Giant reed (Arundo donax L.) as a cellulosic bioethanol feedstock in Central Italy: the agronomist’s point of view

Arundo donax L. (Adx) is a geophytes and sinantropic species, native to the freshwaters regions of East Asia and widely cultivated for horticultural and medicinal uses since ancient times. Giant reed, an unusual C3 grass (high photosynthetic rates and little photoinhibition were observed), showed a strong metal tolerance, suitable for ecoremediation purposes. Pure stands of improved strains exhibited a longevity of +10 years, with a high annual yield of biomass (35 t ha-1 DM).Reduced input requirements (tillage, fertilizers, agrochemicals) and favorable harvest logistics increase the energy production efficiency of this perennial, sub-cosmopolite species. Due to desirable traits, it has been indicated as one of the most promising lignocellulosic herbaceous energy crop in the Mediterrean area. Recently Adx was investigated among potential feedstocks for cellulosic bioethanol in Southern Europe. Some agronomic and ecology aspects of Adx require further evaluation before spreading it on larger areas. In some countries, wild Adx is considered a noxious, invasive plant in riparian systems for its ease of spreading, dense stand, and suffocating canopy, uniquely through vegetative reproduction. Problems of rhizome dissemination, difficult soil and water reclamation of infested areas, reduced biodiversity and risks of fires are frequently claimed. However, none of the cited problems are related to Adx under controlled cultivation, where stripe planting, with alternate perennial and annual crops of native species, mitigate problems of reduced biodiversity, fire hazard, and dissemination. An agro-industrial project, with an estimated output of 40,000 mT/y cellulosic bioethanol, is in progress in Tuscany (Central Italy), based on Chemtex cellulosic bioethanol technology PROESA. This project will exploit some lowland, marginal areas, where Adx has already been introduced over the last decade as an energy crop (CHP plant). Adx will represent ½ - ¾ of the overall feedstock in input to the process, together with corn stalks and cereal straw, collected from nearby upland area