fix: Remove geothermal-sourced HPs and update geothermal-sourced heat source

[amos-schledorn]

Changes proposed in this Pull Request

1. Add installation costs to geothermal sourced heat pumps: For geothermal heating, we're currently ignoring the field "of which is installation" in the DEA data allocating that neither to the heat pump nor to the heat source.
2. Use data for 2000m depth to better align with PyPSA-Eur geothermal heat sources
3. Convert the DEA heat-source costs given per MW of the entire system (heat source + heat pump) to costs per MW heat source:

            (
                df.loc[" - of which is equipment excluding heat pump"]
                + df.loc[" - of which is installation"]
            )
            * df.loc["Heat generation capacity for one unit (MW)"]
            / df.loc["Heat generation from geothermal heat (MJ/s)"]
        )

4. Remove geothermal heat pumps: When applying the same logic to calculate the costs for the heat pump only, we would get very high heat-pump costs (3.37 MEUR/MW_th in 2020). This seems much higher than for similar heat pump data (e.g. 0.67 MEUR/MW_th for excess-heat sourced heat pumps).
   That's contradicting e.g. Pieper et al. who find the costs for the heat pump only to be the same for most heat sources.
   So, I would suggest using excess-heat sourced heat pumps for the heat pump part of geothermal heating and the proposed cost calculation for the heat source.

Checklist

• Code changes are sufficiently documented; i.e. new functions contain docstrings and further explanations may be given in doc.
• Data source for new technologies is clearly stated.
• Newly introduced dependencies are added to environment.yaml (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 GPLv3 license.

[Copilot]

Copilot reviewed 2 out of 17 changed files in this pull request and generated no comments.

Files not reviewed (15)

• docs/release_notes.rst: Language not supported
• outputs/US/costs_2020.csv: Language not supported
• outputs/US/costs_2025.csv: Language not supported
• outputs/US/costs_2030.csv: Language not supported
• outputs/US/costs_2035.csv: Language not supported
• outputs/US/costs_2040.csv: Language not supported
• outputs/US/costs_2045.csv: Language not supported
• outputs/US/costs_2050.csv: Language not supported
• outputs/costs_2020.csv: Language not supported
• outputs/costs_2025.csv: Language not supported
• outputs/costs_2030.csv: Language not supported
• outputs/costs_2035.csv: Language not supported
• outputs/costs_2040.csv: Language not supported
• outputs/costs_2045.csv: Language not supported
• outputs/costs_2050.csv: Language not supported

Comments suppressed due to low confidence (2)

test/test_compile_cost_assumptions.py:118

• Ensure that the removal of 'central geothermal-sourced heat pump' from the test mappings does not leave any gaps in test coverage for related functionality.

"central geothermal-sourced heat pump": "inputs/technology_data_for_el_and_dh.xlsx",

scripts/compile_cost_assumptions.py:928

• Confirm that the new cost conversion formula for the geothermal heat source is adequately covered by unit tests, especially for edge cases involving the input dimensions.

elif tech_name == "central geothermal heat source":

[amos-schledorn]

I'm not really sure where the changes to US data are coming from. Any idea @fneum?

[euronion]

US changes seem to be linked to this commit: 756f989

Looks like the outputs had not been properly regenerated before the PR was merged. fyi @danielelerede-oet

[cpschau]

LGTM, except for the minor spelling mistake and the failing CI.