Learning about our electricity grid the fun way

Suitable for Key Stage 2 (ages 7 to 10) and Key Stage 3 (ages 11 to 13)

Skills: Percentages, Fractions, Rounding, Comparisons, and introducing Carbon Intensities.

This is best done with access to a computer connected to the internet to see the live grid numbers.

How green is our grid: what is currently generating our electricity?

The electricity grid connects all the generators with all the consumers of power across the country. With increased renewable generation on the grid, how much green power is produced depends on the weather. A day with lots of sunshine will be good for solar power. A time with a fair amount of wind will give lots of wind power. When there’s not much of either then other generators need to step in and produce power to keep everything running smoothly.

The Current Grid in Percentages

Go to https://www.gridwatch.templar.co.uk and look at the current electricity grid. You will see something like

Snapshot from midday 27 September 2023. This page is for the electricity grid in Great Britain (GB). The key values from the charts are copied here:

• Demand 31.52 GW
• GB generated:
  • CCGT 7.67 GW (24.34%)
  • Nuclear 5.08 GW (16.12%)
  • Wind 7.42 GW (23.54%)
  • Pumped 0.14 GW (0.44%)
  • Hydropower 0.67 GW (2.13%)
  • Solar 2.55 GW (8.09%)
  • Biomass 1.39 GW (4.41%)
  • Coal 0.78 GW (2.47%)
  • OCGT 0.00 GW (0.00%)
• Imports
  • France (French ICTs or Interconnectors) 2.62 GW (8.31%)
  • Netherlands (Dutch ICT) 1.06 GW (3.36%)
  • Northern Ireland (Irish ICT) 0.32 GW (1.02%)
  • Republic of Ireland (E-W ICT) 0.24 GW (0.76%)
  • Belgium (Nemo ICT) 0.00 GW (0.00%)
  • Norway ICT 1.40 GW (4.44%)

Introducing Percentages (skip if already familiar). Explain that a fraction with a denominator of 100 is equivalent to percent and, if necessary, fractions being division operations. Show the % symbol. 5/100 = 5% = 5 ÷ 100.

Question: show that the electricity produced by GB CCGT (Combined Cycle Gas Turbine, or electricity from natural gas) is 24.34% of GB demand.

Answer: 7.67 GW / 31.52 GW * 100 = 24.33%

Note: the last digit might be different because of rounding error. Rounding error occurs when we shorten (or truncate) the number of digits we write down during the calculation. Here we have used 2 decimal places. When we next use this number to calculate something it is no longer exact so small errors can creep into the calculation. Normally in science and engineering, when we need more accuracy we will keep more digits in our numbers through the calculation steps. This keeps the rounding or truncation errors lower.

Question: what is the amount of GB-produced renewable power as a percentage of GB demand?

Answer: Wind + Hydro + Solar + Biomass = (7.42 GW +0.67 GW + 2.55 GW + 1.39 GW) / 31.52 GW * 100 = 38.17% or we can simply add up the percentages 23.54% + 2.13% + 8.09% + 4.41% = 38.17%.

Question: what is the amount of GB-produced low carbon power as a percentage of GB demand?

Answer: Wind + Hydro + Solar + Biomass + Nuclear = (12.03 GW + 5.08 GW) / 31.52 GW * 100 = 54.28% or 38.17% + 16.12% = 54.29%.

Question: what is the amount of imported power as a percentage of GB demand?

Answer: add up all the power from the Interconnectors (ICTs) = 2.62 GW + 1.06 GW + 0.32 GW + 0.24 GW +0.00 GW + 1.40 GW) / 31.52 GW * 100 = 17.89% or simply 8.31% + 3.36% + 1.02% + 0.76% + 0.00% + 4.44% = 17.89%.

The biggest import into Great Britain comes from France. This is a relatively low carbon grid. The French grid is visible by clicking on the map of France in the corner. You will see something like

• Demand 50.00 GW
• France generated:
  • Nuclear 37.84 GW (75.68%)
  • Hydropower 3.61 GW (7.22%)
  • Gas 1.68 GW (3.36%)
  • Coal 0.00 GW (0.00%)
  • Oil 0.11 GW (0.22%)
  • Biomass 0.68 GW (1.36%)
  • Pumped -0.48 GW (-0.96%)
  • Solar 9.91 GW (19.82%)
  • Wind 2.68 GW (5.36%)
• Imports:
  • Germany -2.45 GW (-4.90%)
  • Belgium 0.00 GW (0.00%)
  • Italy -0.46 GW (-0.92%)
  • Switzerland -1.66 GW (-3.32%)
  • Spain 1.37 GW (2.74%)
  • UK (GB) -2.65 GW (5.30%)

Question: what is the amount of French-produced low carbon power as a percentage of French demand?

