Leading the research that could throw climate change into reverse

Caption: David Dempsey wants to make Aotearoa New Zealand a world leader in carbon removal. (Photo: Corey Blackburn)

A few years back, engineering researcher David Dempsey had a eureka moment on a new way to fight climate change. Now he is guiding a five-year project to pull planet-heating carbon dioxide out of the air and put it back underground.

How has climate change shaped your life and career?

When I was at a bit of a loss about what to do after graduation, I took a look at the Master’s programme and found this position in sea ice research. It’s a really cool field and I got a trip down to Antarctica.

But when I got to the end of my Master’s, I realised that, thanks to climate change, things didn’t look great for the future of sea ice. So I decided to do my PhD in renewable energy – which brought me to geothermal and the genesis of the idea for removing carbon using geothermal power plants.

A few years before I joined the University of Canterbury, I had this moment of inspiration. In 2019, I was watching a presentation where a geothermal engineer from Italy was speaking about their hybrid power station. It used geothermal steam, like we do in New Zealand. But they were able to generate even more electricity by burning waste wood and wood chips to heat the steam up even more.

I thought: that’s really cool. But what if you took all the carbon dioxide from the exhaust of the wood boiler and put it underground? You would basically have negative emissions.

What excites you about the prospect of carbon removal?

We’ve been putting carbon dioxide in the atmosphere for a long time. It’ll stay up there for centuries. This offers the possibility of pulling that carbon out of the atmosphere and locking it away.

It really solves the problem of climate change. This goes beyond ditching fossil fuels. It throws things into reverse. That’s appealing.

Who is helping you with this research?

A keen postgrad student explored this idea to use geothermal power stations for carbon capture. Karan Titus took the concept and threw himself into it. That built momentum, and took us to the point where we could apply for an Endeavour Grant from the Government, which supports a team of 30 people to work on this until 2029.

There are many ways to remove carbon from the air, so we decided to look at two other technologies, alongside the proposed geothermal method. A University of Canterbury colleague down the hall is researching a way to make carbon-absorbing building materials, so we got him involved. We also joined forces with University of Waikato scientists developing a type of carbon removal that farmers could introduce.

Then there are systems and energy modellers, geologists, forestry researchers, spatial scientists, tikanga experts, environmentalists and legal scholars from universities and crown research institutes, plus a communications specialist.

These solutions are going to be expensive to build and get up and running. Scientists will never have the money to deploy these. So we went out to players in the relevant industries – the organisations who could introduce this type of thing first – and asked them to partner with us.

What success would make you crack open a bottle of champagne?

I’d be thrilled if someone told us they were going to build a pilot plant or project, and are talking to Government about getting paid for this as well. By this I mean, they don’t just want to try the process, but they want to try the whole thing including getting financially credited for a removal.

If we knew our work had given them the confidence to take this on, that would be enormous.

At the end of your career, what do you hope will have changed?

I never plan to retire! But I’d love to see atmospheric carbon dioxide levels coming down. They’ve been on an upward trend for a long time, and are likely to stay on an upward trend for some time yet.

If, by the end of my lifetime, we were able to have them on a downward trend, that would be very satisfying. I don’t even know if that is realistic, but that would be the ultimate impact.