International audienceThis study presents an analysis of the environmental performances of Enhanced Geothermal Systems (EGS) located in central Europe based on life cycle assessment (LCA) of ten significant design options. Each of those is identified with a set of several technical parameters including the risk of induced seismicity. Results show that EGS impacts are comparable to those of other renewable energy technologies and significantly lower than those of conventional power plants. A comparison of the ten scenarios enables us to formulate recommendations on the environmental suitability of their design. Moreover, it emerges from this study that the risk of induced seismicity is a key discriminating factor, as it increases proportionally to the environmental benefit. The model based on five impact categories presented in this paper provides a useful tool for obtaining an overview of the environmental constraints of EGS installations and can be replicated to evaluate possible analogous installations exploring other design options

This study presents a generic methodology to produce simplified models able to provide a comprehensive life cycle impact assessment of energy pathways. The methodology relies on the application of global sensitivity analysis to identify key parameters explaining the impact variability of systems over their life cycle. Simplified models are built upon the identification of such key parameters. The methodology is applied to one energy pathway: onshore wind turbines of medium size considering a large sample of possible configurations representative of European conditions. Among several technological, geographical, and methodological parameters, we identified the turbine load factor and the wind turbine lifetime as the most influent parameters. Greenhouse Gas (GHG) performances have been plotted as a function of these key parameters identified. Using these curves, GHG performances of a specific wind turbine can be estimated, thus avoiding the undertaking of an extensive Life Cycle Assessment (LCA). This methodology should be useful for decisions makers, providing them a robust but simple support tool for assessing the environmental performance of energy systems.

8In life cycle assessments of wind turbines and, more generally, of Renewable Energy Systems (RES), environmental 9 impacts are usually normalized by electricity production to express their performance per kilowatt-hour. For most RES, 10 manufacture and installation dominate the impacts. Hence, results are sensitive to parameters governing both impacting 11 phases and electricity production. Most available studies present the environmental performance of generic wind 12 turbines with assumed fixed values for sensitive parameters (e.g. electricity production) that often vary between studies 13 and fail to reflect specificities of wind farm projects. This study presents an approach to build a comprehensive 14 parameterized model that generates unique wind turbine life cycle inventories conditioned by technologically, 15 temporally and geographically-sensitive parameters. This approach allows for the characterization of the carbon 16 footprint of five sets of turbines in Denmark, where wind power is highly developed. The analysis shows disparities 17 even between turbines of similar power output, mostly explained by the service time, load factor and components 18 weights but also by background processes (evolution of electricity mix and recycled steel content). Project-specific 19 inventories with technologically, temporally and geographically-sensitive parameters are essential for supporting RES 20 development projects. Such inventories are especially important to evaluate highly-renewable electricity mixes, such as 21 that of Denmark. 22 Keywords: wind turbine, parameterized model, life-cycle assessment, spatio-temporal variability, carbon footprint. 23 24 2 2 1 Introduction 25 Increasingly competing with conventional energy sources, Renewable Energy Systems (RES) offer a way out of fossil 26 fuels dependency and allow to reduce greenhouse gas emissions (GHG) associated with the generation of electricity [1]. 27The latter, together with heat production, still represents 42% of the world GHG emissions in 2015 per the International 28 Energy Agency. The importance of RES is visible as the installed capacity of these systems increased by 30% 29 worldwide in the last 40 years. However, their development must be intensified and combined with energy efficiency 30 measures to reduce the GHG emissions at a global level, since the electricity demand has more than doubled during that 31 same period [2]. 32In parallel to this development, numerous Life Cycle Assessment (LCA) studies analyzed the performance of RES and 33 their increasing role in regional and national electricity mixessee [3] in the context of Denmarkas well as at 34 worldwide levelsee [4]. LCA has proven to be a relevant tool to analyze the performance of different electricity 35 generation systems [5][6][7][8]. LCA includes all the environmentally-relevant phases of the value chain of electricity 36 production system: from the capture and conversion of primary energy, via the construction, maintenance and disposal 37 of the plant to transform it, down to i...

This study characterizes the environmental performances of large-scale ground-mounted PV installations by considering a life-cycle approach. The methodology is based on the application of the existing international standards of Life Cycle Assessment (LCA). Four scenarios are compared, considering fixed-mounting structures with (1) primary aluminum supports or (2) wood supports, and mobile structures with (3) single-axis trackers or (4) dual-axis trackers. Life cycle inventories are based on manufacturers' data combined with additional calculations and assumptions. Fixed-mounting installations with primary aluminum supports show the largest environmental impact potential with respect to human health, climate change and energy consumption. The climate change impact potential ranges between 37.5 and 53.5 gCO 2 eq/kWh depending on the scenario, assuming 1700 kWh/m².yr of irradiation on an inclined plane (30°), and multi-crystalline silicon modules with 14% of energy production performance. Mobile PV installations with dual-axis trackers show the largest impact potential on ecosystem quality, with more than a factor 2 of difference with other considered installations. Supports mass and composition, power density (in MWp/acre of land) and energy production performances appear as key design parameters with respect to large-scale ground mounted PV installations environmental performances, in addition to modules manufacturing process energy inputs.

