The American physicist and environmentalist Amory Lovins once assured me that controlled nuclear fusion would be a major energy source in the future and that experimental fusion reactors were on the verge of producing more energy than they consumed.
However, this has not happened, despite massive international research efforts over the past 45 years. On the other hand, we all enjoy the proceeds of nature's nuclear fusion reactor in the sun's core, the source of solar energy.
For controlled nuclear fusion to work for us, we need to create conditions like those in the sun, which is difficult.
Research success is probably several decades away, so controlled nuclear fusion represents a slow and risky road to a new energy source.
In the meantime, other technologies such as wind and solar power and energy storage are succeeding. This is putting pressure on the controlled nuclear fusion enterprise, for even if it succeeds technically, it will be extremely complex and expensive, so is unlikely to be economically competitive.
In view of these concerns, it's surprising that controlled fusion research continues to receive financial backing. I think it's partly the attraction of the grand vision for abundant, controllable, low-carbon energy. Funding is also helped by gambler's logic: ''We've spent billions already, so we have to continue until we win''.
Controlled nuclear fusion research has significant industry involvement in some countries and there is bound to be favourable political pressure. Such long-term research programmes can also become embedded in the funding fabric, attracting sympathy support and avoiding the critical scrutiny used for newer initiatives.
I am not aware that we fund controlled fusion research in New Zealand, but we do have similar issues concerning our public research priorities. For example, the Government recently awarded almost $10 million for research over four years to underpin oil and gas exploration in New Zealand (ODT September 9, 2015).
Those who think it's a good idea highlight the wealth generated by New Zealand's petroleum industry and emphasise the possibility of a big win, an ''economy changing'' hydrocarbon discovery. Others are more concerned about the role of petroleum in climate change and say it would be better to use the money to reduce our dependence on oil and gas instead.
On current evidence, the Government seems to be betting that the hydrocarbon exploration industry will have an important role in New Zealand's economy for some time.
But if the industry thrives, we are likely to face adverse climate change implications. So it's odd that we fund research to reduce greenhouse gas emissions in agriculture, through the New Zealand Agricultural Greenhouse Gas Research Centre, and at the same time we support oil and gas discovery, where success means more emissions become inevitable.
I could be wrong of course, but it looks like the Government is not taking the climate change problem very seriously. I think we are out of step here; it would be better for us to take a more consistent and strategic approach when funding research with climate change implications.
• Emeritus Professor Gary Carrington is a fellow of the Royal Society of New Zealand and the Institution of Professional Engineers of New Zealand. Each week in this column, one of a panel of writers addresses issues of sustainability.
