The major work by the IEA CCC on underground coal gasification (UCG) is the 2009 review by Gordon Couch which is available for free download from our bookshop: http://bookshop.iea-coal.org/reports/ccc-151/82191
The principle of UCG is the gasification of deep coal seams (generally >500 m), in situ. In theory, the syngas produced can then be brought up to the surface whilst the ash remains underground. The syngas could be burned like natural gas for energy, processed for hydrogen or diesel, or could be sold to the petrochemical or fertiliser industries. UCG projects could thus be tailored to suit the local market.
Gordon’s 2009 review emphasised the significant amount of work which has been carried out on UCG since its inception as far back as 1868, and how much more needs to be done before it is a viable proposition. However, despite all this time and investment, it is only now that UCG is moving towards commercialisation in any real terms. There is a plant in Uzbekistan that is said to have been producing syngas continuously for over 50 years, http://www.lincenergy.com/clean_energy_uzbekistan.php but, like all UCG projects, the information on this project has not been widely shared. The full-scale Majuba plant in South Africa, could be set to put commercial UCG on the radar but, until what appear to be ongoing bureaucratic issues with the regulatory authorities are dealt with, the plant cannot go into full production.
The limited success of UCG in the past has hinged on the technical challenges of initiating and controlling gasification performance deep underground, as well as a lack of funding, confusion over appropriate applicable environmental legislation, and there will be public acceptance issues. With significant advances in deep drilling technologies, seam mapping and modelling technologies, the technical challenges, at least, are lessening.
The most frustrating factor for those fascinated by the technology is the lack of transparency on who is doing what and how they are doing it. The commercial companies currently engaged in UCG worldwide are known for keeping their data close to their chests. This is probably due to the fact that, whoever masters the commercialisation of this technology first, could open the door to billions of GJ of energy stored in coal seams which is otherwise inaccessible.
UCG has been tested in countries such as Russia, Spain, the USA, Canada, and Australia. Currently, the ongoing activities are largely limited to Australia (Ackaringa basin drilling in 2015 by Linc Energy), South Africa (Eskom/Sasol Majuba plant), Uzbekistan (Yerostigaz plant, now owned by Linc), Poland (proposed project, again owned by Linc and based on recycling of the equipment from the now shuttered Chinchilla plant in Australia), and China (around 30 projects in various phases of development). Projects are also being evaluated in India and Africa (Botswana, Zimbabwe, Mozambique and Namibia).
And now there is the prospect of UCG becoming commercial in the UK. Cluff Natural Resources Ltd has recently obtained eight offshore UCG licences from the UK Coal Authority. These Cluff sites are located in Kincardine and Largo Bay (both in Scotland), Cumbria, Durham, Point of Ayr and the Loughor Estuary. The first site is planned for the Firth of Forth in Kincardine, alongside Longannet coal-fired power station and next door to the Grangemouth petrochemical industry. This is an area of Scotland which appreciates the importance of new industrial developments. In fact, the whole of Scotland is ripe for energy-based investment – as the Industrial Emissions Directive (IED) closes more coal units and there is a moratorium on new nuclear and fracking, Scotland faces an energy crisis within the next decade. Significant investment in hydro, wind, offshore wind, wave and tidal will help to meet the 50% renewables target set by the Scottish Government, but these options are not yet capable of providing the consistent and reliable base-load output required to avoid potential blackouts. With new coal build blocked until carbon capture and storage (CCS) is actualised, Scotland is left with gas as the base-load energy source, leaving the country at the mercy of natural gas availability and pricing. UCG has side-stepped the moratorium on unconventional gas in Scotland due to the fact that all the proposed sites are offshore. However UCG gas used for power production WILL count as a coal-fired plant and will therefore also be limited by the requirement for CCS. And so, for the moment, syngas production for hydrogen and/or chemical use would appear to be the targeted market. So, although UCG may not immediately be an option for direct power production in Scotland, it could significantly offset natural gas and syngas use in the petrochemical and industrial heat sector.
The proposed Kincardine site covers an area of almost 37 km2, containing 335 Mt of coal with an estimated energy resource equivalent to 11 tcf (trillion cubic feet) of gas. The project is currently in the planning and preparation phase but could, in the next year, move to a production test phase. If successful, commercial feasibility is projected for 2018 and beyond.
As stressed by Couch (2009), UCG projects are extremely site specific with the access, drilling, initiation and control of the gasification process all being designed on a case by case base. With the actual site of the process activity being several hundred metres underground, control of the gasification reaction is notoriously challenging. Some projects have come and gone without producing significant quantities of usable gas (eg El Tremedal, Spain) whereas the Yerostigaz plant in Uzbekistan demonstrates that decades of consistent and reliable operation are possible. The success of the new Cluff projects will therefore rely on both expert site selection AND skilled operation.
Anyone wishing to know more about the Cluff projects can check out their website: http://www.cluffnaturalresources.com/
There is also a Coal research Forum on UCG in Leeds in April 2015 for those in the business or who want to ask questions of the experts: http://www.coalresearchforum.org/meetings.html