Make repository REUSE compliant and relicense to MIT

[euronion]

Closes #108 .

Changes proposed in this Pull Request

This PR has two purposes:

1. Introduce REUSE to the repository and make it REUSE compliant (SPDX identifiers for all files or REUSE.toml entry + REUSE badge + reuse check in CI)
2. Re license powerplantmatching from GPLv3 to MIT, the output file to CC BY 4.0 and some other licenses for config files / duke binaries.

The relicensing to MIT is optional, the rest recommend / necessary (espc. the duke binaries have probably always been Apache-2.0? @FabianHofmann @coroa ).

Fun fact: The PR template is already mentioning MIT license, I didn't change it. So most contributors have already agreed ;)

Do we want to relicense? MIT is the standard license for most of our other repositories nowadays.
If yes, I would ask the main contributors to confirm here.

Checklist

• Code changes are sufficiently documented; i.e. new functions contain docstrings and further explanations may be given in doc.
• [n/a] Unit tests for new features were added (if applicable).
• A note for the release notes doc/release_notes.rst of the upcoming release is included.
• I consent to the release of this PR's code under the MIT license.

[FabianHofmann]

The relicensing to MIT is optional, the rest recommend / necessary (espc. the duke binaries have probably always been Apache-2.0? @FabianHofmann @coroa ).

I honestly don't know :)

yes, I would be fine with relicensing

[euronion]

The relicensing to MIT is optional, the rest recommend / necessary (espc. the duke binaries have probably always been Apache-2.0? @FabianHofmann @coroa ).

I honestly don't know :)

You wouldn't happen to know where the .jar binaries are from?
If you do, then I can double check. The Apache-2.0 license is valid for duke==1.2.
I could only find duke==1.2 online, but the ones in our repo appear to be for duke==1.3 (did you get early access? ;) )

[euronion]

yes, I would be fine with relicensing

Great, I'll start the process then!

Change license to MIT

Hi all,
we would like to change the license for powerplantmatching going forward to MIT.
(No changes to the license of past versions of powerplantmatching).
Also the default output file, powerplants.csv, would be licensed CC BY 4.0 for easier reuse.

The MIT and CC BY 4.0 licenses are the licenses of choice for other PyPSA org repositories.
There are various reasons for the change.

• Regarding the MIT license, see the past discussion here: Change PyPSA licence from copyleft GPLv3 to more liberal MIT PyPSA#274
• Regarding the CC BY 4.0 license: The output file is not strictly connected to the package and useful on its own. Thereby MIT is not a suitable license, as it is made to cover software, not data files. Change is highly recommended such that people can use it independently of the package and repository in their work.

I have tagged the contributors of the present and past.
Please confirm here whether you are fine with the license changes by 15th of August 2025.
We're going with a simplified process:
If you do not respond and we have a majority of votes by then, we will go ahead with the license change.

Package authors

• @coroa
• @FabianHofmann
• @fgotzens

Major contributors (>= 100 line additions)

• @fneum
• @lkstrp
• @martinhjel
• @Tomkourou
• @pz-max
• @davide-f
• @LukasFrankenQ
• @cdgaete

[davide-f]

I agree with the change

[coroa]

Sure, full support!

[coroa]

I think I compiled the binaries myself

[fgotzens]

Happy as well with relicensing, thanks!

[fneum]

Happy with relicensing!

[lkstrp]

Yes, I agree with the change

[LukasFrankenQ]

Happy with the change!

[euronion]

Thanks all for the feedback. Given the majority and especially original authors agree, we will proceed with the re-licensing.

[euronion]

PR updated, now RTR.

[fneum]

Merge at will!