12 S&TR April 2007 Fire Underground coal gasification may provide a secure in the energy supply and reduce greenhouse gas emissions. Hole Lawrence Livermore National Laboratory S&TR April 2007 Underground Coal Gasification 13 ORLDWIDE coal reserves are vast, In the early years of UCG, the produce secure and clean energy from its Wover 10 trillion metric tons, but technology gained an “ugly duckling” domestic coal reserves, coal-to-gas and unless cleaner and cheaper ways can be reputation in the U.S. The UCG process coal-to-liquid conversions may become found to convert coal to gas or liquid fuels, yielded gas of low heating quality with commonplace. coal is unlikely to become an acceptable too much hydrogen, and it was considered Applying improved UCG technology replacement for dwindling and uncertain an environmental risk. But as coal-rich to gasify deep, thin, and low-grade coal supplies of oil and natural gas. Mining countries now look to replace imported oil seams could vastly increase the amount coal is dangerous work, coal is dirty to with secure domestic energy sources, make of exploitable reserves. The coal could be burn, and much of the coal in the ground hydrogen fuels, and find ways to limit converted to gas for a variety of uses, and is too deep or too low in quality to be their greenhouse gas emissions, they are emissions of sulfur, nitrous oxides, and mined economically. Today, less than one- rediscovering the potential of UCG. mercury could be dramatically reduced. sixth of the world’s coal is economically In the U.S., coal supplies about “UCG could increase recoverable coal accessible. However, Livermore is helping 50 percent of this country’s electricity reserves in the U.S. by as much as 300 to to revive an old technology that offers because it is the least expensive energy 400 percent,” says Julio Friedmann, who promise to substantially increase usable source. Coal can be gasified or liquefied to leads Livermore’s Carbon Management coal reserves and make coal a clean and make transportation fuels, natural gas, or Program. Another benefit of UCG is economic alternative fuel. Known as chemical feedstocks. Today, the U.S. has that hydrogen accounts for half the total underground coal gasification (UCG), this only one operating coal gasification plant gas product. technology converts coal to a combustible and no commercial liquefaction operations. As with any hydrocarbon combustion gas underground. However, because of the nation’s goal to process, UCG generates carbon dioxide Hoe Creek Centralia Angren Highly prospective Prospective Nonprospective Prior test sites Chinchilla Sites of note Announced or planned This map shows underground coal gasification (UCG) sites worldwide, including planned sites and prior pilot test sites. The sites of note are Centralia, Washington, and Hoe Creek, Wyoming, which are two Lawrence Livermore test sites; Chinchilla, Australia, where the longest pilot in the Western world was recently completed; and Angren, Uzbekistan, where a commercial UCG plant has operated for 50 years. The underlying gray shading shows potential areas for geologic carbon storage. Lawrence Livermore National Laboratory 14 Underground Coal Gasification S&TR April 2007 (CO2), a greenhouse gas. Fortunately, in Centralia, Washington, and the other UCG Revives potential sites for UCG operations in Hoe Creek, Wyoming. Livermore Four years ago, former Laboratory correspond to locations where sites are researchers also patented a UCG process engineer Ray Smith, who led the Energy plentiful for sequestering CO2 in geologic called Controlled Retraction Ignition Point, Program in the Energy and Environment formations underground. UCG also which was used in pilot tests performed in Directorate, encouraged DOE to revisit enhances the storage capacity of the coal Europe during the 1990s. In the U.S., when UCG as a part of its program to develop seam itself to store injected CO2. The gas and oil prices dropped in the 1980s and hydrogen-from-coal technology. After generated gas, called syngas, would be 1990s, efforts to commercialize UCG came Smith’s retirement a year ago, his team taken from the ground and the by-products to a halt. of chemical engineers, geologists, and separated out. The CO2 would then be Today, high prices have returned for all environmental scientists pursued the returned downhole nearby. kinds of fuel, and uncertainties exist about revival of UCG through Friedmann’s political stability in the Middle East. A Carbon Management Program. In February Ups and Downs of UCG renewed U.S. interest in coal gasification 2006, DOE commissioned the team to The idea for coal gasification, either is not surprising. Furthermore, hydrogen prepare a document evaluating the current underground or in aboveground plants is now a welcome by-product because state of UCG technology. Best Practices using mined coal, has been around for of the current interest in alternatively in Underground Coal Gasification was more than 150 years. The technology was fueled vehicles. completed at the end of 2006 and is first