Working out how bad a vehicle is for the environment is far more complex than many people think.
Do you take into account the oil exploration needed to find the petrol to fuel a car? Or the mining for the elements in the battery?
Most arguments over this issue centre on the energy needed to create the battery for an electric vehicle (EV), according to Professor Colin Herron, zero carbon expert at the Institution of Engineering and Technology.
"When making the battery, they have to cure the cells for a period of time, which involves gas or electricity for heating," he said. "That's why there are emissions."
While he often hears arguments suggesting that this means EVs are worse for the environment, Professor Herron said they're based on inaccurate comparisons.
"Usually, they've taken the biggest battery you can make – made years ago in China – compared to a one-litre diesel made now in France."
Such an approach does not take into account facts such as EV batteries can have a 'second life' as electric storage after the car is used, and solely focus on the carbon intensity of electricity generation in some parts of the world.
A study published in Nature in 2020 and based on real-world electric grids found that, in 95% of the world, driving an electric car is better for the climate than a petrol one.
The study found that the average 'lifetime' emissions from EVs are around 70% lower than petrol cars in countries like Sweden, where energy comes from renewables and nuclear, and around 30% lower in Britain.
The only exceptions are places like Virginia, where all the energy used to power the car comes from coal, Herron said.
As a specific example, producing a large 75 kilowatt-hour battery in Tesla's Nevada factory would result in roughly 4,500 kg of carbon dioxide, equivalent to driving a petrol saloon for 1.4 years, according to Chris Brown, owner and managing director of electric finance specialists The Electric Broker.
Producing the same battery in Asia, where carbon fuel sources are used, would result in 7,500 kg of CO2, equivalent to 2.4 years in a petrol-powered saloon.
Herron said car manufacturers are already taking steps to ensure that batteries are made with the cleanest energy possible, and plants in Britain have linked up to the Norwegian interconnector to reduce the carbon footprint of their batteries by using renewable energy.
"There are a few battery plants in Poland, because they're cheaper, but Poland is run off a coal grid," Herron said. "It might come back to bite people that they've put battery plants where power is cheap – but it’s cheap for a reason."
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The major upcoming problem with electric cars is a simple and familiar one, he added, and that's because people buy cars far more powerful than what they actually need. The environmental impact of large batteries is far worse.
"We are replicating the errors that we did with internal combustion," Herron said. "Lots of cars never go beyond the supermarket, but people are now wanting 90 kilowatt-hour (kWh) batteries. The carbon footprint of a 90 kWh battery is a lot higher than my old 30 kWh battery."
Choosing cars with large batteries also limits the number of EVs that can be made in this country, Europe and the world, regardless of how many charge points there are, he added.
"We have an obsession in this country with putting charge points in the ground, with the logic that the more charge points we put in the more cards we will make and get on the road. But the number of batteries determines the number of cars.
"In 2013, Nissan could make 50,000 Leafs a year, and it's not increased production in eight years – because the first battery plant they built could only make 50,000 batteries.
"With the current battery capacity we've got in Europe, the bigger the batteries we make, the less cars we get."
According to new data compiled by research consultancy Radiant Energy Group (REG), in Europe – where sales are rising the fastest in the world – EVs in Poland and Kosovo actually generate more carbon emissions because grids are so coal-reliant.
Elsewhere around Europe, the picture is better, although the relative carbon savings depend on what supplies grids and the time of day vehicles are charged.
Best performers are nuclear and hydroelectric-powered Switzerland at 100% carbon savings vis-a-vis gasoline vehicles, Norway 98%, France 96%, Sweden 95% and Austria 93%, according to the REG study shared with Reuters.
Laggards are Cyprus at 4%, Serbia 15%, Estonia 35% and the Netherlands 37%. An EV driver in Europe's biggest car manufacturer Germany, which relies on a mix of renewables and coal, makes a 55% greenhouse gas saving, the data also showed.
In countries like Germany or Spain with big investment in solar and wind, lack of renewable energy storage means the amount of carbon saved by driving an EV depends heavily on the time of day you recharge.
Reuters contributed to this article.
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