It seems like the economic stars are aligning to give NZ a gentle shove in the right direction, with the Marsden Point refinery potentially shutting down at one end of the country, and the Rio Tinto/Sumitomo smelter at the other.
Both are electricity hogging, CO2 belching relics of the 60's that should go away.. and if Huntly's last coal/gas units get knocked off in the process, so much the better.
A bit O/T but, as others have mentioned, I think there's potential for NZ to use this opportunity to permanently reduce emissions and jump feet-first into a Hydrogen economy.
The real problem with Tiwai point's smelting future isn't the cost of electricity to run it, but the fact it uses the Hall-Héroult process for it's potlines.
For over 100 years this process - invented in the 1880's - has been used to produce the majority of the world's aluminium.
An issue that's become more pressing with the effects of Global Warming, is during production the carbon anode's consumed, producing at minimum, several tons of CO2 - a Greenhouse Gas - per ton of Aluminium.
Rio Tinto Alcan - the world's biggest producer of Aluminium, and Alcoa/Arconic the world's eighth largest, have partnered with Apple in Elysis and have recently reached the commercialisation stage of a new inert-anode smelting technology.
A real breakthrough in Aluminium production that - with electricity supplied from renewables like Hydro - will massively reduce aluminium related CO2 emissions, the main byproduct is Oxygen, and the process's increased efficiency reduces the electricity input required per ton of metal.
For Rio, the success of their new production process appears to have prompted a review of their assets around the world. Tiwai's just one of their smelters listed to close.
Crucially their group have Patent control of the new process's proprietary anode and cathode materials, which - lasting more than 30 times longer than traditional components, and making production up to 20% more efficient - are likely to become the new world standard.
If they don't see the value in converting Tiwai point to the new process there probably is none.