The variability of wind and solar energy technologies is perceived as a major obstacle to employing otherwise abundant renewable energy resources. Based on the available geographically dispersed data for the Western U.S. (excluding Alaska), we analyze the extent to which the geographic diversity of these resources can offset their variability. First, we determine the best match to loads that can be achieved with wind power and photovoltaics with no transmission limitations and then impose large-scale transmission limitations to capture regional specifics of load matching with renewables.

Without energy storage and assuming unlimited energy flows between regions, wind and PV can meet up to 80% of loads in the Western U.S. while less than 10% of the generated power is curtailed. Limiting hourly energy flows by the aggregated transmission line carrying capacities decreases the fraction of the load that can be met with wind and PV generation to approx. 70%. The fraction of curtailed energy does not increase with the onset of transmission limitations...(Read more...)