Answer: Wind + Hydro + Solar + Biomass + Nuclear = (2.68 GW + 3.61 GW + 9.91 GW + 0.68 GW + 37.84 GW) / 50.00 GW * 100 = 109.44% or simply 5.36% + 7.22% + 19.82% + 1.36% + 75.68% + 54.28% = 109.44%. As this is over 100%, this means that there is sufficient French-produced low carbon power to fulfil all of France’s domestic needs.

Note: the Imports (except Spain) appear to be negative. That means France is Exporting electricity to neighbouring countries (and only Importing from Spain).

Question: of total GB consumption, how much is coming from Nuclear Power?

Note: Norway’s grid is largely hydropower, the grid in the Netherlands usually exports excess wind power to the UK (GB), Spain’s grid exports excess solar power at this time (and the Irish interconnectors are probably transferring power derived from natural gas).

Answer: GB Nuclear is 5.08 GW and Imported from France is 2.62 GW. France is generating 37.84 GW from Nuclear power, from a total generation of 56.51 GW (Pumped Storage is consuming power, not generating power at this time). Including the Spanish Import (which we will assume does not contain power from Nuclear), the percentage of Nuclear power in the French grid is 37.84 GW / (56.51 GW + 1.37 GW) * 100 = 65.38%. So total Nuclear = 5.08 GW + 65.38% * 2.62 GW = 5.08 GW + 1.71 GW = 6.79 GW. As a percentage of GB demand this is 6.79 GW / 31.52 GW * 100 = 21.54%.

Question: of total GB consumption, approximately how much is coming from renewables?

Answer: GB Wind + Hydro + Solar + Biomass = 12.03 GW. 2.62 GW is coming from France (3.61 GW Hydro + 0.68 GW Biomass + 9.91 GW Solar + 2.68 GW Wind + 1.37 GW Spanish Solar / 57.88 GW total generation including Spanish import = 31.53%, so 2.62 GW * 31.53% = 0.83 GW), 1.06 GW is coming from the Netherlands (which we will assume is largely Wind for the sake of this problem, so +1.06 GW), 1.40 GW is coming from Norway (which we assume is 100% Hydropower), assume the Irish power is 0% renewable. So total renewables = 12.03 GW + 0.83 GW + 1.06 GW + 1.40 GW = 15.32 GW. As a percentage of GB demand this is 15.32 GW / 31.52 GW * 100 = 48.59%. Given that the grids in Spain and the Netherlands are unlikely to be 100% renewable, and the Irish grid is unlikely to be 0% renewable, we should probably round down the percentage to approximately 48%.

How Green is the Grid?

The International Panel on Climate Change (IPCC) assessed the carbon intensity of different technologies in 2014. Their results are copied here:

Energy Source	Median Lifecycle Emissions (gCO2e/kWh)
Coal	820
Oil	650
Gas	490
Biomass	230
Nuclear	12
Solar	45
Hydro	24
Hydro Storage (Pumped)	grid dependent
Wind (Onshore)	11
Wind Offshore	12
Solar rooftop	41
Solar utility	48

Question: what is the approximate carbon intensity of power produced in Great Britain right now?

Hint: Ignore Pumped Storage as that is delivering power that was originally produced a little while back.

Stretch Question: what is the approximate carbon intensity of the power consumed in Great Britain right now?

Note: we don’t have all the information on what is imported from the Netherlands, Norway, Spain or Ireland so lets assume the power from the Netherlands is 100% Wind, the power from Norway is 100% Hydro (it often is, actually), the power from Spain is 100% Solar, and the power from Ireland is 100% Gas.

The carbon intensity of electricity consumed in Great Britain is lower than the carbon intensity of Great Britain production because the carbon intensity of imports is low (France being a largely Nuclear-powered grid and Norway’s power coming from Hydroelectricity).

Now we understand how we can calculate carbon intensities, why not have a look at https://app.electricitymaps.com/map

With thanks to https://www.gridwatch.templar.co.uk for making power grid statistics of Great Britain and France easily accessible.