Future potentials of sustainable wood fuel from forests in Switzerland

We developed a conceptual framework to quantify the effects of ecological and economic constraints on the spatio-temporal availability of wood fuel from forests. Based on the Swiss National Forest Inventory and the forest management models MASSIMO and HeProMo, a cascade of wood fuel potentials was simulated over a 40-year period for three forest management scenarios and two wood fuel market situations as well as with and without subsidies for managing protection forests. Non-energy material use and ecological constraints greatly reduce the theoretical potential (TP), or wood production, of 9–16 M m³/a or 67–118 PJ/a to an ecologically sustainable potential of about one half to one third of TP. Additionally, economic constraints further reduce wood fuel availabilities to one third to one fifth of TP, which represents the ecologically and economically sustainable potential (1.2–5.3 M m³/a or 10–41 PJ/a). Compared to the current forest management scenario, scenarios to reduce growing stock increase additional available wood fuel amounts two- to seven-fold to non-trivial 1–14 PJ/a, predominantly in the short term. Favorable wood fuel markets increase availabilities by ~22%, and subsidies by ~25%, particularly in the alpine regions. The Central Plateau and Jura are the most promising regions for expanding wood fuel mobilization, where untapped potentials are greatest and dependence on subsidies lowest. Wood fuel potentials are flexible over time and are highly sensitive to wood and energy prices. Reducing growing stocks is a reasonable strategy to mobilize more wood fuel during the energy transition to bridge provisioning gaps of other renewables.