GB electricity carbon intensity.

Half-hourly carbon intensity of electricity for Great Britain and its seventeen distribution regions, with the forecast generation mix. Republished from NESO’s Carbon Intensity API as flat files you can query without an API key.

released CC BY 4.0

Key specificationsas released

Source	NESO Carbon Intensity API (api.carbonintensity.org.uk)
Licence	CC BY 4.0 · attribute NESO
Coverage	May 2018 → yesterday · national + 17 regions
Cadence	30 minutes (settlement periods, UTC)
Units	gCO₂ per kWh delivered

Formats	Parquet · datapackage.json · CSV from the explorer
Refresh	daily 06:15 UTC · scripts/fetch_neso.py
Revision	2026-10-01
Status	released

Characteristic curvesFig. 1–2 · built 2026-11-09

Fig. 1 · National daily mean, Sept 26 → Nov 26gCO₂/kWh

270180900

mean 122 260 · 8 Nov 49 · 9 Oct

SeptOctNov

69 days, one column each. Daily mean of the national half-hourly series (measured where published, forecast otherwise). Refreshed by the pipeline; the first release used NESO's stats endpoint, whose 30-day windows skip six month-end days.

Fig. 2 · South Wales (region 7), half-hourly forecast, 2026-09-29gCO₂/kWh

4002000

00:0006:0012:0018:0024:00

Shaded by NESO's index band, very low (lightest) to very high. Minimum 18 g at 09:30, maximum 322 g at 17:00. The notebook's sheet 02 reads this day.

Pinout · schemaone row per settlement period

Field	Type	Description
from, to	timestamp (UTC)	Start and end of the 30-minute settlement period, ISO 8601.
intensity_forecast	int	Forecast intensity, gCO₂/kWh.
intensity_actual	int · nullable	Measured intensity. National file only; null for every regional row.
intensity_index	enum	NESO band: very low · low · moderate · high · very high.
regionid, shortname, dnoregion	int · text	Regional file only. 1–17; e.g. 7 = South Wales, WPD South Wales.
mix_biomass … mix_wind	float (%)	Regional file only. Forecast generation share for nine fuels: biomass, coal, imports, gas, nuclear, other, hydro, solar, wind.

Absolute maximum ratings · known limitsread before use

Limit	Consequence
Regional values are forecasts	There is no measured regional intensity. Do not describe a regional figure as observed.
Model output, not metered emissions	NESO estimates intensity from the generation mix. A number here is a modelled estimate with its own error: on 29 Sep 2026 the national forecast missed the measured value by 12 g/kWh on average.
Index bands change	NESO revises what counts as “low”. Treat the numbers as the stable field and the labels as commentary.
Average, not marginal	This is the average intensity of everything generating. The emissions caused by adding a load depend on the marginal plant, usually gas, and are not in this dataset.
Grid, not house	Nothing in this dataset says what any building actually consumed or when.

Typical applicationDuckDB, runs in your browser

SELECT date_trunc('hour', "from") AS hour,
       round(avg(intensity_forecast)) AS g_per_kwh
FROM   sample
WHERE  region = 'sw' AND day = '2026-09-29'
GROUP BY 1 ORDER BY 2 LIMIT 3;

Loads DuckDB-WASM on first run (~5 MB, cached by your browser).

Runs in your browser with DuckDB-WASM against the files listed in datapackage.json; nothing is sent to a server. Until the first pipeline run the tables are the sample days; afterwards the yearly and monthly partitions are registered too.

Downloadfiles are the release; the site is the label

datapackage.json checks.log sample_days.parquet national_daily_means.parquet

Yearly and monthly partitions (national/, regional/) are listed in datapackage.json once the pipeline has run; the explorer registers them automatically.

Provenance

Fetched	scripts/fetch_neso.py · GitHub Actions, daily · commit recorded in checks.log
Endpoints	/intensity/{from}/{to} · /regional/intensity/{from}/{to} · 14-day windows
Transform	Flattened JSON → one row per period; generation mix pivoted to columns. Values as served.
Checks	Row counts, missing periods, nulls, value ranges; results in checks.log and on this page.

Used in

Notebook	Notebook sheet 02 · The grid, one Monday

Revision history

2026-10-01	v1 · first release: sample days (29–30 Sep 2026, South Wales and GB) and 12 months of national daily means; full partitions arrive with the first scheduled fetch.
[date]	[next change, and what it breaks]

Cite as

Elliott, J. (2026). DS-001 GB electricity carbon intensity [data set], databased.business, rev 2026-10-01. Derived from NESO Carbon Intensity API, CC BY 4.0.

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