Combustibility of biomass from perennial crops cultivated on a rewetted Mediterranean peatland

A paludicultural experiment was conducted in the Massaciuccoli Lake Basin (Tuscany, IT) to test this restoration strategy to reduce water eutrophication and subsidence phenomena of peat soils. The species tested were three perennial rhizomatous grasses (PRGs), Arundo donax, Miscanthus x giganteus, Phragmites australis, and two woody crops managed as short-rotation coppice (SRC), Populus x canadensis ‘Oudemberg’ and Salix alba ‘Dimitrios’, each of these species promising high productivity under wet conditions. The study aimed to test the combustibility of their harvested biomass as a function of crop age and harvest date. Parameters important for combustion and exhaust gas emissions were analyzed: ash content, concentration of chlorine (Cl), sulfur (S), nitrogen (N), phosphorus (P), carbon (C), hydrogen (H), calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na). Results indicated that the SRC crops appeared the most suitable for combustion. A general improvement in biomass quality with crop age was found for all crops tested, showing a significantly lower concentration of critical elements (Cl, N, S) and ash content in the 3rd year after planting. The biomass quality of PRGs was not significantly improved by a delayed harvest in February, as successfully practiced in northern Europe. In general, although concentrations of the most important critical elements were higher than expected for all crops, the calculated higher heating values were promising. Combustibility performances could be improved by finding an optimal mixture of SRC and PRG biomass.