Skip to main content

Clean Coal on the Ropes

power plant emissions

Clean coal is a seductive proposition for arresting climate change.  It means we could continue to burn coal for power as usual and use carbon capture and storage (CCS) to remove carbon dioxide from the flue gas and bury it underground.  Carbon capture is actually a mature technology, widely used in natural gas processing, where gas is bubbled through a liquid amine mixture which chemically binds to carbon dioxide, letting the desired gas pass through.  The amine solvent is then heated to liberate relatively pure carbon dioxide.

Companies and governments invested in coal have devoted massive resources to try and adapt carbon capture technology for coal fired power, with the typical approach being to bolt on a conventional amine solvent plant to an existing power station.  This approach has, however, failed to succeed.  The Boundary Dam project, a flagship effort aiming to demonstrate that CCS is feasible on an industrial scale, was plagued by budget overruns during construction, and its future remains unclear.  The plant has also seen operating costs blow out, with it now revealed that the amine solvent is to blame.  Although this process can be made to work when removing trace contaminants from natural gas, it appears that the complex flue gas and punishing operating conditions make it incompatible with coal fired power generation.  The solvent degrades too quickly, requiring it to be replaced and creating a large toxic amine waste stream.

The amine waste issue serves as a reminder that CCS is not "clean coal".  Amine solvents, for instance, also create significant new air pollutants.  Sequestered carbon dioxide is a legacy waste that must continue to be monitored.  Coal mining pollutes the land and water.  The transport and processing of coal is responsible for particulate matter emissions.  There are many reasons for us to finally abandon coal, and few compelling arguments for why we should use CCS to keep burning it.


Popular posts from this blog

Australia's Clean Air Myth

I've been thinking a lot about air quality in Australia recently as I wrote up my submission in response to Victoria's Air Quality Statement, which will help shape a future air quality strategy for this state.  The Clean Air Statement presents a rosy picture for air quality in Victoria - our air is repeatedly described as "great" and "very good" - and this leaves the impression that air pollution is not a current health danger to Victorians.  Anecdotally, I have seen this attitude adopted by Australians around the country, who ask me why I need to research air quality in Australia and tell me that we already breathe clean air.  It is true that our air is cleaner than many of our neighbours, but this doesn't mean that it is healthy.  Air pollution in China, for instance, is one of the biggest handbrakes on development in what may soon be the world's biggest economy, and it is meaningless to compare it to Australia.

So, how big is Australia's air …

Is Someone Cheating on the Montreal Protocol?

The Montreal Protocol regulates emissions of ozone depleting substances.  It is ratified by every nation and bans the use of chemicals including chlorofluorocarbons (CFCs), long lived substances which break down the stratosphere's protective ozone layer.  The international treaty has led to decreasing atmospheric levels of CFCs, and the ozone layer is beginning to recover.  It is now being reported, however, that atmospheric levels of one CFC (trichlorofluoromethane, CFC-11) have slowed their rate of decrease, attributed to a new CFC-11 source from Asia.

The origin of these new CFC-11 emissions are unclear, and will be difficult to pinpoint.  They may be from clandestine use of the banned substance, but could also arise from leaky CFC-11 stockpiles.  An international effort to investigate this issue now appears warranted, since it threatens to undo much of the good work of the Montreal Protocol.

CFCs are not the only threat to the ozone layer.  Recent studies have shown that the o…

New Zealand's Toxic Methyl Bromide Problem

Concerns are mounting in New Zealand around the continued use of methyl bromide for fumigation.  Methyl bromide is a highly effective fumigant, but it is also depletes the ozone layer and is harmful to human health.  Under the Montreal Protocol for the regulation of ozone depleting substances, use of methyl bromide is banned for all but a few exempt quarantine purposes. This ban has seen measured atmospheric levels of this substance drop from about 10 to 8 parts per trillion. In New Zealand, however, methyl bromide usage is soaring, with a 2020 deadline to eliminate methyl bromide emissions looming.

One of the biggest exemptions for methyl bromide use is in fumigating logs for export. China and India are the main destinations and both prefer methyl bromide treatment as a bio-security measure. New Zealand is a significant exporter of logs to China and India, and in recent years has grown to become one of the biggest users of methyl bromide worldwide. The NZ government have a 2020 deadl…