Carbon Capture and Storage FAQs
We have an extensive collection of FAQs below that reflect the questions we have been asked at community events, research focus groups and also raised in the media.
Since 2010 CarbonNet has progressed through the concept and feasibility stages (Stages 1 and 2) and is now at Stage 3 - Project Development and Commercial Establishment. Regulatory assessment and approvals, including the pipeline approvals process, and consultation with communities, landowners and other stakeholders is part of this stage.
The project aims to reach a final investment decision in 2024, and commence construction in 2026 (pending approvals), and to be operational in 2027.
CarbonNet aims to provide a commercial scale CCS network for multiple new and existing industries based in the Latrobe Valley.
CCS is used by various industries like manufacturers of fertiliser, steel, concrete, or bioenergy. Such industries are not able to remove their carbon footprint by using renewable energy alone because one or more production steps may generate CO2 as a byproduct. CCS provides a solution.
Connecting these sorts of industries to CarbonNet would support Victoria’s 2035 target to reduce CO2 emissions by 75- 80% on 2025 levels.
Victorian and Federal governments have jointly funded the concept and feasibility stages of the project. Subject to the outcome of the regulatory approvals process, construction, and operation may be determined through a Tender process.
The Latrobe Valley has a long and proud industrial history and is in close proximity to suitable geological storage sites for CCS. This makes it an ideal place to support the development of clean industries as the area transitions out of traditional coal mining and coal-fired power generation.
The geology in Bass Strait, contains the highest quality and largest capacity geological reservoirs out of 25 major basins across Australia (National Carbon Taskforce 2009). Oil and gas have been safely stored in geological structures here for millions of years.
Investigations and analysis show that the geological formations deep below the seabed are well suited to long term CO2 storage. They are also well-characterised, having been explored by the oil and gas industry for 50 years.
CarbonNet has completed an extensive geoscience program that has been subject to independent scientific peer review. The program identified three potential storage sites in Bass Strait for further investigation. The prioritised site is known as Pelican.
The Pelican site is located in Bass Strait, approximately 8km offshore from Ninety Mile Beach, and 1.5km below the seafloor. Pelican is a large sub-surface geological structure shaped like an elongated dome, with many rock layers.
The CarbonNet project Pelican storage site has the capacity to take up to 6 million tonnes of CO2 per year over 30 years and store up to 150 million tonnes of CO2.
This is equivalent to removing the emissions from 1.8 million cars per year, or 45.9 million cars over the 30-year period.
Carbon Capture and Storage
Carbon Capture and Storage (CCS) involves capturing CO2, a greenhouse gas, from industrial processes and then transporting it to a suitable storage site for safe, long-term storage deep underground.
CCS is being investigated in Victoria and implemented around the world because it has the potential to play an important role in reducing greenhouse gas emissions from industry and addressing climate change.
All the technologies required for CCS are well developed, commercially available, and have been used by industries for decades (particularly oil and gas).
As of June 2023, there are 253 large-scale CCS facilities globally. These include 135in operation, 20 under construction and 198 in various stages of development.
In Victoria, carbon storage has been successfully operating in the Otway basin for over ten years. The CO2CRC Otway Project also conducts extensive research with international industry and academic partners to develop and improve processes, reduce uncertainty, and decrease the cost of CCS.
Chevron’s Gorgon Project in Western Australia is currently operating one of the largest CCS projects in the world, storing CO2 approximately 2.5km below their natural gas operations on Barrow Island.
Leading international authorities such as the Intergovernmental Panel on Climate Change, the International Energy Agency, the UK Committee on Climate Change, and USA Environment Protection Agency have confirmed CCS is a proven climate change mitigation measure and has an important role to play to permanently reduce greenhouse gas emissions.
Today, CCS can be commercially viable and cost effective in gas processing, hydrogen and fertiliser production.
As more projects are developed globally, the cost of CCS is decreasing – just as wind and solar technologies have experienced since their early stages of development.
Like many commercially available technologies, cost reductions are possible from learning-by-doing, working at scale, creating a CCS network and by utilising advanced technologies that are in rapid development phase.
During CCS, CO2 must be captured within an industrial process before emission to the atmosphere. This is achieved by integrating a capture plant with an industrial process. Industrial facilities use various technologies to capture CO2, including:
- Pre-combustion capture – the primary fuel (e.g. coal) is converted to gas. This gas is then processed and separated to CO2 and hydrogen. CO2 can then be separated using membranes or solvents and condensed into liquid for transportation.
