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Abstract Electricity is considered the most versatile form of energy derived from commonly used primary source of energy; fossil fuels. Sri Lanka forecast 6.5% annual growth in the demand for electricity, where the recent generation mix (in 2016) comprised of 25% hydro power, 31% oil, 35% coal and 9% renewables, with continued growth in wind and solar energy systems. The national Energy Policy targeted to reach minimum 10% of the demand for gird electricity using non-conventional renewable energy by 2015, and the policy now is to use only renewable energy sources for electricity generation by 2050 through installing large scale wind, solar and biomass power plants. In the path to achieve this growth and transformation, the challenge is to use resources and materials with minimum environmental consequences and damages in construction, operation and deconstruction phases of power plants. This paper looks in to possible environmental consequences, based on life cycle analysis, arising out of different electricity generation mixes comprising thermal, hydro, wind and solar energy. The study shows that, in meeting the electricity demand in 2050 using either solar or wind power alone, or through a mix of the two, would have adverse environmental impacts on freshwater and marine ecotoxicity, urban land occupation, metal depletion, agricultural land occupation and natural land transformation, whereas hydropower adds impact towards water depletion too. It is evident from the results that, in Sri Lanka, future electricity generation mix between wind and solar energy has to be determined mainly considering the land occupation and metal depletion impact categories. Further, the results point to the essential need for a national integrated waste management policy in decommissioning power plants; existing fossil fueled power plants and new large scale solar and wind based power plants, to avoid more adverse environmental impacts associated with decommissioning of different types of power plants. Highlights • The study is about environmental impacts of electricity generation in Sri Lanka. • The evaluation is based on life cycle assessment. • This work discusses environmental merits and demerits of different generation mixes. [ABSTRACT FROM AUTHOR]

Current assessments of the environmental performance of biofuel chains are fraught by a large degree of variability and uncertainty arising from differences in life cycle inventory data for the feedstock production stage, notably crop yields and emissions of reactive nitrogen. This study sets out to improve the accuracy of these data by combining agro-ecosystem modelling and agronomic survey data, in the context of biodiesel production from winter oilseed rape in France. Crop yields and environmental emissions related to crop farming were simulated over the 2010–2030 time period in 8 administrative regions accounting for most of winter oilseed rape production, and the results were fed into a life cycle assessment (LCA) of biodiesel. The effects of changes in climate scenarios and the improvement of fertilization practices were also examined. Compared to the widely used methodology based on fixed emissions factors, ecosystem modelling led to 29–41% lower estimates for direct nitrous oxide (N 2 O) emissions, depending on climate scenarios, which emphasizes the importance of taking local factors into account. The life cycle GHG emissions of biodiesel from winter oilseed rape varied starkly across the studied regions, from 20.6 to 25.7 g CO 2 eq MJ −1 and from 22.9 to 32.4 g CO 2 eq MJ −1 depending on climate scenarios. Overall, biodiesel deployment would abate GHG emissions by 65–78% compared to fossil diesel, not accounting for land use changes effects. Improved fertilization practices mitigated the LCA impact indicators by 3–14%. [ABSTRACT FROM AUTHOR]

Microalgae have been studied as a potential alternative raw material and various technologies have been proposed to transform the algal biomass into energy products. In this study, two bioenergy production systems of very different complexities were modelled to assess their environmental efficiencies: a biodiesel system and a biogas system. Biodiesel system used supercritical extraction and transesterification as key processes; to the best of authors' knowledge, there is no previous work analysing the environmental performances of such production system. Cumulative energy demand, Life Cycle Assessment (LCA) and dynamic LCA for climate change were used to evaluate the environmental footprint of the production systems. Conventional systems for electricity, heat and diesel production were considered for comparison. Energy balance showed that the supercritical extraction and drying steps were the most energy consuming unit operations in biodiesel production and further developments of technologies might be envisaged. LCA showed that climate change was the main contributor to impacts on human health and ecosystem quality due to energy consumed in production steps. Also, heat from biogas was the only product that proved to have a satisfactory environmental performance with regard to other conventional production systems. Finally, dynamic climate change evaluation (used for the first time for bio-chemical processes) revealed no carbon sequestration in microalgae system. [ABSTRACT FROM AUTHOR]

There is a growing awareness of the climate impact of agricultural production, not least from cattle farms. Major sources of GHG emissions from milk production are enteric fermentation followed by fossil fuel use and manure/soil management systems. This study analyzes the potential to eliminate fossil fuel use from milk production farms in Sweden, by using residual farm resources of biomass to obtain self-sufficiency in fuel, heat and electricity. The change from a fossil-based energy system to a renewable system based on A) Biogas based on manure and straw and B) Biogas based on manure + RME were analyzed with consequential life cycle assessment (CLCA) methodology. Focus was energy use and GHG emissions and the functional unit was 1 kg of energy-corrected milk (ECM). The results show that organic milk producers can become self-sufficient in energy and reduce total GHG emissions from milk production by 46% in the Biogas system, or 32% in the Biogas + RME system compared to the Fossil system. [ABSTRACT FROM AUTHOR]

Co-production of high-value biobased products in biorefineries is a promising option for optimized utilization of biomass. Lignocellulosic materials such as agricultural and forest residues have been identified as attractive alternative feedstocks because of their high availability and low resource demand. This study assessed the greenhouse gas (GHG) performance and energy balance of ethanol co-production with biogas and electricity in biorefineries using straw and forest residues. Two calculation methods were used: Method I (ISO), which applied the international standard for life cycle assessment, and Method II, which applied the EU Renewable Energy Directive (RED) methodology. These methods differed in allocation procedure, functional unit and system boundaries. Analysis of the importance of significant methodological choices and critical parameters showed that the results varied depending on calculation method, with co-product handling and the inclusion of upstream impacts from residue harvesting explaining most of the differences. Important life cycle steps were process inputs in terms of enzymes and changes in soil organic carbon content due to removal of residues. Ethanol produced from forest residues generally gave lower GHG emissions than straw-based ethanol. The GHG savings for both feedstocks were 51–84% relative to fossil fuel. Omission of upstream impacts from residue recovery in agriculture and forestry in the RED method means that it risks overlooking important environmental effects of residue reuse. Furthermore, the default allocation procedure used in the RED method (energy allocation) may need revision for biorefineries where multiple products with different characteristics are co-produced. [ABSTRACT FROM AUTHOR]