Public policy changes are the best way to get long-term, sustainable improvements in energy efficiency, Mighty River Power Chief Executive Doug Heffernan told this week’s Environment Waikato Environment Committee meeting.

He said the biggest gains in energy efficiency would come from tougher policies, not behavioural change as it was hard to motivate people to change behaviour when the savings on their power bill from power efficiencies were small.

Electricity demand was rising by 15 to 25 percent, over the next decade, most of it north of Taupo, with increased population and economic growth the biggest drivers.

New Zealand depended on gas but existing discoveries were not enough to supply the country past 2010. Imported gas was being explored as an option, he said. Wind could supply about eight percent of demand, and geothermal 12 percent by 2012 – with most coming from the Waikato and Bay of Plenty. Small hydro stations were untested in a regulatory environment but could supply two percent of new supply.

Some coal was therefore the best option for New Zealand in the decade after 2010 as gas supplies dwindled, he said.

However coal was more expensive than current electricity prices and was competing with LPG. It provided a price cap that gas suppliers would price up to.

Renewable sources, such as wind and geothermal, were preferred and had the potential to become economic now. Thermal options should be deferred for a decade, which would buy time for New Zealand to commercialise new gas discoveries, advance thermal technology and advance public policy in efficiency, he said.

Sustainable commercialisation of geothermal reservoirs to achieve the 12% goal would need changes to current regional policies.

“No more water use should be permitted for abstraction from the Waikato hydro system until the regional water policy is reviewed.