Carbon capture and storage FAQs

We value knowledge sharing and providing information on the science, technology and innovations behind both CarbonNet and CCS.

  • 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.
  • There are a number of published reports and papers available for download.
  • If you have a question about the CarbonNet Project you can send it to CarbonNet.info@ecodev.vic.gov.au.

General

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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.

Victoria offers a world-class opportunity for CCS – Bass Strait’s offshore geology has excellent potential to safely store large quantities of CO2, while also being located close to industry in the Latrobe Valley.

CCS presents an important opportunity for new industries in Victoria consistent with the Victorian Government’s Net Zero Emissions by 2050 target and Climate Change Framework.

A CCS chain consists of four parts:

  • The CO2 is separated and captured at an industrial (natural gas, oil, coal or biomass) facility
  • The CO2 gas is then compressed
  • The CO2 is transported along a pipeline to a suitable geological site
  • The CO2 is injected deep below the ground for long-term storage

The whole process is similar to the oil and gas industry in reverse. Instead of extracting hydrocarbons which have been stored inside rocks for millions of years, CO2 can be injected into the same porous sandstone and stored underneath thick capping layers.

All the technologies required for CCS are well developed, commercially available, and have been used by industries for decades (particularly oil and gas).

As at February 2020 there are 51 large-scale CCS facilities globally. These include 19 in operation, four under construction and 28 in various stages of development. Of all the facilities, 17 are in the industrial sector and two in power generation (Global CCS Institute).

Over one hundred pilot and demonstration projects have also been completed, providing extensive scientific and engineering knowledge across a wide range of industries and geologies.

Globally, more than 220 million tonnes of man-made CO2 has been stored deep in geological structures.

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 reduce greenhouse gas emissions, permanently and cost effectively.

Yes, successful CO2 injection and storage projects are operating in Norway, Canada and the United States. Norway’s offshore Sleipner facility has been storing a million tonnes of CO2 per year since 1996.

In Victoria, the CO2CRC Otway Project has been operating since 2008 and has safely stored 80,000 tonnes of CO2, demonstrating world leading science and best-practice environmental monitoring.

As published in Nature - based on the large body of peer reviewed science globally, 98% of the CO2 injected into a well-selected and regulated CCS site will remain underground for at least 10,000 years.

Yes, right here in Victoria – the CO2CRC Otway Project has injected and stored more than 80,000 tonnes of CO2 – and it has also been used in many other places around the world by the oil and gas industry.

The Global CCS Institute lists 51 CCS projects at various stages worldwide (February 2020). Chevron’s Gorgon Project in Western Australia is storing CO2 in a sandstone reservoir 2.5km below Barrow Island. In the US there are thousands of miles of CO2 pipelines used by the oil and gas industry for enhanced oil recovery.

Visit the Global CCS Institute website for annual global status reports of CCS.

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.

Capturing and safely storing CO2 will significantly contribute to our move to a low-emissions future. Leading scientists and international authorities such as the Intergovernmental Panel on Climate Change have identified CCS as having the potential to safely and effectively help reduce our greenhouse gas emissions.

There is overwhelming scientific agreement that man-made global warming will have an impact on our planet. CO2 is recognised as the chief greenhouse gas, increasing the amount of solar radiation trapped within earth’s troposphere (lower atmosphere) and causing temperatures to rise. If not addressed, the increase in temperatures is predicted to exceed 2°C this century, with widespread impacts on climate and human habitats.

CCS can play a valuable role during the transition to a low carbon economy. CCS does not replace the need to increase energy efficiency or develop renewable energy technologies. Rather, CCS is part of a portfolio approach to addressing the issue of greenhouse gas emissions and climate change.

Fossil fuels still account for approximately 80% of global energy production and energy demand is forecast to increase significantly.

Analysis from the International Energy Agency suggests CCS will contribute around one fifth of required global emissions cuts by 2050.

The EU Commissioner for Energy and Climate Action (2015) Miguel Arias Cañete states that: "Carbon capture and storage will, together with other innovative low-carbon technologies, play an essential role in reaching greenhouse gas emission reduction targets around the globe".

The relative costs of CO2 capture, transport and storage will depend on the location and industry.

  • Storage costs are related to the geological characteristics of sites
  • Transport costs are related to distance and pipeline capacity
  • Capture cost can vary significantly between industries, as some industrial processes separate the CO2 as part of their normal operations

The most cost-effective opportunities for CCS today are in the natural gas processing, fertiliser manufacturing, hydrogen production and biofuel sectors. It is in these sectors that we see most of the existing CCS facilities globally, where total CCS costs are less than US$20/t CO2 (GCCSI 2017).

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.

Capture and storage

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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.

This graph shows how mechanisms may take effect and contribute to the long-term trapping of 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.

Studies have identified Victoria’s Bass Strait as being a world class site for storing CO2. Bass Strait is also attractive as it is located close to the Latrobe Valley and its associated industries.

Detailed modelling will help geologists predict any potential movements of CO2 and the direction and distance it could travel if it was to migrate.

Storage sites will be monitored with the aim of informing regulators of any CO2 movement. If migration beyond the storage reservoir is detected, injection of further CO2 could be stopped. Detailed modelling conducted prior to injection will provide information such as how long after injection ceases the CO2 would continue to move.

The CO2 may also react with other minerals underground and form new rocks, such as calcium carbonate (commonly known as limestone). When this occurs the CO2 will be permanently trapped.

The CarbonNet Project

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The CarbonNet Project is investigating the potential for establishing a commercial-scale CCS network in Gippsland. This network will bring together multiple CO2 capture facilities in Victoria's Latrobe Valley, transporting CO2 via a shared pipeline and injecting it into deep underground storage sites offshore in Bass Strait.

