Why Fimbul?
The software is designed to meet the need for a flexible and robust geothermal simulation platform that combines:
- high performance and scalable computational methods,
- flexible models for porous media and heat transfer,
- support for a wide range of geothermal concepts,
- transparency and reproducibility through open-source development.
Fimbul lowers the threshold for experimenting with geothermal concepts, performing systematic parameter studies, and integrating simulations into research, education, and industrial project development.
Application areas
Fimbul can be used to model and analyze, among other things:
- Geothermal doublet systems for energy production
- Borehole thermal energy storage (BTES / ATES), in both single- and multi-well configurations
- Advanced closed-loop geothermal systems (AGS)
- High-temperature aquifer thermal energy storage (HT-ATES)
- Thermal processes based on heat conduction and fluid flow in porous media
These scenarios are supported through a collection of ready-to-use setups and utility functions that make it easy to define new cases and run simulations.
Technical features
- Developed in Julia as part of SINTEF’s Jutul framework, with seamless integration into other scientific libraries
- Flexible modeling of flow and heat transfer in porous media
- Support for both steady-state and transient models
- APIs for defining geometry, wells, material properties, and operating conditions
- Examples of complete models for several types of geo-energy systems
- Distributed under the MIT license for maximum flexibility and reuse
Where to find the source code and documentation?
Source code (GitHub):
https://github.com/sintefmath/Fimbul.jl
Documentation and examples:
https://sintefmath.github.io/Fimbul.jl/dev/
Publications and scientific references
If you use Fimbul.jl in scientific work, please cite:
- Klemetsdal, Ø., Andersen, O., & Møyner, O. (2025). Fimbul.jl – Fast, Flexible, Robust, and Differentiable Geothermal Energy Simulation in Julia. Sixth EAGE Global Energy Transition Conference (GET 2025). DOI: 10.3997/2214-4609.202521164
You can also learn more about the software from the slides of the following presentations:
- Ø. Klemetsdal, O. Andersen, O. Møyner (2025). Fimbul.jl – fast, flexible, robust, and differentiable geothermal energy simulation in Julia. Sixth EAGE Global Energy Transition Conference & Exhibition (GET 2025), October 27–31 2025, Rotterdam, The Netherlands.
- Ø. Klemetsdal, O. Andersen, S. Krogstad, O. Møyner (2025). Predictive digital twins for optimal operation of GeoTermos (in Norwegian). GeoTermos-festivalen 2025, May 22 2025, Trondheim, Norway.
- Ø. Klemetsdal, O. Andersen, S. Krogstad, O. Møyner (2025). Predictive digital twins for underground thermal energy storage using differentiable programming . 3rd IACM Digital Twins in Engineering Conference (DTE 2025) & 1st ECCOMAS Artificial Intelligence and Computational Methods in Applied Science (AICOMAS 2025), 17–22 February 2025, Paris, France.
- Ø. Klemetsdal, O. Andersen (2024). Proxy models for rapid simulation of underground thermal energy storage . Fifth EAGE Global Energy Transition Conference & Exhibition (GET 2024), 4–7 November 2024, Rotterdam, The Netherlands.