Electric Cars on Great Barrier Island

The way we get around can be an important part of day to day life, and any approach toward more sustainability and less environmental impact needs to address transport. Utilizing renewable energy sources (solar, wind and/or hydro) to power electric cars (E-Car) is certainly the right way – and although the technology is readily available commercially and constantly decreasing in cost – a traditional implementation on Great Barrier Island is just not cost effective. In the following an explanation of why it’s not feasible and suggestions.

It would be great to see an electric ‘fuel’ station on the Island that uses renewable energy to charge E-Cars. Alternatively, individuals could use their private off grid renewable electricity systems. There is no electricity grid on the Barrier.

When it comes to electrical energy, whether renewable or not, one cannot neglect quantity (how much), conversion (how is it ‘made’), storage (how to make it readily available), price and distribution. A rough calculation will illustrate just how much it would cost.


A 100 kW engine, (134 HP), backed by a battery bank that has the capacity of storing this power for an hour (100kWh), would require the maximum amount of energy a 100 kW photovoltaic array can produce in an hour.

In other words:

  • Engine power = 134 HP = 100 kW = 100000 Watts
  • To drive for an hour at peak power, 100 kWh energy is required
  • To produce 100 kWh, a 50 kW solar panel array needs 2 hours of perfect conditions (that’s a 167 panels @ 300 W each!)
  • This is a rough calculation, everything is 100% efficient, there are no cloudy days, etc.

What does solar cost?

  • The price per Watt for solar panels are about 1.2 NZD (190W for 230 NZD on Trademe – 2014)
  • Total installation costs per Watt are significantly higher
  • In the USA average price per Watt is 0.7 USD and average installation at 4.72 USD/Watt
  • A 50 kW solar panel array costs roughly 270000 US Dollars

What about wind or other renewable energy sources and distribution?

We could tap into wind, perhaps geothermal and hydro, and using the tidal or wave power of the ocean is also nothing new, but these are dreams and visions and nothing else for the Barrier. More importantly, any significant investment into a public, large-scale renewable energy plant would require an electricity grid. The price per Watt for converting electricity from other renewable energy sources will most likely be larger than for photo-voltaics.


You may disapprove of this rough calculation, for instance, you don’t need to drive your E-Car at peak power all the time. There are also certainly commercially manufactured E-Cars with considerably less engine power. However, even if the initial costs of purchasing such an E-Car were to be subsidised, solar installation and equipment costs, even if they dropped by a factor of 10, would be the main financial hurdle.

I rephrase, not a financial hurdle, but a waste of money on the Barrier. The above-mentioned example mentions only one E-Car and private households could do a lot more useful stuff with 100 kWh of energy than driving a car for an hour.

The thing is, even when it becomes commercially significantly cheaper to convert suitable, renewable energy for E-Cars than via the route of non-renewable sources, we still wouldn’t necessarily want our very own plant on the Island. It would be more cost-effective to tap into even larger plants on the mainland.


  • The problems with traditional E-Cars are that car manufactures have to assure they comply with international standards, and equip them to market demand. Therefore, cars are heavy and require engines with a lot of power. Lots of power presumes batteries that can store a lot of energy. Fortunately, we don’t have to drive far on the Barrier, so for most forms of private travel battery capacity is not primarily important.
  • We’re not going to make our own cars, but what about E-Bikes, E-Scooters and E-Quads? Remember it is all about reducing the mass of the E-Vehicle and the power its engine requires. A horsepower (HP) is per definition more than a person can produce. Imagine having a 1 HP electric motor on a dual suspension mountain-bike. 2-4 kW solar panel system for private households are not uncommon on the Island; charging your own E-Bike at home is doable and for some the only investment would be the E-Bike, as they already have a suitable solar power system.
  • We need to look into electricity micro-grids on the Island. This is a requirement for any future investment in local innovative energy plants that use renewable energy sources to produce large amounts of electricity. Just like the trucks bring our petrol and diesel, we need a means of distributing energy destined for transport (from the mainland to and) across the Island. Otherwise it is similar to investing into the best education curriculum but have no plans for a school or resources to employ teachers.

A (Not So) Completely Different Approach:

If you’ve read this far, you’ll like the following. The idea of having our own electric ‘fuel’ station, one that converts renewable energy sources to charge traditional E-Cars for Islanders to use as a regular mode of transport, is sort of like the idea of having our own refinery, which refines crude oil.

Fuel stations don’t have their own refinery and oil mine, they rely on distribution and supply chain (I love this term). While the cost for renewable energy equipment will constantly reduce and sooner than later become more cost-effective than traditional methods and while the efficiency of these products continues to increase, it will nevertheless remain more cost-effective to have large-scale plants creating and storing large amounts of energy which can distributed via a grid. Whether that plant is on the mainland or whether we will have our local micro-plant, electricity micro-grids will be required.

Is there a way around a grid?

Although I believe that micro-grids are the only way of creating sustainable energy solutions on the Island in the long-term, there is no need for a grid to establish clean and green transport on the Island.

Instead of transporting diesel and petrol in tanker trucks, one could transport components of renewable fuels. Components that are less hazardous and are the part of a complete, reversible process that relies on renewable energy conversion. The grid would be our road network.

Have a look at aluminium air batteries and vanadium redox flow batteries. These types of batteries are not new, utilizing them in the auto-mobile and transport sector is neither creative nor innovative. The reason why we don’t see commercial products is basically because consumers’ demand for clean and green transport has just begun to be non-negligible in some parts of the world.

For the Barrier, arguably more than for other places, finding suitable solutions, that are doable and manageable is the key. Out of the box and basic copy and paste will not lead anywhere and cost time, resources and money. It is about sampling the best solutions worldwide and adapting them to the Barrier.

I think the Barrier really needs an ‘Energy Discussion’. From the top to the bottom and vice versa. Looking objectively into all forms of renewable energy solutions, gathering detailed information and reproducible research and analytically (with a strong eye on environmental impact, feasibility and long-term employment opportunities) comparing such data, is the first step to finding solutions.

Any significant project on the Island requires such an approach. Too often are we baffled and persuaded by statements from monopolies and groups with vested, private interest. And too often does uninformed public or individual opinion shape the path for the future.

According to the Government, renewables made up 79 per cent  of New Zealand’s electricity generation in 2011 (the vast majority of sources being hydro and geothermal). With more investment and awareness in areas of wind and solar energy, especially in form of subsidies for private households, the mainland is on a clear and simple path of increasing that percentage.

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