What does “open-source” mean?

Open-source software is software whose source code is publicly available for anyone to read, use, modify, and redistribute. Unlike proprietary software, where the code is hidden and access requires a licence, open-source tools are transparent by design. Anyone can inspect how the model works, verify its results, and build on top of it. For energy planning, this means regulators, researchers, and TSOs can independently verify modelling assumptions and outcomes. Our explainer video on “Open Energy Modelling” covers key concepts including “open source” and “open data”.

What is a “workflow” and why does it matter?

A workflow is an automated sequence of modelling steps, from data preparation and network construction through to optimisation and results, that can be run end-to-end with a single command. Open-TYNDP uses Snakemake to manage its workflow. This means every result is fully reproducible: given the same inputs, anyone running the workflow will get the same outputs. It also means the entire modelling process is documented in code rather than in manual steps that are hard to audit.

Is Open-TYNDP a replacement for ENTSO-E’s TYNDP 2024 process?

No. Open-TYNDP is designed as a complementary, transparent tool that enables independent benchmarking and scenario testing independently of the official TYNDP process. It focuses on replicating Scenario Building and Cost-Benefit Analysis of the TYNDP 2024. It is built to strengthen — not replace — ENTSO-E’s planning process.

How does Open-TYNDP relate to PyPSA-Eur?

Open-TYNDP is a soft-fork of PyPSA-Eur, adapted specifically to align with TYNDP 2024 methodology, input data, and network topology. It tracks upstream PyPSA-Eur developments and benefits from the broader PyPSA community. Our explainer video on energy systems modelling frameworks, algebraic modelling languages, workflows and models, covers how Open-TYNDP, PyPSA-Eur and PyPSA are related to one another.

What is a “soft-fork”?

A fork is a copy of an existing software project that is developed independently. A soft-fork stays closely aligned with the original project, regularly incorporating updates and improvements from upstream, rather than diverging into a fully separate codebase. Open-TYNDP is a soft-fork of PyPSA-Eur: it adds TYNDP-specific data, methodology, and network topology on top of PyPSA-Eur, while continuing to benefit from the broader PyPSA community’s development. This means improvements to PyPSA-Eur flow through to Open-TYNDP over time.

Can I run my own scenarios?

Yes. The model is fully open-source and reproducible via Snakemake. New scenarios can typically be configured and run within hours. See the documentation for details.

What scenarios are currently benchmarked?

Benchmarking has been performed for the National Trends (NT) scenario from TYNDP 2024, using climate year 2009. Results are compared against ENTSO-E reference outputs and market model data.

Is Open-TYNDP being updated for TYNDP 2026?

Yes. Open Energy Transition continues to actively develop Open-TYNDP and is currently working on implementing the TYNDP 2026 data and methodology, building on the TYNDP 2024 foundation. This work is developed on the tyndp-2026 branch of the repository. You can follow ongoing work in the issues and pull requests under the label tyndp-2026 in our Github repository.

Where can I report issues or contribute?

Open an issue or pull request on GitHub. Contributions are welcome.

Who funds and maintains Open-TYNDP?

Open-TYNDP is funded by Breakthrough Energy, QCF, and other philanthropies, with previous support from Google.org.

Open-TYNDP is developed and maintained by Open Energy Transition (OET). It is an open-source, exploratory project in collaboration with ENTSO-E, contributions from the wider community are welcome. Anyone can propose improvements, report issues, or extend the tool’s functionality via the GitHub repository.

What tools is this website built with?

This website is built with Jekyll using the Minimal Mistakes theme.