Using the TURBOMATCH and GATE/CYCLE computational thermal-models, detailed design-point performance predictions (relating to efficiency, net specific work and fuel flow), when a low-calorific-value fuel gas is employed (instead of natural gas), are presented. With slight modifications in the fuel supply, combustor and turbomachinery of the engine, in order to accommodate the increase in the mass flow rate across the turbine's expander, such a fuel could be burnt in the industrial gas turbine's combustor, which had originally keen designed for use with natural gas. The results of this study agree with those for nominally-similar electric power generators, that are already operating world-wide using coal-or-biomass derived gaseous-fuels with relatively low energy densities.