News Article

Cost-Effective Energy Recovery for Gas Pipeline Pressure Letdown Stations

October 1, 2021

It has long been recognized that the mechanical devices used at pressure letdown (PLD) stations in gas pipelines generate significant amounts of waste energy, which potentially could be captured and converted to electric power.

While turboexpanders are often used for energy recovery across other industrial sectors, such as refineries, gas liquefaction, petrochemicals and steam PLD, their high capital and operating costs have presented a barrier to widespread deployment in gas pipeline PLD stations.  

Sapphire Technologies, a subsidiary of Calnetix Technologies, is addressing the issue by harnessing high-speed magnetic technologies with a turboexpander generator that converts the kinetic energy produced by the PLD process into usable electrical energy. The clean electricity produced can be used locally or sold back to the grid.  

Sapphire has developed and deployed an integrated system that contains a high-speed turboexpander driving a synchronous permanent-magnet high-speed generator levitated on non-contact active magnetic bearings. All the components are contained in a hermetically sealed flow-through unit, which can be inserted directly into a section of piping in parallel with the existing mechanical pressure reducing valve.