Debunking the speed-fidelity trade-off: Speeding-up large-scale energy models while keeping fidelity

D.A. Tejada, J. Kiviluoma, G. Morales-España

International Journal of Electrical Power & Energy Systems Vol. 168, pp. 110674-1 - 110674-12

Summary:

Energy system models are essential for planning and supporting the energy transition. However, increasing temporal, spatial, and sectoral resolutions have led to large-scale linear programming (LP) models that are often (over)simplified to remain computationally tractable—frequently at the expense of model fidelity. This paper challenges the common belief that LP formulations cannot be improved without sacrificing their accuracy. Inspired by graph theory, we propose to model energy systems using energy assets (vertices), as a single building-block, and flows to connect between them. This reduces the need for additional components such as nodes and connections. The resulting formulation is more compact, without sacrificing accuracy, and leverages the inherent graph structure of energy systems. To evaluate performance, we implemented and compared four common modelling approaches varying in their use of building blocks and flow representations. We conducted experiments using TulipaEnergyModel.jl and applied them to a multi-sector case study with varying problem sizes. Results show that our single-building-block (1BB-1F) approach reduces variables and constraints by 26% and 35%, respectively, and achieves a 1.27x average speedup in solving time without any loss in model fidelity. The speedup increases with problem size, making this approach particularly advantageous for large-scale models. Our findings demonstrate that not all LPs are equal in quality and that better reformulations can lead to substantial computational benefits. This paper also aims to raise awareness of model quality considerations in energy system optimisation and promote more efficient formulations without compromising fidelity.

Spanish layman's summary:

Proponemos una formulación de PL inspirada en grafos para sistemas energéticos que utiliza un único bloque de construcción y conexiones de flujo. Este enfoque reduce las variables en un 26 %, las restricciones en un 35 % y acelera la resolución en 1,27 veces en promedio, sin perder precisión.

English layman's summary:

We propose a graph-inspired LP formulation for energy systems using a single building block and flow connections. This approach reduces variables by 26%, constraints by 35%, and speeds up solving by 1.27x on average, without losing accuracy, offering an efficient alternative for large-scale models.

Keywords: Energy sector coupling; Optimisation modelling; Energy system models; Linear programming (LP); Computational efficiency

JCR Impact Factor and WoS quartile: 5,000 - Q1 (2023)

DOI reference: https://doi.org/10.1016/j.ijepes.2025.110674

Published on paper: July 2025.

Published on-line: April 2025.

Citation:
D.A. Tejada, J. Kiviluoma, G. Morales-España, Debunking the speed-fidelity trade-off: Speeding-up large-scale energy models while keeping fidelity. International Journal of Electrical Power & Energy Systems. Vol. 168, pp. 110674-1 - 110674-12, July 2025. [Online: April 2025]