I love driving my Nissan Leaf pure electric car. But in my home state of Victoria most of the electricity is produced by brown coal generators that emit more than 1,200 grams of carbon dioxide for every kilowatt hour of electricity. So driving an electric car could be responsible for generating more carbon dioxide emissions than a petrol or diesel car of the same size. Not surprisingly, I am often asked: “Don’t you realise that your electric car is responsible for more carbon dioxide emissions than my petrol car?”
The simple answer is “no it isn’t”. In our house we pay a premium so that 100% of our electricity is ‘green’. Australian government legislation guarantees that it comes from newly commissioned renewable sources such as windfarms and solar. So the emissions profile of our electric car is actually low, and far superior to an equivalent fossil-fuel car.
Electric cars are more responsive to the throttle, providing a vigorous feel that has to be experienced to be believed.
The more thoughtful answer is to point out that it is the wrong question to ask. There’s no doubt in my mind that electric cars are the transport technology of the future. One day, everyone’s driving could be close to emissions-free, like mine is. The more of us who buy electric cars and power them with green electricity the faster that day will come. The threshold for being a better environmental citizen in an electric car is to use electricity where the associated carbon dioxide emissions are 700 grams per kilowatt hour or fewer. That’s the crossover point at which a Nissan Leaf produces fewer emissions per kilometre than a similarly sized, best of breed fossil-fuel car such as the Mazda3 diesel.
How long will that take? For brown coal-dependent Victoria, it could be decades. But looking across the entire country, the situation looks more promising. The average emission level across the national grid in 2010 was 841 grams per kilowatt hour, just two-thirds that of Victoria.
How much better might emissions become in the next 30 years? Other countries are ahead of Australia and show us the way. In Germany, the average mix is 461 grams per kilowatt hour – well below the threshold for the best of the fossil-fuel cars. In nuclear-powered France the average mix is an enviably low 79 and in hydro-powered Norway it is an astonishingly low 17 grams per kilowatt hour. So Nissan Leaf drivers are unlikely to be challenged in Germany; in France and Norway, laurels would be thrown at their feet.
But challengers would still score a point if they talked about the embodied emissions in the Nissan Leaf – particularly its battery. It is heavy and complex to manufacture, leading to higher levels of carbon dioxide emissions during the manufacture of an electric car compared with an equivalent fossil-fuel car. Furthermore, emissions also rack up when you count the costs of mining lithium, which is inefficient. However, experts predict that within the next decade the energy density of electric vehicle batteries will double. This means that next decade’s electric cars will deliver the same range for half the battery mass. For that reason alone they will embody fewer carbon dioxide emissions.
What about future generations of diesel, petrol or natural-gas cars? They will certainly continue to become more efficient, but at the end of the day, they will be burning fossil fuels to move a mass of metal, plastic and human beings from place to place. It is not conceivable that their per kilometre emissions can ever be as low as what is achievable with electric vehicles charged by renewable electricity. Will hydrogen powered cars be a contender? Perhaps, and if the hydrogen is manufactured from low-emissions electricity that will be good too.
There are other reasons to drive electric cars. First and foremost, the driving experience is superb. Electric cars are more responsive to the throttle, providing a vigorous feel that has to be experienced to be believed. And at least in our electric car, because of the mass of the battery down low, the car drives with the surety and smoothness typical of a heavy limousine. Another advantage is that charging the car at home every few nights is more convenient and uses less of my time than a weekly trip to the petrol station. On top of all these benefits, electricity is cheaper per kilometre than petrol or diesel.
In summary, if you think nationally rather than worst-case regional, or if you ensure that you plug into a renewable electricity supply, electric cars are already good for the environment. And if you look forward 20 or 30 years it is clear that electric cars will make a major contribution to reducing carbon dioxide emissions.
Alan Finkel is an electrical engineer, neuroscientist and former Chief Scientist of Australia.
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