Skip to main content

A NSW Government website

Alternative storage of captured carbon dioxide

Why store CO2?

The safe and secure long-term atmospheric removal of the carbon dioxide (CO2) captured from coal-fired power stations and other major emission sources is paramount to effectively reducing greenhouse gas emissions in NSW.

The main CO2 storage options currently being investigated include underground geological storage in porous rock formations, algal and bio-sequestration, ocean storage and mineral carbonation.

Apart from the conventional geological storage of CO2 that the NSW Government is undertaking through the NSW CO2 Storage Assessment Program, NSW is actively looking at non-conventional forms of CO2 storage as part of developing a portfolio of storage options to meet differing needs throughout the State.

Project: Permanent large-scare CO2 storage by mineral carbonation in NSW

The challenge:

Reduce greenhouse gas emissions by developing novel ways to safely and securely store CO2.

The action:

Coal Innovation NSW funded Mineral Carbonation International to develop and optimise a promising method of permanently storing CO2 in building materials.

Grant amount:

$3.04 million (EOI Round 2009).

The project:

Mineral Carbonation International Pty Ltd (MCi), a joint venture between the GreenMag Group, Newcastle University and Orica, received grant funding to develop and optimise a promising method of utilising CO2. The project also received funding from Orica and the Commonwealth Government.

The mineral carbonation process mimics and accelerates the Earth’s own carbon sink mechanism process where CO2 is captured in mineral deposits and stored in rocks. These solid products can be used in various applications including building materials.

A key highlight of the project was the development and successful operation of two pilot plants with the capacity to store 150 tonnes of CO2 per year. Processes were developed to produce materials for use in concrete and plasterboard at laboratory scale.

The project made a significant contribution to the field of mineral carbonation, producing data for life cycle analysis, testing and optimising innovative components and processes. It demonstrated this mineral carbonation process is an environmentally suitable CO2 storage solution and can produce materials with potential commercial value.

NSW CO2 mineral carbonation diagram

NSW CO2 mineral carbonation diagrammatic scenario, courtesy of Mineral Carbonation International.

Project: Deployment of silica gels for improved CO2 containment and risk mitigation

The challenge:

Develop rapid response tools for remediating any damage that may occur to wells used for injecting and storing captured CO2.

The action:

Coal Innovation NSW funded the University of New South Wales to determine the efficacy of using silica gels as an inexpensive, non-toxic and effective sealing agent in fractured wellbore cements of CO2 storage well.

Grant amount:

$90,000 (EOI Round 2018)

The project:

Colloidal silica sols are solutions of silica particles suspended in a liquid that transform into solid gels when the pH is lowered. This occurs in the presence of acidic CO2 fluids.

This project analysed the effectiveness of silica gels as a rapid response tool to prevent leaks at a CO2 storage site. CO2 storage reservoirs may leak if fractures to the wellbore cement sealing a CO2 injection well occur. The silica sols can be injected into a well to seal fractures and prevent or mitigate leaks. This technology reduces the risk CO2 leaking from a well and would lower costs of managing long-term geo-sequestration sites.

Through a series of carefully designed laboratory experiments, silica gels were shown to be effective at preventing the flow of CO2 through fractured wellbore cement. The work presented will aid future development of gels tailored to the chemical environment of specific CO2 storage sites.

The project has been completed and the final report, Deployment of Silica Gels for Improved CO2 Containment and Risk Mitigation, contains further details of the project findings (PDF, 848.12 KB).

Sol gel preparation

Sol gel preparation (Courtesy of UNSW)

Project: Low emission coal in the manufacture of carbon fibres

The challenge:

Improve the greenhouse gas emissions footprint associated with the production of carbon fibres used in manufacturing.

The action:

Coal Innovation NSW funded the University of Newcastle to demonstrate a novel method of substituting NSW coking coal for polyacrylonitrile (a petroleum-based chemical) as a cheaper, low emissions alternative feed material used in the manufacture of carbon fibres.

Grant amount:

$753,468 (EOI Round 2018)

The project:

This project is further developing a low emission industrial process to manufacture carbon fibres from coal. If coal could be substituted for polyacrylonitrile (a petroleum-derived material currently used in the manufacture of 90 per cent of carbon fibres) it would reduce the industry’s emissions by ~34% (minimum estimate) and significantly reduce the cost of production (by at least 50 per cent). Coal is uniquely placed to overcome this cost barrier; however, the extrusion process needs to be further developed for fibre production.

This project builds on advanced research into coal conducted at the University of Newcastle, which manufactured carbon fibres by separating and concentrating coking coal’s vitrinite component, thermally extruding this material as it softens and becomes fluid. The extruded material is then drawn down to commercial fibre size (to fractions of a millimetre in thickness) and strengthened by annealing at high temperature.

This project is ongoing and is due for completion in 2021.

Continuous extrusion system

Continuous extrusion system (Image courtesy the University of Newcastle)