This is the fourth Info Note in a series describing technical and economic aspects of small and medium scale combined heat and power systems which use biomass as fuel. The Info Note’s focus is on medium-scale organic Rankine cycle (ORC) CHP systems which produce one to two mW of electricity and 5,000 to 10,000 kW of heat. ORC technology is explained, commercially available ORC systems are described, biomass supply chain considerations are discussed, and the basic economics of an installation are reviewed.