Underground Coal-Gasification, Coal-to-Liquids Fuel Project in Australia  

Green Car Congress has an article out on a Coal-To-Liquids project in Queensland that uses a new underground gasification process (via Energy Bulletin).

Syntroleum Corporation and Australian-based Linc Energy are planning to develop a coal-to-liquids (CTL) project in Australia that integrates Syntroleum’s air-based Fischer-Tropsch technology (earlier post) with Linc Energy’s underground coal gasification (UCG) technology. This will be the first such project to combine the two technologies for the production of synthetic diesel from coal. The CTL work will be part of Linc Energy’s ongoing Chinchilla Project (350 km west of Brisbane) which also includes early development of an integrated power plant.

Underground Coal Gasification (UCG) is a process through which coal is converted in-situ to a syngas that can be used as a fuel for power generation or as a chemical feedstock — e.g., to feed into a Fischer-Tropsch process for the generation of synthetic diesel. UCG has been used in the Former Soviet Union for some 40 years.

In general terms, UCG uses adjacent boreholes drilled into a coal seam (typically > 100m depth). The injection wells are used to feed a pressurized oxidant such as air or oxygen/steam into the coal seam and to trigger the and subsequent down-hole ignition. The production wells recover the product gases.

The UCG syngas, which undergoes sulfur removal and additional conditioning at the surface, is similar to syngas obtained from conventional surface coal gasification systems, but production is achieved at a much lower cost.

According to Ergo Exergy, the providers of the UCG technology used by Linc, typical gas recovered using air injection may have calorific values in the range 3.5 to 5.0 MJ/m3, depending on specific site conditions, with approximately twice these values being achieved with oxygen injection.

UCG differs from conventional above-ground gasification in a number of ways:

* Coal is not mined and chemical processes are arranged to occur in the virgin coal seam in situ.
* The process wells (the collective terms for the injection and production wells in a UCG project) must be connected within the coal seam by the links of low hydraulic resistance to allow production of commercial quantities of gas.
* Process water for gasification usually comes from the coal itself and surrounding rocks, and its influx must be carefully regulated.
* No ash or slag removal and handling are necessary since they predominantly stay behind in the underground cavities.
* The process must be confined within a hydraulic system created in the coal seam so that no leakage of the product is possible and no contamination of the underground environment can occur. Such a hydraulic system is called an underground gasifier, and its design is the most crucial part of a UCG operation.

The Energy Blog also has a post up on this topic.

The Oil Drum also has a post on the prospects for Fischer-Tropsch plant in Montana (which I think is the same as the one I noted a few weeks back).

I'm still not entirely sure about the viability of large scale oil production from coal, though SASOL in South Africa (where there process was widely used during the apartheid era) claims to have produced 1.5 billion barrels of oil using this process over the past 50 years.

Sasol has produced almost 1,5 billion barrels of synthetic fuel from about 800 million tonnes of coal since the first sample of synthetic oil from coal was produced fifty years ago at its Sasolburg plant near Johannesburg in South Africa on 23 August 1955.

Regarded as a world technology leader in the production of coal-to-liquids (CTL), Sasol operates the world's only commercial scale synthetic plant at Secunda, where it produces 150 000 barrels of liquid fuel per day.

Sasol currently supplies about 28% of South Africa’s fuel needs from coal, saving the country more than R29 billion (US5,1 billion) a year in foreign exchange.

“Sasol has pioneered the commercial application of Fischer-Tropsch technology since the early 1950s when we built our first petrochemical plant at Sasolburg and began producing fuel based synfuels and chemicals. This pioneering spirit has resulted in Sasol being recognised as a global technology and innovation leader, and we are now poised to deliver the world's cleanest diesel early in 2006, when our first international commercial scale gas-to-liquids (GTL) plant at Doha in Qatar commences production,” says Sasol chief executive, Pat Davies.

If coal to oil does turn out to be the future and can make up for depletion of "real" oil, then I guess we'll all have to go back to worrying about how soon runaway global warming is going to set in (or set about creating Hubbert curves for "peak coal")...