Some perennial herbaceous species for multiple energy purposes in the Republic of Moldova

Abstract

The sources of renewable energy have acquired considerable interest in recent years, at global and national level. The investigation of local as well as introduced herbaceous plant species for multiple energy purposes is an important objective. We investigated some agro-biological peculiarities, the biochemical composition of the green mass and silage; energy characteristics of dry biomass of the perennial herbaceous species: local cv. Energo of Virginia mallow, Sida hermaphrodita, and an local ecotype of elecampane, Inula helenium, the most frequently used energy crops: maize – for biogas production and wheat straw – for solid biofuel production were used as control variants. It has been established that the gas-forming potential of the green mass of perennial species varied from 440 to 454 l/kg ODM and silage – 433 to 458 l/kg ODM, maize – 536 and 557 l/kg ODM, respectively. The best results of biomethane production were achieved by cv. Energo of Sida hermaphrodita (4000-4050 m3 /ha) versus maize Zea mays (3127- 3296 m3 /ha). Inula helenium substrate had higher content of methane (53.1-53.8 %). The briquettes of Sida hermaphrodita and Inula helenium were distinguished by high bulk density (813-1162 kg/m3 ), moderate gross calorific value (18.3-18.7 MJ/kg) and ash content (1.5-3.0 %), but wheat straw– by low bulk density (704 kg/m3 ) and calorific value (17.0 MJ/kg) and very high content of ash (5.1 %). Potential of energy production – 240-380 GJ/ha. The best results were achieved by cv. Energo of Virginia mallow, due to its high biomass productivity.