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Abstract Poplar (Populus spp.) and willow (Salix spp.) short rotation coppice (SRC) are attractive feedstock for conversion to renewable electricity. Site managers typically optimize biomass production at their sites. However, maximum biomass production does not necessarily equate an optimal CO 2 balance, water use and energy production. This is because many operational actions consume water and energy and emit CO 2 , either on-site or off-site. Coupling a land surface model (ORCHIDEE-SRC) with life cycle assessment enabled us to determine the optimal management for SRC in Belgium. We simulated 120 different management scenarios for each of two well-studied Belgian SRC sites (i.e. Boom and Lochristi). Simulated soil carbon changes suggested substantial carbon losses of 20–30 Mg ha−1 over a time period of 20 years, which were within observation-based uncertainty bounds. Results showed that in Belgium, which has a temperate maritime climate, optimal management of SRC has a rotation cycle of two years without irrigation. Energy inputs for this optimal management were 5.2 GJ ha−1 yr−1 for the Boom site and 5.3 GJ ha−1 yr−1 for the Lochristi site, while the biomass yields at Boom and Lochristi were 9.0 Mg ha−1 yr−1 and 9.4 Mg ha−1 yr−1, respectively. The energy ratio (i.e., ratio of bioelectricity output to cumulative energy input) for this optimal management was 12, on average. Planting density turned out to be unimportant, while rotation length turned out to be most important to obtain the highest energy ratio and still maintain high biomass yield. Scenarios with high energy-input generated more bioenergy outputs, but the energy gains did not compensate for the increased energy inputs. Reductions in energy consumption per unit of bioenergy output should target the agricultural stage since it accounted for the largest energy share in the production chain. Highlights • Water use, CO 2 and energy balance of SRC were compared across managements regimes in Belgium using a modelling approach. • Variation in planting densities from 5000 to 15000 trees ha−1 showed no effect on SRC yields. • Irrigation benefits biomass production, but is energetically too costly to apply. • High energy ratios proved that SRC-based electricity production is energy efficient. • Optimal rotation length was two years without irrigation. [ABSTRACT FROM AUTHOR]

There is an ongoing debate regarding the influence of the source location of pollution on the fate of pollutants and their subsequent impacts. Several methods have been developed to derive site-dependent characterization factors (CFs) for use in life-cycle assessment (LCA). Consistent, precise, and accurate estimates of CFs are crucial for establishing long-term, sustainable air pollution abatement policies. We reviewed currently available studies on the regionalization of non-toxic air pollutants in LCA. We also extracted and converted data into indices for analysis. We showed that CFs can distinguish between emissions occurring in different locations, and that the different methods used to derive CFs map locations consistently from very sensitive to less sensitive. Seasonal variations are less important for the computation of CFs for acidification and eutrophication, but they are relevant for the calculation of CFs for tropospheric ozone formation. Large intra-country differences in estimated CFs suggest that an abatement policy relying on quantitative estimates based upon a single method may have undesirable outcomes. Within country differences in estimates of CFs for acidification and eutrophication are the results of the models used, category definitions, soil sensitivity factors, background emission concentration, critical loads database, and input data. Striking features in these studies were the lack of CFs for countries outside Europe, the USA, Japan, and Canada, the lack of quantification of uncertainties. Parameter and input data uncertainties are well quantified, but the uncertainty associated with the choice of category indicator is rarely quantified and this can be significant. Although CFs are scientifically robust, further refinements are needed before they can be integrated in LCA. Future research should include uncertainty analyses, and should develop a consensus model for CFs. CFs for countries outside Europe, Japan, Canada and the USA are urgently needed. [ABSTRACT FROM AUTHOR]

Smart grids (SGs) have a central role in the development of the global power sector. Cost-benefit analyses and environmental impact assessments are used to support policy on the deployment of SG systems and technologies. However, the conflicting and widely varying estimates of costs, benefits, greenhouse gas (GHG) emission reduction, and energy savings in literature leave policy makers struggling with how to advise regarding SG deployment. Identifying the causes for the wide variation of individual estimates in the literature is crucial if evaluations are to be used in decision-making. This paper (i) summarizes and compares the methodologies used for economic and environmental evaluation of SGs (ii) identifies the sources of variation in estimates across studies, and (iii) point to gap in research on economic and environmental analyses of SG systems. Seventeen studies (nine articles and eight reports published between 2000 and 2015) addressing the economic costs versus benefits, energy efficiency, and GHG emissions of SGs were systematically searched, located, selected, and reviewed. Their methods and data were subsequently extracted and analysed. The results show that no standardized method currently exists for assessing the economic and environmental impacts of SG systems. The costs varied between 0.03 and 1143 M€/yr, while the benefits ranged from 0.04 to 804 M€/yr, suggesting that SG systems do not result in cost savings The primary energy savings ranged from 0.03 to 0.95 MJ/kWh, whereas the GHG emission reduction ranged from 10 to 180 gCO 2 /kWh, depending on the country grid mix and the system boundary of the SG system considered. The findings demonstrate that although SG systems are energy efficient and reduce GHG emissions, investments in SG systems may not yield any benefits. Standardizing some methodologies and assumptions such as discount rates, time horizon and scrutinizing some key input data will result in more consistent estimates of costs and benefits, GHG emission reduction, and energy savings. [ABSTRACT FROM AUTHOR]