I recently heard someone trot out a factoid i’d heard before a couple of times:
The battery on hybrid cars takes so much energy to produce that it’s actually greener to drive a normal car.
As a Prius owner myself I wondered; could this be true?
Toyota have been rather tight-lipped about the exact details of Prius battery manufacture, although this is probably just because they consider their Hybrid Synergy Drive technology commercially sensitive (at least while they’ve got such a lead in the hybrid market over their competitors)
So let’s take a guesstimate at some numbers and see how it stacks up:
A new Prius starts at about £20,845. Let’s be generous to the sceptics and say that making the battery is a whopping 20% of the sticker price of the car (it’s likely much less than this). That means it costs £4169 to make a battery. Again, lets humour the sceptics and say that 90% of the cost of the battery manufacturing process is energy and that Toyota pays the equivalent of 5p/kWh. That puts the energy consumed during manufacture at 270GJ. That amount of energy is equivalent to a little over 1800 gallons of petrol. Toyota rate the hybrid drive as offering an improvment of about 25mpg over a standard drivetrain (using figures from the Auris vs Auris Hybrid), even if that’s only 15mpg in reality then a Prius would only take 27,200 miles to make back the energy used making the battery. Remember, those numbers I chose are extremely pessimistic, it’s likely that the real break-even point was much sooner.
Toyota’s warranty on their hybrid batteries is eight years, so unless you don’t think you’re going to put 27,000 miles on the clock in that time, a hybrid will reduce the amount of energy your driving consumes.
So bottom line: even a rough calculation of the energies involved does not support the claim that building batteries for hybrid cars is more wasteful than driving a conventionally powered car.
If you want to play around with the numbers, you can download this spreadsheet.