HEAT GmbH · ECF-SEN-NDC03 · Working brief · 21 August 2026

Senegal CDN 3.0: one energy balance, three boundaries

Why three different 2024 energy-emission numbers are circulating, what the IPCC and UNFCCC guidance says about comparing them, and the decision path to 31 August.

≈ 9,5
Mt CO₂eq · HEAT SIE series (1A)
11,55
Mt · CDN3 model energy total (2025)
14,82
Mt CO₂eq · Sambou reference approach
Why this brief exists

By the end of this brief you will know where the gap between 9,5 and 14,8 Mt comes from, which IPCC rule settles the comparison, and what decision METE must record before any change to the CDN 3.0 baseline.

Context: energy working group asks to revert to the CDN2 BAU
Contract window closes 31 August 2026
Session with the working group proposed for Monday 24 August
Three ideas carry the whole argument

The map: three ideas, in order

1
The 2024 gap is a boundary problem, and it is decomposable
All three estimates stand on the same SIE energy balances. Emissions did not grow 50 % in one year. Each estimate counts a different set of things.
2
The 2006 IPCC Guidelines already settle how to compare
Biomass CO₂ and international bunkers leave the national total before the reference approach is compared with the sectoral approach. Then a ±5 % agreement test applies.
3
A baseline change triggers a documented target decision
UNFCCC transparency rules require the baseline construction, and any update to it, to be reported. If the BAU moves, METE decides in writing whether the adopted targets move with it.
How we got here

Five dates from analysis to session

14 Aug
M. Sambou estimates 2024 energy at 14,115 Mt CO₂ with the IPCC reference approach on the SIE 2024 balance, and recommends extending the CDN2 BAU to 2035.
17 Aug
Madeleine Diouf Sarr forwards the analysis with the compiled observations on report version 5.0 and asks for a joint session on the BAU.
18 Aug
HEAT accepts the joint review and proposes three slots. No slot is confirmed.
21 Aug
HEAT sends a bilingual technical note with the reconciliation path, and proposes Monday slots.
24 Aug
Proposed working session: reconcile the two estimates line by line with the energy working group.

The concern now has a named author, a number, and a method. That makes it answerable technically, with the documents both sides already use.

Idea 1 · The gap is a boundary problem

Three estimates of 2024 energy emissions differ by up to 5,3 Mt on the same data

A · HEAT SIE series
≈ 9,5
Mt CO₂eq · 2024
IPCC sectoral approach, category 1A, extracted from the SIE balances. 2022 and 2023 are actuals (8,74 / 9,25 Mt); 2024 is extrapolated. Source: model v125 changelog. HEAT calculation · not published SIE figures
B · CDN3 model energy total
11,55
Mt · 2025 (hardcoded)
Model compilation, sheet 3_Sector_Totals. Coverage is broader than the CO₂-only 1A series (non-CO₂ gases, further categories). Source: CDN3 model. Composition to be documented
C · Sambou estimate
14,82
Mt CO₂eq · 2024
IPCC reference approach on the SIE 2024 balance, anchored to the 2018 BUR: 14,115 Mt CO₂, grossed up assuming CO₂ is 95 % of the total. Source: email of 14 Aug 2026. Asserted · results only, no worked file

C sits roughly 50 % above A for the same year, computed from the same energy balance. Real emissions did not grow by half in one year. The gap is methodological, and the next two slides decompose it.

Idea 1 · Demonstration

What each estimate counts

Component of the SIE balance A · HEAT 1A series B · Model energy total C · Sambou reference approach
Fossil fuel combustion (1A) · CO₂includedincludedincluded
Non-CO₂ gases (CH₄, N₂O)excludedincludedgrossed up at 5 %
Biomass CO₂ (fuelwood, charcoal)excluded per IPCCto be documentedunknown · to verify
International bunkers (aviation, marine)excluded per IPCCexcludedunknown · to verify
Non-energy use / feedstocksexcludedexcludedunknown · to verify
Fugitive emissions (1B)excludedto be documentednot covered by reference approach

The three columns cannot agree while their rows differ. Every cell marked "unknown" resolves in minutes once M. Sambou's calculation file is on the table. The A-to-B difference inside the CDN3 model (1,7 Mt for 2025) is documented as part of the same reconciliation.

