The Mobilization of Energy Crop Resources in Moldova

Abstract

In the context of the current sharp rise in energy prices and frequent weather anomalies caused by climate change, humankind faces two major problems: food supply and energy security, which compels us to look for alternative ways of solving these problems, including the reduction of the dependence on fossil fuels and the development of new technological processes for renewable energy production. The main objectives of this study were to evaluate some agrobiological peculiarities and the quality of harvested biomass from local cultivars: ‘Solar’ Helianthus tuberosus, ‘Ileana’ Inula helenium, ‘Vital’ Silphium perfoliatum, ‘Energo’ Sida hermaphrodita, ‘Vigor’ Astragalus galegiformis, ‘Titan’ Miscanthus giganteus, ‘Argentina’ Sorghum almum, ‘Gigant’ Polygonum sachalinense and the prospects of using their biomass as feedstock for renewable energy production. It was found that the studied cultivars, in the second and following growing seasons, were characterised by optimal growth rate and moderate regenerative capacity after being mowed, making it possible to cut by 1-3 times per season, obtaining 4.61-14.25 kg/m2 green mass, which may be used for anaerobic digestion in biogas plants, with biochemical methane potential of 297-336 litre/kg organic matter. Besides, digestate and fugate are believed to be good fertilizers, being rich in plant available nutrients such as nitrogen, phosphate and potash, and could serve as a replacement for fossil based mineral fertilizers in organic farming. The stems of the studied cultivars quickly dehydrate in the autumn-winter period, and can be chopped, milled and used as feedstock for the production by cellulosic ethanol and solid bio fuel. The analysis of lignocellulose composition showed that the dry matter contained 375-517 g/kg cellulose, 211-305 g/kg hemicellulose, 68-134 g/kg acid detergent lignin. The estimated theoretical ethanol yield from cell wall carbohydrates averaged 408-591 L/t. The gross calorific value of stem biomass was 18.63-19.50 MJ/kg. The specific density of densified solid fuel pellets and briquettes meet the quality standard requirements. The obtained results indicate the possibility of using the local cultivars for the creation of energy plantations in the Republic of Moldova. The cultivation and harvesting of these cultivars do not require sophisticated mechanisms and specific equipment like as in forest exploitations.