How green are electric cars?

  • Electric cars
  • Mar 06, 2020

With zero fumes from an exhaust, electric cars are greener than their diesel or petrol counterparts. This does not, however, mean that the manufacture or use of an EV is without any environmental cost of its own.  

Electric vehicles are more intensive to manufacture, and have what is referred to as higher 'embodied carbon'. For EVs this is generally 'paid back' many times over in the life of the car. But not all EVs are created equal. Manufacturing a mid-sized EV with a small 84-mile range results in about 15 percent more emissions than an equivalent ICE vehicle. Yet for a larger, longer-range EV, the manufacturing emissions can be as much as 68 percent higher, according to one study.

Heavy bodywork or long-range batteries can increase the time it takes to pay back the carbon produced in manufacture

Beyond choosing an EV that fits our needs, we can control the carbon an EV contributes with choosing how to power it. The national grid has made huge strides towards renewables in the past decade, reducing the carbon intensity of electricity, yet it is at best only 50% renewable, on average.

By choosing an EV and powering it with clean energy, we are supporting the greenest sources of energy from the grid.

The embodied carbon cost of electric cars

So, an electric car does emit more emissions during its manufacture than a conventional car. This isn't all about the battery, but often due to the fact that components used in an electric car must be lightweight to compensate for the fact that the battery pack is extremely heavy. The lightweight materials, such as carbon fibre and aluminium, require much more energy to produce and manufacture.

Smaller electric cars like this BMW i3 quickly 'pay back' the carbon produced in manufacture

Materials used within the electric car’s motor and batteries can also be the cause of increased manufacturing emissions. Rare earth metals such as neodymium are used in electric car motors in order to increase power output, and these have to be mined, which is carbon intensive.

The processing of lithium and copper also requires huge amounts of energy and has the potential to release toxic compounds. This especially negatively impacts the local environment where this occurs, as the population can be exposed to these compounds through air and groundwater contamination.

However, as electric car battery production becomes more mainstream and more widespread, these problems have a chance of being mitigated by better regulation and advances in technology. For example, scientists are working on replacing cobalt - one of the most expensive parts of a rechargeable battery. Cobalt mostly comes from the Democratic Republic of Congo, where widespread concern has been raised about the violation of human rights.

While we are right to be concerned about the carbon and environmental chains in products like electric car batteries, we have to weigh it up against the well-to-pump environmental cost of extracting oil.

An electric car does emit more emissions during its manufacture, but saves carbon in use

How efficient is an electric car?

Electric cars are far more efficient than traditional engines. It’s estimated that only around 17 to 21% of the potential energy in diesel or petrol is actually converted into power for the car. Electric vehicles, on the other hand, are able to convert around 60% of the electric energy to getting the vehicle in motion. For every mile you drive, an EV will require less energy.

Manufacturers often provide a comparison in 'MPGe' for EVs - and many are capable of 100MPGe or more, compared to what can be as low as 25mpg for conventional cars.

Clearly, EVs are not without environmental impact during their production. However, that extra manufacturing input is a relatively small trade-off compared to continuing burning of fossil fuels. The embodied pollution that occurs during production of the car is paid back many times over through reduced emissions as the car is driven over the years. How fast this is done depends on the driving and the charging.

Firstly, providing you are on a renewable electricity tariff, or generating your own energy at home, you can power an EV with renewable, pollution-free electricity.

Use our free online calculator tool to see the carbon savings you could make by generating your own solar energy, installing a battery to manage use or simply switching tariff.

Electric car battery recycling

When batteries are deemed too worn out for driving, they still have between 70% and 80% of their useful charge left. As a result, there's a chance for them to be used in less critical jobs - they’re especially useful in homes, where solar power can be used to charge them up during the day, and then used during the night. In Japan, Nissan is repurposing their old EV batteries to power streetlights, and Renault has used EV batteries to provide backup power for elevators in France.

When these retired batteries have again completely run out their useful (after)life, it’s possible to recycle them. The precious metals used in EV batteries are, in theory at least, infinitely recyclable, so they can be used in the production of new batteries. This process isn’t straightforward at the moment, as the infrastructure is not yet in place to support mass recycling of lithium-ion EV batteries.

This isn’t just a problem for EVs - but for all sorts of technology such as mobile phone and laptops. Even before the end of life of any significant number of EVs, this kind of waste is already presenting a massive challenge.

Battery recycling isn’t cost effective on the open market yet. It’s estimated that the cost of recycling a lithium-ion battery is around £1, whereas the value of the raw materials extracted from the battery are worth about ⅓ of that. Infrastructure is slowly being put into place for EV battery recycling, and it’s likely that battery recycling will become its own industry before long.

See how much you could save using our free EV and clean energy tool!