Abstarct: The pressure of natural gas (NG) in the transmission pipelines is very higher than which is needed for customers. The NG pressure has been reduced in several steps to provide appropriate consumer's NG pressure. Pressure Drop Station or city gate station (CGS) is the first step that natural gas pressure reduction is happened. The pressure of natural gas is decreased in CGS by regulators and they caused a valuable NG pressure-exergy waste. The pressure reduction causes the temperature reduction. Linear heaters are mostly used to raise the temperature of NG in CGS. Using of fuel cell to provide required CGS heating and using of turbo expander to use pressure exergy of NG has been investigated in this research techno-economically. Both systems have the ability to produce electricity and sells that to the electrical grid. In present work, both of these systems are investigated in three different plans. The first plan is contained a fuel cell system and the second plan is contained turbo expander system; also the third plan is contained fuel cell system with turbo expander system. The modeling of fuel cell is baxsed on a two-step selection process which selects the best fuel cells in ideal operating condition baxsed on economic justification at first step and then, determines the optimal numbers of the selected fuel cells in applied mode at different city gate stations taking into account techno-economic criteria. The modeling of turbo expanders is baxsed on Techno-Economic calculation that causes to choose the most justification turbo expander size for each CGS. The results of investigation in first plan has been shown the biggest CGS (in terms of average NG flow discharge) has the most economic justification and also has been shown noun of studied fuel cells have no economic justification in Iran at this year, but in the next year some of them have economic justification because of initial investment reduction and price changes of energy. Results of second plan has been shown that the best return of initial investment will happen in the CGS which is the biggest CGS and has the smallest standard division criteria of NG flow in the year. At last in the third plan the most explainable project in terms of economic will happen in Abbasabad 400,000 CGS in next year. Simple pay back of investment at this plan will be about 3 years and this plan will be able to import 57GWh electrical energy to electrical grid; also this plan causes 33,563 tons per year reduction of CO2 emission to atmosphere.