Greenhouse gas (GHG) reduction (positive values) or release (negative value) of a poplar SRC (ton CO₂-equivalent ha⁻¹) (± SD) under current and elevated [CO₂], managed for six rotations of two or three years.

ΔN2O emission from fertilization is calculated as a loss of 4% (30) from the amount of fertilizer added (see Table S5). δValues for CH4 mitigation were taken from [37]. ‡Cumulative sum of all fixed and variable costs during the course of the full life cycle (Table S1, S3, S4, and S5). The observed evolution of soil carbon is not an inherent property of the SRC system and was therefore omitted from the calculations. Hence, our calculations underestimate the beneficial effects of SRC when planted on former agricultural lands. We assumed a combined heat and power biomass plant displaces a combined heat and power coal plant with an emission of 103 g CO2 MJ−1 for the combined heat and electricity and 121 g CO2 MJ−1 for just the electricity production [36]. Since coal is among the most GHG emitting fuels, avoided emissions approximate the maximum possible avoided emissions. A combined heat and power gas plant emits 59 CO2 MJ−1 for its combined heat and electricity and 70 g CO2 MJ−1 for its electricity production [36]. The GHGB and mitigation potential for gas instead of coal substitution is given in Table S2.