Viewing 8 posts - 1 through 8 (of 8 total)
  • Would this work ?
  • RamseyNeil
    Free Member

    If we took 100 petrol or diesel cars off the road for a period of time and replaced them with 100 similar electric cars and used the fuel saved to produce electricity to run the 100 electric cars for the same period of time would there be an energy surplus or deficit ?

    newrobdob
    Free Member

    I don’t know the answer or how to figure it out but it is an interesting question!

    fifeandy
    Free Member

    Answer is: It depends!

    If the electric cars have no KERS there will be an energy deficit as there are losses generating/storing the electricity.
    With KERS on the other hand whilst you have less energy to begin with, you can make it go further.

    Fresh Goods Friday 696: The Middling Edition

    Fresh Goods Friday 696: The Middlin...
    Latest Singletrack Videos
    hols2
    Free Member

    Will depend on the period of time and where/how it’s driven. If it’s one week, then the energy used to produce the battery for the electric car will probably be more than any savings. If it’s 50 years, mostly town driving or in rolling terrain with bursts of acceleration and braking, then probably the electric car will be more efficient because a large power station has greater thermal efficiency than a small internal combustion engine and electric vehicles use regenerative braking (i.e. KERS), so the cycles of acceleration and braking will really punish a regular car.

    If it’s doing long trips down an autobahn, then the electric vehicle won’t have such an advantage because there would be very little braking, you’d have to stop to recharge really often, and the battery would probably need replacing every year (hence energy costs in recycling the battery).

    chewkw
    Free Member

    Deficit coz the petrol would evaporate … 😀

    Think I asked me engineer friend before with similar sort of question …

    You need to go nuclear.

    wobbliscott
    Free Member

    There definitely wouldn’t be a surplus. It would be a deficit but not sure by what margin. Rather than extracting the energy from the fuel directly and use it for motive power, you\’re extracting the energy from the fuel and sticking it in another engine that converts electrical energy into motive power, so you have another layer of energy conversion which is never 100% efficient, and mechanical losses – energy wasted through heat and friction. Then you’ve got losses in the distribution of the electricity, which though small are still there.

    bikebouy
    Free Member

    No.

    HTHs.

    hols2
    Free Member

    you\’re extracting the energy from the fuel and sticking it in another engine that converts electrical energy into motive power

    Electrical generation can use huge engines that are optimized for maximum efficiency at constant load. They have very high thermal efficiency, probably about 60% of the energy in the fuel is converted to electricity. A car engine can’t be optimized in the same way, so thermal efficiency is more like 30% to 35%. On top of that, an electric or hybrid car can use regenerative braking to recover energy and recharge batteries. Yes, there will be transmission losses through the power-grid, charging the battery, and in the electric motor, but for stop-start city driving, an electric or hybrid vehicle can still have benefits over a regular petrol engine. The heavier the vehicle, the bigger the advantage because more energy can be recovered from braking. A bus or delivery vehicle doing a lot of stop-start driving around a hilly town is ideal for electric or hybrid. A vehicle that is rolling along a flat autobahn at high-speed will be much less suited for electric because the major factor is aerodynamic drag and there is virtually no energy recovered from braking.

Viewing 8 posts - 1 through 8 (of 8 total)

The topic ‘Would this work ?’ is closed to new replies.

Members Notice New deal added to Members Discounts