Australian UCG Process

UGC: Underground Coal Gasification
Australia is leading the world's renewal of interest in the conversion of underground coal to an energy rich gas named SYNGAS. SYNGAS can be used as high quality feedstock for gas fired power stations and excitingly the production of HydroCarbon liquids as well as a range of other products.

The process has been labelled as "Underground Coal Gasification" where coal is heated creating a chemical process underground and the resultant gas (Syngas) is piped to the surface. Underground coal gasification (UCG) is an in-situ gasification process carried out in non-mined coal seams using injection and production wells drilled from the surface, which enables the coal to be converted into product gas.

In its simplest form, injection and extraction wells are drilled into the coal seam. An oxidant is pumped into the injection well to stimulate combustion and the coal face is ignited, resulting in partial combustion of the coal in the seam. The oxidant may be air, oxygen, steam or a combination of all, depending on the design of the site and the requirements of the product gas.

The partial combustion of the coal results in the formation of a combustible product gas consisting of various proportions of hydrogen, methane, carbon monoxide and carbon dioxide – syngas. The syngas flows through the porous coal seam, is removed through the extraction well and then cleaned.

The process is flexible in operation and is capable of producing commercial quantities of gas to be used as a chemical feedstock or as fuel for power generation. The technique can be applied to resources that are otherwise not economical to extract and also offers an alternative to conventional coal mining methods for some resources. UCG has the advantage over traditional coal mining and gasification in minimising environmental and social harm. The technology could be used to ensure that coal remains a part of the global energy mix by providing a solution to reduce and abate greenhouse gas emissions (GHG). Wiki

underground coal gasification diagram/image

Quick Points

  • Since the 1930s over 50 UCG pilot programs have been conducted world wide
  • The ignition rate can be controlled and can be stopped
  • The gas quality can be controlled
  • Seepage from the chamber is prevented by maintaining a positive external pressure gradient
  • Between 70 - 90% of the coal is utilised
  • UCG has been deemed the "cleanest - greenest" way to utilise coal
  • The technology is widely seen as being ready for commercial development
  • The adoption of UCG will liberate vast quantities of "stranded" coal
  • Three Australian companies have carried out successful UCG trials
  • Australia has several trillion tons of coal that may be suitable for UCG
  • Coal seams more than 2m thick are highly suitable, 1.5- 2m medium suitable and less than 1m thick are unsuitable.
  • Queensland is said to be able to produce syngas worth 1 trillion dollars
  • The USA, China, UK, South Africa, Vietnam and India are currently researching and developing UCG technniques

The difference between underground coal gasification and coal seam gas

UCG Projects Worldwide
Underground coal gasification worldwide

This map shows underground coal gasification (UCG) sites worldwide, including planned sites and prior pilot test sites. The sites of note are Centralia, Washington, and Hoe Creek, Wyoming, which are two Lawrence Livermore test sites; Chinchilla*, Australia, where the longest pilot in the Western world was recently completed; and Angren, Uzbekistan, where a commercial UCG plant has operated for 50 years. The underlying gray shading shows potential areas for geologic carbon storage. Read more -Fire in the Hole

*Over the last few years, the number of activities throughout the world focusing on UCG has rapidly increased. Linc Energy's Chinchilla project, operating from 1997 to 2009 in Queensland, Australia, demonstrated the first long-term UCG pilot in the Western world. That project had advanced to the stage of completing a coal gas-to-liquids pilot that successfully produced ultraclean diesel and aviation fuel. Linc Energy is currently (2014) active overseas with multiple projects using the knowledge gained from their Queenland operations. Linc in response to continued Queensland Govt. interference has delisted from the ASX and is now listed on the Singapore Stock Exchange (SGX) under the code: TI6.

Also in Queensland Carbon Energy have conducted a successful oxygen-injected Syngas production trial resulting in high quality, high volume gas production suited to power generation and multiple chemical synthesis products.

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