Grid carbon intensity

Grid carbon intensity is a measure of how much Carbon Dioxide (CO2) emissions are produced per kilowatt-hour (kWh) of electricity consumed from the national grid. Understanding this “mix” of energy sources is essential for anyone looking to reduce their environmental impact.

The UK Energy Mix

The electricity in your home is supplied by a combination of different power sources:

  1. Renewables (Zero Carbon): Wind, solar, hydro, and biomass.
  2. Nuclear (Zero Carbon): Provides a steady “baseload” of clean power.
  3. Fossil Fuels (High Carbon): Primarily natural gas. The UK no longer uses coal for regular power generation.
  4. Interconnectors: Cables that allow us to share electricity with neighbouring countries like France, Norway, and the Netherlands.

Why intensity varies

The carbon intensity of the grid is constantly fluctuating:

  • Weather: On a very windy or sunny day, renewable generation can account for over 60% of our power, leading to low carbon intensity.
  • Demand: During peak times (like 5pm on a winter evening), renewable supply may not be enough to meet demand. The grid then has to turn on “peaker” gas plants, leading to high carbon intensity.
  • Time of day: Intensity is typically lower at night when demand is low, and during the middle of the day when solar generation is at its peak.

How to use intensity data

By monitoring real-time carbon intensity, you can make smarter choices about when to use energy:

1. Shift your usage

Wait for low-intensity windows to run your tumble dryer, dishwasher, or washing machine. Many modern appliances have “delay start” timers for this purpose.

2. Smart Charging

If you have an EV, configure your charger to only charge during periods of low carbon intensity. This ensures your vehicle is truly “green.”

3. Battery Management

Charge your home battery when intensity is low and discharge it to power your home during high-intensity peaks.

National Average: The UK’s average carbon intensity has dropped from around 500g CO2/kWh in 2010 to under 150g CO2/kWh today. Our goal is to reach a Zero Carbon Grid by 2035.

Tracking the intensity

You can track the grid intensity via:

  • The Carbon Tracker tool on this site.
  • The Carbon Intensity app by National Grid ESO.
  • Smart home integrations: Connect your devices to APIs that automatically trigger actions based on low carbon intensity.