LAUSR

Abstract This paper continues discussion on financial viability and design optimisation of biomass-fired Organic Rankine Cycle (ORC) Combined Heat and Power (CHP) systems. It examines influence of such decision variables as ORC system rated electric power output, architecture and working fluid. The considered ORC system structures are simple, regenerative and regenerative cycle with split heat exchanger. Eight working fluids are considered, namely: MM, MDM, MD2M, D4, D5, toluene, ethylbenzene, and cyclohexane. The system was modelled and simulated using Ebsilon® Professional software. Sample project is assessed in terms of power generation efficiency, Primary Energy Savings (PES), and financial indicators, such as Net Present Value (NPV) and Internal Rate of Return (IRR). Results revealed considerable differences in optimal power output. The optimal value of the ORC generator power output in terms of NPV is within the range from 1000 to 2600 kW depending on the system configuration and the working fluid. In terms of IRR the optimal rated power is between 750 and 1400 kW. The highest values of nominal rated power output have been obtained for ethylbenzene. What is more, the economic indicators get higher values for hydrocarbons than for silicone oils, which are nowadays widely used in biomass fired ORC systems.