Coal and energy: We use coal in many different ways. One of the most important ways we use coal is to generate electricity. The economic deposit of bituminous coal in Bangladesh was discovered at Jamalganj (Joypurhat) in the year 1962 and subsequently more discoveries were made at Boropukuria, Khalaspir, Dighipara, and Phulbari. Jamalganj has the largest deposit to the tune of 1053 million tons. But coal mining from this field is not economically feasible due to very large depths of occurrence from 640 m to 1158 m. Like wise, Khalaspir and Dighipara have a total deposit of 347 million tons occurring at 250 m to 451 m suggesting for an uneconomical mining venture. However, these two deposits could be mined on extreme necessity.

Boropukuria and Phulbari are the only two coal fields having total deposit of 680 million tons that can produce coal economically. The major constraint that lies with the tonnage of coal recovery in these two fields is the choice of mining method between underground mining and open cast mining. The maximum recovery of coal from underground mining stands to only 20 percent of the reserve while that for open cast mining goes upto 80 percent. An underground mining would produce maximum of 136 million tons of coal from these two mines combined. The total 136 million tons would generate about half giga watt hour electricity during the entire mine life time.

Although, 01 ton bituminous coal has a BTU (British Thermal Unit) equivalent to energy that can generate about seven and half megawatt hour of electricity, the efficiency of electricity generation by burning coal amounts to maximum of 50 per cent only. Although, an ideal efficiency of electricity conversion from coal burning is 77 per cent, it is very hard to achieve. The bottom line is that the conversion of coal into electricity is very inefficient. The efficiency expressed as a fraction of the temperature of the combustion of coal, and the temperature at which the spent combustion energy is expelled. On the otherhand, 38 million tons of coal is equivalent to 01 TCF (trillion cubic feet) of gas, and 01 MMCF (million cubic feet) of gas can produce approximately 3+ mega watt electricity.

Considering 50 per cent efficiency and gas equivalence of coal, it is estimated that with 500 MW per day generation capacity would serve for about 30 years from these two coal mines. On the otherhand, for the same 30 years of electricity generation would be possible at the rate of about 2000 MW and more per day if an open cast mining venture is undertaken. The above calculation is based on the assumption that the entire produced coal would be used for only electricity generation. Nonetheless, it looks very encouraging and lucrative from energy development perspective; however, there lie enormous flaws and constraints from social and environmental points of view.

Coal and environment: The major problems with the coal mining are its adverse impact on the environment and society. Although underground mining and open cast mining have variable impacts, by and large, both have commons. The major adverse impacts from underground mining are sudden ground subsidence in the mining area and production and drainage of acid mine, commonly known as acid mine drainage. Ground subsidence can cause disaster to habitat and the loss of cultivable lands by water logging. On the otherhand, the prevention of acid mine drainage from contaminating surrounding hydrogeological environment is also a difficult task. Hazard related impacts are mostly sudden water flooding and explosion from gasification inside the mine. Already in Boropukuria mine there happened water flooding, gasification, and ground subsidence. However, the adverse outcomes from underground mining are manageable. Although, an open cast mine can produce more than 80 per cent of coal reserve, the socio-environmental impacts are adversely enormous. Social impacts add greatly to environmental impacts. However, a transparent socio-environmental impact assessment may minimise all the odds.

Natural gas and energy: The use of gas in electricity generation has gained quite a fast momentum in recent time mostly due to its low cost involvement in a more environment friendly way. However, there are incidences of socio-environmental disaster pertaining to natural gas exploitation as envisaged from Magurchara and Tengratila blow-out. Presently, about 80 per cent of daily electricity is produced from natural gas which is about 51 per cent of daily gas production in Bangladesh. The next major gas consumption sector is fertilizer that consumes about 21 per cent of daily gas production. The daily gas production is currently being about 1600 MMFC. Fifty one percent of daily gas production currently can generate about 3200+ megawatt of electricity daily. Our present daily electricity demand is about 5000 megawatt which is projected to 15000 megawatt by 2020.

If we want to generate 15000 megawatt of electricity daily, under the present scenario (51%) of daily gas production, we need to produce about 8500 MMCFD gas by 2020. Do we have such huge reserve that could produce such large amount of gas? However, according to Wood Mackenzie, a reputed energy consultant from UK in Petrobangla, who has calculated gas demand scenario of Bangladesh for 2020, it is about 4000 MMCFD (see graph).

This projected requirement is almost half of what I have calculated. This major anomaly perhaps lies with the understanding between the total requirement and the requirement for electricity generation alone, which needs to be clarified.

Task ahead: It is well understood that using coal as raw material for electricity generation is very cumbersome task both from socio-economic and environmental points of view. The existing socio-economic conditions of the country do not advocate for open cast mining, so underground mining will limit coal production to a maximum of 20 per cent only. Even if we operate underground mining at all the four coal fields, the daily combined coal production would generate electricity to contribute only 10 per cent of the projected demand of 15000 megawatts by 2020. The only way to increase coal contribution for electricity generation is to venture for open cast mining. This needs absolute conscientious support of the people living in the coal mining areas.

To gain people's confidence and support it needs a massive social motivation drive. They will have to be provided guarantee for same living standard and quality, if not better, after resettlement. The environmental odds likely to crop up due to open cast mining must be minimized. Even then the major raw material demand for electricity generation points toward natural gas use. Hence, we are left with no option to explore and produce natural gas more and more.

We have gone through some strong debates in the past as to how much natural gas we do have. The proven gas scenario is not very encouraging although hypothetical scenario stands bright. Except Bibiana field having proven and probable reserve of 2.5 TCF or more, no major discovery has yet been made by the IOCs operating under PSC. Now, I put forward an open question as to what has gone wrong in spite of the fact that we have quite a good number of potential structures? Why those have failed to gain due attention? As for example, about 70 km long and 10-15 km wide Sitakund structure is one of the known largest structures we have. Five wells were drilled, of which four were drilled by PPL (Burmah) maximum up to 1024 m depth, and the fifth one was drilled by Petrobangla up to 4005 m depth. It is very interesting to note that three wells drilled by PPL have detected oil at shallow depth within 1000m. In addition, oil seep at Khaiyachara in Sitakund structure has also been detected. There are enormous gas seepages at Kumira, Barbkund, Labanakhya, and Bariadhala. In spite of all these positive indications, Petrobangla drilled an absolutely dry hole with a total depth of 4005m. All these wells were located in the south central part of the structure and, in addition, the fifth well was drilled in the eastern flank over a major fault.

My recent study revealed that drilling location was not rightly selected. All geophysical and geological evidences strongly suggest that the northern half of the structure possesses an excellent trapping condition. One should bear in mind that Rokhia, Feni, and Semutang gas producing structures are located within 50km around Sitakund structure. Simply, it cannot be justified that Sitakund structure is not a prospective one. Should we go for drilling here? The answer is yes. I would strongly recommend taking a risk of only 30-40 crore Taka while thousands of crore have been wasted in various sectors. We have another gas discovery at Kutubdia. It was discovered in 1977. Although, Shangu field has been developed but Kutubdia has long been ignored. I find no reason why Kutubdia has not yet been developed. Similarly, it is quite a surprise why Halda and Srikail gas discovery has failed to develop.

Dr. Aftab Alam Khan is Professor, Department of Geology, Dhaka University.