Fast Growing Energy Forest (FGEF): Carbon-negative Biomass Production on Marginal Lands through Climate-resilient Willow Plantations

The transition to renewable energy systems requires sustainable biomass sources that do not compete with food production. This study investigates the Fast growing Energy Forest (FgEF) system as a carbon-negative solution based on the cultivation of fast-growing willow (Salix spp.) on marginal lands and along highways. Experimental plantations were established in the Right-Bank Forest-Steppe of Ukraine across different forest site conditions (A3, C3, and D3), including marginal agricultural lands and areas along transport infrastructure. Biometric parameters, including plant height, stem diameter, and survival rate, were measured over the first three years of cultivation. Biomass productivity and carbon sequestration potential were assessed using a stratified approach combined with an integrated Life Cycle Assessment (LCA) and Techno-Economic Analysis (TEA) framework. The results demonstrate that biomass productivity increases with improving site conditions, reaching 7.9, 11.05, and 13.8 t·ha.¹·yr.¹ for A3, C3, and D3 dry biomass, respectively. However, productivity under A3 conditions remains sufficient for economically viable biomass production. ANOVA analysis confirmed the significant influence of both cultivar and site conditions on growth performance. Economic modeling showed strong financial performance, with a payback period of 3–5 years depending on the implementation phase. At the European scale, the availability of 60–70 million hectares of marginal land, combined with additional biomass potential along transport corridors, could enable the production of up to 791 TWh of renewable energy annually. The findings confirm that the FgEF system represents a scalable, economically viable, and environmentally sustainable approach to biomass production, enabling the effective use of marginal lands while supporting decarbonization and energy independence without compromising food security.