airmosaic-ai

Output Unit Compatibility

Problem

GCAM sector output uses two independent unit fields: price-unit for sector/cost and output-unit for physical-output. Direct multiplication only produces a meaningful monetary proxy when the two units are compatible.

Compatibility Matrix

Scenario	Price Unit	Output Unit	Compatible?
Both mass/commodity	1975$/kg	Mt	Yes: Mt->kg conversion
Both energy	1975$/GJ	EJ	Yes: EJ->GJ (service proxy)
Mixed	1975$/GJ	Mt	No: different physical dimensions

Handling Incompatible Units

When units are incompatible (e.g. iron and steel in some GCAM-China configs):

1. Mark the row as incompatible_or_unknown
2. Do not calculate cost * output as revenue
3. Investigate the input configuration to determine if price-unit should be changed
4. If external price data is available, use that instead of GCAM sector/cost

Common Unit Override Patterns

Some sectors need explicit unit overrides because the model input configuration assigns energy-based price units to mass-output sectors:

UNIT_OVERRIDES = {
    "coke": {"price_unit": "1975$/kg", "output_unit": "Mt"},
    "iron and steel": {"price_unit": "1975$/kg", "output_unit": "Mt"},
}

Apply overrides before computing revenue proxies, and document which overrides were applied.

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