IRENA’s assessment of flexibility is carried out with the IRENA FlexTool. The FlexTool is a detailed, user-friendly tool that intends to analyse not only the traditional concept of flexibility (concerning, for example, flexible thermal and hydropower generation with high ramping capability and very low start-up time), but also other innovative technologies that enrich the concept of flexibility, such as flexible demand, energy storage and sector coupling.

The FlexTool is capable of analysing system operations using a time step that represents real-world challenges (an hour or less in the case of variable renewable energy, VRE) and also of carrying out least-cost optimisation of the generation mix, as well as flexibility solutions with regard to grids, storage, the demand side and sector coupling. The FlexTool, however, does not study the very short term (second/sub-second time scale); although this also is relevant for power system flexibility, it calls for another type of assessment.

The FlexTool is data-driven. This means that the model structure is relatively general, and the input data have a large role in specifying what the model does. The required inputs to perform a FlexTool simulation include demand, generation mix, hydrological data, VRE time series, interconnections and fuel costs. If the system being analysed is divided into different nodes, transmission data – divided by node – are required in addition to the mentioned data.

Download IRENA FlexTool 

The FlexTool was developed with the VTT Technical Research Centre of Finland Ltd., with the aim of assisting IRENA members in making a relatively quick assessment of potential flexibility gaps as well as highlighting the most cost-effective mix of solutions to fill in such gaps. It is currently the only publicly and freely available (open-source) tool that performs both capacity expansion and dispatch with a focus on power system flexibility.

Read more about power system flexibility for the energy transition and on IRENA FlexTool methodology in the IRENA report. In addition, a few country case studies highlight the application of the IRENA FlexTool in the existing real-world situations, including: