The closure of Tiwai's aluminium smelter near Bluff will have negative implications for the electricity industry - especially those who supply it with power - as it fears a lot of generated electricity will become useless.
It was announced on Thursday the smelter will close next year, and it's estimated 1000 jobs will be lost as a result.
Tiwai uses 13 percent of New Zealand's overall power supply, and its biggest energy source is the Manapouri underground hydro station, owned by Meridian Energy.
If Tiwai shuts, most of the power it soaks up won't be used, Meridian's CEO Neal Barclay says.
"There will be a year or so that certainly there's more hydro generation spilled, if you like, in terms of water running rather than generating electricity."
Contact Energy's nearby Clutha dam is in a similar situation since it supplies about one-third of Tiwai's power.
Contact Energy CEO Mike Fuge says the dam is a "cracking asset".
"It delivers great value for us and great value for New Zealanders. We just have to think hard about getting that power to other users and north to the rest of the country."
The owner of New Zealand's national power grid already has a $100 million plan to strengthen the power lines from the lower south hydro stations to the rest of the country. But IBISWorld Energy analyst James Caldwell says it's unlikely consumer power prices will drop ahead of the power line plan.
"This isn't going to be finished by before 2023, so any effect of consumer electricity prices is very unlikely to be felt before the middle of 2023."
Meridian wants it to happen earlier - but until then, there's a risk power bills will go up to cover the cost of moving power.
"Someone has to pay for the transmission, and so those costs will simply be redistributed to everyone else... It will potentially raise the network part of the power pricing," Fuge says.
Meridian says it's already in talks with other businesses to sell its Manapouri power when the smelter closes.
