Brian Fallow: Plug in, take off - it's a new century for cars

Are plug-in vehicles part of our future?

Energy Minister David Parker is among those who think so.

"My own view is that over the next 20 years we are likely to see the rapid deployment of electric cars," he told a workshop on climate change policy in Wellington last week.

Mention vehicles and electricity in the same sentence and eyes tend to roll as people think of golf carts or English milk floats, powered entirely by batteries - vehicles of limited range and feeble acceleration.

But various ideas in various stages of development envisage using electricity to augment primary energy sources used to propel vehicles.

The front runner is probably the plug-in hybrid.

A conventional hybrid, such as the Toyota Prius, derives all of its energy from the fuel in the tank. It has an electric dynamo/motor and batteries to store and use energy that would otherwise be wasted when the vehicle is braking or idling.

In a plug-in hybrid, the electric side of the design is scaled up and the petrol engine used less. Unlike an ordinary hybrid, it is plugged into the mains to charge its batteries.

In today's hybrids, the electric motor provides extra power for acceleration and hill climbing, enabling the vehicle to have a smaller, more efficient petrol engine.

A plug-in hybrid has enough battery-powered range to cover most daily use by suburbanites - commuting, school runs, shopping and so on. The petrol or diesel motor is a back-up.

There are other concepts.

Fuel-cell vehicles, which run on hydrogen, raise the question of whether it is better to generate the hydrogen centrally, which would require new infrastructure to reticulate the gas, or generate electricity centrally and use it to make hydrogen from water in the vehicle or in the garage.

Vehicles which run on compressed air stored in tanks made of space-age materials are another possibility, either in a pure or hybrid form.

The incentives to make something along these lines work are powerful.

Instead of relying on oil for power, with the energy security and price risks that entails, a flexible portfolio of primary fuels would make vehicles go. Anything than can generate power becomes a transport fuel.

And if that fuel is coal, there is at least the possibility of capturing and storing the carbon dioxide if it is used at one place to generate power. If it is turned into liquid fuels and burned in the vehicle, greenhouse gas emissions are largely unavoidable.

It would be good for local air quality, too, potentially an important factor in the burgeoning cities of Asia.

A plug-in hybrid would be cheaper to run than a petrol-driven car. The Ministry of Economic Development's Energy Outlook, issued two weeks ago, says that at today's domestic power price of 17c a kilowatt/hour a plug-in hybrid's fuel cost would be equivalent to 40c a litre of petrol, about a quarter of the present price.

But what about the capital costs?

Parker says the cost of batteries has come down because of the development of cell phones, even as the price of oil has climbed.

Automotive batteries cost about $1400 a kilowatt hour of storage. That is three times more than cellphone batteries but it is lower than it used to be. A target of $775 a kW/h for automotive batteries is thought to be achievable.

And they can stand 1500 cycles of charging and draining, heading towards a target of 2000 cycles.

At $775 a kW/h, batteries able to store 15 kW/h would cost $11,625 and give a vehicle a range of about 150km between recharges. If they needed to be replaced after 2000 cycles, that would be 300,000km on the clock.

The Energy Outlook looks at several scenarios, including one in which plug-in hybrids are widely adopted.

Under this scenario, 15 per cent of the light vehicle fleet - cars, vans and small trucks - is plug-in hybrids by 2015, and they are driven about half the time on electricity so that about 7 per cent of that energy demand has been switched to electricity.

The proportion rises to 40 per cent of light vehicles by 2025 and 60 per cent by 2030 as battery technology improves.

Oil consumption is 40 per cent lower by 2030 than it would otherwise be under the business-as-usual projection, and 20 per cent lower than it is now.

The reduction is not greater because batteries are not much good for heavy trucks and off-road vehicles such as tractors, bulldozers, locomotives and ferries.

The Energy Outlook has raised eyebrows by not considering the coal-to-liquids option Solid Energy is keen on for Southland lignite.

That would use essentially the technology employed by Nazi Germany, or South Africa during the era of apartheid and oil embargo, to turn low-grade but abundant coal into synthetic petrol and diesel.

In principle if it is possible to capture and store the carbon dioxide produced in turning the lignite into electricity, it should also be possible to do the same for the gas produced while turning lignite into liquid transport fuels.

But the liquid fuels themselves would present the same climate change problem as the petroleum products they replaced.

They would be no worse but no better either. Defenders of the coal-to-liquids option say it does not require a big change in the national vehicle fleet or in the way people use their cars.

But if the past century teaches us anything, it is that a technology whose time has come can quickly sweep all before it.

Remember when there were no cellphones and no internet? It is not that long ago.

Yet the engines we rely on for road transport are essentially inherited from the century before last. This technology is mature to the point of senility.

Sinking a lot of investment capital into synfuels might prove to be a costly dead end, akin to breeding the finest carriage horses just as Henry Ford came along.