- Post-combustion capture - occurs after the primary fuel is burned and the CO2 is contained in the exhaust gas. The exhaust gas is captured, the CO2 is then separated from the other gases using membranes or solvents.
- Oxyfiring, or oxyfuels, involves gasifying fuels in pure oxygen rather than in air. This creates a flue gas with a high CO2 concentration, simplifying the capture process.
After capture, CO2 is compressed into a dense liquid then transported to an injection site for storage in a sub-surface reservoir. Injection takes place with sufficient pressure to displace any water currently stored within the porous rock of the reservoir.
At depths of 800m or more, CO2 will remain in a compressed, dense liquid-like form, allowing each reservoir to store vast quantities of CO2.
The energy sector has extensive experience relating to the injection and storage of CO2.
Generally, CO2 is stored between 1km and 3km beneath the surface. CO2 needs to be injected at a depth greater than 800m so that the pressure ensures the CO2 remains in a dense liquid-like state.
CO2 is contained within suitable, porous rock overlaid by thick layers of non-porous cap rock. These naturally occurring, underground storage reservoirs are at depths of 800m or greater. CO2 is trapped in the same way that oil and gas has been trapped naturally for millions of years in similar structures and by the same cap rocks.
Prospective storage sites are subject to extensive studies to confirm suitability. Studies can involve 3D model simulations over long time frames (thousands of years), seismic testing with sound waves and appraisal drilling to retrieve rock samples and verify data.
Key geological characteristics sought when selecting potential storage sites include a storage reservoir which is porous and permeable to hold the CO2, a trapping mechanism for the stored CO2 and a cap rock to contain the CO2.
Trapping mechanisms include:
- Structural/stratigraphic trapping – the most common trapping mechanism where the CO2 (which is lighter than water) rises within the reservoir and is trapped by the overlying cap rock. In many instances, this is similar to how oil and natural gas has been trapped for millions of years.
- Residual trapping – CO2 becomes trapped as residual droplets within the pore spaces in the reservoir rock.
- Solubility trapping – where CO2 dissolves into water present in the porous rock.
- Mineral trapping – where the dissolved CO2 reacts with and is bound to the surrounding rock to form solid carbonate minerals.
Over time, a combination of these mechanisms may take affect and contribute to the long-term trapping of the CO2.
Depleted oil and gas fields generally offer excellent CO2 storage sites - with a geological trap, a porous reservoir and a sealing cap rock. These sites have always held oil and gas, as well as other gases such as CO2, for millions of years.
There are several existing commercially available technologies for CO2 capture that have been developed to produce high purity CO2 for commercial markets such as enhanced oil recovery, chemical manufacturing and food processing.
Some known CO2 uses are:
- Carbonation of soft drinks.
- Supplement to greenhouses as a plant growth accelerant.
- Base for producing large volumes of calcium carbonates (limestone) and sodium bicarbonates (baking soda).
- Growth medium for algae production which can then be used for oil production or as a source of stock feed.
- Raw material for the production of formic acid, an organic substitute for inorganic acids such as hydrochloric and sulphuric acids.
It is not anticipated that these CO2 uses will ever be able to cater for the large volumes that need to be captured to make a significant impact on climate change. Therefore, other methods of reducing CO2 emissions are required, such as permanent geological storage.
CCS has been in safe commercial operation globally for over 45 years, there are multiple facilities successfully and safely operating globally with over 6,000km of CO2 pipelines operating in North America alone.
In Australia, CCS projects must comply with relevant laws and strict regulatory requirements that include the monitoring of the pipelines and stored CO2.
CO2 exists naturally in the atmosphere (humans and animals breathe it out), it is absorbed within water (vast amounts of CO2 is absorbed in the oceans) and by plants and trees. CO2 forms the bubbles in our carbonated drinks and creates the bubbles at natural spa baths in Victoria and worldwide.
When applying for an injection licence, an applicant must undergo a rigorous assessment to ensure the nominated storage site has an appropriate seal and is suitable for CO2 containment. The regulators will only grant licences that have met these strict criteria.
An applicant is required to prepare a monitoring and verification plan prior to conducting any injection operations. This plan includes an operator’s response to non-routine situations, including losses and migration of CO2, pressure reduction and other markers about the storage formation that may indicate a leak.
