Heat pumps putting load on grid

The increasing use of heat pumps as air-conditioners has left national grid operator Transpower having to deal with unexpected power demand spikes during summer.

Transpower executives told Parliament's commerce select committee yesterday that in Auckland in particular there had been an obvious increase in power demand during hot weather with residents using heat pumps to cool their homes.

The units are becoming cheaper and popular as an efficient source of heat, but can also be used as air-conditioners.

Transpower chairman Wayne Brown said winter peaks from heater use were a common issue, but increasing power demand in summer was presenting new challenges.

Summer peaks were now closing in on winter peaks, he said.

"It used to be a large gap, so you could actually take out some lines during summer for maintenance a bit more easily ... but that gap is diminishing a bit, and we've always made use of that gap."

At the same time, the efficiency of heat pumps was helping to limit the winter peaks, he said.

Transpower was working with the Energy Efficiency and Conservation Authority on the issue.

Questioned about the Resource Management Act and difficulties it presented in terms of reaching grid upgrade goals, Transpower chief executive Patrick Strange said it was not the company's number one problem.

The main problem was the placing of powerlines and towers. Legislation meant that although there was a right for pre-1992 towers to be where they were, there were no easements or ability to constrain what happened under them.

It made dealing with farmers more difficult, and in built-up areas there was nothing to stop "underbuild", where houses were built under lines.

Transpower copped flak in February when a cable fell and damaged three houses in South Auckland.

Dr Strange said it made maintenance difficult and a way had to be found to stop underbuild from occurring.

- NZPA