Nobel Laureate and former United States Energy Secretary Steven Chu says New Zealand has an opportunity to quickly ramp up its use of renewable energy because of the huge strides being made in wind, solar and other clean technologies.

The distinguished physics professor, who is attending several events at the University of Otago, is a strong advocate for sustainable energy and encouraged a massive increase in solar power during his time in Barack Obama's Cabinet.

In the US, energy generated by wind and solar sources was now equivalent to hydro and would double in coming years.

"Renewable energy, which has been always cast as much more expensive, is becoming the low-cost option for many, many parts of the world," Professor Chu told the Herald yesterday.

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"It's not true of every part of the world, it depends on whether you have wind or solar," he added, noting that New Zealand, with its many overcast days, lacked the solar resources of Australia.

But he said this country's significant hydro resources meant it could easily "go well above" 50 per renewable energy at a "very low cost".

At present, New Zealand gets nearly 40 per cent of its energy and 80 per cent of its electricity from renewables - mostly geothermal and hydro.

Increasing the use of clean energies would reduce the country's dependence on imported oil, which cost around $9 billion a year.

Professor Chu said New Zealand's relatively small greenhouse gas emissions on a global scale should not discourage it from moving to a lower-carbon economy.

Many of the world leaders in energy efficiency were smaller European nations such as Norway and Denmark. Professor Chu said these countries were not changing the world, but in deciding to commit to renewables they had become technological leaders. Denmark is now one of the biggest exporters of wind turbines in the world.

Regulators, academics and NGOs would need to guide power companies towards low-carbon alternatives.

Under current policy settings, these companies were only required to prevent blackouts and provide a return on investment.

"You don't expect utility companies which are controlled monopolies to be the most innovative companies in the world."

Professor Chu, now employed by Stanford University, also spoke of the promising developments in battery technology.

At present, most electric cars were costly and had a range of around 160km. This meant people in rural areas had "range anxiety" and were unlikely to invest in an electric vehicle.

Professor Chu's expectation was that advances in battery technology would allow the production of a "fairly inexpensive" car with a range of 400-500km within five to 10 years.

"If this happens, you can imagine a four- or five-passenger car costing $20,000-25,000 which would satisfy the driving needs of most people. And charging an hour, not overnight."

Transport makes up around 20 per cent of New Zealand's total carbon emissions, and the Government is believed to be interested in increasing the electric car fleet to cut this. At present, the Government rewards electric car ownership with zero road-user charges, but there are still fewer than 100 electric cars on roads.

While he was excited by the rise of renewables, Professor Chu was optimistic about climate change.

"I'm worried. But I think the good news is more young people are beginning to realise how important it is.

"I just hope some of the people of my generation will show a little more concern for their children and grandchildren."

Steven Chu

• Professor of Physics and Molecular and Cellular Physiology at Stanford University.
• US Secretary of Energy 2009-2013.
• Co-recipient of Nobel Prize for Physics 1997.