Using Tiwai's power to cut pollution from our internet searches

"Tiwai Point Aluminium Smelter" by ungernz is licensed under CC BY-NC 2.0.

This article originally appeared in Stuff, by Eloise Gibson. The One Hot Minute podcast is is a companion series to Stuff’s One Hot Minute video series, in which guests get just 60 seconds to deliver their big idea about climate change.

If Tiwai Point aluminium smelter shuts, there’ll be a big question hanging over New Zealand’s electricity market: what do with all the renewable power generated at the bottom of the South Island?

The surplus electricity could be enough to power 2 million electric vehicles – but bringing it north to Auckland and Wellington could be both expensive and inefficient. On the other hand, it could cut people’s power bills and lower the country’s emissions.

Scientists at the MacDiarmid Institute for Nanotechnology have suggested some bold ideas to use the electricity near where it’s generated, including a data centre to shrink the carbon footprint of our internet searches, or making silicon for solar panels by purifying South Island sand.

Co-Director Nicola Gaston told Stuff’s One Hot Minute podcast clean energy from the Lake Manapouri hydro station could also create green hydrogen to run trains, by splitting water into hydrogen and oxygen.

“It’s not necessarily about strongly supporting any one technology... I’m saying we need a plan,” Gaston said.

Each year, about 13 per cent of all the power generated in New Zealand country goes to the Rio Tinto-owned smelter – mostly from the turbines of the Meridian-owned hydro dam on Lake Manapouri.

If Rio Tinto pulls out of New Zealand, this chunk of the country’s renewable power could be put to other uses.

The clean electricity could be used to decarbonise activities that currently have a high climate impact, because they’re carried out in countries that burn a lot of fossil fuels for energy, said Gaston.

For example, South Island silica could be highly purified to make solar cells – an energy-intensive process that, if carried out somewhere else, might use energy from fossil fuels.

Another option is powering a green data centre – another activity that, when hosted overseas, often comes with a high carbon footprint. New Zealanders’ internet searches and video streaming carry a hefty climate cost, from the fossil fuels burned to cool offshore server farms.

“The carbon cost associated with computing or ICT more generally is increasing really, really rapidly,” Gaston told the podcast. “Just think about everybody doing stuff on their phones all the time.”

After the announcement Tiwai was set to close in 2021, lines company Transpower brought forward an upgrade of its cables to transport electricity north. Currently, fossil-fuelled power stations, such as Huntly's coal and gas units, supply a portion of the country's power.

But there’s a possibility that bringing Manapouri’s power north could delay the building of other planned renewable plants, raising questions about whether the move would truly reduce New Zealand’s emissions.

Tiwai Point's future remains uncertain. Although the company announced its plans to close New Zealand operations in 2021, Labour has said it would like to see the smelter stick around for a few more years.

If and when the smelter goes, Gaston said supporting upgraded transmission lines to bring the electricity north would be the easiest thing for the Government to do, if it decided to get involved, whereas producing hydrogen or manufacturing silicon for export were more likely to be private sector activities.

November 23, 2020