Transpower could build new power lines between Oamaru and Livingstone in a push costing up to $70 million to improve an electricity network already at capacity.
The national grid owner yesterday confirmed it had shortlisted three options with eight-figure price tags to reinforce regional electricity supply in the Lower Waitaki Valley.
The shortlist was developed after two years working with Network Waitaki, Alpine Energy, councils and electricity users to establish future demand and ways to meet it.
A recent report suggested seven major projects, including irrigation schemes, a dairy factory and Holcim's cement works, could increase the peak load to 190MW by 2020.
That would be 200% more than this year's peak load, outstripping the the capacity of the 110kV transmission network in a barrier to industrial and economic growth.
Transpower grid development general manager John Clarke yesterday said the network was already at capacity.
The basic upgrade option, worth about $30 million, would see a new switching station built at Glenavy to connect lines between Timaru, Oamaru and Waitaki, and new capacitors at the Oamaru substation.
Mr Clarke said that option required the least work but carried the highest chance of power supply interruptions in the longer term.
It also meant Network Waitaki would have to build a new line from Oamaru to Ngapara.
The "secure upgrade" option would meet forecast demand - but might struggle with unexpected demand - by improving the Waitaki-Glenavy and Oamaru-Glenavy lines and a new switching station at Glenavy.
A new line would still be needed between Oamaru and Ngapara.
It was considered a "long-term fix" of more than 20 years but, because the lines were at capacity, the upgrade would be difficult and temporary lines might have to be built, impacting on existing line landowners, Mr Clarke said.
The "new regional supply line" option, costing about $70 million, would involve a 110kV double-circuit line from Livingstone to Oamaru and a new switching station at Glenavy.
Mr Clarke said the third option would be best for projected and unexpected demand, but accepted it would also mean lines would have to be built on often privately owned properties.
There was no preferred route for the new lines - extensive consultation and the resource management process would help find one - but Transpower identified a wide area between Livingstone and Oamaru to help it consult as widely as possible, Mr Clarke said.
The number of properties in that area was unavailable yesterday.
Transpower has sent about 2500 information packs to potentially affected landowners, businesses, councils, and other interested parties.
With Network Waitaki and Alpine Energy, it will consider the feedback during December and January before reporting back to landowners in February.
It will take its investment proposal to the Commerce Commission in March and work would happen between 2012 and 2015.
