LF Energy Summit Europe 2026

Energy systems are undergoing rapid transformation as sector coupling intensifies and variable renewable generation grows, creating a pressing need for flexible and transparent modeling tools. While many open-source frameworks offer rich features, extending them with new mathematical models typically requires writing custom software, a barrier for many analysts.

We present GEMS (Generic Energy Systems Modelling Schema), a high-level modelling language designed to make multi-energy system adequacy and planning studies both more expressive and more accessible. GEMS brings model definitions out of the codebase and into simple YAML configuration files, where users describe variables, parameters, and constraints using natural mathematical expressions. These expressions are parsed into abstract syntax trees and automatically expanded into a complete optimization problem. This model-agnostic architecture enables rapid experimentation, lowers development and maintenance costs, and promotes true reusability: adding a new model requires no code, only data. The language is already supported in Antares Simulator and in the Python package GemsPy.