'Clean coal' will never be feasible, say scientists

Issue 

When a respected scientific journal carries a peer-reviewed article branding the key technology behind "clean coal" as "profoundly non-feasible", you'd think governments and coal corporations would react in some fashion.

After all, the proposed Waxman-Markey climate bill in the US reportedly promises "clean coal" a staggering US$60 billion in subsidies. Here in Australia, the Rudd government last year pledged to spend A$2.8 billion to develop carbon capture and storage.

That's a lot of money for dodgy science. In order to survive, the coal industry keeps the prospect of "clean coal" hanging before society's rapt gaze, like some modern-day star of Bethlehem.

For all that, there hasn't been a whisper about the journal article in mainstream news outlets. We haven't even had the Murdoch press try to stigmatise the authors as left-wing bullies and tricksters.

The article appeared in the January issue of the Journal of Petroleum Science and Engineering and was called "Sequestering Carbon Dioxide in a Closed Underground Volume". It was written by professors of engineering Michael Economides, of the University of Houston, and Christine Ehlig-Economides, of Texas A&M University.

Neither Texas nor the US petroleum industry are hotbeds of green radicalism, and the Economides husband-and-wife team are no leftists. Michael Economides, an oil firm chair and energy commentator as well as an academic, is an outspoken denier of human-caused climate change.

But whatever their views on other topics, the duo clearly know their oil and gas reservoirs.

Closed volumes

Although their article is highly technical, it rests on a startlingly simple premise: for carbon dioxide to be locked away from the atmosphere, the rock structures into which it is pumped must be closed volumes. If the structures were to outcrop on the land surface or seabed, the injected gas would have a potential route of escape.

Most of the theoretical work performed to date on geological CO2 sequestration, however, assumes just such an outcropping. Based on experience from pumping carbon dioxide into oilfields to keep the oil flowing, these analyses count on pressure remaining constant at some distant point.

What the Economides team has done is to explore the dynamics of pumping CO2 into a closed volume, where the reservoir pressure will build up. "Instead of the 1-4 percent of bulk volume storability indicated prominently in the literature", they report, "our finding is that CO2 can occupy no more than 1 per cent of the pore volume and likely as much as 100 times less."

From this, they conclude that sequestering the gas underground will "require from 5 to 20 times more underground reservoir volume than has been envisioned by many, including federal government laboratories".

Fantastical

What would this volume be, for a single medium-sized coal-fired power station of 500 Megawatts capacity? Unless hundreds of injection wells are drilled, constraints on injection pressure mean the reservoir has to be enormous, "the size of a small US state". Hopes of using geological sequestration to deal with the vast emissions of the coal-fired energy industry, the authors argue, are therefore fantastical.

To drive home their conclusion, the authors cite the example of the much-referenced Sleipner gas field under the North Sea, now being used for carbon dioxide sequestration. Sleipner sequesters about one million tonnes of CO2 per year.

The annual output from a single modest-sized 500 MW power plant, though, is about three million tonnes.

"There is no need to research this subject any longer", Michael Economides concluded in a February 20 editorial in a newspaper in the coal-mining state of Wyoming. "Let's try something else."

Are the Economides duo correct?

That is for engineers to decide, but the fact that the article passed peer review is important.

While this does not guarantee correctness, it shows experts agree that proper scientific methods were followed, and that the results obtained are plausible.

If the calculations in the article are borne out, the world thermal coal industry will take big losses. In Europe and the US, the environmental movement has coal interests on the run. Not a single new coal-fired power plant, according to the Truthout site on February 27, broke ground in the US during 2009.

In Australia the picture is different, with coal-fired power enjoying something of a renaissance. Greenpeace reports that as many as 12 new coal-fired plants are under construction, planned or proposed in all states except Tasmania.

Stock markets

Meanwhile, the stock markets are dizzy with the expectation of profits from the export of thermal coal from vast new Queensland mines.

It is not surprising that Australia's conservative media, while thundering about the emails of harassed climate scientists, should ignore the bombshell that now threatens "clean coal". Trash the myth that power station emissions will one day be safely locked away, and two key underpinnings of Australian capitalism — cheap energy, and the income stream from coal exports — lie open to intensified attack.

In this case, the conservatives might well practice a little of the "transparency" they urge on others.

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