Optimization of a methane expansion liquefaction cycle for small scale LNG plants

Nowadays there is a growing interest towards small scale natural gas liquefaction plants, mainly due to the increasing energy demand and quest for cleaner combustion. LNG is seen not only as an energy vector, but also as a final product to be used directly, in particular as a fuel for vehicles and ships. For producing LNG directly on site to supply a refuelling station, a micro-scale plant is necessary. In this paper methane expansion liquefaction cycles are considered for their simplicity and they are compared on the basis of energy efficiency and costs. The analysis highlights that is possible to achieve the economic feasibility of the project even with the simple liquefaction cycles considered.