How green is an electric car, really? | Top Gear
BBC TopGear
BBC TopGear

How green is an electric car, really?

The Big Electric Question #1

Published: 26 Apr 2019

It’s the first rock lobbed at electric cars, so let’s deal with it first. Electricity comes from burning fossil fuels, so how can you ignore that CO2? Well, we’re not ignoring it, we’re factoring it in. Power stations are more efficient than car engines, so if you transmit that electricity over the grid, put it into an EV (and they are very efficient, actually), then your EV is responsible for half the CO2 per mile than even an economical petrol or diesel car. Both those numbers include extraction and refining and distribution inefficiencies for the petroleum – well-to-wheel in the jargon.

And on a summer’s day, the UK actually gets all its electricity from renewables. Yes, in winter the UK uses some fossil-fuel electricity. Yes, nuclear is counted as ‘renewable’ in this analysis and it isn’t really carbon-free because of the immense energy in its mining and waste-disposal. But even so, EVs do far better than even that worst-case one-to-two ratio of entirely fossil-fuel electricity. As a happy bonus, because electricity supply is moving rapidly towards renewables, an EV bought today will be responsible for less and less CO2/km as it gets older.

Advertisement - Page continues below

Now, manufacturing. The most recent studies I’ve seen, including one by the immensely thorough ICTT (the guys who unearthed Dieselgate), put the carbon impact of manufacturing an EV at just under three times a piston car*.

The lifetime CO2 emissions for an EV are half what they are from a conventional car

The actual car is about equal, but the EV’s impact is doubled by its battery. That embodies the energy all the way back to the lithium mine and the grid electricity used by the Chinese battery factory. Then, for good measure, that figure assumes that in the lifetime of the car it will need a replacement battery. But that’s 2015 data. We now know batteries last longer than early predictions said, and anyway, they can be recycled or reused for grid energy storage.

Most important of all, the energy to build a car is far less (eight times less in the case of a piston car) than the energy used to run it over its life. This means by the time an EV is just a few years old, it has offset its manufacturing deficit.

Advertisement - Page continues below

The ICTT says for a car in the UK, the lifetime CO2 emissions for an EV, including the global mining and manufacturing, and the electricity to run it, are half what they are from a conventional car. All of which rather punctures that oft-repeated mantra that running a decades-old Land Rover is greener than buying a new Leaf. Sorry.

That’s not to say it’s all honey and daisies. The metals and minerals in many batteries come from countries that allow maltreatment of workers and leaking of highly toxic pollutants. Car assembly plants here in Europe or Japan run clean and the workers are reasonably looked-after.

Much of the battery industry is hidden away in places of which we know little. Carmakers – who are the customers in this case – should push their battery and cell suppliers harder for transparency and better regulation. It’d be a start if China decarbonised the grid that powers the cell factories. It’s possible: Tesla’s Gigafactory uses entirely renewable electricity.


More from Top Gear

See more on Electric