Feasibility of small-scale gas engine-based residential cogeneration in Spain

► Profitability is obtained within the whole small-scale range of powers. ► The stepped structure of prices strongly affect the feasibility of the projects. ► The inclusion of thermal storage notably affects the profitability of the plant. ► Big chance for increase the feasibility exists in retrofitting old installations. ► The system of tariff updating balances the future variations in the price of fuels.