New Zealand's economy could miss out on up to $50 billion worth of economic growth because of the Zero Carbon Bill, according to official analysis.

But Climate Minister James Shaw tells the Herald the figure does not worry him and says the cost of doing nothing could be much higher.

A regulatory impact statement (RIS) for the bill also reveals a number of "innovation assumptions" needed for New Zealand to reach the target of net zero greenhouse gas emissions – apart from biogenic methane – by 2050.

This includes 95 per cent of light vehicles and 50 per cent of