Renewable energy powered New Zealand well-placed to reap benefits of EVs, but other countries need to up their clean energy supply

Electric vehicles (EVs) alone are not enough to combat climate change and could actually increase carbon dioxide emissions unless paired with significant renewable energy generation, a new study suggests.

Research spanning 26 countries over 15 years found electric vehicle adoption could in fact contribute to higher carbon emissions in regions where electricity generation still relies heavily on fossil fuels such as coal and oil.

In fact, if EVs are charged with electricity generated by coal-fired power plants, they could indirectly contribute to higher emissions than petrol or diesel vehicles, especially when the entire lifecycle from production to disposal is taken into consideration.

The global study, published in the journal Energy, analysed data from 2009 to 2023 using an extended STIRPAT framework, which examines the impact of population, affluence and technology on environmental outcomes.

A research team from the University of Auckland and Xiamen University found electric vehicle uptake shows a consistent positive correlation with carbon dioxide emissions across all quantiles measured.

What the researchers - Stephen Poletti, Simon Tao and Boqiang Lin - found challenges the common assumption that electric vehicles automatically reduce carbon emissions regardless of how their electricity is generated.

According to the paper, electric vehicles only begin to deliver emission reductions when renewable energy generation exceeds a critical threshold - approximately 48 per cent of the total electricity mix.

Globally, the world's renewable energy supply from mainly solar, wind and hydro accounts for just over 30 per cent of the total.

"EVs are only as green as the grid they plug into, and government policies should aim to increase the adoption and integration of renewable energy like solar and hydro. This can be achieved by setting ambitious renewable energy targets and providing adequate subsidies such as tax credits to producers and consumers of renewable energy," Poletti said.

New Zealand is well-placed to reap the benefits of EVs, as over 80 per cent of electricity generation in the country is renewable, the researchers said.

The researchers examined multiple factors affecting emissions, including economic growth, population density, green technological innovation, and renewable energy consumption.

While EVs showed a concerning positive relationship with emissions, the study found green technological innovation consistently helped reduce carbon dioxide output.

To that effect, the researchers recommend governments accelerate their transition to renewable electricity generation to ensure electric vehicles can fulfil their potential in helping combat climate change.

Removing subsidies for fossil fuels, and implementing carbon pricing mechanisms could also incentivise renewable energy development, the researchers added.

Higher population density also demonstrated a significant negative relationship with emissions, suggesting more compact urban development may contribute to lower carbon footprints.

The study identified economic growth, measured as per capita gross domestic product, as the strongest driver of increased carbon emissions across all countries in the analysis. A coordinated climate policy that integrates electric vehicle adoption with renewable energy expansion is important here.

They also suggest countries should focus on promoting sustainable urbanisation and effective population density management while encouraging the development of environmentally friendly green building standards.

It's worth noting EVs and other New Energy Vehicles (NEVs) provide other environmental benefits, one of the studies linked to in the paper suggests. Research from China shows subsidising private sector NEVs led to significantly improved air quality, reducing very fine particulate matter (PM 2.5 micron) from exhaust gases.

Such fine particulate matter can stay in the atmosphere for a long time, and is believed to cause lethal diseases and cancers for millions of people every year.