Seven reasons New Zealand could be a carbon removal powerhouse

New Zealand: the place to go for stunning scenery, hobbit-spotting, bungy jumping – and the world’s best flat white. If our research goes well, perhaps carbon dioxide removal will join that list.

Complementing greenhouse gas reductions, carbon removal covers all the ways – from restoring a wetland to a gas-absorbing machine – to pull carbon dioxide out of the atmosphere and store it long-term, so it doesn’t contribute further to climate change.

We’re a team of nearly 30 academics and early-career researchers working to make these activities a reality for our country. We believe Aotearoa New Zealand will require diverse forms of carbon removal to meet its national and international climate goals. Yet we also know the country has some wonderful assets that will help to capture carbon dioxide from the atmosphere and store it for centuries – even millennia:

1. Abundant geothermal energy. New Zealand is well-known for its steaming hot pools, powered by geothermal reservoirs. Carbon dioxide readily dissolves into the fluids in these reservoirs. Our experts believe we can utilise geothermal fluid after it leaves power stations, injecting it away from the reservoir to trap emissions from the atmosphere for long-term storage. We’re also studying whether the rock types in these deep underground systems might react with carbon dioxide, solidifying and permanently storing the carbon.

2. Tonnes (literally) of wood waste. Wood is a concentrated source of carbon dioxide, helpfully filtered out of the surrounding air by the tree as it grew. New Zealand’s vast commercial forestry sector produces 4 to 5 million tonnes of waste wood: branches and offcuts, often left behind to rot after a harvest. We want to see more of this material collected, and combusted to release carbon dioxide – which would be captured and perhaps pumped underground. Alternatively, the organic waste could be transformed into biochar and spread on soils. The processes would also generate renewable energy.

3. Growing bioenergy sector. Combusting wood offers us another chance at carbon removal, using the leftovers. The ash produced in any wood boiler contains a significant share of calcium and magnesium compounds, which can interact with carbon dioxide in the air or concentrated sources. A new, solid carbonate is formed – actively reducing planet-heating gases in the atmosphere. We believe this calcium or magnesium carbonate would be a good component in concrete, which is typically a very high-emitting material to produce. Around 7% of New Zealand’s energy is produced by burning bioenergy – wood or other organic matter – so we already create large volumes of ash, which is often treated as a waste product. Our Government is encouraging the growth of bioenergy, which would further boost ash production and offer a great opportunity to produce lower-impact concrete.

4. Deposits of carbon-capturing minerals. Basalt and dunite rocks also contain lots of calcium, iron and magnesium – which, of course, react with carbon dioxide from the air. This happens on mountains and hillsides around New Zealand, whenever these raw minerals become exposed. To speed up this natural process, we can take these rocks, crush them into a fine powder and spread them on soils. Then we just need…

5. Lots of rain. Before the carbon dioxide reacts with rock, it needs to encounter water. As rain falls and hits the ground, the moisture interacts with the planet-heating gas and forms carbonic acid. This weak acid reacts with that calcium, iron and magnesium in the powdered rock. The more rain, the more carbonic acid is available for this carbon-capturing process – and New Zealand’s temperate climate is known for abundant rain! In addition, it’s the rain that washes the newly formed bicarbonate ions into streams and rivers and out to sea, where some eventually settle on the ocean floor and becomes solid carbonates.

6. Vast amounts of farmland. There are around 13 million hectares of farmland across Aotearoa – if carbon-capturing rock powder was applied to a significant proportion of this land, we estimate we could achieve million-tonne scale per year. Notably, the powder itself offers another benefit: it can help to control the acidity of the ground, boosting grass or crop growth.

7. Can-do attitude. New Zealand is proud of its entrepreneurial spirit, known locally as our “number 8 wire” attitude. On the carbon dioxide removal front, we see evidence of this in the breadth of the support we’ve received: we’re partnering with Iwi businesses, multinationals and councils to undertake our research, and are being guided by leaders in academia and industry. It’s pleasing to see the New Zealand Government developing frameworks to incentivise and regulate new options. As momentum to fight climate change mounts at all levels, we hope that Kiwi businesses and Iwi organisations will embrace the carbon removal tech that we’re developing.

Of course, no matter how well-suited a place might be, developing carbon removal will have its challenges. Spreading rock on farmland may increase the amounts of heavy metals in the soil, for example. Using a new type of carbonate might alter the physical properties of the cement. A local Māori community might worry about the wider environmental impacts of a new bioenergy-geothermal plant. Where we can, our team is trying to pre-empt these issues and see if and how they can be mitigated.

When our work wraps in 2029, we hope to have mapped the most suitable removal options for the country, balancing out the benefits and the trade-offs. If you have any thoughts, we’d love to hear from you.