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.
SIMON WILD 
Simon,
Issues with Electric Car infrastructure or lack of it:
http://www.guardian.co.uk/environment/electric-cars?INTCMP=SRCH
And the way to deal with those issues:
http://www.guardian.co.uk/environment/2013/feb/20/estonia-electric-car-charging-network
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?
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