CNG ships economical, flexible

June 20, 2005
A fleet of CNG ships could act as both transportation and storage facilities and could discharge directly into a land-based grid without expensive liquefaction or regasification facilities, said P. Lothe of Knutsen OAS Shipping AS, Haugesund, Norway, in a presentation May 2-5, 2005, at the Offshore Technology Conference in Houston.

A fleet of CNG ships could act as both transportation and storage facilities and could discharge directly into a land-based grid without expensive liquefaction or regasification facilities, said P. Lothe of Knutsen OAS Shipping AS, Haugesund, Norway, in a presentation May 2-5, 2005, at the Offshore Technology Conference in Houston. Lothe said new ship designs allow more gas now to be transported at ambient temperatures.

A new type of ship has been introduced which contains a large number of vertical pipes and designed according to enhanced pipeline design principles for transporting compressed natural gas. The weight of the containment system is 50% of the weight required by conventional pressure ship design codes, making possible a large storage volume.

Lothe said this concept for CNG was introduced by Knutsen OAS and has been developed with assistance from Europipe GMBH and Det Norske Veritas. He says economic evaluations show the new Knutsen Pressurized Natural Gas (PNG) concept is highly competitive compared to pipelines and LNG transport for distances of 3,000 nautical miles. The advantage, he says, is less investment in infrastructure and greater flexibility. The potential market for CNG carriers is large because more than half of the world’s known reserves are associated and stranded gas.

Lothe’s paper covered the key steps in the ship’s development process, a summary of the risk study, the cargo-containment design, qualification testing, and the PNG economics for different transportation scenarios.