Harvesting of wood for energy generation : a quantitative stand-level analysis in an Italian mountainous district

The first aim of the study was to present the methodology applied by the model WOody biomass and Carbon ASsessment to compute the past potentially available residues (RA; branches and tops only; t·yr−1 of dry matter, DM), potentially generated heat and electricity (TE, EE, respectively; GJ·yr−1) and potentially avoided CO2 emissions into the atmosphere (EM; t·yr−1 CO2) for the final combustion process. The available residues are computed at the forest stand level through a recovery rate based on six technical parameters. The methodology was applied to the public stands of Valle Camonica district (Italy) (total area: 3.67·104 ha; period: 1984–2016). The mass of residues calculated for that period was used to estimate the current supply, i.e. 2.15·103 ± 6.04·102 t·yr−1 DM. By assuming that this mass was used in an Organic Rankine Cycle (ORC) unit of a local centralized heating plant, TE = 2.06·104 ÷ 2.41·104 GJ·yr−1 and EE = 5.08·103 ÷ 5.95·103 GJ·yr−1. By assuming that: (i) heat generated by the ORC replaced heat produced by conventional natural gas-based plants; (ii) electricity generated by the ORC replaced electricity generated by Italian natural gas-based plants-mix (combined heat and electricity production) EM = 1.85·103 ÷ 2.17·103 t·yr−1 CO2.