Worldwide Developments in UCG and Indian Initiative

摘要

Concept of converting coal in-situ into gas has existed for many years. Basically it involves drilling a pair of wells into a coal seam and injecting gasifying agent like oxygen or air and steam through the Injector and after ignition and gasification of coal, the gas is brought to the surface through the other hole (Producer) and used as fuel or chemical feedstock. The first experimental work can be traced back to 1912 when William Ramsey began work in Durham, U.K. Intensive coal gasification work began in the then USSR in 1930s at a shallower depth. This led to industrial scale projects in several parts particularly in Russia and Uzbekistan. One project of Uzbekistan is still operational. These trials established the basic technology of UCG. There was a renewed interest in UCG in Western Europe in view of energy shortage in 1944-1959. Borehole method was tested in Newmann Spinney and Bayton in U.K. This could not be sustained for long as during 1960s, low cost fuel was available in plenty and therefore there was a period of lull on the progress of UCG in Europe. Oil/gas price and supply have dictated the pace of progress in UCG. After the first oil crisis, USA again embarked on the development of UCG in 1972 and continued in 1980s, involving in the process a number of institutes and agencies. This led to considerable technological development. There were concerns on environmental pollution which the trial raised. It was thought appropriate to test the application of technological developments that had taken placed in oil and gas industry in UCG. In 1990s deviation and in seam drilling was tried in "A1 Tremidal" in Spain. The trial was successful and it proved the viability of directional drilling and benefits of CRIP technology (Controlled Retractable and Injection Point). As a result of Spanish trial, Department of Trade and Industry Technology (DTI), U.K., emphasized growing importance of UCG as clean coal technology. In its report of 2004 on the Review of Feasibility of UCG in U.K., UCG has been identified as an additional source for energy security within the context of a low carbon economy, if planning and environmental issues can be dealt with. China has carried out 16 field trials since 1980s and has involved a number of agencies in order to address various issues in a comprehensive manner. Technology transfer agreement was executed with DTI-UK and a UCG Centre has been created in China University of Mining and Technology. Attempts are also being made in China to carry out gasification at deeper depths. Recently Australia has carried out a successful trial in Chinchila involving several agencies like Sydney University, Ergo Energy, Linc Energy, GE etc. Japan has overseas coal interests and has involved University of Tokyo for experimental studies. New Zealand carried out a small trial in 1994 with the help of USA. Other countries like Pakistan, Ukraine and Romania are also interested in UCG. In India, a beginning was made in UCG in 1980s. Two pilot bore holes were drilled north of Mehsana town of Gujarat to see the suitability of application of UCG technique. However, further study on the subject has not been made since then. Recently there has been a surge of interest in UCG and as a consequence ONGC has signed an agreement with Skochinsky Institute of Mining (SIM), Russia. MOUs are also being executed with other coal/lignite based companies like Coal India Ltd, Gujarat Mineral Development Corporation Ltd, Gujarat Industries Power Corporation Ltd., Neveli Lignite Corporation Ltd., etc. The paper attempts to highlight continuous worldwide efforts for technological development for harnessing coal through in-situ gasification. The technology assumes all the more significance in view of limited resources of oil/gas and abundance of mineable and un-mineable coals.