds of hours each year.