Compressed Natural Gas (CNG): An Alternative to Liquid Natural Gas (LNG)

摘要

Natural gas is becoming one of the most important resourcesof energy, with its share in the world consumption expected toincrease dramatically over the next two decades. Currently,natural gas is transported to the markets by pipelines and asliquefied natural gas (LNG). Transporting the natural gas bypipelines is convenient and economically attractive onshore.For the offshore transport of natural gas, pipelines becomechallenging as the water depth and the transporting distanceincrease. LNG, an effective means of transporting gas for longdistances across the seas, constitutes 25% of the world gasmovement. But LNG projects require large investments alongwith substantial natural gas reserves and are economicallyviable for distances such as 2500 miles and beyond.Compressed natural gas (CNG) technology provides aneffective way for shorter-distance transport of gas. Thetechnology is aimed at monetizing offshore reserves, whichcannot be produced because of unavailability of pipeline orbecause the LNG option is very costly. Technically, CNG iseasy to deploy with lower requirements for facilities andinfrastructure. “Coselle” and “VOTRANS” are two would-becommercial, high-pressure gas storage and transporttechnologies for CNG. Technical and economic analyses ofthese two technologies were done in this study and acomparison is provided. The results show that for distances upto 2500 miles natural gas can be transported as CNG at pricesranging from $0.93 to $2.23 per MMBTU compared to LNG,which can cost anywhere from $1.5 to $2.5 per MMBTUdepending on the actual distance. At distances above 2500miles the cost of delivering gas as CNG becomes higher thanthe cost for LNG because of the disparity in the volumes ofgas transported with the two technologies.