Not Just your Granny’s Fuel
No longer just used to produce heat in the conventional sense, the possible future for coal lies in many different directions. Some of these are well established areas; others are growing in commercial importance and market entry; and others still are at the frontier of research and development activities
With conventional energy reserves dwindling, industry and government view unconventional natural gas, such as CBM, as having an important role in securing Canada’s energy future. According to the Alberta Geological Survey, Alberta’s coalbed resource could contain approximately 500 trillion cubic feet (tcf) of natural gas, compared to Alberta’s natural gas reserve of 42 tcf.
CO2 Sequestration and Enhanced CBM in Alberta
The next step in the coal utilization chain is storage of carbon dioxide and CBM production, commonly referred to as CO2 enhanced CBM (ECBM). ECBM has the potential to improve both production rates and the ultimate recovery of CBM gas. The potential for CO2 storage in coal beds is great and represents a significant greenhouse gas abatement technology. Sequestration within coal seams is one of the most attractive options, due in large to the abundant availability of coal resources and carbon dioxide’s sorption into coal; not only is the sorption high, but it has the added advantage of displacing methane—which has a sorption capacity up to 10 times lower than the carbon dioxide—and thereby enhancing the CBM recovery.
CBM through ECBM followed by Bacterial Regeneration
There are many methanogenic bacteria in nature that can convert CO2 to methane; in recent years researchers discovered that ongoing methane production is occurring in deep coal beds. The question that is now being raised is whether the microorganisms involved in this biogenic methane production could be manipulated and exploited to enhance and increase the methane recovered during CBM operations. Furthermore, when coalbeds have been fully exploited of CBM by using carbon dioxide, the CO2 soaked seams could then be further biologically converted to methane and/or hydrogen.
Research in the area of ECBM/Regeneration is, however, still in its infancy and much remains to be learned about the limitations of microbial growth in coalbeds. If the process turns out to be economically feasible, microbially enhanced coalbed methane can expand the life and value of coalbeds, playing a vital role in CO2 storage.
In-Situ Gasification
It was in the 1930s and ’40s when the early development of in-situ coal gasification (UCG) took place, almost entirely in Russia; it was developed as a method to utilize coal resources without the need for mining. Russia’s practical demonstration of the technology proved that UCG can operate reliably in a variety of coal deposits targeted for the generation of heat and/or power, respectively. The caution, however, is that the fuel produced in the Russian installations would not be compatible with most fuel gas applications in North America and these differences may lead to difficulties in any future domestic installation.
The Future
Canada’s low-cost indigenous coal resource fuels about 20 per cent of the Canadian electricity system, and will continue to play a vital role in the future of power generation. However, as with all energy sources—whether fossil, alternative, renewable or nuclear—there are increasing social and economic pressures for the energy supplies of today and tomorrow to be secure, cheap, and environmentally benign. For coal, these challenges are being addressed through increased awareness and positive action from governments and industry. Through the progressive development, demonstration, and deployment of cleaner coal technologies, we are helping to secure our own energy future.
Dr. Ian J. Potter is Director, Sustainable Energy Futures at the Alberta Research Council—a position focused on ensuring that ARC can respond effectively and efficiently to energy and environmental challenges and opportunities. Dr. Potter received his bachelor of engineering in marine engineering from the Royal Navy Engineering College, and masters and doctorate degrees in mechanical engineering from the University of Calgary.
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