Emission inventory from the use of coals and policy recommendations for coal utilization

Abstract

At present, about 73% of total electricity generation of Bangladesh are done using natural gas fuel. However, as the reserve of natural gas is diminishing day by day at an alarming rate, it has become essential for the country to strive for an alternative fuel source. Coal can be considered as a potential substitute in this scenario which is currently used in power generation, brick production and steel foundries as a secondary alternative in most of the cases. Coal mining has been initiated in 2005 in the Barapukuria coal mine, one of the six bituminous coal mines of Bangladesh. This mine alone cannot cater to the local coal demand. In 2016, 0.51 Mtoe coal was extracted from the mine, while 1.09 Mtoe coal was imported. The demand is expected to go up and to achieve the vision of 2030 Government has considered instigating necessary steps to set up a number of coal-fired power plants across the country. But environmental impact of these proposed coal fired power plants is one of the biggest concerns and most of the coal which will be used in these power plants will be imported coal. So it is essential to analyze these imported coal to predict the extent and exploits of its utilization & pollution factors. Environmentalists and concerned strongly resist coal mining and setting up of coal fired power plants in environment sensitive locations. To overcome these sociopolitical issues Bangladesh Government is trying to form a "Coal Policy" asking for the formation of coal-zone and simultaneously for accelerating subsequent development of coal mines. Several drafts have been prepared, but yet to be formalized. The current draft focuses on the exploration and development of new mines, but lacks specific direction on coal utilization. This research program is mainly experimental based, which determines different proximate, ultimate analysis values of different imported coal sources and also determines several mineral matters and pollution loads from a coal combustion process. The proximate analysis of coal is an assay of the moisture, ash, volatile matter, and fixed carbon as determined by series of prescribed or standard test methods. The ultimate analysis of coal involves determination of the weight percent carbon as well as sulfur, nitrogen, oxygen and chlorine through standard procedures like ASTM methods. Weight percent of constituents like mercury and chlorine were also measured. Thermodynamic simulation was also done to predict the effluent behavior from coal combustion. The objective of the research is to find out the specifics of coal utilization & environmental impact of coal fired power plants to recommend specific policies in order to promote the utilization and import of better quality coals which is a dire need for future energy security of the country. Four coal samples from different sources were analyzed for this study. Ash content varied from 3.37 to 12.31%, where volatile matter and fixed carbon varied from 25.32 to 48.46% and 43.50 to 62.37% respectively (dry basis). Calorific value suggested that, all coal samples would be suitable for power generation as they ranged between 22 to 30 MJ/kg. An overall pollution estimation from power plants and brick kilns by using pollution abatement technologies in these sectors was also shown. This estimation suggested that in 2030, total CO2 emission from power plants and brick kilns would be 103.6 million tons compared to the current emission of 12 million tons. Whereas, 174 thousand tons of SOx, 862 thousand tons of NOx would be emitted in the same year compared to current emission of 103 thousand tons of SOx and 42 tons of NOx. Significant increase in ash production (90 thousand tons to 5405 thousand tons in 2030) from power plants in 2030 was seen from the pollution load prediction.