Energy is the dominant factor that determines the welfare of the country and people; it influences the level of development of all spheres of activity in society. In recent years, at global and national level, greater attention has been paid to the use of biomass for the production of renewable energy. To determine the plant species that are the most suitable for biomass production, their biological peculiarities and productivity, the biochemical composition and the thermophysical properties, the social and the ecological impact must be investigated thoroughly. The study of local as well as introduced herbaceous plant species for further processing into various types of bio fuels is an important objective. We have investigated some agro-biological peculiarities, the biochemical composition of the harvested green mass and prepared silage, the thermophysical properties of the dry biomass and the solid fuel of the perennial plant species: Silphium perfoliatum cv. Vital, Sida hermaphrodita cv. Energo and Inula helenium cv. Ileana. It has been established that the biogas potential of green mass substrates varied from 440 to 532 l/kg ODM and from 443 to 452 l/kg ODM of silage substrates; the methane potential in green mass substrates varied from 236 to 275 l/kg ODM and from 228 to 244 l/kg ODM of silage substrates. The briquettes produced from Silphium perfoliatum and Sida hermaphrodita reached a specific density of 949-1162 kg/m³, but from Inula helenium – 813 kg/m³, versus maize briquettes, which reached a specific density of 923 kg/m3.