CSIRO researchers are conducting field trials of carbon mineralisation in basalt formations, a permanent carbon storage method that converts CO2 into solid carbonate minerals through natural chemical reactions.

The trials, taking place in the Surat Basin in Queensland, involve injecting CO2 into deep basalt layers where it reacts with calcium and magnesium in the rock to form stable carbonate minerals. Unlike conventional geological storage where CO2 remains in gas or liquid form, mineralisation permanently locks carbon into rock.

Dr. Linda Stalker, who leads CSIRO’s geological storage research, said mineralisation addresses one of the main concerns about conventional carbon storage. “People worry about leakage from storage sites. Once CO2 has mineralised, it’s not going anywhere. It’s chemically identical to the limestone that’s been stable in the Earth’s crust for millions of years.”

The process isn’t new. Researchers in Iceland have demonstrated carbon mineralisation in basalt at the Carbfix project, where over 95% of injected CO2 mineralises within two years. But Iceland’s geology is unusual, with highly reactive basalt and abundant water. Whether the approach works in Australia’s drier conditions remained an open question.

CSIRO’s trials aim to answer that. They’ve drilled into basalt layers about 1,500 metres underground and are injecting small amounts of CO2 mixed with water. Monitoring wells track how quickly mineralisation occurs and whether the process matches predictions from laboratory experiments and computer models.

Early results are encouraging. After six months, monitoring suggests that roughly 30% of the injected CO2 has already mineralised. If that rate continues, most of the CO2 would be converted to solid minerals within two years, comparable to the Iceland results.

Australia has extensive basalt formations that could potentially store billions of tonnes of CO2. The challenge is that most are far from major CO2 emission sources. Carbon capture only makes economic sense if you can transport CO2 to storage sites at reasonable cost.

That’s driving interest in carbon transport infrastructure. Several proposed CO2 pipeline projects would collect emissions from industrial facilities and transport them to suitable storage sites. But those pipelines are expensive and face regulatory and community approval challenges.

The Surat Basin trials are partially motivated by their proximity to coal-fired power stations and industrial facilities in central Queensland. If basalt mineralisation proves viable there, it could provide storage capacity for regional industries pursuing carbon capture.

Carbon capture and storage (CCS) remains controversial. Environmental groups often criticise it as a way for fossil fuel industries to continue operating rather than transitioning to renewable energy. Proponents argue that CCS is necessary for hard-to-decarbonise industries like cement and steel production, regardless of what happens in the energy sector.

Australia’s carbon credit scheme now recognises permanent geological storage, allowing companies to generate carbon credits by capturing and storing CO2. That’s created commercial incentives for CCS projects, though carbon prices remain too low to make most projects economically viable without subsidies.

The federal government’s CCS Development Fund provides $500 million in grants and concessional loans for CCS infrastructure. Several projects have received funding, including the controversial Moomba carbon storage project in South Australia.

The basalt mineralisation research builds on decades of CSIRO work on geological storage. Australia’s CO2CRC research program, which ran from 2003 to 2017, demonstrated safe geological storage in conventional reservoirs and trained a generation of researchers in the field.

One interesting aspect of basalt mineralisation is that it works better in offshore environments where water is abundant. Several proposed projects aim to store CO2 in offshore basalt formations, potentially at much larger scales than onshore storage.

The Gippsland Basin offshore Victoria has both depleted oil and gas reservoirs suitable for conventional storage and deeper basalt formations for mineralisation. Some researchers have proposed using both, storing CO2 in conventional reservoirs initially while it gradually migrates into underlying basalt and mineralises over decades.

The CSIRO trials include detailed monitoring of groundwater chemistry, microseismic activity, and ground deformation to verify that storage operations don’t cause unintended environmental impacts. That monitoring is critical for regulatory approval and community acceptance.

Carbon storage projects need to demonstrate that CO2 won’t leak into shallow aquifers or reach the surface. The monitoring requirements are stringent, involving sensors, regular well testing, and atmospheric monitoring around injection sites.

Whether basalt mineralisation becomes a significant carbon storage method in Australia depends on several factors beyond technical viability. The economics need to work, which means higher carbon prices or continued subsidies. Regulatory frameworks need clarity about liability and long-term stewardship. And communities near proposed storage sites need to accept the technology.

The CSIRO trials will continue through 2026, with final results expected in early 2027. If successful, basalt mineralisation could become part of Australia’s carbon management toolkit, complementing emission reductions and other carbon removal approaches.

It won’t solve climate change by itself, but it could be useful for dealing with residual emissions from industries that are difficult or impossible to fully decarbonise with current technology.