Measuring and Comparing Energy Flexibilities

Flexibility in energy supply and demand becomes more and more important with increasing Renewable Energy Sources (RES) production and the emergence of the Smart Grid. Socalled prosumers, i.e., entities that produce and/or consume energy, can offer their inherent flexibilities through so-called demand response and thus help stabilize the energy markets. Thus, prosumer flexibility becomes valuable and the ongoing Danish project TotalFlex [1] explores the use of prosumer flexibility in the energy market using the concept of a flex-offer [2], which captures energy flexibilities in time and/or amount explicitly. However, in order to manage and price the flexibilities of flex-offers effectively, we must first be able to measure these flexibilities and compare them to each other. In this paper, we propose a number of possible flexibility definitions for flex-offers. We consider flexibility induced by time and amount individually, and by their combination. To this end, we introduce several flexibility measures that take into account the combined effect of time and energy on flex-offer flexibility and discuss their respective pros and cons through a number of realistic examples.