Exploration firm Cluff Natural Resources (CNR) has been awarded rights to explore for offshore underground coal gasification prospects off the UK's coastline.
The rights are through two conditional underground coal gasification (UCG) licences, options for leases and non-exclusive exploration licences.
UCG sees the exploitation of coal seems to extract syngas through the UCG process. This involves converting the coal, in situ, through a controlled gasification process into syngas, which is brought to surface via a production well.
The technique has been heavily researched and other companies are looking to use the same technique at other sites in the UK. Its development has been aided more recently by developments directional drilling.
CNR's new licenses cover two offshore deep UCG prospects at North Cumbria, north-west England, and Largo Bay, off Fife, Scotland, and were awarded by the UK's Coal Authority.
The license at North Cumbria covers 8,238 hectares, Largo Bay covers 7,796 hectares.
The latest awards increase CNR's UCG licenses to five, covering a total area of 30,881 hectares. The other three licenses are off Kincardine, near Sterling, Scotland, in the Loughor Estuary, Wales, and the Dee Estuary, west coast of England.
CNR said its next step would be to apply for planning and environmental permits in order to develop the projects
UCG according to CNR:
The conversion of the coal to syngas is achieved through a controlled underground gasification process initiated by the injection and ignition of oxidants into the coal seam. The coal seam is ignited and gasified, generating a syngas consisting of methane, hydrogen, carbon dioxide and carbon monoxide.
The rate of gasification is controlled by the injection rate of air or oxygen, but this is typically 0.5 tonnes of oxygen for each tonne of coal gasified.
All UCG processes are similar in that they require a minimum of two boreholes that have to be connected, or linked, together to form a complete circuit for the gases to flow through:
• one to inject the gasifying agents and start ignition, known as the injection well; and
• the other to recover the syngas produced, known as the production well.
Historical UCG technology varied from driving underground roadways, or drilling in seam boreholes from underground roadways to vertical boreholes. Thanks to the advancements made with drilling technology in the oil industry it is now possible to perform directional drilling from the surface and the application of this technology is vital to the future development of UCG.
Image: Cluff's new license area off north-west England.
Subscribe
