ARCHER pulls 1.2 MW [1] to run it’s 4920[1] compute nodes (each of which is 24 cores). That’s just under 250 W power per node: 6 kWhr of energy in 24 hrs. A 24-hour single-node job consumes 8.6 ‘kAU’ in the internal compute units used for accounting.
So that’s roughly 0.7 kWhr / kAU, or 700 kWhr / MAU.
The UK electricity grid carbon intensity is roughly 400 g / kWhr averaged over the year: making 280 kg CO2 per MAU of Archer calculation.