Effects of membrane processed renewable biogas fuels on natural gas designed turbine's power cycle and fuel consumption

This research analyzed and explored two different configurations of membranes, carbon dioxide selective and methane selective membranes, to produce processed biofuels (Fuel 2 and 3) from crude biogas plant (Fuel 1) for the first time. In addition, the effect of crude and processed fuels on gas turbine performance was researched in order to assess the viability of the biogas as a renewable resource to generate electrical power. Under optimum conditions that maximized product purity and recovery while keeping the operating parameters at a minimum level, carbon dioxide selective membrane produced methane purity of 87% and recovery of 90% (Fuel 2) at selectivity of 1084, stage cut of 0.31, and feed pressure of 32 bar. Methane selective membrane with selectivity of 746, stage cut of 0.65, and feed pressure of 35 bar produced processed biogas with higher methane purity of 95% and recovery of 92% (Fuel 3) than those from the carbon dioxide selective membrane. The processed fuel also was found to be the most compatible when used in the gas turbine. This can be noticed in the gas turbine graphs, as the processed fuels were found to nearly replicate the gas turbine working in design conditions with natural gas. Although the crude biogas (Fuel 1) containing 69% methane, 27% carbon dioxide and 4% water worked with the gas turbine with the highest efficiency, there were issues related to the highest fuel consumption and aerodynamic-related aspects. The upgraded biogases (Fuel 2 and 3) containing 87% and 95% methane, 9% and 5% carbon dioxide, 4% and 0% water, respectively on the other hand, provided an almost similar gas turbine performance with the natural gas. The use of the upgraded biogases in the gas turbine are important to ensure that the gas turbine works well as it is intended to perform.