UCG

UCG is an in-situ gasification process whereby underground coal seams are converted into Synthesis Gas (‘syngas’) through the injection of oxidants delivered via an injection well.  The syngas is then delivered to the surface via a production well to be used as a fuel feedstock for power generation and various energy products.  This process, which utilises between 70-95% of coal within the seam, is controlled remotely and does not require man access or other costly infrastructure in comparison with traditional methods of mining.

Syngas is a base feedstock for a range of energy products:

• fuel gas (syngas) – direct fuel gas combustion and power generation
• synthetic natural gas (‘SNG’)
• methanol – gasoline
• transport fuels – diesel and naphtha
• as well as chemical production like hydrogen and ammonia

 The following coal seam characteristics are most suitable for UCG:

• Depth of 100–600 metres (330–2,000ft)
• Thickness more than 2 metres (6ft)
• Ash content less than 45%
• Minimal discontinuities
• No usable aquifers close to the coal seam

Importantly, application of UCG considerably reduces the environmental impact of harnessing the energy value of the coal and disruption to the surface of the land is lessened significantly in comparison to disruption caused by traditional extraction methods like opencast or shaft mining.  These factors are not only favourable to local communities but also to governments looking to maximise a country’s energy potential.  UCG technology can also be applied to coal assets that would otherwise be unprofitable or too complicated to extract through traditional mining methods.  UCG therefore has the potential to unlock the value of Europe’s substantial undeveloped coal assets.

The concept of UCG has been in existence for over 100 years, and was applied on a large scale after World War II in the Soviet Union.  Development has accelerated in the last five years, particularly in Australia, South Africa and China.  South African companies Eskom have been engineering and operating UCG pilot facilities since January 2007 and Sasol are operating commercial surface gasifiers and have engineered UCG pilot facilities in Secunda. Both companies have provided valuable insight on the process to the UCG community. According to the World Coal Association China have over 30 ^[i] projects in different phases of preparation that apply UCG technology.

^[i] http://www.worldcoal.org/coal/uses-of-coal/underground-coal-gasification/