International audienceComposite indicators are synthetic indices that are used to rank country performances in specific policy areas. Many do, however, suffer from methodological difficulties. Specific difficulties linked to indices for environmental sustainability are analyzed through the illustration of several sets. The most critical issues are linked with a poor analytical framework and a lack of common unit for the aggregation. Some measure directly the state of the environment while other use proxies such as pressure or response indicators or even a mix of these. A new composite index for environmental sustainability was developed in the EU project EPSILON, which aimed at assessing European regional sustainability for policy decision making related to the improvement of regional sustainability. Indicators are expressed according to a coherent framework issuing from the ‘driving force–pressure–state–impact–response' approach with an innovative weighting scheme derived from human health impact assessment based on disability adjusted life years (DALYs). Results are compared with a more conventional aggregation technique based on an equal weighting coupled to various normalization technique

Task 12 SustainabilityTask 12 Sustainability -Methodological Guidelines on Net Energy Analysis of Photovoltaic Electricity What is IEA PVPS TCP?The International Energy Agency (IEA), founded in 1974, is an autonomous body within the framework of the Organization for Ec onomic Cooperation and Development (OECD). The Technology Collaboration Programme (TCP) was created with a belief that the future of energy security and sustainability starts with global collaboration. The programme is made up of 6.000 experts across government, academia, and industry dedicated to advancing common research and the application of specific energy technologies.The IEA Photovoltaic Power Systems Programme (IEA PVPS) is one of the TCP's within the IEA and was established in 1993. The mission of the programme is to "enhance the international collaborative efforts which facilitate the role of photovoltaic solar energy as a cornerstone in the transition to sustainable energy systems." In order to achieve this, the Programme's participants have undertaken a va riety of joint research projects in PV power systems applications. The overall programme is headed by an Executive Committee, comprised of one delegate from each country or organisation member, which designates distinct 'Tasks,' that may be research projects or activity areas.

In the life cycle assessment (LCA) context, global sensitivity analysis (GSA) has been identified by several authors as a relevant practice to enhance the understanding of the model's structure and ensure reliability and credibility of the LCA results. GSA allows establishing a ranking among the input parameters, according to their influence on the variability of the output. Such feature is of high interest in particular when aiming at defining parameterized LCA models. When performing a GSA, the description of the variability of each input parameter may affect the results. This aspect is critical when studying new products or emerging technologies, where data regarding the model inputs are very uncertain and may cause misleading GSA outcomes, such as inappropriate input rankings. A systematic assessment of this sensitivity issue is now proposed. We develop a methodology to analyze the sensitivity of the GSA results (i.e. the stability of the ranking of the inputs) with respect to the description of such inputs of the model (i.e. the definition of their inherent variability). With this research, we aim at enriching the debate on the application of GSA to LCAs affected by high uncertainties. We illustrate its application with a case study, aiming at the elaboration of a simple model expressing the life cycle greenhouse gas emissions of enhanced geothermal systems (EGS) as a function of few key parameters. Our methodology allows identifying the key inputs of the LCA model, taking into account the uncertainty related to their description.

International audienceA coupled Life Cycle Costing and life cycle assessment has been performed for car-bodies of the Korean Tilting Train eXpress (TTX) project using European and Korean databases, with the objective of assessing environmental and cost performance to aid materials and process selection. More specifically, the potential of polymer composite car-body structures for the Korean Tilting Train eXpress (TTX) has been investigated. This assessment includes the cost of both carriage manufacturing and use phases, coupled with the life cycle environmental impacts of all stages from raw material production, through carriage manufacture and use, to end-of-life scenarios. Metallic carriages were compared with two composite options: hybrid steel-composite and full-composite carriages. The total planned production for this regional Korean train was 440 cars, with an annual production volume of 80 cars. The coupled analyses were used to generate plots of cost versus energy consumption and environmental impacts. The results show that the raw material and manufacturing phase costs are approximately half of the total life cycle costs, whilst their environmental impact is relatively insignificant (3-8%). The use phase of the car-body has the largest environmental impact for all scenarios, with near negligible contributions from the other phases. Since steel rail carriages weigh more (27-51%), the use phase cost is correspondingly higher, resulting in both the greatest environmental impact and the highest life cycle cost. Compared to the steel scenario, the hybrid composite variant has a lower life cycle cost (16%) and a lower environmental impact (26%). Though the full composite rail carriage may have the highest manufacturing cost, it results in the lowest total life cycle costs and lowest environmental impacts. This coupled cost and life cycle assessment showed that the full composite variant was the optimum solution. This case study showed that coupling of technical cost models with life cycle assessment offers an efficient route to accurately evaluate economic and environmental performance in a consistent way