Underground Coal Gasification
It starts with coal
The gasification of coal is not new. It is the conversion of coal to a gas (known as synthesis gas or syngas) through a series of reactions involving heat, oxygen, coal and water.
Underground Coal Gasification (UCG) is the process of gasifying coal in-situ, which is simply where it lies under the ground.
UCG provides access to coal, ‘stranded’ deep underground, eliminating the need to mine it and process it through a surface gasification plant.
UCG technology has evolved through numerous trials since the early 1900s. Commercial scale UCG sites for power generation have been operating in the former Soviet Union for over 40 years.
How UCG works
UCG transforms underground coal into a high quality synthesis gas (syngas) of carbon monoxide, hydrogen and methane as heat and oxygen are introduced.
In its simplest form, UCG works like this:
- Vertical wells are drilled into the coal seam. These are linked together horizontally by drilling or combustion links.
- The coal seam is ignited and air or oxygen is pumped into a well (the injection well) to drive coal combustion and gasification.
- Through partial combustion and a series of subsequent reactions controlled by heat, pressure and water influx, the coal is converted to syngas.
- When coal combustion occurs, heat and carbon dioxide are produced. These become active in some of the gasification reactions.
- Syngas flows from the gasification chamber through the horizontal connection in the coal seam and flows to the surface through another well (called the production well).
UCG background
Commercial UCG has been successfully operated for more than 40 years at the Yerostigaz facility in Angren, Uzbekistan. Yerostigaz is the only remaining UCG site in the former Soviet Union.
UCG produces a high quality synthetic gas (syngas), containing carbon monoxide, hydrogen and methane.
UCG produced syngas can be economically used for a variety of purposes, including:
- the production of liquid fuels when combined with Gas to Liquids (GTL) technology
- power generation in gas turbine combined cycle power stations
- a feedstock for different petrochemical processes, for example producing chemicals or other gases such as hydrogen, methane, ammonia, methanol and dimethyl ether
Linc Energy has proven the combined use of UCG to Gas to Liquids (GTL) technologies. UCG to GTL technologies have the ability to provide energy alternatives to address increasing global demand for energy products. With these technologies, Linc Energy is set to become the leading producer of cleaner liquid fuels and other associated products.
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