Idea 2 · The guidance already settles the comparison

Four exclusions come before any reference-vs-sectoral comparison

2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 2 (Energy), Chapter 6, Reference Approach. Mandatory for Paris Agreement inventories under Decision 18/CMA.1.

Biomass CO₂
Excluded from national totals and reported as a memo item. Fuelwood and charcoal are a large share of Senegal's balance; this single exclusion can account for roughly 4 to 5 Mt of the gap. IPCC 2006, Vol. 2, Ch. 6 · estimate: hypothesis, to verify against SIE 2024 biomass rows
International bunkers
Fuel sold to international aviation and marine transport is excluded from national totals and reported as a memo item. Order of magnitude here: 0,3 to 1 Mt. IPCC 2006, Vol. 2, Ch. 6 · estimate: hypothesis
Non-energy use
Fuel used as feedstock or where carbon is stored is excluded or adjusted. Small contribution expected for Senegal. IPCC 2006, Vol. 2, Ch. 6
Statistical difference
The balance's own statistical difference is reported, and is not an emission. Small contribution expected. IPCC 2006, Vol. 2, Ch. 6

M. Sambou correctly describes the reference approach as a reliability check on the sectoral approach, with agreement expected within about ±5 %. That test is defined after these exclusions are applied on both sides. His email asserts the band; the exclusions are what the worked file will show.

Idea 2 · Demonstration

Applying the exclusions is expected to close most of the 5,3 Mt gap

C · Reference approach, as assertedAll apparent fuel consumption, SIE 2024 · Sambou email 14 Aug14,82 Mt
less: biomass CO₂ (memo item)Hypothesis · to verify against SIE 2024 biomass supply rows− 4 à 5 Mt
less: international bunkers (memo item)Hypothesis · aviation and marine rows of the balance− 0,3 à 1 Mt
less: non-energy use, statistical differenceHypothesis · small− small
Expected reconciled reference figureCompare with A ≈ 9,5 Mt (sectoral, 1A)≈ 9,5 à 10,3 Mt

If both methods land in this range, they agree within the ±5 % expectation of the guidance, and the CDN 3.0 energy BAU stands. If a residual gap survives correct accounting, the BAU is recalibrated from that evidence. Either way, the numbers decide.

All deduction values are hypotheses until verified in M. Sambou's calculation file and in HEAT's own reference-approach run on the archived SIE 2024 (Rapport SIE-2024, édition 28/04/2025). Both checks are the agenda of the Monday session.

Idea 2 · The boundary of the remedy

Two remedies, compared on the same criteria

Criterion
Extend the CDN2 BAU to 2035
Reconcile, then keep or recalibrate the CDN3 BAU
Data vintage
Built on pre-2020 drivers and older emission factors. Evidence status: documented in CDN2 model files.
Calibrated against actual SIE 2022 to 2025 balances. Evidence status: model v125 changelog.
Fit with official statistics
Reintroduces the disconnect from published SIE data that the August workshop itself criticised.
Anchors the baseline to the same official balances the working group uses.
Supporting argument
Rests on agreement between the 2018 BUR and CDN2 in 2020. CDN2 was calibrated on that BUR, so the agreement is circular.
Rests on a line-by-line arithmetic check both sides can run on the same file.
UNFCCC reporting
A baseline swap must still be documented under the ICTU guidance, with assumptions and methods restated.
Reconciliation result documents itself: one shared table enters the technical annex.
Idea 3 · A baseline change triggers a documented target decision

The same absolute target reads as a larger cut when the BAU rises

Current CDN3 energy BAU
X %
Reduction percentage communicated for a given absolute target, measured against the current baseline trajectory.
Higher BAU, same absolute target
> X %
The identical tonnage target now shows a larger percentage reduction. The mitigation effort has not changed; the denominator has.

This asymmetry cuts both ways and should be named openly in the room. UNFCCC guidance handles it through documentation: the ICTU annex of Decision 4/CMA.1 requires Parties to describe reference points and baselines, the assumptions and methods behind them, and updates to them. Paris Agreement Article 4.13 requires accounting that ensures transparency, accuracy, completeness, comparability and consistency.

