Are EVs worth plugging in? Photo / Cole Slawson
An EV could still be cheaper to run after road user charges are introduced on April 1, a new study says.
But it will depend on where you charge.
The Electric Homes report, produced by the non-profit Rewiring Aotearoa and peer-reviewed by Professor Shaun Hendy, says it costs $102,935 to run an average-priced petrol car over 15 years - including the up-front price of the vehicle, servicing and fuel bills.
It says an EV costs more upfront, and will incur RUCs, but lower servicing and energy bill costs will see a cheaper total cost of ownership over the period at $91,751.
But that’s only if you charge your EV at home.
If you top-up at more expensive public fast chargers, where the going rate is 80 cents per kilowatt hour, the total cost of ownership for an EV is more expensive than a petrol car at $116,310.
The cheapest 15-year option is an EV charged by home solar panels, which is put at $83,838 (a home solar installation can easily cost north of $20,000; one Tesla Powerwall battery will cost you $11,800 alone, two is $23,600, three $35,400 plus a $1900 Gateway to connect them to your home and your solar panels - which will cost thousands more. Rewiring Aotearoa says that if your bank offers a low-interest “green loan”, solar power can cost 17-28 cents per kilowatt hour compared to the average home paying 33c per kWh. Actual costs will depend on the size of your home, what kit you choose and other factors).
The report says a petrol car has the highest annual running cost ($4336) followed by an EV topped up at public fast chargers ($3867), an EV changed from the grid at home ($2230) and an EV charged by solar at home ($1703).
It says: “The cost of filling a 50 litre tank of a petrol vehicle is about $130 (at $2.60 per litre), which includes fuel excise similar to RUCs. Filling the ‘tank’ of an electric vehicle to go the same distance is about $30 from the grid, and about $10 from solar, before RUC costs.”
Its EV costs included $2000 for a home charger mains power trickles chargers at 1.4kW - meaning it can take up to 50 hours to fully charge an EV. A 7.4kW home charger can supply around 40km of range per hour. A 25kW public fast charger can deliver about 33km of range in 15 minutes, a 50kW fast charger 66km in the same quarter hour. The exact charging times depend on make, model and battery age.
READ MORE: App calculates the charging cost, and RUC cost, for individual road trips
The study used an average-priced new petrol car ($37,900) and an average-priced new petrol car ($56,300).
It quotes European research that sees EVs reaching price-parity with petrol cars by 2026. A Garner study released earlier this month predicts electric cars will be cheaper to make than an ICE (internal combustion engine) equivalent by 2027, largely thanks to big car makers moving to cheaper “gigagasting” manufacturing - though with the flipside that it will make EVs more difficult to repair, and insurance more costly.
For road user charges, 11,000km mileage per year was used, close to the AA’s figure for the average NZ driver (11,500). EV owners will pay $76 per 1000 in RUCs from April 1, implying $836 per year in RUCs. There will also be a $12.44 (online) or $13.71 (over the counter) admin fee each time you buy a block of RUCs.
The Clean Car Discount, phased out on December 31 last year, was not factored into the report’s sums.
The authors say they allowed for batteries degrading over time. For example, it notes Tesla’s Powerwall 2 has a 70 per cent capacity warranty of 10 years.
The report says an EV produced in China (home to most of the world’s electric vehicle production, including a giant Tesla plant) creates 12.3 tonnes of carbon dioxide emissions (6 tonnes for the vehicle and 6.3 for the battery). A petrol car’s manufacture involves an average 6.7 tonnes of CO2 emissions. Both figures are drawn from a European Federation for Transport and Environment study.
But it says that given NZ’s “highly renewable grid”, an EV will emit about 0.26 tonnes of CO2 per year if it drives 11,000km per year, and a petrol car around 2.58 tonners per year - meaning an electric car will make up its greenhouse gas deficit within two years - both figures are drawn from an Agrilink NZ lifecycle study.
“While our electricity grid is around 80 per cent renewable, only around 30 per cent of the country’s total energy use is renewable because we are so reliant on fossil fuels for transport, heating and industry,” the report says.
For energy efficiency between electric and ice vehicles, it takes a US Environmental Protection Agency ice average of 24.7 miles per gallon (or 10km per litre) while an average EV is rated at the kilowatt per hour energy efficiency equivalent of 116.8mpg.
Early Tesla adopter Ian McCrae underlined this point by plastering a “EV powered by Indonesian coal” sticker on his car, a reference to imports used to fire up the Huntly power station when it’s required to supplement our hydro and geothermal generation.
But the report says the average household could save $1500 per year at current interest rates and around $4500 with a low-interest loan if they electrify their home by by shifting from gas heating and a gas cooker to a heat pump and electric cooker, and similar moves.
Rewiring Aotearoa’ chief executive Mike Casey said, “While our lights, dishwashers and ovens are mostly electric, there are still a lot of households that burn fossil fuels for water heating, space heating, driving and cooking. And because our fossil fuel prices are so high, electrification of households and businesses is now a smart, economic decision, not just a smart environmental decision.”
Chris Keall is an Auckland-based member of the Herald’s business team. He joined the Herald in 2018 and is the technology editor and a senior business writer.
Politicians are urged to prioritise unity and decisive action amid economic challenges.