The prefeasibility study of a biomass fuelled CHP based on a steam Rankine cycle employing back-pressure process proposed to utilize apple pruning residues as biomass sources to obtain bioenergy in Isparta Province was carried out. Since Egirdir has the highest apple production among the districts of Isparta province, it is reasonable to build biomass fuelled CHP plant in Egirdir district. Therefore, economical analysis was conducted for the catchment area with the radius of 59 km taking Egirdir district as the central point. Both equations and data used to calculate the capital and operating cost of biomass CHP plants were obtained from the available literature. The production of electrical and heat energy, and revenues were evaluated. The economic viability of 7.8 MW(e) CHP plant was evaluated based on the net present value (NPV), benefit-to-cost ratio (B/C ratio), internal rate of return (IRR), and payback period (PBP) considering electricity purchase prices of 0.066 euro cent/kWh and heat sale price of 0.0225 euro cent/kWh. It has been concluded that certain financial mechanisms have to be put into effect, such as increasing market price of electricity produced from CHP plants to give an incentive to producers, as well as fundraising to support construction of CHP plants, and offering both long-term credits and tax breaks for investors.