The development of underground coal gasifi cation by Mike Rycroft, features editor Underground coal gasification (UCG) coupled with carbon capture and storage (CCS) offers huge potential as a method of exploiting large coal resources on land and offshore. In addition to numerous projects worldwide, there are several projects both active and being planned in South Africa. UCG is a method of converting unworked being used as the base reference. UCG does not reveal the true value. The UCGA coal, while still in the ground, into a somewhat “falls in the cracks” as far as is addressing this with the UN expert group combustible gas suitable for industrial regulatory treatment is concerned. In on resource classification and all agree heating, power generation, and the South Africa, UCG is specified as mining that it is better to work together towards a manufacture of hydrogen, diesel fuel in the proposed Mineral and Petroleum common solution. The economics of UCG or chemical feedstock. The economics resources development Act (MPRDA) can be very site specific, and depend are attractive, it offers carbon capture amendments. heavily on the coal seam characteristics. options, and the cost of operating and implementing UCG is lower than many There is a constant positioning of UCG What is needed for the industry to move other coal technologies. The technology in the context of coal mining. Pilot and forward? demonstration plants are an essential offers the possibility to exploit coal reserves A level playing field, with other energy that are unmineable due to geological part of UCG resource prospecting, but sources (nuclear, oil and gas, wind, reasons and proximity to population prospecting timelines cater for conventional coal bed methane, coal mining) for centres, in a manner which will cause mining. Pilot and demonstration plants the licensing of UCG minimum impact on surface features under mining rights have other challenges. Clear regulatory and environmental and minimise the pollution associated frameworks with mining. Details required A recognised resource valuation Regulators may need to deal with standard such as a syngas index The development of UCG competing bids from other users of coal. An industry recognised best practice According to Julie Lauder, CEO of the It is sometimes difficult for a new industry standard Underground Coal Gasification Association since others are already licensed. In (UCGA), UCG has the potential to countries such as Australia, there are issues Industry recognised training significantly increase global coal stocks over overlapping tenements CBM/UCG, What is holding back UCG development? and turn these into a high value synthetic though both can be done at the same site! gas, cleanly, safely and cheaply. UCG Despite 50 years of trials no commercial There is no clear definition for UCG nor a could increase the world’s economically UCG project has been demonstrated, standard UCG reserve valuation formula. recoverable coal reserves substantially. according to John Kessels of the IEA [2]. Investors, bankers and analysts alike There is a steady decline in the quality Recent progress with pilot projects show of the coal produced with exhaustion would prefer an industry standard, giving considerable promise, and commercial of reserves of higher grade coals. Many one less uncertainty to worry about. The operations could be possible within countries are turning increasingly to the current coal valuation method relates to ten years, providing greatly increased use of indigenous reserves of lower quality mining and is not suitable for UCG as it confidence in the technology. coals, sometimes the only significant energy resource available. But there are many aspects and challenges in taking a new technology such as UCG to market [1]. Global UCG activity MoU’s have been signed in Canada, Hungary, India, Indonesia, Poland, South Africa, Turkey, USA, and Vietnam, and research projects are underway in Bulgaria, China, Germany and Japan. There is a huge upturn in interest and potential investment in Australia, which is leading the world. Many coal-rich nations have engaged in dialogue and investigation, with increased commercial activity and potential for the next few years. Basic regulatory issues Modern UCG is a new industry and therefore new to everyone, the public, the media and also the regulators. Licensing policies for UCG are now being written in some countries, with mining usually Fig. 1: Block diagram of the UCG gas treatment process. energize - August 2013 - Page 23 GENERATION Constraints There is a lack of understanding of the requirements of a successful UCG project by both investors and regulators, and the topic is poorly covered in the literature. In addition there is an acute shortage of people with appropriate inter- disciplinary academic and management skills and experience as well as a lack of understanding of the geological knowledge needed. UCG is being promoted by different industry groups who do not share knowledge and government support is lacking to underpin deployment of the technology. The major trials, over the last 50 years Fig. 2: Externally fired gas turbine. or more have been in the USSR, Europe, USA, Australia, South Africa and China, during which other technologies have of parameters which are controllable or providing greatly increased confidence progressed dramatically (e.g. computer measurable. Modelling can help, but few in the technology. Keeping more of the power and use, and directional drilling). models have been validated. Site selection knowledge in the public domain could Tests rarely ‘proved’ more than one or two criteria have not yet been well defined greatly enhance the chances of UCG aspects of the technology, and many as there is insufficient information and becoming an accepted and widely had unwanted side effects. The USSR experience. Environmental issues e.g. gas applicable technology. claimed commercial scale operations, escape through fractured rocks, or water but only some 15 – 20 Mt of coal was contamination have not been adequately Power for Africa gasified and syngas quality was variable. addressed. The process requires a unique The European model of large power The US DOE programme from 1973 – 1989 multi-disciplinary integration of knowledge plants is not the solution for providing addressed engineering concerns and from geology and hydrogeology with the under-developed rural areas with power, compared methods for enhancing coal thermodynamics of gasification. says Alan Golding of Analytika Holdings permeability. The development of the [3]. Current thinking is more inclined to controlled retracting injection point (CRIP) Site selection is key to success smaller more distributed power generation was a major advance. The single most important decision that will units which reduce distribution costs. Current pilot projects determine the technical and economic The advantage of UCG is that it can be performance of UCG is site selection. A economical at 60 MW. UCG commercial operations are being successful test in one location where the assessed in: There are many areas in Africa that are geology is favourable does not prove that without power that have coalfields that Australia by Carbon Energy at UCG can be widely applied. It will need could be exploited using UCG, such as: Bloodwood Creek, and Linc Energy at a series of successful demonstrations in Chinchilla different geological settings to establish North East Basin South Africa at Eskom’s Majuba power where UCG can be safely carried out on plant a commercial scale without environmental The only information is from drilling undertaken to the east in Zimbabwe. China at the Gonggou mine, damage, as coals lie in such a wide There are indications that there could be Wulanchabu city, Inner Mongolia variety of geological settings, at different depths, seam thickness and with different thick occurrences at depth of coal but to Canada (Alberta) Swan Hills at a depth permeabilities and properties. date no borehole has intersected coal in of 1400 m Botswana. Pilots have been successfully carried Linking UCG and CCS out with no reported environmental North West Basin The Bloodwood Creek development in problems. All are planning to expand Australia is being linked to a practical The most unexplored coal basin in to demonstration and then commercial demonstration of CCS. CCS may add Botswana is mapped as Upper Karoo (an scale. Relatively little has been published another site selection constraint in that area of sedimentary and volcanic rocks). about the outcomes (or the problems/ Any exploration that has been undertaken it will be easier to do if there are nearby challenges). is solely for water supply. Research into part-depleted oil wells or gas fields. Use of water borehole logs has indicated that this Advantages/opportunities the cavities formed in the coal seam by area is not necessarily Upper Karoo and this UCG has been suggested for CCS but this The process allows exploitation of coal area may have potential as an exploration will require an extensive effort to establish generally considered uneconomic for target as there are descriptions of black the conditions for long-term containment. conventional mining, with minimal surface shale and carbonaceous mudstone. disturbance as most of the ash remains Conclusions underground. UCG could provide low- Western Basin Despite 50 years of trials no commercial cost syngas in a number of countries with A largely unexplored coal basin in substantial coal resources.