The Otway Project in Victoria has demonstrated CO2 can be stored safely underground in Australia The Callide Oxyfuel Project in Queensland is the largest demonstration of oxyfuel technology in the world to date The IEA says CCS is a critical component in the portfolio of low-carbon technologies combating climate change The IEA expects CCS to contribute 14% of global emissions reduction by 2050 The Intergovernmental Panel on Climate Change says without CCS, the cost of reducing emissions to 2100 increases 138% Canada’s Boundary Dam – the first large scale CCS project in the power sector – began operation in October 2014 Since 1986, the Sleipner Project has been storing a million tonnes of CO2 per year in the North Sea

Strategic overview

COAL21 strategy on low emission fossil fuel technologies
Assessment of CO2 storage in Australia
Types of storage for CO2
Types of capture for CO2
High Efficiency, Low Emissions Technologies (HELE)
Fugitive emissions

The international strategy for low emissions fossil fuel technologies is chiefly focused on the development of carbon capture and storage (CCS) technology and high efficiency, low emissions (HELE) fossil fuel utilisation technology.

Much of the activity for carbon capture technology and HELE research, development and deployment is occurring internationally (such as in North America, Japan and Europe) where large technology corporations and equipment manufacturers are located.

For carbon storage, which involves the use of geological formations such as thick sedimentary basins located deep underground, activity is occurring in a range of individual nations. Geology is quite variable and conditions differ widely between specific locations. So prospective geological storage sites need to be individually characterised. However there are general learnings that can be applied across a range of sites in different nations.

COAL21 strategy on low emission fossil fuel technologies

The COAL21 investment strategy is aimed at facilitating early demonstration of low emissions coal technologies, including CCS, through targeted co-investment with other stakeholders (government, electricity generators, equipment suppliers, other industry investors), so as to complement the international research, development and demonstration activities for low emissions fossil fuel technologies.

The priorities for COAL21 investment are as follows:

  • Proving storage in Australia
  • Engagement with projects actually sequestering CO2
  • Promoting multi-sector involvement in CCS
  • Promoting community acceptance of CCS and coal’s ongoing use
  • Reducing greenhouse gas emissions from coal mining operations.
Assessment of CO2 storage in Australia

Australia has many sedimentary basins, some of which are well known and explored, and others with little or no information. There are large thick basins along the north western, western and southern margins of the country. The onshore basins with significant sedimentary thickness are concentrated in the central east of Australia with one basin in the west.

A high-level, qualitative approach was used by the Carbon Storage Taskforce (established by the Australian Government to report in 2009) to rank the basins for their suitability to store CO2.

The results of the Australian basin ranking are shown on the map below. In this figure, the highest ranked basins are shown in green, the next in yellow, then orange, and the lowest ranked basins in pink. Basins shown in pink are considered to be unsuitable as storage basins, and those in orange are unlikely to be suitable. Areas noted in white represent geology which is non-basin in nature.

Chart: Australia’s basins ranked for CO2 storage potential

Source: Carbon Storage Taskforce, National Carbon Mapping and Infrastructure Plan – Australia concise report

It is important to recognise that every storage site will require a detailed, comprehensive assessment of the particular characteristics that will determine its capacity to store CO2 safely and securely. This begins with pre-competitive storage data collection and progresses through a series of stages to exhaustive site characterisation if the early stage data looks sufficiently promising.  Pre-competitive data collection is being funded by a combination of government and industry, including the COAL21 Fund.  The COAL21 focus has to date been chiefly in those states where there are significant black coal resources.

Types of storage for CO2

There are three types of geological carbon storage:

  • Conventional trapping – this relies on an impermeable sealing rock layer (in the form of an anticline or up-turned dish) located above the porous and permeable storage rock. In Australia the CarbonNet Project in Victoria is examining geology representative of this type of storage.
  • Horizontal migration assisted trapping (MAT) – this relies on an impermeable sealing rock layer above the porous and permeable storage rock which does not have an anticline or up-turned dish shape to fully trap stored CO2.  The CO2 is trapped in the horizontal direction by MAT, in which CO2 is progressively retained in the pores in the storage rock after bulk migration through the rock ceases. In Australia the COAL21 funded CTSCo Project in the Surat Basin in Queensland is examining geology representative of this type of storage.
  • Vertical and horizontal migration assisted trapping (unconventional trapping) – this relies on the sealing potential of multiple, non-continuous low permeability sealing layers located above the porous and permeable storage rock.  The CO2 is trapped in both the horizontal and vertical direction by MAT, assisted by the low permeability sealing layers.  In Australia the South West Hub Project in the Harvey region of Western Australia and the COAL21 funded Otway Project in Victoria are complementary and examining geology representative of this type of storage. Success in these projects has the potential to double the storage volume for CO2 internationally.
Types of capture for CO2

