Burning quality question

The nation’s power industry has taken major strides towards zero emissions in recent years, thanks to extensive investigation of what happens when different Australian coals are burnt under varying conditions.
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Staff Reporter

Much of this work has been carried out by the CRC for Coal in Sustainable Development, and its predecessor the Black Coal CRC. A team led by Professor Peter Nelson has carried out tests on the NOx, SOx and heavy metals emitted by the ten main classifications of Australian coal under different firing regimes.

The research is not only providing valuable clues to power generators on how to tune their combustion systems to minimise emissions without loss of efficiency but also the ability to report on them with greater confidence. It has helped revise the all-important National Pollution Index workbook – previously extensively based on US coals – to cover local coals.

One example was a CCSD study that showed that a critical international assessment of Australia’s power industry as the world’s worst mercury-emitter had got it wrong by a factor of almost ten – because it was based on overseas coals.

Nelson says the evidence to date indicates that NOx and SOx emissions from power stations do not pose significant environmental problem in Australia, as samples taken near the plant are well below the “critical load” limit used in the US and Europe. New research is under way, however, to explore more fully the extent to which they may be entering rainwater and the catchment.

Research into heavy metal emissions – mercury, cadmium, chrome and arsenic mainly – found that some of the more toxic compounds tend to gasify and then condense on the ultra-fine ash particles in the stack. For this reason, researchers recommended the use of cloth filters for particle extraction as these have proved more efficient at mopping up sub-micron particles than normal electrostatic precipitators, thus preventing the escape of the more toxic compounds.

The next step in the research is to investigate whether power station emissions have any detectable impact on human health, Nelson says.

The work of CCSD into assessing coal quality has made a major contribution to both coal producers and users - and to the ultimate aim of zero emissions, says Dr David Cain of Rio Tinto, who chairs the CRC’s research committee. “CCSD is outstanding among CRCs in the extent and breadth of industry support. It has been a valuable link between Australian coal producers and users when no other existed, creating a forum where the two industries could share views and work together. Its research agenda is set by industry and is free of government intervention.”

Workable greenhouse solutions

Five years ago, geological storage of carbon dioxide was an idea practically no-one thought worthy of consideration.

Today, thanks to some hard slog by the CO2CRC (and its predecessor the Australian Petroleum CRC), geosequestration is having a real effect on the policy thinking of energy companies and government departments. And Australia is developing a reputation among global leaders for developing practical, workable strategies to address greenhouse gas concerns.

CRC chief executive Peter Cook recalls the time – 1999 – when only a few gas companies were willing to fund GEODISC, as the research project into the feasibility of underground carbon storage was then known.

“Then it was seen by most of industry and government as being of little relevance. Now, it is regarded by many as potentially a very important part of our total greenhouse mitigation strategy.”

Cook is at pains to point out that geosequestration is a not a “silver bullet”, but it has a lot to offer, especially as the world transits fossil energy for renewables.

“This is now widely recognised across the board – by coal and oil producers, the power industry, government policymakers and the greenhouse technology sector.

“Australia’s research into the potential of geosequestration has had an international impact, with many major international companies being part of the CO2CRC. Closer to home, a New Zealand consortium has joined the Centre, and consideration of geosequestration is playing a significant part in New Zealand’s conversion to similar thinking,” he says.

Also significant is Cook’s appointment as lead author for the chapter on geological storage in the forthcoming Special Report on Carbon Dioxide Capture and Storage by the Intergovernmental Panel on Climate Change (IPCC). The report, due out in late 2005, is the next big event in the greenhouse science calendar.

“I think we can say that Australia is now a significant player in looking at options to mitigate climate change – and that carbon dioxide geosequestration is now starting to have a very important impact on international thinking about how we tackle greenhouse problems in the post-Kyoto era.”

Australia’s Mining Monthly