data(nordic): per-zone carbon intensity for Swedish bidding zones SE1–SE4

[avalyset]

Hi! This proposes replacing the uniform 18.0 gCO2eq/kWh placeholder currently shared by all four Swedish bidding zones in codecarbon/data/private_infra/nordic_emissions.json with per-zone, derived values. Data-only change — happy to adjust anything based on your review.

This is a companion to #1260, which does the equivalent for Norwegian zones NO1–NO5. The two PRs are independent and can be merged in either order.

What

Zone	before	after (gCO2eq/kWh)
SE1 (Northern Sweden)	18.0	20.6
SE2 (North-central Sweden)	18.0	20.1
SE3 (South-central Sweden, incl. Stockholm)	18.0	14.5
SE4 (Southern Sweden)	18.0	17.4

NO1–NO5 and FI are unchanged (byte-for-byte; only SE blocks + file metadata touched).

Why the placeholder is worth improving

The current 18.0 is identical across SE1–SE4 and is systematically wrong in both directions: it undervalues SE1 and SE2 (true CI ~20 gCO2eq/kWh, ~+12–15% error relative to 18.0) and overvalues SE3 (true CI ~14.5, ~−19% error). A single uniform constant cannot represent structurally different zones.

The clearest case for per-zone values

SE3 is Sweden's nuclear-dominant zone. Nuclear generation carries a lifecycle factor of ~12 gCO2eq/kWh (IPCC AR5), well below any fossil source. As a result, SE3's true CI sits at 14.5 gCO2eq/kWh — the 18.0 placeholder is roughly 19% too high. This error is structurally absent in the Norwegian zones, which are predominantly hydropower and have no nuclear-dominant zone; Norwegian CIs cluster near or above 18.0 rather than well below it.

SE1 and SE2, by contrast, give the undervaluation counterpart: their hydro-and-wind mix yields CIs of ~20 gCO2eq/kWh, making the placeholder ~12–15% too low. Together, SE3's overvaluation and SE1/SE2's undervaluation make the two-way error explicit and large — a single uniform value is wrong in opposite directions across the four Swedish zones.

Source & method

• Source: ENTSO-E Transparency Actual Generation per Production Type (A75), per bidding zone, full year 2025.
• Method: production-based generation-mix weighted average (ENTSO-E A75 + IPCC AR5 Annex III lifecycle factors) — each generation source weighted by its share in the annual mix and multiplied by its IPCC AR5 Annex III lifecycle emission factor.
• This PR updates the static nordic emission factors only; it does not modify the Electricity Maps API integration (electricitymaps_api.py) or any other data path.

A point we'd like your steer on: the factor basis

We derived these with IPCC AR5 Annex III (Table A.III.2) lifecycle medians (coal 820, gas 490, hydro 24, wind 11, nuclear 12, …) rather than CodeCarbon's carbon_intensity_per_source.json. Our reasoning:

• IPCC AR5 is a single, peer-reviewed, consistent-lifecycle basis, and it keeps these numbers identical to the upstream derivation's DOI-frozen record (so there's one citable value per zone, not two).
• The main table difference is gas (AR5 490 vs your 743, carbon_intensity_per_source.json:9), but fossil gas is a negligible share of the Swedish mix, so the choice has minimal effect on these values — we flag it only for transparency.

That said — this is a recommendation, not a correction of your table. If you'd prefer internal consistency with carbon_intensity_per_source.json, re-deriving with your own per-source factors is a one-line change on our side; just say the word.

Honest characterization (per-zone drift notes added)

A multi-year analysis (2022–2025) is carried in the per-zone note fields:

Zone	Drift	Recommendation
SE1	Mix drifting (hydro→wind shift, −3.8% CI)	More frequent than annual updates recommended
SE2	Stable: CI −2.4%, mix shifts <5pp	Annual update sufficient
SE3	Nuclear share eroding −6.4pp; CI +7.8% (below 15% threshold)	More frequent than annual updates recommended
SE4	Material drift: CI +15.2% (solar growth)	More frequent than annual updates required

SE4 shows the most active drift (monotonically rising CI driven by solar growth, Solar=48 gCO2eq/kWh vs wind=11). SE2 is the only SE zone below both materiality thresholds.

Reproducibility

Every value is traceable. Derivation method, pre-registered before computation, is in the ADR chain (esp. ADR-0001 CI method); the per-zone results and multi-year drift analysis are in the repo's docs/. Frozen and citable:

• Repository: https://github.com/avalyset/khepri
• DOI (concept, all versions): 10.5281/zenodo.21042581

Tests

The existing Nordic test (test_get_emissions_PRIVATE_INFRA_NORDIC_REGION) previously hardcoded the placeholder 0.018 for SE2; updated to 0.0201 to match the new derived value. All 9 Nordic tests pass; 8 package integrity tests pass. No other code changes.

Thanks for maintaining CodeCarbon — glad to iterate on any of this.

[benoit-cty]

Thanks for your contribution.
Can you give us the exact link to review the source of the value ?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.68%. Comparing base (3161c53) to head (20de124).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1262      +/-   ##
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+ Coverage   89.64%   89.68%   +0.04%     
==========================================
  Files          48       48              
  Lines        4771     4771              
==========================================
+ Hits         4277     4279       +2     
+ Misses        494      492       -2     

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[avalyset]

Hi Benoît, thanks for taking a look.

The values are derived rather than taken from a single source, so the "source" is a short chain:

Generation data: ENTSO-E Transparency, Actual Generation per Production Type (A75), per bidding zone, full year 2025. The raw series isn't committed (fetched reproducibly from the ENTSO-E API), but the exact EIC codes per zone are in ADR-0006.

Emission factors: IPCC AR5 Annex III, Table A.III.2 lifecycle medians (hydro 24, wind 11, nuclear 12, solar 48, gas 490 gCO2eq/kWh).

Method: production-based generation-mix weighted average — each source weighted by its annual share, multiplied by its factor.

• Core method: https://github.com/avalyset/khepri/blob/main/docs/decisions/0001-ci-beregningsmetode.md
• Swedish per-zone extension (EIC codes, nuclear handling): https://github.com/avalyset/khepri/blob/main/docs/decisions/0006-se-per-sone.md

The four SE values, the drift analysis, and the nine-zone table are in the README, and the whole thing is frozen and citable at https://doi.org/10.5281/zenodo.21042581.

So there's no single CSV that says "20.6" — the value is traceable through method + the two sources above. Glad to add a worked example for one zone (e.g. SE3) showing the mix × factors arithmetic explicitly if that helps.

[avalyset]

Quick follow-up, @benoit-cty — I've since published a corrected version (same concept DOI, now resolves to v1.2):

https://doi.org/10.5281/zenodo.21042581

Two things this fixes for your review: the SE per-zone drift results are now included in full (docs/se-drift-results-2022-2025.md), and one correction to my earlier note — the factor source is IPCC WG III AR5 Annex III lifecycle medians (I referenced "Table A.III.2" above; the manuscript and repo now cite "Annex III" without that sub-ID). Factor values are unchanged (hydro 24, wind 11, nuclear 12, solar 48, gas 490 gCO2eq/kWh). Method in ADR-0006 (SE CI) and ADR-0007 (SE drift).