UCG - An Industry in the Making?
Ecoal, Vol. 74, May 2011
Not all coal is accessible using current mining technologies. Many experts believe underground coal gasification (UCG) could double the availability of coal globally, and this is leading to growth in a sector many outside the coal industry know little about.
There is no doubt that of all fossil fuels, the world's coal reserves are the most abundant. Coal is spread widely across the globe - around 70 countries have sizeable coal reserves. On current projections coal reserves will last for about the next 120 years, twice as long as gas, and three times longer than oil.
However, reserves of coal (that is, coal that can be economically recovered using current technology - see definitions below) are dwarfed by the world's total coal resources. It is estimated there are about 900 billion tonnes of recoverable coal reserves globally, and as much as four times that amount in total resources.
What is UCG?
UCG is the on-site gasification of coal in the coal bed deep below the surface. This happens by drilling holes into the coal and injecting air, oxygen, or steam to ignite and fuel the underground combustion process. A separate well is used to bring the gas produced through the underground combustion to the surface.
UCG is both an extraction process (like coal mining) and a conversion process (gasification) in one step, which produces synthetic gas. This gas can then be processed to provide fuel for power generation, diesel fuels, jet fuels, hydrogen, fertilisers and chemical feedstock.
The invention of UCG is widely attributed to Carl Wilhelm Siemens, who first presented the idea to a conference in London in 1868. Much of the early development of UCG technology began in Soviet Russia, however the process became less popular following the discovery of significant natural gas resources in Russia in the 1960s.
Trials of the technology have continued globally since then with significant efforts under way in Europe, the USA and Australia.
Reprising its early role in the development of UCG, London earlier this year saw a gathering of international leaders in the industry when the UCG Association held it's annual meetings and conference.
Developments in UCG
With the world's hunger for energy, new energy technologies are likely to play an important role in the future energy mix. UCG allows access to coal resources that are not economically recoverable by other technologies, usually because the coal deposits are too deep, low grade, or coal seams are too thin.
It is in this context that interest in UCG has grown in recent years. New entrants to the industry are trialling new UCG technologies and some traditional energy sector companies are exploring its future potential.
Given its huge energy needs, it is no surprise that China is one of the world's leaders in developing UCG technology - around 30 projects are currently under way. India also plans to use underground gasification to access an estimated 350 billion tonnes of coal that would otherwise likely be difficult to recover. In South Africa, Sasol and Eskom both have UCG pilot facilities that have been operating for some time and helping build the knowledge base for future deployment. Demonstration projects and studies are also currently under way in a number of countries, including the USA, Europe, Japan, Indonesia, Vietnam, India, Australia and China, with work being carried out by both industry and research establishments.
In a carbon constrained world, UCG in combination with carbon capture and storage (CCS) is also being considered as a potential low emission coal use. Representatives of the UCG industry argue that UCG provides a potential affordable, low-carbon option for power generation as it can undertake CCS as part of the gasification process and still remain price competitive.
Foundations for the Future
With continuing growth in global energy demand, no solution to the energy challenge can be set aside. Both conventional and nonconventional uses of coal, such as UCG, will play an important role in addressing energy security challenges well into the future. However, with increasing public demand, UCG, like conventional coal use, will need to address environmental concerns.
While there have been many UCG trials, some of these have met public resistance due to environmental concerns. Pollution of the water table has been key amongst these concerns and community concern about this was one of the factors that led to cancellation of a project in Queensland, Australia in 2010.
The recent UCG conference in London, however, highlighted that significant work is under way to improve the performance of UCG both from an economic and environmental perspective. These challenges will need to continue to be addressed in order for governments and industry to support wide-scale deployment of UCG as an energy source.
Photo: Linc Energy
About the UCG Association (UCGA)
UCGA is a member organisation made up of technical industry experts, researchers, academics and those working in commercial energy roles.
UCGA was formed in 2005 to promote the commercial, industrial and social benefits of UCG technology. As the industry grows, UCGA's role has evolved and now focuses on the promotion and development of the highest standards of education and professional performance amongst UCG engineers, scientists and others working within the industry, to ensure environmental and public safety.
The UCG Association supports the global development of UCG to ensure that UCG commercial projects will play a lead role as a low carbon energy technology for the future.
UCGA brings together oil and gas companies, energy associations, universities, UCG operators, technology specialists, exploration, drilling and well services, downstream gas processors, power generators, chemical manufacturers and other special interest groups, lawyers, banks, governments and regional development agencies.
The Association benefits from close working relationships with an array of energy sector professionals and support services.
The UCG Association has reciprocal membership with the WCA.
Further information on UCG is available at: www.ucgassociation.org
