Carbon-negative technology could remove a million tonnes of CO2 a year

Karan was born in India but grew up in Indonesia and has always been passionate about working in renewable energy. He came to New Zealand to complete the Master of Energy programme run by the University of Auckland’s Geothermal Institute and was then taken on as a research assistant at the institute.

“I worked with some of the best geothermal engineers in the world and it was an incredible experience,” he says.

Wanting to take his career to the next level, Karan embarked on his PhD last year, working with researchers at the University of Canterbury on technology which can combine geothermal energy with bioenergy from forestry waste, with the aim of reducing carbon emissions from both.

Forestry absorbs CO2 from the atmosphere as the trees grow, but it is released back into the atmosphere again if the forestry waste is simply left to rot. The technology Karan is working on sees the forestry waste burned to generate electricity, and the CO2 given off captured and injected underground in geothermal water once it is cooled after energy production.

It works well as most geothermal plants already have systems to send fluids underground, called reinjection wells, and they are often located close to the country’s forestry plantations. It could be a real win for New Zealand - boosting renewable electricity output and making supply more consistent without the need to burn coal when hydro lake levels are low, while at the same time cleaning up forestry waste and locking up the CO2 emissions underground.

Technology hugely promising

Early results are promising. Karan has shown that a theoretical combined geothermal and bioenergy plant could remove a million tonnes of CO2 each year, equivalent to taking 200,000 cars off the road.

“We think it’s a hugely promising step forward, particularly as the world’s economies continue major plans for decarbonisation,” he says. “Aotearoa is a beautiful country with an abundance of natural resources. We have a real opportunity and responsibility to lead the way in the collective global decarbonisation effort.” 

“It has the potential to be both good for the climate and good for the economy,” says doctoral co-supervisor UC Civil and Natural Resources Engineering senior lecturer Dr David Dempsey.

Only last month, Karan’s research paper “Accelerating Decarbonisation” earned him Best Student Paper at the Carbon and Energy Professionals New Zealand conference. “It shows strong initial industry engagement with my work as part of the wider effort to tackle climate change,” he says.

Karan is grateful for the opportunities he has been given since arriving in New Zealand, especially his time working as a research assistant at the Geothermal Institute. “In New Zealand, there is a relatively informal work environment where senior staff are quite open to being approached and sharing their knowledge,” he says.

“But you raise the stakes when you’re working on a job. You’re delivering to people who have hired your expertise and you know you are having a real-world impact.”

While the world faces huge challenges with climate change, Karan says it is an exciting time to be exploring new technologies in the renewable energy industry, and New Zealand is the right place to be.

Buoyed by the early results of his technology, he says the next stage will be to design different configurations and explore its economic viability.

Studying in New Zealand “best decision”

The geothermal community is quite small but very supportive, Karan says, and he has learned so much since coming to New Zealand. “I have had access to vast expertise and to valuable networking opportunities.

“International students are empowered to succeed here. Many of my fellow students who have returned to their home country or moved on to another country have all been very successful. This is testimony to the opportunities that the education experience provides.

“I cannot even really imagine where I would be if I hadn’t come to New Zealand. It’s probably the best decision I ever made.

“My dream is to make a contribution which will have an impact in our collective fight against climate change. In my heart I need to know that, through the opportunities I had, I did my best to make a difference.”