In Part 1 of this post, we discussed the environmental trade-offs of retaining or replacing a petrol or diesel car based on the lifetime CO₂ (carbon dioxide) emissions incurred during manufacture, use and scrappage of that car. Now it’s time to consider how a battery electric car fares when subjected to the same scrutiny.

What is indisputable is that, for the electric vehicle (EV), there is no equivalent to the CO₂ tailpipe emissions produced by an internal combustion engine (ICE). Just as importantly, from a health point of view, there are no other gaseous emissions such as oxides of nitrogen or unburnt hydrocarbons. The particulate emissions from combustion are also absent; although particulates from brakes, tyres and the road surface will exceed those from an equivalent ICE vehicle due to the greater weight of the EV. Given that around 40,000 deaths per year in the UK are deemed by the UK Committee on the Medical Effects of Air Pollutants to be a consequence of atmospheric pollution arising from road transport, the electric car, at the point of use, is an unequivocal winner from both an environmental and health perspective.

During manufacture, there is overwhelming evidence to show that, today, building an EV generates more CO₂ and other greenhouse gases than the equivalent ICE vehicle. Battery production, currently heavily centred on China and other Asian countries, is the major, fossil fuel-intensive processes that tips the balance against the EV. With newer, renewable energy-powered ‘giga factories’, producing batteries in the same region of the world as the car assembly plant, the balance will swing towards the EV within the next few years.

Once the electric car reaches its destination, the battery needs to be recharged. Unless recharged from a wholly renewable source of electricity, this is also not a CO₂-free process. In practice it will depend upon the energy mix of the grid at the time of re-charging. In those regions of the globe with a heavy dependence on coal-fired power generation, there is an argument that the electric car simply shifts the point of greenhouse gas emission from the urban high street to the point of generation.

With a decreasing UK dependence on coal in the generation of electricity, driving and recharging a small hatchback with a 30-45kWh battery, results in emissions of CO₂ equivalent to around 35grammes per driven kilometre (g/km). A luxury EV with a battery capacity of 90kWh, would result in around 50g/km when in use. Both emission figures are well below those of even the smallest, most efficient ICE car: for example, the 2020 Mk8 VW Golf with a petrol engine produces 122g/km and few ‘City cars’ achieve much below 95g/km. So, the key question is: how long before the lower emissions of the EV, when on the road, offset the higher emissions during production?

As with the ‘Retain or Replace’ discussion for an ICE car in Part 1 of this post, there is no single answer to the question. It will depend greatly on where the vehicle (and particularly the battery) was produced, the size of the vehicle and how the EV is used (eg a life of urban commuting or long-haul motorway journeys).

A recent statement from Volkswagen, who have a vested interest in both EVs and ICE models, claimed that, on average, a new battery electric vehicle would need to travel 77,000 miles before it would have ‘saved’ the CO₂ associated with its production. Imperial College, London, state that the luxury EV with its 90kWh battery is responsible for more CO₂ emissions during production than over a 15-year lifetime. Both statements seem reasonable when looking at the chart below. This shows the EV lifetime CO₂ emissions superimposed, in red, on the same chart as the ICE ‘Retain or Replace’.

What is clear is that even with the higher emissions associated with its production, within less than 2½ years the medium sized EV (eg VW ID3) will have generated less CO₂ than the modern, fuel efficient ICE car (eg Citroen C1). The luxury EV (eg Jaguar I-PACE) will take just over 7 years to achieve the same result when compared with the medium sized 2019 ICE car (eg Ford Mondeo).

So, your EV may not be a zero-emission mode of transport but, over a lifetime of use, it should be greener than most ICE cars and, as our global power generation becomes cleaner, that margin will increase.

Factors such as the deployment of a charging infrastructure, which carries an associated CO₂ ‘footprint’, the availability of scarce elements required in lithium battery production and in the components of efficient electric motors, carry their own implications for the future of EVs. Recycling these scarce materials is also not trivial nor energy-free.

Finally, as noted in the post on this blog in December 2014, hydrogen fuel cell EVs are becoming increasingly available (albeit with their own fuelling infrastructure requirements). Crystal ball-gazing by those who try to predict the future of personal transport, is an interesting pastime.