Pylon opponents back new type of transmission line

Opponents of Transpower's plan to build a new line of pylons into Auckland are pinning some hope on a new type of high-tech power line.

The use of the line on existing structures was put forward as an alternative to the pylons in a submission made to the Electricity Commission yesterday by 3M.

The company suggests that its new high-performance line can provide transmission capacities up to three times greater than existing transmission lines.

It can also operate at elevated temperatures with reduced sag.

Lobby group Underground In Manukau yesterday backed the proposal and joined 3M in urging the Electricity Commission to consider the line.

"It appears to be the answer to securing supply for the next 15 years, saving a large enough sum to ensure that any future lines can be buried underground," said Catherine Tuck, the group's chairwoman.

But Transpower has questioned the new technology's suitability for the Waikato to Auckland project.

Chris Roberts, spokesman for the national grid operator, said Transpower was aware of the 3M product.

"It has not been considered by anyone for a long length of line," he said.

"There are other companies starting to produce similar products, and we are looking at them for where they may be applicable. But we don't believe it's applicable for the 200km of line into Auckland."

Mr Roberts said Transpower had already looked at the option of upgrading the existing lines, and there were serious issues around that "no matter what sort of wire you are going to hang".

3M's submission includes details of several places in the United States where the product has been used commercially, but the distances covered so far are shorter than Transpower's proposed line.

Transpower has faced a barrage of criticism since it put forward its original plan to build pylons between Whakamaru and Otahuhu to upgrade Auckland's energy supply.