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g/km CO2

  • 28-11-2022 10:48am
    Registered Users Posts: 2,726 ✭✭✭

    Quick question re calculating CO2 emissions for a car charged off the national grid

    Average of all Island Market 258gCO2/kWh

    Take 300km driving

    Typical New E.V. = 16 kWh/100 km so 300km = 48kWh

    >Total CO2 = 48 x 258 = 12,384 g/C02

    Typical New Diesel car = 120g/Co2 per km

    >Total CO2 = 120 x 300 = 36,000g/C02

    So on average the EV would have roughly 1/3 the Co2 as the diesel. Obviously this can be reduced further if somebody has solar at home etc but taking average all Island Market electricity into account seems a logical approach. Am I missing anything from my calculations - charging losses maybe?


  • Registered Users Posts: 10,230 ✭✭✭✭the_amazing_raisin

    I'd say it's worth accounting for charging losses, but also see if you can account for the charging time

    Most people charge at night and the grid tends to be greener during that time

    I think Eirgrid publishes statistics on it but I'm not sure they include CO2 generation. You might be able to estimate it using the average fuel mix

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost (Escapist magazine)

  • Registered Users Posts: 5,595 ✭✭✭10-10-20

  • Registered Users Posts: 11,908 ✭✭✭✭KCross

    I've posted the CO2 calculations for night rate charging each month over the last few years.

    Column 5 of this table

  • Registered Users Posts: 1,954 ✭✭✭innrain

    I don't think it is a fair comparison. In the EV case the the figures represent the amount of CO2 produced during the fuel production and transmission while in the diesel case these are missing completely. Is is so negligible? I doubt so.

  • Registered Users Posts: 10,230 ✭✭✭✭the_amazing_raisin

    You're absolutely correct that the CO2 emissions of an ICE car doesn't account for the extraction and transportation costs, something which I always felt was a sham

    Considering the vast majority of our petrol and diesel arrives via tanker powered by bunker fuel, and is brought to forecourts using a big truck belching diesel, I would say the true CO2 emissions of even the most efficient car are horrendous

    At least with the estimation for an EV you have a clear picture of what the true environmental impact is

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost (Escapist magazine)

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  • Registered Users Posts: 515 ✭✭✭VikingG

    The figure of 120 gCo2/km seem fair - SEAI has it at 122 across all cars. However one factor you are missing is the CO2 it takes to produce a litre of diesel and then get it the pumps - this would add 24 to 30% onto the diesel emissions. I dont know if the CO2 rate for producing electricity from Gas takes the same into account for producing and piping the Gas to the power plant, perhaps if it didnt you are right to discount it from the diesel figure as well.

  • Registered Users Posts: 1,954 ✭✭✭innrain

    There should not be left out at all I'd say. Pretty sure Gas has smaller footprint in the production and transport. Also renewable play a major role and is increasing day by day. It needs to be incorporated anyway. Having said that, by focusing solely on CO2 it is also a trap as we will reach the wrong conclusion: diesel is better than petrol.

  • Registered Users Posts: 5,645 ✭✭✭kirving

    Which is a completely understandable conclusion, given that until VW were exposed (in the US), diesel was forced onto the population here, through a laser focus on tailpipe CO2 above all else. E85, popular in the US and Scandinavia was taxed out of existence here, despite the growing of the crop absorbing much of that CO2.

    The other major issue with many EV's, is that it takes quite a long time to negated the additional CO2 emitted during their production. Driven in the EU, Volvo estimated that the XC40 Recharge would need to be driven 84,000km to breakeven with the alternative ICE. Most cars of course make it to this mileage, so it's a step in the right direction, but the benefits will not be realised for some time yet.

    Page 25 here:

  • Registered Users Posts: 10,230 ✭✭✭✭the_amazing_raisin

    To be fair I'm glad E85 never took off here. It was a good idea on paper but unfortunately in the US it's led to a serious waste of land to produce ethanol that could be used for food production (plus associated emmisions from farming)

    Think this video was a pretty good overview

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost (Escapist magazine)

  • Registered Users Posts: 6,180 ✭✭✭zg3409

    Gas vents a lot of methane etc, and byproducts of diesel and petrol are used in plastics and millions of other products. In long term cost of fuel byproducts may increase

    In terms of battery manufacturing CO2 versus ICE build CO2, the CO2 of ICE use is based on gentle driving and real world driving with cold engine etc gives much higher values. Batteries in EVs will definitely be recycled and reused so it's unlikely any will every end up in landfill, and future EVs will be made with less CO2 using recycled battery raw material.

    In terms of CO2 of one versus the other it's hard to take into account all the inputs and as said charging at night is more green.

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  • Registered Users Posts: 2,726 ✭✭✭Casati

    Looks like 2am to 8am is a lot higher than the Island Market 258gCO2/kWh figures I am using?? Seems most nights are over 300 in KCross table?

    Regarding charging loss - google is telling me 15% is a reasonable assumption - does that sound right or does it matter charing at home versus public charging?

  • Registered Users Posts: 11,908 ✭✭✭✭KCross

    Looks like 2am to 8am is a lot higher than the Island Market 258gCO2/kWh figures I am using??

    Yea, I was wondering where you got your data point from as it didn't tally with the smartgrid website data?

    Did you get 258 from a report from a few years ago, maybe?

    If you go back to 2020, and before, it was probably in the 200s but we have started using coal again so our CO2 figure has gone back up to 300+ this year.

    Regarding charging loss - google is telling me 15% is a reasonable assumption

    That seems a little high to me. It depends on the car, but I'd say 5-10% would be closer to reality but I guess you could put in worse case scenario to make your figures more believable, I suppose.