Our planet-saving origin story

How the world might one day view carbon removal researchers (via ChatGPT)

Just like The Avengers found, it’s easier to save the world as a team.

We’re a group of Kiwi academics with a climate change-fighting mission: to put millions of tonnes of greenhouse gas back where it can do no more harm.

Our origin lies with associate professor of engineering at the University of Canterbury David Dempsey. The renewable energy expert had just left a conference in 2019 when he had an idea to use geothermal power stations to actively draw planet-heating carbon dioxide out of the air.

“It didn’t seem like a huge moment at the time,” David said. “But the concept kept coming back to me. I thought it could be big if we got it right.”

Geothermal power stations harness the heat of the Earth to generate electricity. Long pipes bring up hot steam to rotate the station’s turbines, and other pipes deliver the cooled liquid back to the system so it can heat up again in a renewable cycle.

David had learned of a recently opened Italian geothermal station that went one step further. When the steam reached the surface, it got another dose of heat – from a large boiler burning wood. That allowed it to better push the turbines, creating additional electricity.

Now David envisioned a third step: capturing carbon. He knew the smoke from the wood fire contained a whole lot of carbon dioxide, which the trees had absorbed from the sky.

At the time, Icelanders were working on dissolving carbon dioxide into geothermal fluid – because it typically releases the gas when it reaches the surface.

So, David imagined, why not capture some extra carbon dioxide, mix it into the cooled fluid, and send it back underground where it wouldn’t add to climate change?

“You would basically have negative emissions. That would give us a brand-new way to fight climate change – really, to reverse it.”

To road-test the concept, David turned to the Sustainable Energy Research Group (SERG), including Rebecca Peer and a passionate PhD student, Karan Titus. The team’s research found the idea had merit.

But to bring it to life, David knew he needed wider help.

“With any engineering project, there are a bunch of reasons why it might fail. It’s not always the technical reasons, because we’ll often have worked those to death. But things like local regulation or the scheme’s environmental impacts can be project killers. So I realised we’d need a much larger team to make this work.”

Again, SERG was able to assist, with energy modelling specialist Jannik Haas joining Rebecca. The pair can tell us what New Zealand would have to build, and when, to do carbon removal at scale.

“I didn’t want to just focus on one type of carbon removal either,” David said. “So we joined forces with the University of Waikato’s Terry Isson, who was investigating a type of carbon removal that could be done on farmland.”

A colleague down the hall, Allan Scott, was also working on a pioneering way to make cement. Rather than the standard high-emitting process, he wants to use waste wood ash – and is developing a method that would allow this ash to draw more carbon from the air before it is used.

David also reached out to the University of Auckland’s Geothermal Institute, co-led by John O’Sullivan. No organisation is better placed to model the effect David’s idea would have on New Zealand’s geothermal reservoirs.

Mila Adam and Michael Rowe, with University’s geology department, can replicate the conditions of a geothermal reservoir within the lab, indicating how the addition of carbon might affect the rock itself – and find ways to encourage the carbon to solidify.

Graham Coker, with the Bioeconomy Science Institute, was tapped to find out the impact on the land of taking waste wood to power the hybrid geothermal plants.

To answer questions about the best locations in New Zealand for carbon removal, David enlisted three scientists: Earth Science NZ’s Matt Hill, the University of Waikato’s Andrew La Croix and the University of Canterbury’s Andy Nichol.

David wanted to complete his team with specialists studying law, environment and Mātauranga Māori. With expertise crossing these different fields, Barry Barton and Jennifer Campion at the University of Waikato, Adrienne Paul of Mahi Ngātahi Law (a specialist division of Halliwells Lawyers) and John Reid of the University of Canterbury jumped on board.

“It’s a big broad team, and everyone brings their own strengths,” David said. “People were keen to contribute, since it’s a worthwhile mission.”

In early 2024, David submitted a proposal to a contestable science fund, the Endeavour Fund. With its support, the team could work to develop carbon removal for the next five years.

“It’s a rigorous process. Every proposal is put through tough, but impartial, assessments of the science and potential impact. If you make it through, then the Government chooses the programmes that best align with its priorities.”

Six months later, he got the good news: the project would get $10 million of funding, enough to support 16 researchers at institutes and universities across the country, plus another 16 early-career academics and PhD candidates.

“It was exciting to get started,” David said. “This is all about contributing to the big mission of fighting climate change.”