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Compressed Natural Gas


Compressed Natural Gas (CNG) a popular form of high pressured natural gas, used as fuel for vehicles. In view of the present day extent of air pollution in the major cities of Bangladesh, CNG is considered as an ideal environment-friendly fuel, causing minimum pollution and Greenhouse effect compared to other conventional vehicular fuels. CNG is produced by pressing natural gas at 3,000 psi pressure (conventional cooking gas is supplied at 25 psi pressure at the burner). Natural gas is usually transmitted by pipelines to refuelling stations and compressed at a pressure of 3,000 psi with the help of specially installed compressors to enable it to be loaded as gas cylinders for vehicles. Vehicles that are equipped with appropriate fuel conversion kits and tanks (gas cylinder) can comfortably run on CNG.

A CNG conversion plant was conceived in Bangladesh in the backdrop of concern about serious emission problems and their effect on the environment. Much of the deathly haze that hangs over the cities comes from suspended particulate matter and noxious gases. Motorised vehicles are mainly responsible for this problem. Diesel run vehicles contribute a significant part of all vehicular pollution. The conversion plant for CNG has thus created the opportunity to use natural gas as fuel for different types of vehicles in Dhaka City.

Till now, five CNG conversion, filling and marketing stations have been operating in different points of Dhaka City - Joarshahara, Mohakhali, Motijheel, Asad Gate and Kalyanpur under the management of Rupantarita Prakritic Gas Company Ltd (RPGCL), a subsidiary of petrobangla. Under a CNG Pilot Project, 16 petrol and 13 diesel run vehicles were converted into CNG at the Project's Joarshahara Refuelling Station cum Workshop and were successfully operated in Dhaka City. Later, in 1994-1995 four additional refuelling stations were established in Dhaka. In the same financial year, 750 petrol, 250 diesel kits, and 2,000 CNG cylinders for converting vehicles were imported. In the following year the company imported 1,000 additional petrol kits. But all these stations have failed to provide satisfactory services to customers for various reasons. Indeed, RPGCL can no longer meet the demand for CNG supply and conversion of vehicles. Only 1,200 vehicles have so far been converted to CNG. In 1996-97, one K-type diesel ferry owned by Bangladesh Inland Water Transport Corporation (BIWTC) was converted by RPGCL to CNG. A CNG refuelling station is in the process of being set up at Aricha ferry terminal. The government has decided to establish 6 more CNG refuelling stations in Dhaka City, import 1,000 petrol kits and 1,000 cylinders, and modernise the Joarshahara workshop. Also, 10 autorickshaws have been targeted for conversion into CNG. Company engineers have already converted three wheeler 'Mishuk [Mishuk] and autorickshaw to CNG at its own workshop.

In July 2000, RPGCL signed an agreement with Tanjin Machinery Import and Export Company (TMIEC) of China to form a joint venture company namely Compressed Natural Gas Distribution Company (CDC), in order to install 51 CNG filling stations in the country. RPGCL will have 25% share of CDC and TMIEC will have the rest.

Encouragingly, the demand for conversion facilities is increasing. Given the limitations of existing CNG conversion capacity and refuelling stations, the government has decided to allow private operators in this sector. At the initial stage, four private operators - Natural Gas Resources Ltd, East Coast Group Ltd, Texas Gas Company Ltd and Prem International - were permitted to develop CNG conversion, filling, and marketing facilities under certain conditions. One such condition is that within the next five years private operators will have to develop five CNG filling and marketing stations, each with adequate workshop facilities for conversion of vehicles. These private operators hope to cover the whole of Bangladesh in phases wherever piped gas facilities are available to operate CNG refuelling stations. Private operators have been asked to maintain New Zealand/European standards in operating filling stations and installing conversion kits and cylinders. The gas tariff for production and selling of CNG will be fixed by the government from time to time.

The cost of installation of one refuelling station for CNG is considered around Taka 11 million. Conversion of a vehicle costs approximately Taka 22,000 to 30,000, depending on the fuel tank size. If CNG pressure at the refuelling dispensers point is available as per the required level, approximately Tk 80 worth of CNG (at a rate of Tk 7.35/cu m) will be enough for a sedan car to run 100 km (for octane users, the same car will run for a maximum of 30 km at the same cost at the prevailing fuel rate) in Dhaka. One of the major constraints of CNG vehicles, however, is its comparatively lower energy density. There is loss of power, especially in heavy-duty vehicles. CNG buses have a limited range (depending on the number of CNG cylinders and their storage capacity installed) and require frequent refuelling. The typical diesel buses run 350 km a day, but the CNG charge lasts only 250 km. [Mushfiqur Rahman]