Decision D1, for METE, in writing: if the reconciliation leaves a residual gap and the BAU is recalibrated, do the adopted targets move with it, or are the targets held and the percentages restated? This is a ministry policy call. It is not a consultant call, and not a working-group call.

The path to 31 August

Three steps, two inputs, one closing date

1Reconcile · Monday 24 Aug
Working session with M. Sambou, M. Mbaye Diagne and M. Papa Lamine Diouf. Reference approach with correct exclusions, both sides, same SIE 2024 balance. Output: one shared table.
2If they converge (±5 %)
The CDN 3.0 BAU is confirmed. The reconciliation table enters the technical annex, and the version 5.0 comment on the energy BAU is closed with evidence.
3If a residual gap remains
Recalibrate the BAU from the evidence found. First obtain METE's written decision D1 on the treatment of the adopted targets. A full re-cut of model and report package does not fit before 31 August and would be arranged separately.

Two inputs requested before the session: M. Sambou's calculation file (the exclusions can be verified there in minutes) and the SIE 2023 report (PDF), which also closes an open custody gap in the project's source register.

What you can now do

Contributions

You can run the check
You can decompose the 5,3 Mt gap yourself: take the reference-approach figure, remove biomass CO₂ and bunkers per IPCC 2006 Vol. 2 Ch. 6, and compare against the 1A sectoral series within ±5 %.
You can answer the CDN2 proposal
You can explain why reverting to the CDN2 BAU conflicts with the recalibration on actual SIE 2022 to 2025 data, and why the 2018 BUR agreement argument is circular.
You can frame the METE decision
You can state decision D1 precisely: if the baseline moves, do adopted targets move too? And you can point to Decision 4/CMA.1 ICTU requirements for documenting the answer.
You can hold the scope
You can separate what fits before 31 August (reconciliation, documentation, bounded changes) from what does not (a full model and report re-cut), and route the latter to a separate agreement.

Apply the exclusions, then compare. The numbers will tell us whether the BAU moves.

Official guidance and project sources

References

  1. IPCC (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 2: Energy, Chapter 6: Reference Approach. Rules for apparent-consumption CO₂ estimation; exclusion of biomass CO₂ and international bunkers from national totals (memo items); comparison of reference and sectoral approaches. ipcc-nggip.iges.or.jp
  2. IPCC (2019). 2019 Refinement to the 2006 IPCC Guidelines, Volume 2: Energy. Updated guidance; Parties are encouraged to use it under the Paris transparency framework.
  3. UNFCCC Decision 18/CMA.1 (Katowice, 2018), annex. Modalities, procedures and guidelines for the enhanced transparency framework: national inventories shall use the 2006 IPCC Guidelines and 100-year GWP values from IPCC AR5.
  4. UNFCCC Decision 4/CMA.1 (Katowice, 2018), annexes I and II. Information to facilitate clarity, transparency and understanding of NDCs (ICTU): reference points and baselines, assumptions and methodological approaches, and updates to them; accounting guidance for Article 4.13 and 4.14.
  5. Paris Agreement, Articles 4.13 and 13. Accounting for NDCs promoting transparency, accuracy, completeness, comparability and consistency; the enhanced transparency framework.
  6. UNFCCC Decision 5/CMA.3 (Glasgow, 2021). Common reporting tables and formats for biennial transparency reports under Article 13.
  7. République du Sénégal (2018). Biennial Update Report (BUR). Last full national GHG inventory; anchor year for both CDN2 and the current reference-approach estimates.
  8. SIE Sénégal. Rapport du Système d'Information Énergétique, édition 2024 (28/04/2025); édition 2023 requested. National energy balances; common activity-data source for all estimates in this brief.
  9. M. Sambou (14 Aug 2026). "CDN3 : Inventaire GES secteur énergie", email. Reference-approach estimate of 14,115 Mt CO₂ / 14,82 Mt CO₂eq for 2024; recommendation to extend the CDN2 BAU. Results only; worked file requested.
  10. HEAT GmbH (2026). CDN3 Senegal model v125 changelog; technical note of 21 Aug 2026 (FR/EN). HEAT 1A series (8,74 / 9,25 Mt for 2022/2023), custody register, reconciliation path.

Decision paragraph numbers are cited at decision level; verify exact paragraph references against the official texts at unfccc.int before external use.