# Nigeria National Grid Location-Based Emission Factor — NEFDB Phase 1 ## 1. Input data Source file: `datasets/grid_electricity/derived/nigeria_generation_by_fuel_latest.csv` | fuel_type | generation_gwh | data_year | confidence_flag | |-----------|---------------:|----------:|-----------------| | gas | 7,281.71119 | 2020 | high | | hydro | 75.59301 | 2020 | low | | oil | 0.00000 | 2020 | low | | solar | 0.00000 | 2020 | low | | wind | 0.00000 | 2020 | low | | coal | 0.00000 | 2020 | low | | biomass | 0.00000 | 2020 | low | | other | 0.00000 | 2020 | low | **Total generation used in denominator:** 7,357.30420 GWh (gas + hydro). Important limitations noted in the source file: - The gas total is only the eight NIPP/IPPs that had generation records in `MWh` in the Energy Databank 2020 file after correcting the `ELPD_NESCO_GEN` unit error. - The hydro total is only 75.59 GWh because the Kainji, Jebba and Shiroro records for 2020 carried non-MWh units (`MW` / `Bill.Cubic Meter`) and were excluded. Independent NERC/TCN estimates put 2020 hydro at roughly 8,500–9,500 GWh. ## 2. IPCC emission factors and NCVs Methodology follows the UNFCCC "Tool to calculate the emission factor for an electricity system": ``` emissions = fuel_input_energy × emission_factor fuel_input_energy = electricity_generated / thermal_efficiency ``` Fuels with zero generation emit zero emissions regardless of the factor. ### 2.1 CO₂, CH₄ and N₂O factors From **IPCC 2006 Guidelines, Volume 2, Chapter 2, Table 2.2** — *Default emission factors for stationary combustion in the energy industries (kg of greenhouse gas per TJ on a net calorific basis)*, page 2.16 (PDF page 16): | fuel | CO₂ (kg/TJ) | CH₄ (kg/TJ) | N₂O (kg/TJ) | |----------------------|------------:|------------:|------------:| | Natural gas | 56,100 | 1 | 0.1 | | Crude oil | 73,300 | 3 | 0.6 | | Gas/diesel oil | 74,100 | 3 | 0.6 | | Residual fuel oil | 77,400 | 3 | 0.6 | | Other bituminous coal| 94,600 | 1 | 1.5 | | Sub-bituminous coal | 96,100 | 1 | 1.5 | | Lignite | 101,000 | 1 | 1.5 | ### 2.2 Net calorific values From **IPCC 2006 Guidelines, Volume 2, Chapter 1, Table 1.2** — *Default net calorific values (NCVs)*, page 1.18 (PDF page 18): | fuel | NCV (TJ/Gg) | |----------------------|------------:| | Natural gas | 48.0 | | Crude oil | 42.3 | | Gas/diesel oil | 43.0 | | Residual fuel oil | 40.4 | | Other bituminous coal| 25.8 | | Sub-bituminous coal | 18.9 | | Lignite | 11.9 | ### 2.3 GWP basis Non-CO₂ gases are converted using **AR6** 100-year GWP values: - CH₄: 28 kgCO₂e/kgCH₄ - N₂O: 265 kgCO₂e/kgN₂O - Biogenic CO₂ from biomass is excluded from the Scope 2 location-based factor. ## 3. Thermal efficiency assumption The Nigerian NIPP/IPP plants captured in the dataset are predominantly simple-cycle gas turbines. Literature values for similar Nigerian plants range from roughly 28 % to 34 %, while NERC’s MYTO allows a benchmark heat rate of 10,000 MJ/MWh (≈ 36 % efficiency). For this calculation a representative **gas thermal efficiency of 35 %** is used. Conversion: ``` 1 GWh = 3.6 TJ fuel_input_TJ = generation_GWh × 3.6 / η ``` ## 4. Step-by-step arithmetic ### 4.1 Gas - Generation: 7,281.71119 GWh - Useful electricity output: 7,281.71119 × 3.6 = 26,214.1603 TJ - Fuel input (η = 0.35): 26,214.1603 / 0.35 = **74,897.6008 TJ** - CO₂: 74,897.6008 TJ × 56,100 kg/TJ = 4,201,755,406 kg = **4,201.755 ktCO₂** - CH₄: 74,897.6008 × 1 kg/TJ = 74,897.6 kg = 0.07490 ktCH₄ → 0.07490 × 28 = **2.097 ktCO₂e** - N₂O: 74,897.6008 × 0.1 kg/TJ = 7,489.8 kg = 0.00749 ktN₂O → 0.00749 × 265 = **1.984 ktCO₂e** **Gas total GHG = 4,201.755 + 2.097 + 1.984 = 4,205.836 ktCO₂e** ### 4.2 Hydro - Generation: 75.59301 GWh - Emissions: **0 ktCO₂e** ### 4.3 Oil, coal, solar, wind, biomass, other - Generation: 0 GWh each - Emissions: **0 ktCO₂e each** ### 4.4 National factor ``` EF = total emissions / total generation EF = 4,205.836 ktCO₂e / 7,357.304 GWh EF = 4,205,836,000 kgCO₂e / 7,357,304,000 kWh EF = 0.57165 kgCO₂e/kWh ``` **Final location-based grid emission factor = 0.572 kgCO₂e/kWh (rounded)** The CO₂-only factor is 0.571 kgCO₂/kWh; the non-CO₂ contribution is < 0.2 %. ## 5. Cross-check against NERC 2024 The 2024 NERC Annual Report states: - Total grid generation in 2024: **37,093.70 GWh** - Hydro generation in 2024: **11,469.85 GWh** (30.92 % of total) The Energy Databank 2020 file used here totals only **7,357.30 GWh**, i.e. roughly one-fifth of a typical Nigerian annual generation total, and it is missing most large hydro plants. No scaling adjustment was applied because the dataset already provides the most disaggregated fuel-level information currently available for NEFDB Phase 1. The factor is therefore a **Phase 1 best-effort estimate** derived directly from the available plant-level records, not a fully representative national-grid mix. ## 6. Uncertainty and confidence | source of uncertainty | approximate impact | |----------------------------------------------------------|--------------------| | Incomplete generation coverage (missing large hydro & other thermal plants) | High; denominator understated and renewable share under-counted. | | Gas thermal efficiency assumed at 35 % | Medium; ±5 percentage points changes the factor by roughly ±8 %. | | IPCC default CO₂ EF range for natural gas (54,300–58,300 kg/TJ) | Low-to-medium (≈ ±4 %). | | CH₄/N₂O GWP choice (AR6) | Negligible impact on the final value (<0.2 %). | **Confidence: low.** Recommended actions before using this factor for reporting: 1. Incorporate NERC/TCN official national generation-by-fuel totals when a 2020 (or later) breakdown is obtained. 2. Add plant-specific or technology-specific thermal efficiencies for the Nigerian fleet. 3. Re-derive the factor and supersede this Phase 1 value.