Design and Build of Pressure to Power - Natural Gas (NG) Expander-Generator


During the pressure reduction of natural gas within the gas distribution network a significant amount of power is released to the environment.


In 2017 D&T completed NPD of a 250kW gas let-down expander/generator (GLDE) for a refrigeration engineering company. The 250kW turbo expander was designed to operate in parallel with a pressure reducing valve at pressure reducing and measuring station (PRMS).

The package is a 2-stage expander, with preheat of the working fluid, for converting the energy from pressure reduction within the natural gas distribution network. It is a bolt-up semi-hermetic eco-friendly machine which operates at inlet pressure of 52barg and outlet - 32barg, generating electrical outlet power of 250kW(net).

The machine integrates a permanent magnet generator, radial inflow turbines and a shaft suspended on gas bearings. It was certified for operation in the US.


The machine was subjected to a comprehensive testing regime at a live gas test site in the UK gas network. The tests carried out included verification of the of a full-scale proof of concept machines performance under steady state conditions as well as verified safety features for both controlled and emergency fast stop scenarios.

The project was subsequently cancelled as TPG D&T was dissolved with the customer searching for a new supplier of equipment. A new solution is yet to reach the market.

Architecture Two stages, permanent magnet generator with gas bearings
Process media Natural gas
Inlet temperature 80°C
Inlet pressure 52barg
Pressure ratio 1.6
Rated power 250kW(net)
Rotational speed 22,000rpm
Compliance Certified for use in the US (API/UL)

Note: TPG D&T business was dissolved in 2017. Its core Technical Team, who pioneered this project formed C2 Technology, to continue D&T’s business of developing innovative technologies for energy industry.

Return to our case studies…

Contact Us:

Follow Us: