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Publisher's Letter

Natural gas means geosequestration is unnecessary

My “Publisher’s Letter” last month poured scorn on “carbon pollution” and geosequestration, which is now known as “Carbon Capture & Storage Technology”. As you might expect, there has been significant criticism of that viewpoint but considerable support as well.

Coincidentally, David Knox, CEO of Santos, has put the case for using natural gas to fire Australia’s thermal power stations, some 80% of which are currently coal-fired.

As he points out, “if we are serious about confronting climate change, and if we are to deliver the Government’s target of a 60 percent reduction in carbon emission by 2050, we need to reduce the carbon intensity of Australia’s baseload power generation”. He goes on to state “that gas fired power technology (known as combined cycle or CCGT) emits only 40 percent of the carbon emissions of the existing” average coal-fired power station. In fact, it already delivers 80 percent of the carbon reduction hoped for from geosequestration.

Now David Knox could be dismissed as simply selling his wares but he is nonetheless correct. He also highlights the peak load ability (as well as base load) of gas-fired stations and their greatly reduced use of water compared to coal-fired stations. In fact, a gas-fired power station only uses 1% of the water required for a coal-fired station. I am not referring to the water required for cooling but to the water required for coal scrubbing.

He could have added that the extraction of natural gas causes none of the problems of damage to water resources by coal mining. Nor does it cause subsidence as in the case of long-wall mining or have the need for extremely costly landscape remediation, as in the case of open-cut mining.

Nor does a gas-fired station produce huge quantities of ash which must also be disposed of. The more you think about it, using Australia’s massive gas deposits for electricity generation is a very good idea.

You can read the full text of the Santos submission to the Australian Government’s energy white paper process on the Santos website at http://www.santos.com/Archive/NewsDetail.aspx?p=121&id=1145

Not only is using natural gas for power stations more environmentally friendly, it is thermodynamically much more efficient, particularly when employed in “combined cycle”. This is where the hot exhaust from the gas turbines is used to generate steam and run a turbo-alternator. The net result is that gas-fired power stations not only emit less carbon dioxide than coal-fired stations, they produce far less emissions than would be produced with a coal-fired power station which was using some sort of (yet to be proven) carbon capture and storage system.

So rather than introducing an elaborate and expensive emissions trading scheme (ETS), the government should be seriously contemplating converting Australia’s existing coal-fired power stations to gas. And if it cannot do it for the black coal stations, it should certainly do it for the brown coal power stations in Victoria. Admittedly the conversion process will be expensive but it will be much cheaper and easier to implement than the proposed ETS. Furthermore, it could be done easily over the next 10 years or so.

Leo Simpson

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