Homecharged EVs still cheaper to run

AUCKLAND: An electric vehicle 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 nonprofit Rewiring Aotearoa and peerreviewed by Prof Shaun Hendy, says it costs $102,935 to run an averagepriced petrol car over 15 years — including the upfront 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 mean a cheaper total cost of ownership over the period at $91,751.

But that is only if you charge your EV at home.

If you topup at more expensive public fast chargers, where the going rate is 80c a kilowatt hour, the total cost of ownership for an EV is more expensive than a petrol car at $116,310.

The cheapest 15year 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 lowinterest ‘‘green loan’’, solar power can cost 1728c a kWh 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 50litre 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 trickle charger 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.

The study used an averagepriced new petrol car ($37,900) and an averagepriced new electric car ($56,300).

It quotes European research that says EVs will reach priceparity with petrol cars by 2026. A Garner study released earlier this month predicts electric cars will be cheaper to make than an 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% 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 is driven 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% renewable, only around 30% 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 internal combustion vehicles, it takes a US Environmental Protection Agency ice average of 24.7 miles per gallon (or 10.5km per litre) while an average EV is rated at the kilowatt per hour energy efficiency equivalent of 116.8mpg. — The