System design and operation for integrating variable renewable energy resources through a comprehensive characterization framework

The name itself – VRE for variable renewable energy – encapsulates the essential challenge: these energy sources are attractive precisely because they are renewable and yet problematic because they are variable. Thus, integrating large penetrations of VRE resources such as wind and solar into the electricity grid will necessitate flexible technologies and strategies. This paper establishes characterization metrics of both individual VRE resources and aggregated VRE resource sets with the goal of quantifying the integration requirements of various typologies. Integration requirements over multiple time scales are considered including hourly, weekly - seasonal, and inter-annual flexibility, as well as transmission expansion to connect neighboring wind and solar sources, and demand response mechanisms. The respective integration requirements are quantified through storage and demand response utilization rates, VRE curtailment rates, non-VRE ramping requirements, system costs, and GHG emissions. The results from VRE resources across South America clearly quantify the impact that integrating different VRE regimes has on the electricity system design and operation: not surprisingly integrating VREs on a grid with low non-VRE flexibility incurs the largest integration requirements, while smoothing net VRE production with out-of-phase resources is an effective integration strategy.