Multiscale analysis for the valorization of biomass via pellets production towards energy security

The defossilization of household heating systems is one of the paramount goals of renewable energy, where pellets are regarded as a promising option. A multiscale techno-economic analysis is performed to determine first the raw material yield to pellets as well as estimating CAPEX and OPEX as a function of the biomass processed. Next, the location of the facilities is evaluated in the agricultural counties of Castilla y León through the formulation of a MILP facility location problem, including economic, social, and environmental objectives. The lignocellulosic materials considered are pinewood, eucalyptus wood, corn stover, and switchgrass. For substituting the natural gas-powered boilers in towns with over 500 inhabitants, 860,000 t/yr of pellets will be necessary. 98.1% substitution is achieved deploying 13 pellet plants, 11 based on pinewood and 2 on corn stover, representing 26.4% of the resources available and it is necessary to invest 164.8 M€ with an annual profitability of 133.0 M€. The emissions substituting these boilers are reduced by 94.8%. Switchgrass is studied separately as it is not currently grown in Castilla y León, although, its introduction would decrease the OPEX from 127.5 €/t to 63.9 €/t while the social and environmental impact is adversely affected.