The project was established by the Victorian government in 2009 and has been jointly funded by the State and Commonwealth since 2010.

The geology in Bass Strait, located adjacent to the Latrobe Valley, 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. Pelican is a large sub-surface geological structure shaped like an elongated dome, with many rock layers.

The drilling of an offshore appraisal well in 2019-20 at the Pelican site in Bass Strait represented a major milestone in CarbonNet’s history and was the final offshore activity for Stage 3 of the project.

Operations were completed successfully over an eight-week period, concluding in late January 2020. More than 100 crew worked daily in shifts to drill the well and undertake supporting investigations to confirm the geology and extract rock samples.

During 2020 rock samples will be analysed to assess their composition, the amount of space they have available to be filled by fluids like water or CO2, the ease with which fluids can flow through them and their strength and resistance to CO2.

Combined with the valuable data acquired from the 2018 marine seismic survey, the well data will be used to model the Pelican site for long-term storage of CO2 as CarbonNet works towards establishing a carbon capture and storage (CCS) network in Gippsland.

Over the next two years, CarbonNet will work towards obtaining a CO2 Injection Licence for the Pelican site. It will also continue to assess pipeline corridors to the selected injection site.

Defining the commercial structure and underlying principles to attract private sector investment is a primary focus during this stage of the project. Various business models are being examined to enable the provision of a CCS service to industry in Gippsland, such as the HESC project.

Community and stakeholder engagement will also increase. The project has a broad range of stakeholders that includes landholders, the local communities, industry and regulators.

Should CarbonNet progress to a commercial stage, construction and operations could be expected to begin in the mid to late 2020s subject to relevant approvals and private sector investment.

Safety

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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 sea water 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.

Environment

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No, groundwater aquifers are typically less than 200m below ground. CarbonNet is investigating injecting CO2 a lot deeper - over 1000m below the seabed, at a site 8km offshore. CarbonNet has modelled a range of scenarios accounting for uncertainties and sensitivities in key water quality parameters. No impact to onshore aquifers is expected.

Modelling work has also been conducted by CO2CRC and CSIRO who have assessed the potential impacts on the onshore aquifer and determined the project will have no impact on the onshore water table or groundwater quality.

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.

CarbonNet’s OAW enabled the collection of rock core samples from the proposed carbon storage reservoir. These samples provide further insights into the properties and formations of the rock layers below the seabed and confirm its suitability to store CO2. Samples of formation fluids were also collected to confirm that they are compatible with CO2 storage and that no adverse chemical reactions will occur.

Before the OAW was drilled, predictions were made of the thickness, distribution, and quality of the different rock layers that will be reservoirs and seals at the Pelican site. These predictions were made on the basis of the 2018 3D seismic survey over the Pelican site and have now been checked against the actual OAW results. All layers were found as predicted, within 5m to 15m of the forecast depth, down to almost 1500m below seabed (i.e. to 99% accuracy). The lithologies were very close to those predicted with only minor local variations. The geological model for the storage site will be updated with new information, and only minor changes are anticipated.

Valid pressure seals were found, and excellent reservoir properties were measured in a 24-hour injection test of sterilised water. Additional information about rock strength, regional tectonic stress, reservoir and seal chemistry/mineralogy, and subsurface fluids are all being evaluated. At this stage no significant changes have been detected when compared to the knowledge gained from earlier oil and gas exploration and appraisal wells around the Pelican site.

On a regional scale, the storage capacity of the Gippsland basin is over 30 GT (30 billion tonnes), which is equivalent to all existing emissions from the State of Victoria for 300 years. Therefore, the possibility of not being able to store all the CO2 from potential projects in Gippsland is highly unlikely, since the future economy will decarbonise through a variety of methods, and CCS is not intended to be the sole solution to emissions reduction.

Regulation and responsibility

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    Several key pieces of legislation underpin the sequestration of CO2 depending on whether it is onshore or offshore in the Victorian or Commonwealth jurisdiction, including:

    • Victoria's Greenhouse Gas Geological Sequestration Act 2008
    • Victoria's Offshore Petroleum and Greenhouse Gas Storage Act 2010
    • The Commonwealth Offshore Petroleum and Greenhouse Gas Storage Act 2006

    Like any infrastructure project in Victoria, a wide range of other planning and environmental approvals will be required prior to any development commencing.

    All operations to date have related to site appraisal. Storage approvals will be another project stage and require further approvals. An Environment Plan for the offshore appraisal well was approved by the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) in April 2019 and a summary is available on the NOPSEMA website.

    Ownership and responsibility for the stored CO2 depends on a number of factors relating to the individual project and the relevant legislation.

    The project’s approach covers the identification, evaluation, and prioritisation of risks. We have then followed this by a systematic application of resources to minimise, monitor, and control the probability or impact of identified risks occurring.

    When planning operational activities, a wide range of potential risks are assessed, with methods selected and applied to reduce the risk to a level that is both as low as reasonably practicable (ALARP) and acceptable to stakeholders and regulators. Selection of appropriate equipment, working practices, and designs can reduce risk to close to zero.

    At key steps of the Pelican site evaluation process, international expert panels have assembled to review and challenge the technical data and interpretation of the proposed storage site. Experts have been sought with experience of other CO2 injection projects worldwide, with oil and gas operating experience, and with skills in risk analysis and safe process design. These panels of experts are known as Peer Panels, similar to the way that scientific publications are reviewed and challenged by scientific peers before they can be published in a reputable scientific journal.

    To date, five peer reviews have been conducted and each one has endorsed the suitability of the Pelican site for CO2 storage and the methods CarbonNet has used to make its evaluation.

    Contact us

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    Page last updated: 30 Dec 2020