Electric vehicles (EVs) seem very attractive at first sight. But when we look more closely, it becomes clear that they have a substantial carbon footprint and some downsides in terms of the extraction of lithium, cobalt and other metals. And they don’t relieve congestion in crowded cities.

In this response to the question, we touch briefly on the lithium issue, but focus mainly on the carbon footprint of electric cars.

The increasing use of lithium-ion batteries as a major power source in electronic devices, including mobile phones, laptops and electric cars has contributed to a 58% increase in lithium mining in the past decade worldwide. There seems little near-term risk of lithium being mined out, but there is an environmental downside.

The mining process requires extensive amounts of water, which can cause aquifer depletion and adversely affect ecosystems in the Atacama Salt Flat, in Chile, the world’s largest lithium extraction site. But researchers have developed methods to recover lithium from water.

Turning to climate change, it matters whether electric cars emit less carbon than conventional vehicles, and how much less.

Emissions reduction potential of EVs

The best comparison is based on a life cycle analysis which tries to consider all the emissions of carbon dioxide during vehicle manufacturing, use and recycling. Life cycle estimates are never entirely comprehensive, and emission estimates vary by country, as circumstances differ.

In New Zealand, 82% of energy for electricity generation came from renewable sources in 2017. With these high renewable electricity levels for electric car recharging, compared with say Australia or China, EVs are better suited to New Zealand. But this is only one part of the story. One should not assume that, overall, electric cars in New Zealand have a close-to-zero carbon footprint or are wholly sustainable.

A life cycle analysis of emissions considers three phases: the manufacturing phase (also known as cradle-to-gate), the use phase (well-to-wheel) and the recycling phase (grave-to-cradle).

The manufacturing phase

In this phase, the main processes are ore mining, material transformation, manufacturing of vehicle components and vehicle assembly. A recent study of car emissions in China estimates emissions for cars with internal combustion engines in this phase to be about 10.5 tonnes of carbon dioxide (tCO2) per car, compared to emissions for an electric car of about 13 tonnes (including the electric car battery manufacturing).

Emissions from the manufacturing of a lithium-nickel-manganese-cobalt-oxide battery alone were estimated to be 3.2 tonnes. If the vehicle life is assumed to be 150,000 kilometers, emissions from the manufacturing phase of an electric car are higher than for fossil-fueled cars. But for complete life cycle emissions, the study shows that EV emissions are 18% lower than fossil-fueled cars.

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