feat:improve PtX excess heat handling

[amos-schledorn]

Integrates utilisation of excess heat from Power-to-X processes (electrolysis, Fischer-Tropsch, Sabatier, Haber-Bosch, methanolisation, fuel cells) into the new heat-source structure.

Changes

definitions/heat_source.py

• 6 new PTX heat sources in HeatSource enum
• HeatSourceType categorization (INEXHAUSTIBLE, SUPPLY_LIMITED, STORAGE, PROCESS_WASTE)
• Renamed has_constant_temperature → temperature_from_config
• Moved some of the logic from prepare_sector_network.add_waste_heat() to HeatSource enum
• Removed unnecessary __init__ from HeatSource enum

prepare_sector_network.py

• add_waste_heat(): Reduced from ~80 lines to ~30 using loop over PtX HeatSources

Small refactoring changes

• Updated build_cop_profiles/run.py to use temperature_from_config
• Updated build_heat_source_utilisation_profiles.py to use temperature_from_config
• Updated rules/build_sector.smk to use temperature_from_config

Config Changes

sector:
  heat_source_temperatures:
    geothermal: 65
    electrolysis_excess: 200
    fuel_cell_excess: 200
    fischer_tropsch_excess: 200
    haber_bosch_excess: 200
    sabatier_excess: 200
    methanolisation_excess: 200
  ptx_heat_losses: 0.05
  heat_sources:
    urban central:
    - air
    - electrolysis_excess
    - fuel_cell_excess
    - fischer_tropsch_excess
    - haber_bosch_excess
    - sabatier_excess
    - methanolisation_excess
plotting:
    tech_colors:
    # necessary additions for waste heat carriers

Waste Heat Efficiency Changes

The old implementation used hardcoded approximations. The new implementation uses efficiency-heat values from technology-data where available:

Process	Old Formula	New Source	Value (2050)
Fischer-Tropsch	0.95 - efficiency (~0.15)	technology-data efficiency-heat	0.15
Electrolysis	0.84 - efficiency (~0.14)	technology-data efficiency-heat	0.129
Haber-Bosch	calc based on industry ratios (0.15 * total_energy_input / electricity_input ~3.75)	technology-data efficiency-heat/electricity-input	0.146
Methanolisation	technology-data heat-output / hydrogen-input (~0.088)	same calculation*	~0.088
Sabatier	0.95 - efficiency (=0.15)	same calculation*	0.15
Fuel Cell	0.95 - efficiency (=0.45)	same calculation*	0.45

Checklist

• I tested my contribution locally and it works as intended.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to pixi.toml (using pixi add <dependency-name>).
• Changes in configuration options are added in config/config.default.yaml.
• Changes in configuration options are documented in doc/configtables/*.csv.
• For new data sources or versions, these instructions <https://pypsa-eur.readthedocs.io/en/latest/data_sources.html>_ have been followed.
• A release note doc/release_notes.rst is added.

Testing

Configs

Base branch

scenario:
  clusters:
  - 8
  planning_horizons:
  - 2040

clustering:
  temporal:
    resolution_sector: 25h

countries: ['DE', 'DK']

plotting:
  energy_threshold: 0
  enable_heat_source_maps: true
  interactive_bus_balance: 
    bus_name_pattern: "*urban central*"

sector:
  district_heating:
    supply_temperature_approximation:
      max_forward_temperature_baseyear:
        DE: 110
        DK: 80
      min_forward_temperature_baseyear:
        DE: 75
        DK: 55
      return_temperature_baseyear:
        DE: 60
        DK: 50
      relative_annual_temperature_reduction: 0.0
  ttes: true

solving:
  options:
    noisy_costs: false

Feature branch, same config but with same temperatures as implicitly assumed before

(only changes are waste heat efficiencies)

sector:
  district_heating:
    heat_source_temperatures:
      geothermal: 65
      electrolysis_excess: 200
      fuel_cell_excess: 200 
      fischer_tropsch_excess: 200
      haber_bosch_excess: 2
      sabatier_excess: 200 
      methanolisation_excess: 200

Feature branch, default config

Results

objective values

Scenario	Objective (€)	Δ vs Base
Base (no PTX waste heat)	117.25 bn	-
Feature, 200°C PtX temps	117.31 bn	+0.056%
Feature, default PtX temps	117.32 bn	+0.61%
Feature, 200°C PtX temps, hard-coded base branch heat-efficiencies (-> equivalent to base)	117.25 bn	+0.0002%

Excess heat utilisation

Process	Base	Feature, 200°C PtX temps	Feature, default PtX temps
Fischer-Tropsch	0.05	0.04	0.03
Sabatier	0.01	0.01	0.01
Haber-Bosch	3510.00	510.47	506.12
Methanolisation	0.04	0.03	0.03
Electrolysis	1765.32	1575.85	1556.97
Fuel Cell	0.12	0.18	0.14

Urban central heat balance

Base

Feature, 200°C PtX temps

Feature, default PtX temps

[amos-schledorn]

Note: 36110d5 fixed a bug that caused the return flow temperature to be used in the COP approximation of all heat sources, including those pre-heating the return flow.
-> The above results assume incorrect COPs for heat sources above the return temperature boosted via heat pumps.

[cpschau]

Great work @amos-schledorn! I think I am finally getting a sense for the convenience of enums 😄

I only have one question about the processing of the HB heat efficiency. Other than that, this looks good to me!

[cpschau]

Why is the heat efficiency value of the technology data not used directly?

[amos-schledorn]

This is because the Haber-Bosch link's bus1 is electricity -> scaling of "efficiency-heat" [MWh_th/MWh_NH3] to [MWh_th/MWh_el] is necessary .

[cpschau]

Understood (because electricity is on bus0).