Electricity and hydrogen production potential assessment by using turbo expander in natural gas pressure reduction stations

The process of transmitting natural gas through pipeline networks starts at production facilities and ends with the gas reaching usage locations after traveling for kilometers at high pressure. The transmission of natural gas is made possible by compressor stations increasing the pressure of the gas and compressors provide their energy by consuming large amounts of natural gas. A portion of the consumed energy can be recovered at pressure reduction stations installed along natural gas pipelines. Equipment consisting of turbines and generators, called turbo expanders, can reduce the pressure of natural gas while simultaneously generating electricity from energy recovery due to pressure differences. In this study, energy balance calculations were made with turbo expander installation modeling based on the data of a pressure reduction station built on the international natural gas transmission line (UBDI). The effect of pressure and temperature values at station inlet and outlet on energy recovery was examined. The electricity generation potential was calculated based on the annual flow rate, and the potential for hydrogen production as a second product was also evaluated. Similar calculations were made with the data of Pendik RMS-A type pressure reduction station, which is a city entrance station on the national transmission line installed. Thus, the energy recovery potentials of the two stations were revealed. Based on the characteristics of a commercially available TE system, it was determined that the UBDI has an 11MW electricity generation potential and a potential for hydrogen production of 1200 Nm3/h using PEM electrolysis in the modeled system. This allows for the reduction of energy costs in the natural gas transmission process, enabling a more sustainable energy management. Furthermore, the study emphasizes the importance of energy recovery and offers a new perspective on hydrogen production as the fuel of the future.