CCS activities

Capture CO₂ capture technology has been in use since the 1920s and is undertaken routinely in natural gas production.

Compression Following capture of the CO₂, it is compressed into a dense liquid to reduce its volume and make transportation by pipeline or ship easier. Gas compression is routine at liquefied natural gas (LNG) facilities.

Transportation Gas transportation in large volumes is usually achieved by pipelines or ships. In Europe and Asia, ships for CO₂ transportation are under construction, with the first expected to begin operations by 2025-26. CO₂ is transported safely, at scale every day, all over the world through pipelines or trucking.

Injection Once it reaches the permanent storage site, the CO₂ is pumped or injected underground using the same drilling technologies that have been used in the oil and gas industry for more than 100 years. The CO₂ is pumped down and injected into a porous and permeable geological reservoir. The injected CO₂ then forms a “plume” that moves away from the well. The CO₂ within the plume is then either progressively trapped as it migrates, dissolves into the water in the reservoir or reacts with the rocks and water to form minerals.

At a suitable geological storage site, the CO₂ is injected into deep underground rock formations, often at depths of one to two kilometres or more.

The CO₂ moves slowly through the porous rock, filling the tiny gaps known as ‘pore space’. Possible storage sites include depleted oil or gas fields, and rocks containing unpotable saline water.

These sites generally have an impermeable trap, also called a ‘seal-rock’, above them. The seal and other geological features prevent the CO₂ from migrating to the surface. Such sites have been demonstrated to securely contain fluids and gases for millions of years.

In Australia, offshore CCS is a highly regulated activity, overseen by the Department of Climate Change, Energy, the Environment and Water (DCCEEW) as well as the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA). Comprehensive CCS monitoring programs are implemented to ensure the injected CO₂ plume behaves as predicted and is permanently contained underground in the licenced storage site.

Monitoring tracks injection pressures and temperature to confirm the injectivity and saturation of CCS wells, provides time-lapse seismic survey data to map the CO₂ plume over time, and assesses soil and shallow aquifers.

The Northern Territory has vast offshore basins deemed by Geoscience Australia as highly suitable for very large-scale and long-term CCS projects. This means the Northern Territory can make a substantial contribution to a cleaner northern Australia through CCS, while also supporting national and Indo-Pacific net zero goals.

Beyond natural gas, the proposed CCS Hub on Darwin’s Middle Arm peninsula has the potential to assist other industry groups to decarbonise by transporting CO₂ to CCS injection site(s).

The Darwin CCS Hub is likely to also include common marine infrastructure for the importation of CO₂ from overseas to support global net zero achievements.