Economic assessment of Eucalyptus globulus short rotation energy crops under contrasting silvicultural intensities on marginal agricultural land
Abstract
Evolving bioenergy markets requires consideration of marginal lands for woody biomass production worldwide. Growing short rotation woody crops for bioenergy (SRWCs) on marginal land minimizes concerns about using croplands for agricultural production and reinforces sustainability of wood supply. Evaluation of the profitability of marginal land that may have SRWCs potential as sources of biomass for energy production has been rarely reported. This study attempts to account for investments uncertainties on SRWCs production considering Eucalyptus globulus managed under contrasting silvicultural intensities on marginal land by comparing four environments and four levels of initial planting density. Our study consider biomass yields over this gradient of productivity and biomass market prices and costs from local contractors. We estimated mean annual aboveground dry biomass increments (MAIs) and evaluated the economic feasibility of various cycles of harvest (2–6 years) using Monte Carlo simulation to examine how uncertainty over the input variables affects NPV of SRWCs. MAIs that ranged 3.91–18.07 Mg ha−1 yr−1 increased with stand density and harvesting age. Rotation length affected economic outcomes although the returns were poor due to high establishment and maintenance costs, low productivities and low biomass prices. Under an average scenario, current market price of biomass, absence of subsidies and current costs, SRWC are not profitable when productivities are lower than 351m3 ha−1 of green biomass.