Where in China do coal fires occur?Coal reserves of China are concentrated in the northern part of the country. The coal mining belt stretches 5000 km in China, from east to west, with a width of 750 km in the north-south direction. Coal fires are spread in this entire belt.
International Institute for Aerospace Survey and Earth Sciences (ITC) has worked for nearly a decade to study these coal fires in two test areas - one in Xinjiang and the other in the Ningxia Hui autonomous region. For more information on these studies and projects visit the ITC's Coalfire Homepage.
The figures given by various scientistific groups vary in this regard. According to reports of the Beijing Remote Sensing Corporation (BRSC), Aerophotogrammetry and Remote Sensing Bureau of China Coal (ARSC) and works of Professor Guan Haiyan from China, the annual loss of coal due to coal fires in China is between 10 to 20 million tons. However, figures given by Rozema et al. in 1993 are 10 times higher which means that 100 to 200 million tons of coal are lost due to coal fires in China. This is 5 to 10 times the amount of coal exported by China annually. In 1992, the carbon dioxide released from burning of such large amounts of coal in China itself was projected to be 2 to 3 % of the world's total carbon dioxide emission from fossil fuels (source: Cassells and van Genderen, 1995).
About how much (in dollars) would you estimate it will cost to put out all the fires?
This is difficult to answer. The direct economic loss due to the burning coal resources in China is estimated to be about 125 to 250 million US dollars. The economic loss due to trapped/ unreachable coal is much higher and is reported to be approximately 1.25 billion US dollars (Zhang Xiangmin, 1998).
The fire fighting costs vary a lot depending on the nature of the fire and the method proposed to fight it. One needs to make a thorough investigation on all the properties associated with that fire, then propose the most suitable method. The costs vary from site to site. We still have not made a complete cost-benefit study in this regard for the whole of China.
Can all these fires be put out in one go? Is this even a goal?
It is possible to put out a majority of the fires and to keep the other fires in control so that they do not spread and cause more damage. It is simpler to put out the more recent fires affecting near surface coal seams. The financial involvement is also a point of concern. Putting out all the fires in one go is not practically possible and not the intention. Sometimes it is more feasible to isolate the fire and let it burn away the affected coal seam, than to try to put it out. As far as this fire does not spread to neighbouring seams and due preventive measures are taken so that no new fires occur, I would consider our research efforts well rewarded.
How much progress has been made in coal fire projects in China?
In the projects related to the two test areas mentioned above several tasks have been completed. First of all the areas affected by fires (surface fires as well as underground fires) were detected and mapped. Mapping was carried out using remote sensing data from different platforms. For regional mapping coarse resolution thermal data from the AVHRR (spatial resolution 1.1 km - not very useful) and night time Thematic Mapper thermal band from Landsat satellite (spatial resolution 120 metres - quite effective) were used. Once the areas affected by fire were broadly identified, detail surveys were carried out using airborne data. Special aircrafts with optical and thermal sensors were flown synchronous with the satellite overpass and ground campaigns. These gave very good results for mapping the fire areas, estimating depths of fires and quantifying the amount of coal lost. Such campaigns carried out at different times (multitemporal surveys) helped to monitor the progress/changes in the fires. As a result of these activities the techniques to identify, map and monitor the coal fires are now well established.
On the basis of these results and other information on the geology and topography of the area, distance to the water bodies, concentration of settlements and infrastructure etc., fire risk maps and fire fighting priority maps have been generated. All this information is generated and stored in a geographical information system (GIS), specifically designed for coal fire areas. For the project in the Ningxia region the GIS, called COALMAN was designed and implemented under the supervision of Dr. Zoltan Vekerdy. For more information on COALMAN visit the homepage of Dr. Zoltan Vekerdy.
The GIS mentioned above has been developed with constant involvement of the local fire fighting authorities and mining engineers in China. All the fire prevention plans and fire fighting techniques proposed by the system are made keeping in mind the local conditions. For example, liquid nitrogen fluxion is a very effective way to cool the temperature of the hot coal strata, but this is not proposed as it would not be economically feasable in this study area. The GIS system only proposes solutions but interaction of the local expertise is a very important step in the final decision making.
What next steps need to be taken to deal with the problem?
Some recommendations I would put forward are:
Most of the coal mining areas in China are located in remote and rather sparsely populated areas. The terrain is also quite tough with a very poor transport and communication infrastructure. Also, there is a wealth of coal present. It is for these reasons that the coal fires which cause so much pollution and harm were not given due attention in the past. The Chinese Government as well as other organisations round the world are now more aware of the problem and are considering it more seriously.
