# Hydro Anomaly Verdict: ELPD_NESCO_GEN 2020

## Summary of findings

The derived file `NEFDB/datasets/grid_electricity/derived/nigeria_generation_by_fuel_latest.csv` reports 75,593.01 GWh of hydro generation for 2020. That total comes almost entirely from a single portal series:

- **Code:** `ELPD_NESCO_GEN`
- **Description:** `NESCO Hydro Power Plant - Generation`
- **Year:** 2020
- **Raw value:** `75,593,010`
- **Stated unit:** `MWh`

A value of 75,593,010 MWh equals **75,593 GWh**. This is physically and statistically impossible for the NESCO hydro plant (and for any Nigerian hydro asset) when compared with independent references:

- Nigeria’s total grid generation in 2020 was about **35,720 GWh** (National Bureau of Statistics).
- Hydro’s share of quarterly generation in 2020 ranged from ~23.6% to ~26.6% (NERC quarterly reports). That implies full-year hydro generation of roughly **8,400–9,500 GWh**, i.e. only **11–13%** of the reported NESCO figure.
- Kainji Hydro alone — one of Nigeria’s three large hydro plants — generated about **4,037 GWh** in 2020 (Elec-T / NERC-class sources). The NESCO plant is a much smaller plant group in the Jos/Plateau area.
- NESCO is the Nigerian Electricity Supply Corporation, a private utility operating small/mini hydro schemes. Public sources describe its current hydro capacity as roughly **19–26 MW** and total annual output in the order of **~100–175 GWh** for hydro+thermal combined.

The raw NESCO value, after dividing by 1,000, becomes **75,593 MWh = 75.6 GWh**, which is consistent with a ~25 MW hydro fleet operating at a moderate capacity factor. The same pattern holds across the entire NESCO generation series (1962–2022): all values are about 1,000× larger than plausible annual output for a small hydro fleet.

## Exact raw rows for ELPD_NESCO_GEN (source CSV)

Extracted from `NEFDB/datasets/grid_electricity/energy_databank_generation_by_plant.csv` (columns: `code,description,year,value,unit`):

```csv
ELPD_NESCO_GEN,NESCO Hydro Power Plant - Generation,2018,77861600,MWh
ELPD_NESCO_GEN,NESCO Hydro Power Plant - Generation,2019,75987310,MWh
ELPD_NESCO_GEN,NESCO Hydro Power Plant - Generation,2020,75593010,MWh
ELPD_NESCO_GEN,NESCO Hydro Power Plant - Generation,2021,45655100,MWh
ELPD_NESCO_GEN,NESCO Hydro Power Plant - Generation,2022,12708930,MWh
```

The same records appear in `energy_databank_generation_by_plant.json` as objects such as:

```json
{
  "code": "ELPD_NESCO_GEN",
  "description": "NESCO Hydro Power Plant - Generation",
  "year": 2020,
  "value": 75593010,
  "unit": "MWh"
}
```

## Comparison against independent references

| Reference | Year / period | Hydro figure | What it implies for NESCO |
|---|---|---|---|
| National Bureau of Statistics — Power Sector Data 2020 | 2020 | Total generation 35,720 GWh | NESCO alone cannot exceed this; actual figure must be << 1% of it |
| NERC Quarterly Report Q1 2020 | Q1 2020 | Hydro share 26.55% of ~8,610 GWh = ~2,290 GWh quarterly | Hydro is dominated by Kainji/Jebba/Shiroro, not NESCO |
| NERC Quarterly Report Q2 2020 | Q2 2020 | Hydro share not stated; Jebba/Kanji/Shiroro dispatch rates 41–77% | Same three large hydro plants carry the hydro share |
| NERC Quarterly Report Q3 2020 | Q3 2020 | Hydro share 23.55% of ~8,265 GWh = ~1,950 GWh quarterly | Again Kainji/Jebba/Shiroro dominate |
| NERC Quarterly Report Q4 2020 | Q4 2020 | Hydro share 24.71% of ~9,628 GWh = ~2,379 GWh quarterly | Same |
| Elec-T / NERC data — Kainji alone | 2020 | ~4,037 GWh for the year | A single large hydro plant is ~50× smaller than the portal’s NESCO value |
| Public NESCO profiles | 2020s | ~19–26 MW hydro capacity, ~100–175 GWh/year combined hydro+thermal | 75,593 GWh exceeds NESCO’s plausible output by ~400–1,000× |

## Other hydro plants in the same source

The source CSV also contains the three large government hydro plants, but their 2020 records are **not** in MWh and were therefore (correctly) excluded by the derivation script:

- `ELPD_KAINJI_GEN` — 2020 value `2,953,275`, unit `MW`
- `ELPD_JEBBA_GEN` — 2020 value `2,678,912`, unit `MW`
- `ELPD_SHIRORO_GEN` — 2020 values are in `Bill.Cubic Meter`

Consequently the derived hydro total for 2020 is effectively just the NESCO value, magnifying the error.

## Verdict

**B. Unit / scale error** (which is itself a data-quality issue in the source portal, D).

The most parsimonious explanation is that the portal stores or transmits the NESCO value in **kWh** but labels it **MWh** without dividing by 1,000. The alternative — that a ~25 MW hydro fleet genuinely produced 75,593 GWh — is physically impossible. The raw numeric magnitude, and the fact that dividing by 1,000 produces a plausible ~75.6 GWh annual output, strongly supports a decimal-place / unit-scale error rather than a mislabelled fuel type or wrong plant mapping.

## Recommended correction or action

1. **Correct the NESCO series.** Treat the raw value as being in **kWh**, convert to MWh, and then to GWh:

   - `75,593,010 kWh ÷ 1,000 = 75,593 MWh ÷ 1,000 = 75.593 GWh`

   Apply the same ÷1,000 correction to **all** years in the `ELPD_NESCO_GEN` series, since the scale error appears consistent from 1962 onward.

2. **Re-derive the 2020 hydro total.** After correction, NESCO hydro for 2020 is ~75.6 GWh, not 75,593 GWh. The current derived file should be regenerated with the corrected value.

3. **Do not simply exclude NESCO.** The plant is a real hydro generator; excluding it would omit ~75 GWh of renewable generation.

4. **Add a data-quality flag to the dataset.** Document that `ELPD_NESCO_GEN` values were divided by 1,000 to fix a probable unit-scale error from the source portal.

5. **Assess completeness of the hydro total.** The present source excludes Kainji, Jebba, and Shiroro because their 2020 records carry non-generation units (MW / Bill.Cubic Meter). The best-available hydro total for 2020 is therefore NERC’s own figure (~8,400–9,500 GWh); if the derived file must rely on the Energy Data Bank, it should clearly flag that the large hydro plants are missing and that the total is incomplete until better plant-level generation records are obtained.

## Confidence level

- **High** (>95%) that the 75,593 GWh figure is erroneous and that the true value is orders of magnitude smaller.
- **Medium-high** (~80%) that the correct scale factor is ÷1,000, giving ~75.6 GWh for 2020. The scale factor is inferred from plausibility; portal metadata alone does not confirm it.
- **Low** for replacing the missing Kainji/Jebba/Shiroro generation inside this dataset; use NERC/TCN sources for a complete hydro total.