ARCHER pulls 1.2 MW  to run it’s 4920 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.
A relatively small research project doing hybrid calculations can easily consume 10s of MAU: generating a lot of atmospheric carbon dioxide!
By comparison, an economy return flight from London to Boston (for Fall MRS) generates 800 kg of CO2.
So flying London to Boston and back for Fall MRS, adds as much carbon to the atmosphere as 3 MAU of calculations on Archer.
Interestingly, if you were to own a 24-node server in your lab continuously running calculations, this equals roughly 8.6 (kAU) * 365 = 3.1 MAU for the whole year.
My take home message was to be less concerned about the travel to conferences to present my energy-materials science, and more careful with spending HPC time wisely!