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Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Ralph E. H. Sims, Professor Emeritus, Sustainable Energy and Climate Mitigation, Massey University
"The share of electric and plug-in hybrid vehicles has increased recently in NZ, probably as a result of high petrol and diesel prices more than the aim of reducing a car-owner’s carbon footprint. A recent US study has shown there to be significant greenhouse gas emission reductions from EVs compared with internal combustion (petrol and diesel) vehicles (ICVs) when also taking into account their total life-cycle emissions. These arise from when a vehicle is manufactured, repaired and disposed of at the end of life.
"The study authors recommend government intervention to encourage early disposal of ICVs (often not economically sound otherwise) in order to replace them with EVs and hence reduce emissions, not only greenhouse gases but also exhaust emissions that impact on human health.
"The US analysis examined various options including 'retiring' an ICV after 11 years and replacing it with an EV. A reduction in life-cycle emissions resulted regardless of the annual distance travelled. But do these results apply to NZ?
"Due to our higher renewable energy shares, the NZ electricity system has a lower level of CO2 / kWh generated than the US grid where coal- and gas-fired power generation hold a lot higher share. Hence an EV in NZ would have a lower life-cycle carbon footprint than the same model operated in the US.
"Also NZ has one of the oldest fleets in the world since the life of a car, ute, or van is often over 20 years. This leads to sharing the emissions from manufacturing a vehicle over a longer period and hence lower emissions per km driven, although emissions related to repairs and maintenance would be higher. Hence, a policy, as suggested by the US study, for a government to subsidise early retirement of ICVs than would otherwise occur makes little sense in NZ.
"The key message of the US study however is that the life-cycle emissions from an EV are far lower than from an equivalent ICV, especially when allowing for battery recycling technologies that are gaining traction. So why the current Coalition Government has repealed legislation to encourage the greater uptake of EVs is hard to understand."
