This paper presents a developed general computer program, which is a flexible computational tool for biomass energy surveying of an interested wide geographical area (w.g.a.) and its properly selected interior zones for the purpose of identifying possible cogeneration or combined heat and power (CHP) unit installations in proper site locations, which in turn are fully assessed in techno-economic terms. In addition the program, based on the available in the w.g.a. forms of solid biomass and the geographic distribution of the pertinent feedstock, makes a hierarchical order of these taking into account their quantities and energy characteristics, which ultimately leads to definite combinations and thus to desired mixed solid biomass fuel for steady annual contribution (or with seasonal preference in order to reduce the storage costs) of the participating solid biomass residues to be used for the fuel supply of the associated CHP unit. Last the program is conducive to performing reliable sensitivity analysis work as function of key system parameters or quantities. As a case study a w.g.a., belonging to the north-east part of Eastern Macedonia-Thrace Region of Greece, is thoroughly analyzed taking into account the specific techno-economical constraints applicable (due to national energy and development laws, etc.) to this area and the pertinent practical results are presented.