widely used in the U.S. during the late awaiting official release by DOE. 1800s. Lamplighters made their rounds The document explores the UCG efforts in many of our largest cities lighting that have been undertaken worldwide. streetlights fueled by “town gas,” the Importantly, it also addresses the issues product of early and relatively crude forms that were problematic in previous of coal gasification. Once vast fields of UCG operations by evaluating the potential natural gas were discovered and pipelines application of technological advances built to transport the gas to consumers, the in areas such as environmental risk use of town gas disappeared. assessment, combustion-process modeling, From the 1930s through the 1990s, geologic subsurface characterization, and the former Soviet Union invested in geomechanics. developing UCG technology at numerous Over the last few years, the number sites and was successful at the commercial of activities throughout the world scale in several locations. China has been focusing on UCG has rapidly increased. developing the technology since the 1980s The Chinchilla project, operating from and currently has the largest operational 1997 to 2003 in Queensland, Australia, UCG program. Their approach uses demonstrated the first long-term UCG abandoned tunnels in conventional mines. pilot in the Western world. That project During the energy crisis of the 1970s, has now advanced to the stage of raising U.S. interest spiked in all forms of capital for a coal gas-to-liquids pilot that alternative energy, and the Department of will make ultraclean diesel and aviation Energy (DOE) invested billions of dollars fuel. In South Africa, the electricity to develop efficient coal-gasification supply company Eskom is developing technologies for power generation. Over UCG at the Majuba Coal Field and 30 UCG pilot tests were run across the achieved ignition in January 2007. U.S. At that time, the hydrogen by- In the United Kingdom, the government product of UCG was viewed as a liability, undertook a five-year effort to review reducing the perceived quality of the gas. The Majuba UCG Project in Mpumalanga, UCG and study the feasibility of using In addition, groundwater-contamination South Africa, is producing high-quality syngas the technology for exploiting coal on land problems resulted at two sites. for power generation. This photo shows the first and offshore. A new UCG partnership, The Laboratory, a pioneer in the study flare on January 20, 2007, when the UCG plant launched in the United Kingdom in 2005, of UCG, developed two test sites—one successfully started operations. draws its membership from more than Lawrence Livermore National Laboratory S&TR April 2007 Underground Coal Gasification 15 eight countries. The partnership hosted Energy Dialogue Coal Working Group, The Powder River Basin is a massive its second international conference in with collaboration from governments coal and natural-gas deposit that spans the February 2007, and Livermore chemist within the Asian-Pacific Partnership on Montana–Wyoming border. It is the largest and environmental scientist Elizabeth Clean Development and Climate. Burton source of coal mined in the U.S. and is one Burton delivered the keynote address. represented the Laboratory and made of the largest deposits of coal in the world. In India, interest in the potential of technical presentations at the workshop. GasTech, Inc., and the Wyoming Business UCG is particularly high. India is the Industry is reengaging with the Council recently completed a feasibility world’s third largest coal producer Laboratory to pursue UCG. On March study showing UCG to be a better option (383 million tons of bituminous coal in 30, 2006, Lawrence Livermore signed with respect to cost, emissions, and 2005) and uses coal for about 60 percent a memorandum of understanding with environmental effects compared with of its own energy needs. Although India Ergo Exergy, which has licensed its conventional coal-fired stations and has vast coal resources, much of it is low proprietary Exergy UCG technology, integrated gasification combined-cycle grade, with high ash content. In addition, or EUCG, to clients in Wyoming, South plants. New UCG field pilots are planned the coal lies in steeply dipping deposits Africa, India, Australia, New Zealand, for the Powder River Basin. Ergo Exergy that are difficult to mine conventionally. Canada, and Italy. The two organizations Technologies, Inc., will be involved in this India also has a shortage of natural gas. have agreed to cooperate in conducting test operation. A November 2006 workshop on UCG, research on UCG technology, specifically hosted jointly by the Indian Ministry of in the areas of process simulation and The UCG Process Coal and DOE, was heavily attended by carbon sequestration, with an emphasis on In the UCG process, injection wells representatives from India’s coal industry. evaluating the environmental performance are drilled into an unmined coal seam, At least three pilot projects are now in the of a large-scale operation.