Dr Bruce Smith, ' />

New Zealand's entire fleet of cars could be made up of electric vehicles powered by wind turbines, a conference will hear today.

Dr Bruce Smith, director of modelling and forecasting at the Electricity Commission, will tell a biofuels and electric vehicles conference in Wellington that electric vehicles have the ability to smooth the peaks and troughs of electricity supply so efficiently they could triple the country's capacity to use wind power.

He estimates that if 2.5 million of New Zealand's roughly 4 million registered vehicles were electric, the whole electric fleet could run off 3000MW of wind generation - about three times the amount of wind power that is built or ready for construction today.

Electric vehicles are not yet widely available in New Zealand but car companies are already touting them as a way to reduce greenhouse gas emissions.

However in order for their owners to get maximum reduction in greenhouse emissions, the cars must be powered by electricity generated from renewable sources such as wind and water rather than fossil fuels.

About 70 per cent of New Zealand's electricity comes from renewable sources.

Dr Smith said he had not finished the calculations required to prove wind energy could power all the country's cars.

But electric cars could make it possible to build many more wind turbines because they solved one of wind power's major inefficiencies - that energy is wasted overnight and at other times when people use little electricity because the wind is blowing and not being used.

Dr Smith said electric cars could be plugged into smart electricity meters, similar to ones already being rolled out by major electricity retailers, designed to recharge the car's batteries whenever electricity was most plentiful.

When the wind stopped blowing and electricity ran short, the cars could give some of their energy back to the system until the supply of power was restored.

Dr Smith said it would be economic to ramp up wind power only if the price of carbon reached about $60 a tonne. Forecasters predicted it would do so by 2020 but the actual price would depend on the exchange rate and overseas carbon markets.

If carbon emissions topped that price, a fleet of electric cars could improve energy efficiency so much that "spare" electricity from wind power built to supply cars could be used for other things.

Dr Smith has asked the National Institute of Water and Atmospheric Research and the MetService to prepare a model showing how much wind there was in 15 spots around the country every 10 minutes over the past several years to help the Electricity Commission work out how much wind power was available and where.

For every megawatt of wind power that is built at the moment, about half as much electricity again is needed from another source - such as hydro, geothermal or burning fossil fuels - to provide back-up when the wind drops.

Dr Smith said that if electric vehicles became popular, it was not expected to be until after 2020.

But he wants the electricity grid to develop in such a way that enough wind power to supply electric cars can be made available if needed.

Meridian Energy is running a trial with Mitsubishi Motors New Zealand to test the iMiEV electric car in New Zealand. The car will be built in Japan from August, initially priced at about $60,000, and Mitsubishi NZ hopes it will be on sale here from next year.