Electric versus Petrol versus Biofuel cars

One the questions that was asked in my water footprint post was how much water is used in the production of petrol? Well, I thought I would cover biofuel and electric cars at the same time. So which is better?

I have taken the water and energy involved in the production of the different fuels, together with how much energy is generated from the fuel and then looked at how they compare for a small car (similar to mitsubishi miev) driving for 100km.

So not surprisingly when we grow food to make fuel it uses a lot of water, and also a lot of energy – think about the fertilizer, processing equipment etc.

Per Unit Litres of water used in production of fuel MJ of energy used in the production of fuel MJ output per unit
Biofuel Corn litre 2,845 23 31
Biofuel Soybean litre 11,397 26 39
Petrol litre 18 8 35
Electric from Coal Power Station kwh 8 1 4
Electric from Solar PV kwh 0 0 0


The following is a for small 5l/100km size car, similar to the Miev

Per 100km Travelled
litre water per 100km MJ per 100km
Biofuel Corn 14,225 113
Biofuel Soybean 56,985 128
Petrol 90 38
Electric from Coal Power Station 268 44
Electric from Solar PV 0 0

But what is more of a surprise is how well the electric car charged from a coal fired power station compares to a petrol car, this is assuming that if you brought an electric car you wouldn’t have a large enough solar panel on your roof for charging your car. So for a small energy and water penalty we would be reducing the exhaust and noise pollution in our cities – better health and also increasing the ability to be able to naturally ventilate offices.

Now this doesn’t take account of carbon emissions because I wanted to focus on the amount of water and energy used, and based purely on that an electric car seems to be the better option.

I heard today that the NRMA predict that by 2025 30% of the cars in Australia will be electric. Based on the amount of water used in biofuels and the fact that Australia will be importing 80% of its oil use by 2030 I can see why.

Which would you choose? Would you use the E10 fuel at the pump? Looking at those figures I don’t think I would.

3 Comments on “Electric versus Petrol versus Biofuel cars”

    • Thanks Ed. Interestingly Better Places recently exited Australia, about the same time as the NRMA said that electric cars would increase! Maybe their business / process model wasn’t right?

  1. Pingback: Tri Harder Part 6 – What about flue emissions and maintenance? – Simon Wild

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