Heat pump sales spark fears

Dramatic growth in household heat pumps is sparking fears for the future of the country's already stretched power supply.

National grid company Transpower says the number of householders buying heat pumps, and particularly their use as summer air-conditioners, is likely to affect projections of electricity load used to plan for new transmission lines and equipment.

Figures from the Energy Efficiency and Conservation Authority (EECA) show nearly one in five (19.4 per cent) New Zealand homes now have at least one heat pump, compared with only 4 per cent in 2000.

In the year to March 31, 2008, 111,040 heat pumps were sold, 41 per cent more than the previous year.

Close to 40 per cent of Canterbury homes now have heat pumps.

Transpower chief executive Patrick Strange told the Electricity Engineers' Association's conference in Christchurch yesterday that the growing number of people with heat pumps would have an effect on grid planning.

"I do shudder a bit about heat pumps. Consumption is going up and electricity planning has to reflect that," he said.

In electricity load forecasting the only certain thing was "we have always been wrong", Strange said.

Energy and Resources Minister Gerry Brownlee told the conference he was also sceptical about demand growth forecasts.

"Although power consumption fell by 5 per cent in the last quarter, when the economy picks up, so will energy use."

Householders turning away from increasingly expensive gas heating towards electricity and heat pumps would also have an impact on power demand.

Estimates of a 1.5 per cent to 1.8 per cent annual increase in electricity demand were "light", with a more realistic annual growth figure somewhere in the 2 per cent to 2.5 per cent range.

Strange told The Press heat pumps were efficient and ideal for parts of the country with colder winters, like Canterbury.

"My big worry with heat pumps is in areas like Auckland. They do drive up winter load, but initially some of the load will go down because they are more efficient than what they are replacing. But then people will use more electricity."

Aucklanders also tended to use heat pumps as air-conditioners in the summer, which could lead to a secondary summer peak in electricity use as well as the country's traditional winter peak, he said.

Orion New Zealand chief executive Roger Sutton, chairman of EECA, had only "limited concern" that Cantabrians would use heat pumps frequently enough as air-conditioners to cause a secondary summer power-use peak. "The winter is much harsher here than our summer."

Heat pumps are one of the options in Environment Canterbury's Clean Heat programme that householders using open fires and outdated log burners can switch to.

Christchurch residents can get a $500 subsidy towards a heat pump, pellet fire, fully enclosed fixed-flued liquid fuel or gas appliance, or ultra low-emission solid fuel burner.

The city had its fourth high pollution night of the winter on Thursday, with 61 micrograms of particulates per cubic metre of air. The highest so far this season was 83 micrograms per cubic metre of air on June 4.

Brownlee said the five per cent reduction in electricity generation in the March quarter was due to the recession and reduced power use by the Tiwai Point smelter.

- © Fairfax NZ News