A power cut on Monday night has raised questions about electrifying New Zealand's car fleet.

Nearly 18-thousand North Island households were shut off after cold weather pushed up demand.

An energy consultant says although 80 per cent of our energy is renewable -- we still need support from coal and gas.

Meanwhile, the Government's pushing for electric vehicles and offering a subsidy for EVs.

But Geoff Hunt says every EV added puts load on the network.

He says we'll have to burn more coal or gas - so every EV should come with a bumper sticker that says coal burner.

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