energy produced from gasoline after a journey of 488 miles
Last Post 22 Mar 2012 10:23 AM by mleis. 1 Replies.
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New Member

21 Mar 2012 09:08 AM
    Hi Guys ive been trying to work out the ENERGY produced from gasoline during a journey of 488 miles for a car. i worked it out below can you confirm if its correct or incorrect asap.

    ive been told by someone that they thinks its not possible to work out Energy produced over a distance in KWh and has to be done in only KW, but i think you can. lemme know if im right or wrong please.

    range traveled is 488 miles
    fuel consumption rate is 4.2L of petrol consumed every 100km, equivelant to 0.042L in 1km therefore i found there is 1.6km in a mile so i worked out 0.0672L petrol consumed in a mile .

    converted this value into British Thermal Units.
    27533 BTU in one litre of petrol therefore in 1 mile this is
    0.672L x 27535=1850 BTU.

    coverting to watt-hours, i found 0.293Wh in one BTU therfore,
    0.293x1850 = 0.54205KWh in one mile

    changing for 20 miles
    0.54205 x 20=264.5204KWh

    i then adjusted this value for 70% efficiency losses as a car engine only is about 30% efficienct. I got a final answer of around 80KWh for 488 miles

    is this correct, can i have my final answer in KWh or does in have to be in watts.

    Thanks- i posted this question previously but i wrote the info wrong
    New Member
    New Member

    22 Mar 2012 10:23 AM
    This is correct to use KWh. A Watt is just a rate, which is Joules/second, and the Wattage used by your vehicle varies moment to moment depending upon your acceleration, velocity, wind drag, elevation change, etc.

    You can find the average Wattage used by your vehicle during your trip, and just multiply it by the appropriate time unit that it took to travel the distance to find the total amount of energy used.

    Ex- (Joules/second)*seconds of travel = Total Joules (energy) used during travel.

    1 KWh = 3,600,000 Joules

    Time and distance are always related, so your method works as well.