Earth Notes: GB Grid Intensity YELLOW

Grid is OK; but you could still avoid CO2 emissions by postponing running big appliances such as dishwashers or washing machines

You might have saved as much as 60% carbon emissions by choosing the best time to run your washing and other major loads.

Latest data is from Sat Jan 23 01:15:00 UTC 2021. This page should be updated every few minutes: use your browser's refresh/reload button if you need to check again.

Follow this grid status on Twitter @EarthOrgUK.

This free service is in BETA and may be unavailable or withdrawn at any time and is provided "as-is" with no warranties of any kind.

This page shows the current "carbon intensity" of the GB National Grid (ie the England/Scotland/Wales portions of the UK electricity grid) as a simple traffic-light indicator. Carbon intensity is a measure of how much greenhouse gas (especially CO2 or carbon dioxide) is emitted to generate a fixed amount of electricity.

Anything other than a GREEN light suggests that you should consider deferring heavy loads (eg starting a dishwasher or washing-machine at home) because the carbon intensity is relatively high, or because of other factors. Avoiding running major appliances such as washing/heating/cooking during RED times will save CO2 emissions.

You should still conserve first: don't run things that don't need to be run at all, don't leave things on that can be turned off at the wall, run full loads in your washing machine and dishwasher, etc, etc, before worrying about carbon intensity.

Planning ahead: note that in the UK/GB peak demand for electricity will usually be 4pm to 9pm especially on week days in winter (and a lesser peak around 9am/10am), and peak carbon intensity is often around peak demand, so try to avoid big loads then; if possible run loads such as your dishwasher and washing machine overnight, eg on a delay timer or just as you go to bed, or if you have local microgeneration that can cover much/all of the load.

There is argument about whether this marginal cost calculation reflects reality, ie in practice is there simply a gas turbine somewhere that gets spun up a little if you demand extra power. There is much less argument about the value of lowering demand generally, and about lowering peak demand on various parts of the infrastructure.

Shifting loads to the night when energy is going into grid-scale storage such as pumped hydro, avoids pulling it out when you would otherwise run/dispatch the load, and thus saves round-trip losses of ~25% for that load.

Technical Stuff

You don't need to understand the numbers below, but some people like to see them!

Effective grid carbon intensity for a domestic user is currently 285gCO2/kWh including transmission and distribution losses of 7%.

Latest available grid generation carbon intensity (ignoring transmission/distribution losses) is approximately 266gCO2/kWh at Sat Jan 23 01:15:00 UTC 2021 over 28361MW of generation, with a rolling average over 24h of 226gCO2/kWh.

Minimum grid generation carbon intensity (ignoring transmission/distribution losses) was approximately 113gCO2/kWh at Fri Jan 22 03:00:00 UTC 2021.

Maximum grid generation carbon intensity (ignoring transmission/distribution losses) was approximately 279gCO2/kWh at Fri Jan 22 18:15:00 UTC 2021.

Average/mean grid generation carbon intensity (ignoring transmission/distribution losses) was approximately 226gCO2/kWh over the sample data set, with an effective end-user intensity including transmission and distribution losses of 242gCO2/kWh.

Recent mean GMT hourly generation intensity gCO2/kWh (average=226); *now (=266)
  • 114
  • 113
  • 115
  • 129
  • 160
  • 194
  • 221
  • 233
  • 245
  • 250
  • 249
  • 253
  • 260
  • 265
  • 272
  • 277
  • 278
  • 275
  • 276
  • 276
  • 272
  • 264
  • 266
  • 170
Mean GMT hourly generation GW (all, zero-carbon)
  • 27
  • 18
  • 27
  • 17
  • 26
  • 17
  • 27
  • 17
  • 30
  • 16
  • 34
  • 16
  • 38
  • 15
  • 39
  • 15
  • 38
  • 13
  • 36
  • 12
  • 37
  • 12
  • 36
  • 12
  • 37
  • 12
  • 38
  • 11
  • 40
  • 11
  • 43
  • 11
  • 42
  • 11
  • 40
  • 11
  • 37
  • 10
  • 35
  • 9
  • 32
  • 9
  • 29
  • 9
  • 28
  • 9
  • 28
  • 15

Current/latest fuel mix at Sat Jan 23 01:15:00 UTC 2021: BIOMASS@2450MW CCGT@12029MW COAL@1796MW INTEW@0MW INTFR@2002MW INTIRL@0MW INTNED@0MW INTNEM@1000MW NPSHYD@321MW NUCLEAR@4950MW OCGT@86MW OIL@0MW OTHER@226MW PS@0MW WIND@3501MW.

Generation by fuel category (may overlap):

fossil @ 49%
import @ 11%
nuclear @ 25%
renewable @ 22%
storage @ 0%
0MW [PS]
zero-carbon @ 31%

Overall generation intensity (kgCO2/kWh) computed using the following fuel intensities (other fuels/sources are ignored): BIOMASS=0.3 CCGT=0.36 COAL=0.91 INTEW=0.45 INTFR=0.09 INTIRL=0.45 INTNED=0.55 INTNEM=0.55 NPSHYD=0.0 NUCLEAR=0.0 OCGT=0.48 OIL=0.61 OTHER=0.3 WIND=0.0.

Rolling correlation of fuel use against grid intensity (-ve implies that this fuel reduces grid intensity for non-callable sources): BIOMASS=0.4789 CCGT=0.9264 COAL=0.9821 INTFR=0.9635 INTIRL=-0.7987 INTNEM=0.9641 NPSHYD=0.5851 NUCLEAR=-0.1623 OCGT=0.3918 OTHER=0.5042 WIND=-0.9390.

Key to fuel codes:

Combined-Cycle Gas Turbine
East-West (Irish) Interconnector
French Interconnector (including INTELEC and INTIFA2)
Irish (Moyle) Interconnector
Netherlands Interconnector
Nemo (Belgian) Interconnector
Non-Pumped-Storage Hydro
Open-Cycle Gas Turbine
Pumped Storage Hydro


This estimates the carbon intensity of generation connected to the National Grid GB (Great Britain) high-voltage transmission system, ignoring (pumped) storage and exports but including imports via interconnectors. This excludes 'embedded' generation, eg connected directly to the distribution system, such as small diesels, domestic microgeneration and a significant chunk of wind power, all of which also benefits from reduced transmission/distribution losses, so actual intensity may be somewhat different to (and probably lower than) that reported. However the emissions cost of each marginal/conserved kWh is probably accurately reflected.

This page updated at Sat Jan 23 01:21:05 UTC 2021; generation time 4258ms.

See also:

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See code on GitHub.

This free service may be unavailable or withdrawn at any time and is provided "as-is" with no warranties of any kind.
Some data used to generate this page is licensed from ELEXON.
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Copyright © Damon Hart-Davis 2010--2021. [home]