The average New Zealander uses 10 times as much energy as someone from a developing country, Massey University associate professor Mark Waterland says.
How much do we really need, and where will it come from in 50 years' time, when fossil fuel has run out, he wonders.
"That's probably the most important question facing the planet at the moment."
He and fellow Massey associate professor Shane Telfer give a free talk on the subject in the Wanganui War Memorial Centre tonight at 7.30. They ask people to bring their open minds and be prepared to question and discuss.
Related talks in Tauranga and Napier, provided by The MacDiarmid Institute, got a spirited response and they expect the same from Wanganui and Nelson.
The sun provides as much energy to the earth every day as the world's entire fossil-fuel reserve, Mr Waterland said.
It is widely distributed and enough for all human energy needs. But he thinks we should be looking for a range of sources.
"There's waves, wind, solar, biomass - anywhere we can see energy being wasted. I think that's what the future is going to look like," he said.
The technology to extract energy from those sources is already available, he said.
"We could start using it tomorrow if we wanted to."
He did not think New Zealanders would be willing to turn to nuclear energy, and said nuclear power stations also barely recovered from the energy costs of building them.
The regions will have an advantage in an alternative energy future. Energy could be locally sourced, and locally used.
Big cities will be different. Aucklanders have little choice but to get in their cars and drive across their sprawling city.
"In Palmerston North and Wanganui most people could get on their bike and bike to work. The smaller centres have a tremendous advantage."
And human nature is another powerful factor in the future of energy.
"Collectively we are very irresponsible, while some individuals are quite responsible. A group of individuals offered a choice that will benefit themselves at the expense of the group - they will nearly always take it," Mr Waterland said.
Scientists like himself can use their knowledge of materials to tap into new sources of energy. Or they can use it to filter out the climate-changing carbon dioxide from vehicle emissions.
He does not think it is up to governments alone to respond to the challenge of climate change.
"Ultimately its everyone's everyday action that's going to lead to the change. Government can provide incentives."