The aim of this study was to evaluate life cycle environmental impacts associated with the generation of electricity from biogas produced by the anaerobic digestion (AD) of agricultural products and waste. Five real plants in Italy were considered, using maize silage, slurry, and tomato waste as feedstocks and cogenerating electricity and heat; the latter is not utilized. The results suggest that maize silage and the operation of anaerobic digesters, including open storage of digestate, are the main contributors to the impacts of biogas electricity. The system that uses animal slurry is the best option, except for the marine and terrestrial ecotoxicity. The results also suggest that it is environmentally better to have smaller plants using slurry and waste rather than bigger installations, which require maize silage to operate efficiently. Electricity from biogas is environmentally more sustainable than grid electricity for seven out of 11 impacts considered. However, in comparison with natural gas, biogas electricity is worse for seven out of 11 impacts. It also has mostly higher impacts than other renewables, with a few exceptions, notably solar photovoltaics. Thus, for the AD systems and mesophilic operating conditions considered in this study, biogas electricity can help reduce greenhouse gas (GHG) emissions relative to a fossil-intensive electricity mix; however, some other impacts increase. If mitigation of climate change is the main aim, other renewables have a greater potential to reduce GHG emissions. If, in addition to this, other impacts are considered, then hydro, wind, and geothermal power are better alternatives to biogas electricity. However, utilization of heat would improve significantly its environmental sustainability, particularly global warming potential, summer smog, and the depletion of abiotic resources and the ozone layer. Further improvements can be achieved by banning open digestate storage to prevent methane emissions and regulating digestate spreading onto land to minimize emissions of ammonia and related environmental impacts.

Anaerobic Digestion (AD) has been recognized as a viable solution to produce renewable energy and to reduce global warming especially when secondary feedstock and/or wastes are used. Several LCA studies analysed the environmental performances of biogas production systems. The results of this review highlight that the goal, scope, life cycle impact assessment (LCIA) methodology, feedstocks and geographical regions covered by the studies vary widely. Most studies are based in Europe, several in China and few in South and North America and in Africa. To better highlight how the choices on the feeding mix, the digestate storage, the surplus heat valorisation as well as the plant size can affect the environmental performances of agricultural AD plants four plants have been analyzed in this study. The results suggest that the energy crops production and the operation of anaerobic digesters, including digestate emission from open tanks, are the main contributors to the impacts from biogas electricity. This entails that it is environmentally better to have smaller plants using slurry and waste rather than bigger plants fed with energy crops. Recovering heat waste as well as covering of digestate tank would improve significantly the environmental sustainability of biogas electricity, and particularly the global warming category. We are pleased to enclose the revised version of our original manuscript of our paper entitled "Agricultural anaerobic digestion plants: What LCA studies pointed out and what can be done to make them more environmentally sustainable" which can hopefully be published in Applied Energy.Many thanks to the reviewers for their comments; they helped us to improve the manuscript.We hope that the manuscript in the revised form is appropriate for publication in Applied Energy.On behalf of all the Authors, as corresponding Author, yours sincerely, Cover Letter Title: Agricultural anaerobic digestion plants: What LCA studies pointed out and what can be done to make them more sustainable Dear Editor, we would like to thank you for the reviewers' comments. We are grateful to all the reviewers for devoting their time to review our manuscript. As you can see, we have taken most of them into consideration to modify the paper. We hope that the paper in this current revised version can be accepted for publication. Below, we enclose an explanation of how we have addressed the questions raised. Reviewer #1The manuscript is working on the review of the environmental impacts of biogas production. It includes good results, an interesting methodology, and related to the scope of this Journal. I suggest to accept it after some minor revisions. Thank you for your positive comments and for useful suggestions.The authors should write about the difference between their study and the following research: * Hijazi, O., Munro, S., Zerhusen, B. and Effenberger, M., 2016. Review of life cycle assessment for biogas production in Europe. Renewable and Sustainable Energy Reviews, 54, 1291-300. Done, we specified in the int...

The aim of this study was to deepen the assessment of the environmental impacts of a white wine produced in Sardinia (FU 750 ml), performing an attributional LCA. The system boundaries were extended, from 'cradle to gate' (partial LCA) of a previous study, to 'cradle to grave' (total LCA), in order to identify the environmental impacts occurring along the wine life cycle stages (vine planting, grape production, wine production, bottling and packaging, distribution, final disposal of the glass bottle). Some assumptions were made in order to quantify the environmental impact of the transportation phase, regarding the few data which were available. Inventory data were mainly collected through direct communication with the Company involved in the study. Results showed that the environmental performance of wine was mostly determined by the glass bottle production (for all impact categories except ozone layer depletion). The second contributor was the agricultural phase, which included two sub-phases: vine planting and grape production. Results showed that the vine planting sub-phase was not negligible given its contribution to the agricultural phase, mainly due to diesel fuel consumption. Transportation impact was found to be relevant for long distance distribution (USA); the impact categories more affected by transport were acidification, eutrophication, photochemical oxidation and global warming potential. Suggested opportunities to reduce the overall environmental impact were the introduction of a lighter glass bottle or the substitution of the glass bottle with a polylaminate container.

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Despite its enormous size and economic value, there is currently scant information on environmental impacts from the catering sector. At the same time, the awareness of and preferences for environmentally sustainable food preparation and consumption are growing. In general, two catering approaches are practiced: cook-serve and deferred. In the former, food is cooked and immediately served to consumers while the latter allows for the food to be prepared at times and places completely different from consumption. This study, based in Italy, focuses on environmental impacts of deferred catering with the aim of evaluating different options for food preparation and distribution, to help identify environmentally sustainable solutions. For these purposes, the case of pasta, one of the most popular foods worldwide, is considered. Two main types of deferred system (cook-warm and cook-chill) and cooking technologies (pasta cookers and range tops) used in the catering sector are evaluated. The results suggest that cooking in pasta cookers saves up to 60% of energy and 38% of water compared to range tops and therefore reduces by 34-66% the impacts associated with pasta preparation. The environmental impacts of pasta cooking could also be reduced by using gas rather than electric appliances as the impacts of the latter are higher by 13-98%. In the current study, pasta cooking is the major hotspot in both the cook-chill and cook-warm chains. Overall, the impacts from the cook-chill chain are 17-96% higher than from the cook-warm system, mainly because of the use of refrigerants and higher consumption of energy.

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Barley is an ancient crop and a great source of nutrients. It is the third largest agricultural commodity produced in Denmark and represents a relevant crop in Italy too. Due to the increasing customers awareness of sustainability issues, it has become essential to evaluate the environmental impact and the use of resources in food production and distribution systems. However, especially in agriculture, difficulties are encountered when emissions from fertilisers and pesticides need to be modelled, due to a variety of modelling options and their dependency on the availability of site-specific information. How to address these difficulties might affect the results reliability. Hence, this study aims to evaluate, using the life cycle assessment (LCA) methodology, the influence of different models for estimating emissions from fertilisers and pesticides on the environmental impacts of barley cultivation in Denmark and Italy. Two models for fertilisers and pesticides' emissions have been applied; these differ on the extent of data requirements and complexity of calculation algorithms, which might increase the results accuracy and robustness. The results show that the modelling options do affect the environmental impacts of barley production, in particular climate change, eutrophication categories, acidification and freshwater eco-toxicity. This study estimates that the variations for such categories range from 15% in the case of climate change to 89% in the case of marine eutrophication. These findings highlight the importance of the emission modelling options as well as the constraints of data requirements, critical aspects when a LCA study on agricultural products is carried out.