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In developing countries dung cakes combustion as a household cooking fuel is a common practice; however this traditional fuel comes along with related environmental issues. The objective of this study was to assess the environmental impacts of the substitution of dung combustion by biogas systems in rural Ethiopia. For this purpose, the method of life cycle assessment was applied according to ISO 14040 and 14044 standards with a consequential life cycle assessment approach. In terms of greenhouse gas emissions, the results demonstrate that mainly avoided methane and nitrous oxide emissions from dung drying and dung combustion lead to an environmental advantage of biogas systems in all scenarios of this study. Also the utilization of biogas digestate as organic fertilizer contributes considerably to savings of greenhouse gas emissions. The results indicate that about 13′542t of carbon dioxide equivalents can be saved annually in Ethiopia by the biogas plants installed in the years 2009–2013. Dung combustion causes indoor pollution by releasing high amounts of nitrogen oxides and particulate matter emissions and thereby having a direct negative impact on health. These emissions can be reduced considerably when using biogas instead of dung cakes for the provision of household cooking energy. Substituting traditional energy sources - dung cakes - with biogas systems, would lead to primary energy demand savings as well as potential environmental advantages regarding global warming, eutrophication, acidification, terrestrial eco-toxicity and human toxicity. Besides that, lower emissions from plant-available nutrients as well as particulate matter reduction, can create the basis for more efficient agricultural systems and potentially increase the health of the rural population. Nonetheless, to ensure a reduction of global warming potential it is mandatory building technically mature biogas plants with low methane leakage. [ABSTRACT FROM AUTHOR]

The utilization of agricultural biomass for anaerobic digestion is increasing in Germany since the first version of the Renewable Energies Sources Act ( EEG) in 2000. Main products of this conversion process are biogas and digestate, whereby the biogas is mainly used for generation of heat and electricity in combined heat and power plants ( CHP). This study investigated the potential environmental impact of anaerobic digestion processes with different agricultural substrates by the life cycle assessment ( LCA) method. It focuses on liquid manure and energy crops as feedstock on the one hand and a comparison of four virtual model plants on the other hand. Besides global warming potential ( GWP), the impact categories eutrophication potential ( EP) and acidification potential ( AP) are presented in this work. The results show that greenhouse gas emissions can be reduced with anaerobic digestion of liquid manure as well as energy crops, particularly when digestate storage tanks are gas-tight. When energy crops are fermented together with liquid manure, the biggest credit for the avoidance of greenhouse gas emissions was given for the generation of electricity. The results differ from those of GWP when looking at the AP and the EP. These impact categories show similar results with a reduction of emissions for liquid manure in mono-digestion but increasing emissions for digestion of energy crops together with 0-35% liquid manure. [ABSTRACT FROM AUTHOR]

Food production causes large environmental impacts. In Switzerland, more than half of the initial potato production is not directly consumed by humans but lost. To analyze the environmental impacts caused by these losses, we conducted a Life Cycle Assessment concerning the demand for nonrenewable energy resources, the global warming potential, human toxicity and ecotoxicity (terrestrial and aquatic). We allocated these environmental impacts at each stage of the Swiss potato supply chain to marketable potatoes and potato losses. Furthermore, this study investigated how potential loss reduction scenarios and various loss treatments (animal feed, biogas, incineration) might affect the total ecological performance of the supply chain. The results showed that potato losses were responsible for 39% of the total terrestrial ecotoxicity, 31% of the total potato supply chain's global warming potential, 31% of its human toxicity, 27% of its aquatic ecotoxicity and 23% of its demand for nonrenewable energy resources. The results indicated in general that environmental benefits due to the loss treatments were bigger than benefits achieved by the loss reduction scenarios. Loss treatments, in particular feeding and fermentation, could reduce the examined impacts, but not generating losses represented a better option, especially at the household stage (the impacts here were 8–42 times as high as the impacts of losses at agricultural production). A combination of loss reduction and loss treatment could overcompensate the environmental impacts caused by potato losses because potatoes may be used to substitute for other goods. [ABSTRACT FROM AUTHOR]