If the CO2 is not behaving as predicted, the operator is able to act quickly to mitigate the leak as per response procedures. For example, if movement beyond the storage reservoir is detected, injection of further CO2 would be stopped, removing the pressure and reducing further leaks.
Earthquakes do occur in Gippsland, mostly onshore where the Strzelecki ranges have been uplifted over millions of years from below a former seabed to form the present-day rolling hills of Gippsland. These earthquakes are generally not felt at the surface but occasionally are large enough to cause very minor damage.
The geological structures in the Gippsland Basin have been selected as they have sealing layers, or cap rock, that have contained large volumes of oil and gas for millions of years. As such it is considered extremely unlikely that stored CO2 will leak.
In the unlikely event of leakage beyond the sealing cap rock many secondary layers of rock create additional boundaries between the storage reservoir and the surface.
If CO2 was to permeate to the surface, a very gradual escape of CO2 would be expected, with migration potentially taking thousands of years. At spa baths, such as Hepburn Springs in Victoria, CO2 is naturally released into the atmosphere every day and these small levels do not pose a danger.
No, CO2 cannot explode or burn – indeed it is used in fire extinguishers to put out fires. CO2 is a non-flammable compound that is always present in our natural environment and is essential for plant and animal life.
The CO2 will be transported in a high-pressure gas pipeline, like those used for natural gas. All high-pressure pipelines in Australia must be built to meet the strict requirements of Australian Standard 2885, with Appendix T giving guidance for pipelines for the transport of CO2.
Risk of leakage is taken very seriously and has been investigated thoroughly during the storage reservoir assessment and selection. Project data and peer reviewed site assessments indicate that it is extremely unlikely CO2 will leak to the surface.
Geological structures, such as those in the Gippsland Basin, have sealing layers or cap rock that have contained large volumes of oil and gas for millions of years, and the same types of structures and the same sealing layers will be used for CO2 storage.
Rigorous assessment and mapping of storage sites, plus extensive modelling to predict the CO2 behaviour, have been undertaken ensuring strict selection criteria for the long-term safe storage of CO2 has been met.
But what if it does leak?
Any escaping CO2 would be identified through monitoring systems, and the situation remedied. Should CO2 permeate to the surface, a very gradual escape of CO2 would be expected, with migration potentially taking thousands of years, it would then dissolve into seawater and be rapidly diluted to a safe concentration by waves, tides, and ocean currents. Careful scientific studies undertaken by CSIRO have shown that ecosystem impact would be insignificant.
A monitoring network is being implemented for the CarbonNet project with monitoring technologies currently trialled by researchers in the Gippsland region and at the Pelican site between 2016 and 2019. This initiative monitored the ocean, atmosphere and seismology around the Pelican site and has established data around existing natural variation.
CO2 will be injected at pressure and rates well below the technical limits indicated by modelling and site assessments - leaving a large buffer. Automatic pressure limits will be applied using fast-response valves and electronic pressure monitoring systems.
The recent offshore appraisal well measured the pressure in the planned reservoir. It also measured how much force would be required to break the reservoir and seal rock. Further tests on samples of rock recovered from the well will produce strength results on a whole range of subsurface rock types to make sure all aspects of the reservoir are secure.
CCS projects are heavily regulated to minimse any potential risks and must meet stringent conditions to proceed. Projects that have the potential to pose and environmental risk must go through an Environment Effects Statement process which is a comprehensive assessment of potentially significant environmental, social, economic and planning aspects of a project. This process provides a pathway for the approvals required to construct and operate a CCS pipeline and storage.
The construction of CCS infrastructure is similar to that of any infrastructure. Construction of pipelines is carefully monitored, rehabilitation works are carried out after construction is completed, and the storage areas are naturally occurring geological sites.
During construction and operation, environment management plans are required to be developed and approved by various bodies such as NOPSEMA or the Department of Energy, Environment and Climate Action.
Whilst some fossil fuel producers do employ CCS as part of their operations, the technology has much wider applications across a range of industries. CarbonNet provides an effective emissions reduction option for essential industries that are unavoidably carbon-intensive and have no current alternatives to achieve deep emissions reduction.
While the CO2 injected may be at a range of temperatures, it is unlikely these would be noticeable or even measurable at ground level.
Research will be undertaken to investigate this further.
Ownership and responsibility for the stored CO2 depends on a number of factors relating to the individual project and the relevant legislation.
Page last updated: 17 July 2023