Flexibility, dynamism and diversity in energy supply and demand: A critical review

Flexibility is vital to the operation of electricity systems. It ensures that the system can keep supply and demand in balance in real time. Until recently the provision of flexibility was a fortunate by-product of thermal power generation using fossil fuels as a convenient storage medium. The rapid emergence of renewables poses a major challenge to this model. As thermal power stations are increasingly displaced with more variable renewable sources of electricity, new forms of flexibility are urgently needed. Two promising candidates for this role are energy storage and demand side response. This paper argues that in low carbon systems flexibility may at times and in certain places supersede the need for component efficiency, in order to improve overall system efficiency. We reach this conclusion after reviewing the origins of flexibility on the supply and the demand side. In both domains the concepts of material redundancy, tolerances and skills are pertinent and help our understanding of the potential for and limitations to flexibility. On the demand side new capacities may need to be developed, including skills and societal norms, if the gap between technical and realised potential is to be closed.