This project brings together existing knowledge on the problem of combustion of in-situ fossil-fuel deposits, in particular coal occurrences. It links the physical properties of coal and its combustion emission products to detection and monitoring options with state-of-the-art earth observation techniques, and with an outlook to future methods, including improved sensors, (semi)automated detection algorithms and spatial sub-surface combustion modelling. Concerning fire extinguishing it focuses on the technical difficulties of monitoring and auditing aspects of reduction schemes (such as the Clean Development Mechanism), with an inventory of current fire fighting techniques.
Uncontrolled combustion of coal and organic shale deposits
This report, performed within the framework of the Scientific Assessment and Policy Analysis for climate change program (WAB), mainly deals with uncontrolled combustion of coal and organic shale deposits. A coal fire is defined as a burning or smoldering coal seam, coal waste or organic shale. Coal fires are reported mainly from China, India, the United States, Australia, Indonesia, and occasionally from other countries. Coal fires can ignite naturally or through human influence, the latter of which being the cause of most coal fire ignition.
In this study four parts related to the uncontrolled combustion of coal and organic shale deposits are examined:
In-situ and laboratory modeling of combustion
As a follow-up of modeling coal fires, the convection and combustion model has been applied to simulate combustion of an oil shale cliff near Kimmeridge Bay, Southern England. It provides a good perception of the in-situ ignition and dissemination behaviour. Translation of the results to other regions in the world and to coal deposits is possible when local geological conditions and petrophysical parameters are known. In addition, local climate is also an important factor. Therefore, it remains complicated to estimate a world wide CO2 contribution from fossil-fuel deposits and it is essential to do an inventory based on occurrence and climate and associated permanent and seasonal fires is essential.
Case studies in China, with detailed tables on coal loss in mines for the provinces Ningxia, Inner Mongolia and Xinjiang
An overview is given of coal fire related research over the last two decades. In addition, new tables are presented that are compiled by the Chinese mining authorities. The estimates are made by the coal mining companies. In the province of Ningxia 37 coal fires have occured of which 14 have been extinguished. The total amounts for the province of Inner Mongolia is estimated at 64 individual coal fires. The Xinjiang province coal fire fighting team has already extinguished 8 coal field fires during the last 50 years, and is presently working on 31 more coal fires. In 1995, the Xinjiang coal fire fighting team made a plan to extinguish all the coal fires in Xinjiang by the year of 2015, instead of by the previous target year of 2020.
The potential of automated detection of thermal anomalies in readily available remote sensing data
At present, there is still not a feasible way of quantifying the development of fossil fuel fires by using routinely available remote sensing data, but it is possible to indicate the existence and relative size of a fossil fuel fire with the aid of (semi)automated algorithms and with geotechnical data-based convection models. The authors conclude that, today, the link between in-situ fossil fuel fire models and remote sensing monitoring cannot be made, yet.
An estimation of greenhouse gas emission
It is estimated that the upper limit for the CO2 release from China is not larger than 100 Mt (CH4 included), being 0.38% of the global annual human-induced CO2 budget. The authors assume that this number, in reality, is still too high and estimate that the amount of directly burnt coal due to fossil fuel fires in China is no larger than 10 Mt, providing an upper limit of the CO2 release of 25 Mt (48 Mt including methane), which is 0.096% (and 0.18% respectively) of the global annual human-induced CO2 budget. Based on the worldwide coal reserves and production figures, as well on the climate zones, this study concludes that the worldwide emission of CO2 as a result of uncontrolled combustion cannot be more than four times the probable emission in China. This upper limit is 100 Mt (192 Mt including possible CH4). This corresponds with 0,4% (and 0,7% including methane) of the annual worldwide human-induced CO2 budget.
Clean Development Mechanism (CDM)
Large energy companies investigate the possibility of extinguishing the large number of coal fires burning in northeastern India, and west and north-central China. However, to date, no coal fire-related emission trading agreement is known to have been signed anywhere in the world. A requirement for obtaining CDM certificates would be a baseline level definition for coal fire-related greenhouse gas emission, which has yet to be established. It needs to be known how much CO2 equivalent a certain coal fire releases to the atmosphere over a certain amount of time. Based on such a baseline a company could get the proper credits for extinguishing this fire. Such baselines are a pressing need, especially in China and India.