All over the globe we’re seeing reports of how great electric cars are going to be – compared to equivalent vehicles powered by gasoline. Sure the data is all there and it’s undeniable when it comes to cars.
The one report missing however is if large electric vehicles would be cleaner and cheaper.

To find out we’ll need to compare two average vehicles capable of moving, say, 1 tonne of produce. One powered by diesel, the other powered by electricity – both in New Zealand conditions with New Zealand data. This should cut through the confusion.

Let’s start by looking at efficiencies. A typical diesel engine has an efficiency rating of 30%. Unfortunately most of the energy in diesel fuel is released as heat and noise (as you can tell when you pull up next to one at the lights). It’s bad news for diesel in this case, as a typical AC motor has efficiency ratings of around 90% according to MES-DEA figures. Even when taking into consideration the approximate energy loss of 10% via heat and noise through the existing gearbox, differential, and even the onboard recharging system, an electric vehicle can have a peak efficiency of up to 82% from power socket to tyre.

Ok, so round one goes to the electric vehicle – but it’s not over yet. What about the cost per year? Is this where we see the so-called future of electric transport pulled apart at the seams? It’s not too hard to find out.
A company called Smith Electric Vehicles make an all-electric version of the Ford Transit. It may only be able to travel a maximum of 100 miles per charge, but it’s a good place to find economy figures.

The same sized Ford Transit van running on diesel operates at an average of 12 litres per 100 km according to fuelsaver.govt.nz. This means that if the vehicle travelled 27,500 km, with diesel at $1.16 per litre it’ll rack up a yearly bill of $5093 per annum. This includes Road User Charges at 4.6 cents per kilometre. Now that’s actually not too bad for a large vehicle.

By using Smith’s figures, we can work out their vehicle uses around 0.25 kilowatt-hours every kilometre. In New Zealand a kilowatt-hour costs around 20 cents. Knowing that electric vehicles are exempt from paying Road User Charges, the electric Transit works out to cost 8 cents per kilometre in electricity only. So at 27,500 kilometres per year that’s $2,200 worth of electricity.

Alright, that’s fair. Round two to the electric vehicle. But what about carbon output? We’ve all heard reports from both sides of the argument – so which one is actually cleaner? Fortunately we’ve got official New Zealand figures to work from.

The NZ governmental figures from med.govt.nz claim New Zealand diesel emissions are at 2.618 kilograms of CO2 released per litre of diesel burnt in an engine. This means our Ford Transit would release 310 grams of CO2 per kilometre if it had an average economy rating of 12 litres per 100 kilometers travelled. Again, this is pretty good for a large vehicle.

However, time to bring out the other side of the story. Let’s compare NZ electricity emissions figures for electricity. At present, 200 grams of CO2 gets released with every kilowatt-hour of electricity generated, day or night. This is an average figure as some of our electricity is renewable, and some of it is from gas and coal. Using those figures however, we can see how the electric vehicle fares.
If our electric vehicle chews through 0.25 kilowatt-hours of electricity per kilometre, then it would release (wait for it) 50 grams of CO2 per kilometre. That’s less than a quarter of the diesel version.

So there we have it; the debate is over. Round three goes to the electric van. It’s obvious now that even in a large vehicle, the overall winner for efficiency, cleanliness and cost of ownership is the electricity.
I guess that’s a knock-out.