How big an EV fleet can New Zealand’s grid handle?

I have been talking a lot lately (wait for it) about whether we have the infrastructure for a large electric vehicle fleet.  The main worry is that countries don’t have the infrastructure to charge up an entire fleet of electric vehicles, so I thought I’d  figure out exactly how many EVs the New Zealand grid can handle.

We will need to increase generation capacity

With a fleet of four million cars, vans, utes, small trucks, and large trucks, charging all these vehicles could take up almost the entire currently installed generation capacity we have for electricity. 

According to Transpower, current electricity generation stands at 9,284 mega watts (MW).

Research from Canterbury University [1] suggests that, if 100% of the fleet was electric, we’d need somewhere between 8,100 and 9,000MW to charge them all at the same time.

But not in the next ten years… just

As it stands, less than 0.02% of the vehicle fleet is made up of electric vehicles.  If they were all charged at once, they’d use about the same proportion of the grid’s electricity, 0.02%.

At this point you can still argue about heat pumps having more of a draw from the grid than electric cars, but what happens when we get more EVs?

Scenario analysis from the Ministry of Transport [2] suggest that electric vehicles will make up 10% of the fleet in the late 2020s. At 10% of the fleet, electric vehicles will be adding an extra 800-900MW to daily grid demand, which shouldn’t be a problem for grid capacity if they’re charged at night – which is when most EV owners charge their electric vehicles anyway.

At what point will we need to beef up our energy supply?

Assuming off-peak charging, we’d need to start adding to electricity capacity when the electric vehicle fleet gets to about 15-20% of the fleet, or 600,000-800,000 cars.  According to Ministry of Transport’s electric vehicle fleet projections, this will happen from 2030 – only a few years after we hit the 10% mark.

But, by the time 2030 rolls around, the EV fleet is expected to be expanding at such a rapid pace that this additional capacity will need to be in place, well in advance.

Planning ahead

With electric vehicles making up such a small proportion of the current vehicle fleet now, it can be hard to envisage what infrastructure changes will need to be made to accommodate more EVs in the future. And there are even concerns that the technology will be surpassed by other vehicle types in a decade’s time.  Stuck between a rock and a hard place, we should tread carefully around what developments we lock in to accommodate electric vehicle growth before it becomes significant. But we also need to think about what changes need to be in place before a growing electric vehicle fleet becomes a problem for electricity generation, consumption, and distribution.  Plans and developments now, need to be made with the flexibility for the demand potential posed by the rapidly growing electric vehicle fleet. 



[1] slides 48 and 49 .  We have updated the figures for the size of the New Zealand fleet as at September 2017.


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