Underground coal gasification: A viable coal mining option
Shamsuddin Ahmad from Canada
The Bangladesh government should take immediate steps to start exploiting energy from our coal deposits adopting a technically appropriate, economically feasible and environmentally friendly method. There is no controversy about the disastrous effects of coal mining, as we faced at Boropukuria.
Open pit coal mining has also disastrous environmental and social effects. People of my locality do not want to go anywhere leaving their ancestral homes and the graves of their forefathers. Three persons were shot dead during violent protests in 2006, which compelled the then government to accept the fact that there will be no open pit coal mine. Prime Minister Shiekh Hasina also expressed her solidarity with the people opposing open pit coal mine in September 2006. Yet, we have the best affordable, safe, cheap and environment friendly option i.e., Underground Coal Gasification (UCG).
The UCG is a method of converting unworked coal-coal still in the underground-into a combustible gas, which can be used for power generation or the manufacture of hydrogen, synthetic natural gas or diesel fuel.
The UCG technology allows countries that are endowed with coal to fully utilise their resource from otherwise, unrecoverable coal deposits in an economically viable and environmentally safe way. The UCG turns this resource into high value products: Clean power, liquid fuels, syngas, fertiliser and other chemical feedstock. It uses a similar process used in surface gasification.
The main difference between both gasification processes is that in the UCG the cavity itself becomes the reactor so that the gasification of coal takes place underground instead of at the surface.
The basic UCG process involves drilling two wells into the coal seams, one for injection of oxidants (water/air or water/ oxygen mixtures) and another well some distance away to bring the product — gas — to the surface.
The coal at the base of the first well is then heated to temperature that would normally cause the coal to burn. However, through careful regulation of the oxidant flow, the coal does not burn but rather separates into the syngas. This is known as CRIP (controlled retraction injection point). The syngas is then drawn out through the second well. The advantages in the use of this technology, especially in the emerging markets of China, India and South Africa, are the low plant costs (as no surface gasifiers are required) and the absence of coal transport costs.
The technology also presents the opportunity to release emissions, as there are fewer surface emissions. The UCG technology could also have synergies with CCS (carbon capture and storage), as the CO2 could be stored in the coal cavity after gasification.
In the last few years there has been significant renewal of interest in UCG, as the technology has moved forward considerably. China has about 30 projects in different phases of preparation that use underground gasification.
India plans to use underground gasification to access an estimated 350 billion tonnes of coal. In 2007 India compiled a 93-page status report on underground coal gasification that drew interest of many of the country’s biggest companies.
South African companies, Sasol and Eskom, have UCG pilot facilities that have been operating for a considerable period of time giving valuable information and data. In Australia Linc Energy has the site, which first started operating in 2000. Carbon Energy has completed a successful commercial scale study in Blood Wood Creek in 2008.
Wild Horse Energy of Australia secures third major Hungarian UCG licence to explore the 25 km Amilie coalfield in western Hungary. In central Alberta Swan Hills Synfuels has developed a UCG demonstration project at a depth of 1400 metres. The first phase of the demonstration project was completed in June and July 2009 and resulted in a range of successes that would assist in future development stages of the commercial projects.
This is the deepest underground coal gasification ever conducted in the world. At 1400 metres below the surface (4600ft), the depth showcases the opportunity to utilise deep vast coal reserves for future energy production.
Demonstration projects and studies are also currently underway in a number of countries, including the USA, Western and Eastern Europe, Japan, Indonesia, Vietnam, India, Australia and China.
Coal reserves in Bangladesh: Currently, we used to say our coal reserve is nearly 3.0 billion tonnes. If we evaluate the deep coal reservoir at Bogra, Singra and Sylhet our coal reserve may reach 6.0 billion tonnes. Through UCG project one tonne of coal can be converted into 1.5 to 2.0 barrels of liquid fuel. So, we have potential reserve of coal equivalent to 9.0 to 12 billion barrels of oil.
Bangladesh has some 45 years of experience in drilling and we have expertise to independently drill wells for UCG. One medium-capacity drilling rig could be dedicated for this project and a UCG project could be initiated as early as possible. If we could start this task in the month of our Independence in 2010, we can achieve production of syngas or liquid fuel from our 100 trillion cubic feet of gas or 9.0 to 12 billion barrels of liquid fuel within the year 2015.
One South African company estimated that the cost of synthetic diesel per barrel would be USD 17 or 1/3 of the price of methane per unit through the UCG process.
The writer, former head of Drilling, Bapex, can be reached at e-mail: [email protected]
https://www.thefinancialexpress-bd.com/more.php?page=detail_news&news_id=118236&date=2010-11-25
