Abstract This article presents the results of an 11-year field experiment (2008–2018) conducted in Poland to investigate the biomass yield and energy efficiency of fodder galega (Galega orientalis Lam.) in high-input and low-input production technologies. The demand for energy in the production of fodder galega biomass ranged from 13.0 to 14.2 (year of plantation establishment) to 6.4–8.2 GJ ha−1 (years 2–11). Agricultural intensification increased energy inputs by 11% on average. Dry matter yield (DMY) and energy output peaked in years 4 and 5 (14.7–15.3 Mg ha−1 and 122.4–131.1 GJ ha−1, respectively). In the high-input production technology, DMY was 0.62 Mg ha−1 y−1 higher, energy output was 4.9 GJ ha−1 y−1 higher, the maximum DMY was achieved one year later, and the rate of decrease in biomass yield and energy output in the last years of the experiment (years 9–11) was 30% lower in comparison with the low-input system. The energy efficiency ratio of fodder galega ranged from 2.28 to 2.42 (year 1) to 8.04–16.53 (years 2–11). Productivity was 4% higher in the low-input than in the high-input technology. Fodder galega biomass was characterized by higher energy efficiency in the high-input technology (by approx. 2–12%) only in the last years of the experiment (years ≥10).