Fabian Gemperle

Woody biomass from sustainable sources, from suitable assortments, and used with state-of-the-art combustion technologies is a renewable and environmentally friendly energy source. In combination with other renewable energies, such as solar, wind or hydropower, wood is an important component of an energy system that is no longer or only minimally based on fossil fuels. Technologies for converting woody biomass into energy are well understood, with various pathways available. However, a key challenge lies in precisely assessing the sustainable forest biomass or fuelwood availability, which has been the focus of numerous studies at the global, national and regional levels. In this study, we aim to assess Switzerland's realistic, sustainable forest fuelwood potential, focusing on local precision and spatially explicit estimation. This novel method is based on three key pillars: [1] initial stock volume estimation, [2] harvest intensity estimation, and [3] energy content estimation. For model fitting we used data from Switzerland's National Forest Inventory, which tracks changes in stock and harvest over time through 5 repeated surveys of more than 6000 plots, combined with remote sensing data. To verify the approach, we calculated a conservative fuelwood use scenario in which twigs and bark remain in the forest and assortments are fed into cascading use: in total, a yearly sustainable potential of around 19 PJ of dry wood is available. In many Swiss cantons, the sustainable fuelwood potential has already been reached, reflecting current forest management practices.