There are three types of capture technology for CO2 applicable to power generation:

  • Post-combustion capture – this involves separating CO2 from the gas stream produced after coal or other fossil fuels are burnt (combusted). With many examples of the technology already in commercial use it is the most developed capture process, capable of removing up to 90% of emitted CO2. In Australia, the COAL21 funded CTSCo Project is planning the use of post-combustion capture as a retrofit to an existing coal-fired power plant in Queensland.
  • Oxy-combustion capture – fuels are burnt in a mixture of pure oxygen and recycled combustion gases instead of normal air. The gas stream produced by combustion is primarily composed of CO2 and water vapour. The water vapour is condensed out and the CO2 is then captured. In Australia the COAL21 funded Callide Oxyfuel Project in Queensland has successfully demonstrated the retrofit of an existing coal-fired power plant with oxy-combustion technology and is currently the largest scale deployment of this technology in the world.
  • Pre-combustion capture – for coal-based application, by using a process called Integrated Gasification Combined Cycle (IGCC) technology, the CO2 can be removed. This is accomplished not by burning, but by reacting the coal with air or oxygen then further chemically converting it to produce a synthetic gas that consists mainly of hydrogen and CO2. The CO2 is then separated before the hydrogen is combusted. In Australia the COAL21 funded ZeroGen Project in Queensland examined the feasibility of deploying IGCC technology with pre-combustion capture.

Capture technologies can also be applied in oil and gas processing and refining, chemicals manufacture, smelting, cement, iron and steel and other industrial production. For example, the proposed Abu Dhabi Carbon Capture, Utilisation & Storage Project is to be the world’s first, large-scale CCS project in the iron and steel sector. The CO2 is to be transported 45 km for injection into Abu Dhabi National Oil Company reservoirs for Enhanced Oil Recovery (EOR). This project is moving into construction.

High Efficiency, Low Emissions Technologies (HELE)

There are two types of HELE technologies for power production for coal-based application:

  • Conventional HELE – this involves improvement of conventional coal-fired power generation technology (pulverised coal boilers) by operating at higher pressures and temperatures, which allows more efficient (lower CO2 emission) operation. This is the focus of a range of international R&D efforts.
  • Alternative HELE – this involves the development of non-conventional power generation technology which offers more efficient (lower CO2 emission) operation and/or lower cost CO2 capture. A number of different technology options, such as chemical looping combustion, are the subject of international R&D efforts. In Australia, COAL21 funded R&D includes the Direct Injection Carbon Engine, an adaptation of large scale low and medium speed diesel engines to be fuelled with a coal-water slurry.
Fugitive emissions

Carbon Capture and Storage reduces greenhouse gas emissions resulting from the use of coal. However, there are also greenhouse gases emitted during the mining of coal. The greatest source of greenhouse gas emissions from mining coal arise from so called “fugitive emissions”. All coal seams contain some level of gases, most commonly a mix of carbon dioxide (CO2) and methane (CH4). These gases are released when the coal is mined, and this release is referred to as fugitive emissions.

Coal industry fugitive emissions currently account for around 5% of Australia’s total annual greenhouse gas emissions, which is a relatively small proportion. Nonetheless, the coal industry is actively working to reduce fugitive emissions from mining. This includes:

  • R&D projects into the mitigation of methane release, particularly in underground but also in open cut mines, through the coal industry’s R&D program, ACARP. This work is undertaken through ACARP’s Minesite Greenhouse Gas Mitigation Technical Committee with supplementary funding provided by coal companies. It includes improved drainage in underground mining and R&D into abatement of methane in mine ventilation air.
  • A series of COAL21 funded projects that will:
    • design and demonstrate a duct to safely connect commercially available methane abatement technology to the ventilation system of an underground coal mine; and
    • investigate novel abatement concepts with potential to achieve emissions abatement in a smaller and lower cost installation.