The CO2 for the fuel is pretty easy to calculate. It's the 2-4kg or so per litre (depending on where it's sourced). We'll call the carbon footprint of a generat

The CO2 for the fuel is pretty easy to calculate. It's the 2-4kg or so per litre (depending on where it's sourced). We'll call the carbon footprint of a generator negligible as it's mostly Aluminum (20kg CO2e/kg new or 1kg/kg recycled and steel (2kg/kg), it's maybe 10kg/kW so max 200kg. It will be lost in our error for the dirty fuel source once we use 50kg or so of fuel. The carbon cost of keeping some fuel out of circulation is hard to quantify, and tanks are essentially free so I will call the capacity cost 0. ~3kg/kg for fuel is really convenient because when combined with ICE efficiency, it's about 1kg/kWh This https://climate.mit.edu/ask-mit/how-much-co2-emitted-manufacturing-batteries https://climate.mit.edu/ask-mit/how-much-co2-emitted-manufac... says every kWh of NMC causes 2-16t of emissions. I'm sceptical this applies in 2022 given that $130 only buys 5t of coal, but we'll use it as indicative. So for our generator we have 200P + 4E + 0C where P, E and C are power, total energy used and hours of capacity respectively. If we assume 2C charge rate and 4000 cycle life, our battery is 2400 * max(P/2, C) + 2400/4000E So E = 600C + 6/40E Assuming P is small compared to C, then any capacity used less than ~550 times in the 8 or so years it lasts is better off as a generator. This is a function of the carbon intensity of battery though. At 200kg (https://spiral.imperial.ac.uk/bitstream/10044/1/79316/2/Revised%20Manuscript%20%28clean%29.pdf https://spiral.imperial.ac.uk/bitstream/10044/1/79316/2/Revi...) it's about 50.