Greenhouse gas mitigation potential of a second generation energy production system from short rotation poplar in Eastern Germany and its accompanied uncertainties

This study investigates the variance of the overall greenhouse gas mitigation potential of a complete second generation stationary bio-electricity production system, generated by poplar wood chips (Populus spec.) in Germany, using Monte Carlo simulations. We computed the GHG emissions as EB = (−0.034 ± 0.021) kg CO2e MJ−1 (mean ± SD) and the mitigation factor as MFB = (0.274 ± 0.021) kg CO2e MJ−1 following a life cycle assessment-based approach. Additionally, avoided nitrous oxide (N2O) emissions due to land use change were considered in the assessment. The most important factor for the overall mitigation variability was the uncertainty of the organic carbon changes in the soil, followed by the variability of yields. The uncertainty of (i) direct N2O emissions from the poplar site or (ii) the reference rye site as well as (iii) the uncertainty of heat recovery percentage was of minor importance. Uncertainties in the global warming potentials of nitrous oxide and methane and in the transport distance were found to be irrelevant. The uncertainty of the GHG mitigation which was associated with this specific electricity generation by poplar wood chips gasification was significantly lower compared to the variability of another common bio-electricity system (biogas). Uncertainty implications seem to be system-specific and therefore should be analysed separately for each bioenergy pathway under consideration. -- Highlights: •0.274 ± 0.021 kg CO2e mitigation MJ−1 from poplar wood chips gasification. •Variability of soil organic carbon was most important for the mitigation uncertainty. •Overall variability was lower compared to the variability of bio-electricity from biogas. •Bioenergy systems should be analysed separately regarding their uncertainty aspects