Noxious gas best buried

A team of Australian scientists is working on a plan to cut Australia’s greenhouse gas emissions by injecting surplus carbon dioxide deep underground.

Dr Peter Cook, Executive Director of the Australian Petroleum Cooperative Research Centre (APCRC) will outline a proposal developed to examine the options of capture, separation and geological disposal of carbon dioxide (CO2) at the Third AMEEF Innovation conference at Brisbane’s Marriot Hotel, on 17 August.

‘CO2 is a major greenhouse gas and there is a growing view that geological disposal of CO2 could be one of the most environmentally acceptable ways to halt the rapid rise of CO2 emissions without adversely impacting on economic development,’ says Dr Cook.

‘At this stage it appears possible to securely store CO2 underground for thousands of years,’ he says.

The proposal, based on a project called Glad-Rock 1, is focused on the Gladstone-Rockhampton region of Central Queensland. It combines the research expertise of the APCRC and the CSIRO Energy Sector. It is due to commence later this year.

The CO2 emissions to be captured and disposed of would come from burgeoning industries, and electricity generators in the Gladstone Rockhampton region.

‘In many cases we are just putting the CO2 back where it came from,’ says Dr Cook.

CSIRO is to explore the existing range of capture and separation technologies for CO2 and assess their suitability for the region. The APCRC will research ways to dispose of the CO2 in the subsurface.

‘Capture separation and sequestration through geological disposal all need to be considered on a site-specific basis due to the range of industries involved, the variation in the mix of emissions and the variability of geology, hydrogeology and tectonics,’ says Dr Cook.

Geological disposal of CO2 involves injecting the CO2 in a semi-liquid form deep underground in places like coal seams, depleted oil and gas fields, large voids and cavities or into unusable or saline aquifers.

The Gladstone-Rockhampton region is one of around five areas in Australia displaying rapid industrial growth. As a consequence it is also responsible for a significant proportion of the increase in Australia’s greenhouse gas emissions.

Other hot-spots for economic growth and greenhouse gas emissions include the Hunter Valley, Victoria’s Latrobe Valley, the Kwinana area of WA and the Sydney-Newcastle region.

‘The regional approach proposed here is unique in Australia and possibly unique in the world as the few studies undertaken so far have focused on a particular industry or sector rather than on a region,’ says Dr Cook.

There are six main methods of geological disposal. Preliminary studies suggest the following three are most suitable for Australia.

One of these is to use CO2 from industry to extract methane from coalbeds. The CO2 adsorbs onto the coal, displacing the methane that is recovered and used in energy production. The CO2 remains underground, locked up in the coal.

CO2 could also be locked away through adsorption in deep, thick, unmineable coal seams.

‘Australia has large volumes of deep coal and this option may be an important one, though the seams would have to be those where there is no reasonable prospect of mining in the future,’ says Dr Cook.

Possibly, the most favourable option is disposal of CO2 in deep saline aquifers that are too deep or too saline to be used as a water source.

‘Overseas experience and our knowledge of Australian geology suggest this option may hold the greatest potential for Australia. But we need to ascertain its technical applicability to Australia and most importantly define what the cost will be,’ he says.

Glad-Rock 1 is an outgrowth of an APCRC research program called GEODISC that involves five research groups – CSIRO, the Australian Geological survey Organisation, Curtin University, Adelaide University and the University of NSW.

GEODISC, which began in July 1999, is investigating the geological disposal of CO2 specifically for Australia’s natural gas industry, and is supported by six natural gas companies and the Australian Greenhouse Office.

‘Its outcomes will have implications for other industries and the Glad-Rock project will draw on some of its findings,’ says Dr Cook.

CSIRO’s Energy Sector Coordinator, Dr John Wright says, ‘The only techniques available for medium to large scale CO2 sequestration use forests, oceans or geological disposal.’

‘Australia’s ‘Kyoto target’ from The Framework Convention on Climate Change held in Kyoto in 1997 allows for an 8% growth in emissions above 1990 levels by 2008-2012. Australia is already 16 % above this target and major action needs to taken such as large scale sequestration,’ he says.

Glad-Rock 1 is being coordinated by the Australian Minerals Industry Research Association (AMIRA International).

On the web at www.csiro.au