Last week I wrote a short item regarding EVs and the ‘infrastructure’ challenge that might be posed by a nation (or neighbourhood) of EV owners plugging in at the same time.

An electrifying debate has ensued, with pitched battle underway amongst those commenting. Can our homes and local/regional/national grids handle the load if everyone plugs in for an overnight top-up before going to bed? Some are quite cautious about it; others say ‘no prob’.

It’s an argument over both how consumers will actually behave (and what their EV charging needs will be) and also the basic physics of electricity. One would think that there’s no much room for argument over the Amps and Volts.

But there appears to be, and it’s beyond my pay grade.

So I looked for what might be an unassailable source on the technical aspects. And here it is: Standards NZ: Electric vehicle (EV) chargers for residential use. Everything you could possibly want to know about charging your EV.

Why dwell on this? Because EVs are coming.

Meanwhile it’s still unclear whether — eventually — if you and ten of your EV neighbours all plug in at 10pm, will you crash the grid? At the moment, we’re far from market saturation!

So while the debate is a bit academic at the moment, it does underscore that policy pronouncements and strategic visions (whether energy transformation or reform of health care delivery) must take into account the achievable pace and logistics of implementation.

Meantime, the industry hasn’t been sitting on its hands according to Nigel Purdy, a self-described “young-at-heart electrical engineer” who happens to be Group Development Manager Growth and Innovation for Unison.

Nigel commented to BayBuzz: “It’s important to remember that this is a multiyear and, in actual fact, a multidecade transition for the country. There are no surprises here when it comes to planning and preparing for the transition to electric vehicles (EVs).  Lines companies have been forecasting scenarios to plan and prepare for increased uptake of EVs and the additional load on the network for many years.

“We have many options available to us to accommodate this exciting future of transport in New Zealand. These include providing additional capacity where required, but also encouraging the introduction of new technologies that manage and optimise when and how EVs draw their charge from within the house and the network. These technologies not only make the most of the available network capacity but can also minimise the cost of charging, for example by using overnight charging and off-peak rates.  Successful trials of managed charging in Auckland and Wellington have demonstrated that these options are both feasible and attractive to consumers.”

We’ll hear more from Unison in the future.

Without question, investment will need to be made at the household and grid operator (the Unisons of NZ) levels to ensure optimum convenience and performance as the nation electrifies (and not just in transportation).

Alternatively, you can follow the advice of my neighbour — a well-wired electrician who’s “indifferent” on EVs — and wait for a hydrogen car. That said, he’s impressed like I am with the Ford-150 Lightning (“pretty cool” he says) , Ford’s global bet on EV pick-up trucks/utes. And Labour’s answer, in time, for farmers and tradies.

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  1. Tom:
    The NZ Standard you link is the best written and most comprehensive piece I have seen on charging systems. It’s not for everyone though because of the technical language. For general consumption we have to rely on the interpretation of aspects of the Standard, by marketing people and others with a vested interest in profiting from the migration to EVs. Therein lies a problem. Have you noticed how often statements are made, and while being technically correct, they are completely unrealistic in the real world. Here’s an outlandish example : A new plug-in hybrid is being advertised as having a “combined range” of 650kM, and in the next sentence the petrol consumption is stated as “1.9 L per 100kM”. And this is with a petrol engine of 2.4L. Actually the maximum range on battery alone is only about 50kM. That means about 92% of the combined range is with a standard petrol engine, and an engine of that capacity will burn at least 7 L/kM. The 1.9 figure quoted is for a standardised mix of urban driving, mostly on battery, and where the petrol engine gets to charge the battery during your driving, as long as you are not driving too far. Beware of the marketing hype.
    Which brings me to Hybrids. The worst of both worlds. Expensive. More complicated engine management systems. The battery must be charged using the petrol engine. A minor efficiency gain running the engine at the optimum point on its power/economy curve. Very small gains from regenerative braking. Can’t get more energy out than you put in, and all the energy comes from running the petrol engine. Hybrids ought to be banned if we are serious about CO2 reduction.
    Let the debate continue.

  2. Let’s look at some numbers Honda claim for their Jazz Hev 2.84L/100km (urban cycle?) and for their Jazz ICV 5.8L/100 a saving of 50% with only a 0.86 KWh battery. Most Jazz Hev reviewers put the real-world economy at 4.5L/100 km on a 400 km motorway trip where the ICE is mostly in play. A small BEV averages 20 KWh/100 km. New Zealand’s electricity carbon intensity is between 200 to 300 gm CO2/KWh. But for urban commuting the respective carbon footprints for a Jazz HEV and a Leaf is 64 gm and 50 gm CO2/km – not much difference. Now consider the CO2 footprint of the BEV battery at 147 kg/KWh (real factory data based on a Ford Focus) You need a 40 to 60 KWh for a practical range of 240 km. The penalty is another 6 to 8 tons of CO2 per vehicle. Now CO2e for manufacture 6 tons for a small ICV 17 tons for Ford Mondeo 35 tons for a top of the range Landrover Discovery. A twin Cab Ute somewhere between a Ford Mondeo and a Landrover. We are currently importing 80,000 light vehicles/pa. Our ownership has increased from 600/1000 in the early 2000s to 800/1000 now. A holistic policy for transport carbon reduction: limit the ownership of larger than necessary vehicles; extend the life of our current fleet by regular maintenance; improve the infrastructure for alternative modes of travel; reduce the dependence on car ownership. The conversion of the light vehicle fleet to BEVs is an overrated policy solution

  3. I wonder at what point in the transition of our national vehicle fleet to a predominantly EV fleet, all wanting to charge overnight, will ‘Off-peak’ become ‘Peak’ with the appropriate re-alignment of costs?

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