Evaluating energy flexibility requirements for high shares of variable renewable energy: A heuristic approach.

Efforts to reduce carbon intensity of electricity involve increasing shares of variable renewable energy (VRE), including a trend towards decentralized generation. Ensuring their high utilization necessitates addressing generation variability at different spatial and temporal scales, likely involving a coordination of multiple systems (e.g. flexible loads, storage, dispatchable generation). This paper presents a methodology for estimating the energy flexibility required from such a synchronized system. The simple data-based approach uses local load and VRE production patterns, and provides a regional assessment considering (1) indicators to evaluate energy flexibility requirements based on VRE self-consumption (2) visualization methods to observe consumption and production patterns' impact on flexibility requirements across day/week/year and (3) simple algorithms to estimate the energy flexibility requirements at different timescales. The approach is demonstrated for three Swiss distribution system operators, for both current and increased shares of VRE generation. The largest benefits for optimal self-consumption are realized for the energy flexibility timescale of 6–12 hrs. Medium- and long-term (seasonal) storage appears beneficial at VRE penetration levels beyond 40%. The proposed framework can be readily utilized to assess energy flexibility requirements of different regions, and serve as a basis for identifying a suitable mix of strategies needed to address them. • Variable renewable energy raises flexibility needs at various spatiotemporal scales. • Novel metrics evaluate energy flexibility needs using aggregated time-series data. • They consider the effect of spatial and temporal mismatch on renewable energy use. • A simple algorithm estimates how they evolve with increased shares of renewables. • As proof-of-concept, the method is applied to multiple case studies in Switzerland. [ABSTRACT FROM AUTHOR]