Tiny Bubbles, Big Ambitions: Australia's CO2 Field Trial

CO2CRC begins a landmark microbubble injection trial at Australia's Otway Test Centre to reshape underground carbon storage.

13 Mar 2025

Australia has no shortage of ambitions when it comes to carbon capture. What it has lacked, until now, is a field-scale test of whether the science holds up outside a laboratory. In March 2026, CO2CRC, the country's leading carbon storage research body, began injecting CO2-rich gas into the subsurface at its Otway International Test Centre in Victoria, using a technique that generates microbubbles rather than conventional gas streams. Up to 10,000 tonnes will be injected over the course of the trial, making it the first dedicated field test of this approach at an active storage site anywhere in the world.

The method's appeal lies in what happens after injection. Conventional CO2 injection tends to produce buoyant plumes that rise rapidly and collect as free gas near the top of a geological structure. That free gas is the problematic kind: mobile, prone to leakage, and difficult to monitor. Microbubble injection, by contrast, slows the upward movement of CO2 and encourages it to dissolve into surrounding formation water. Dissolved CO2 is far more stable and far less likely to migrate toward the surface.

Laboratory work at the University of Texas at Austin, conducted in partnership with CO2CRC, produced encouraging results. Researchers built a metre-scale sand tank to simulate reservoir and caprock conditions and observed that microbubble injection substantially reduced plume growth and improved dissolution trapping compared with conventional methods. The Otway trial is designed to find out whether those results survive contact with reality.

The site chosen for injection is, by design, a difficult one. Researchers are targeting a sub-optimal reservoir, on the basis that a technology which performs well in poor geology will be far more commercially useful than one that requires ideal conditions. Many of the storage sites located nearest to major industrial emitters are geologically imperfect. If microbubbles can make them viable, the effective global storage capacity expands considerably.

Monitoring will be extensive, drawing on seismic imaging, pressure sensors and inter-well logging across a 100-metre span between injection and observation wells. The trial volume has been matched to a previous conventional injection at the same site, allowing a direct comparison. The Australian government is providing up to $10m per project through its Carbon Capture Technologies Program to advance such work toward commercial scale.

Whether the bubbles behave in the ground as they do in the laboratory remains, for now, an open question.