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Renewable energy systems are especially challenging both in terms of planning and operation. Energy system models that take into account not only the costs but also a wide range of environmental impacts support holistic planning. In this way, burden-shifting caused by greenhouse gas mitigation can be identified and minimised at an early stage. The Life cycle Assessment based ENergy Decision support tool LAEND combines a multi-criteria optimising tool for energy system modelling and an integrated environmental assessment for the analysis of decentral systems. By a single or multi-objective optimisation, considering costs, environmental impact indicators as well as weighted impact indicator sets, the model enables the determination of optimal investment planning and dispatch of the analysed energy system. The application of LAEND to an exemplary residential quarter shows the benefit of the model regarding the identification of conflicting goals and of a system that compensates for the different objectives. The observed shift of environmental impacts from the use phase to the production phase of the renewable electricity generators points further to the importance of the integration of the entire life cycle.

We integrate life cycle indicators for various technologies of an energy system model with high spatiotemporal detail and a focus on Europe and North Africa. Using multi-objective optimization, we calculate a pareto front that allows us to assess the trade-offs between system costs and life cycle greenhouse gas (GHG) emissions of future power systems. Furthermore, we perform environmental ex-post assessments of selected solutions using a broad set of life cycle impact categories. In a system with the least life cycle GHG emissions, the costs would increase by ~63%, thereby reducing life cycle GHG emissions by ~82% compared to the cost-optimal solution. Power systems mitigating a substantial part of life cycle GHG emissions with small increases in system costs show a trend towards a deployment of wind onshore, electricity grid and a decline in photovoltaic plants and Li-ion storage. Further reductions are achieved by the deployment of concentrated solar power, wind offshore and nuclear power but lead to considerably higher costs compared to the cost-optimal solution. Power systems that mitigate life cycle GHG emissions also perform better for most impact categories but have higher ionizing radiation, water use and increased fossil fuel demand driven by nuclear power. This study shows that it is crucial to consider upstream GHG emissions in future assessments, as they represent an inheritable part of total emissions in ambitious energy scenarios that, so far, mainly aim to reduce direct CO2 emissions.

Purpose Following water, tea is the second most consumed drink worldwide and has the peculiarity that not only its production but especially its preparation can be associated with considerable greenhouse gas (GHG) emissions. The aims of this study were to calculate the cradle-to-gate and cradle-to-grave product carbon footprint (PCF) of Darjeeling tea and to identify potentials to reduce GHG emissions along its life cycle. Therefore, various options for action and their impact on the PCF were modeled by using a scenario analysis. Methods To assess the PCF of Darjeeling tea, the method based on ISO/TS 14067 was used with some limitations. Besides one base scenario, alternative cradle-to-gate scenarios and different use profiles were modeled. The results were split in a cradle-to-gate and a cradle-to-grave perspective. For the cradle-to-gate phase a functional unit of one kilogram loose black Darjeeling tea was chosen, whereas for the cradle-to-grave phase one liter black Darjeeling tea that is prepared and ready to drink in Germany was seen as appropriate functional unit. Primary data for the present study has been collected from local farmers, manufacturers, and agents in Darjeeling, Kolkata, and Rotterdam. For secondary data, the database ecoinvent 2.2 was mainly used. Results and discussion The cradle-to-gate PCF of 1 kg Darjeeling tea is between 7.1 and 25.3 kg CO 2 e depending on the cultivation method, energy sources used, or mode of transportation. The cradle-to-grave PCF for 1 l organic Darjeeling tea is about 0.15 kg CO 2 e. The largest share, 51 %, makes up the use phase, which is clearly dominated by the boiling of water. The variety of possible use profiles yields results of great breadth. It shows that the life cycle of organic Darjeeling tea transported by ship, depending on the preparation variants can cause emissions from 0.12 to 0.51 kg CO 2 e/l tea. Conclusions The main reduction potentials for GHG emissions were identified in the process of water boiling, the intercontinental transport mode, and the cultivation method. Since the climate impact of tea strongly depends on the way in which it is prepared, the consumer has a decisive influence on the PCF. Therefore, in order to make a reliable statement about the climate performance of consumer goods such as tea, the whole life cycle must be considered.

Sustainable development embraces a broad spectrum of social, economic and ecological aspects. Thus, a sustainable transformation process of energy systems is inevitably multidimensional and needs to go beyond climate impact and cost considerations. An approach for an integrated and interdisciplinary sustainability assessment of energy system transformation pathways is presented here. It first integrates energy system modeling with a multidimensional impact assessment that focuses on life cycle-based environmental and macroeconomic impacts. Then, stakeholders’ preferences with respect to defined sustainability indicators are inquired, which are finally integrated into a comparative scenario evaluation through a multi-criteria decision analysis (MCDA), all in one consistent assessment framework. As an illustrative example, this holistic approach is applied to the sustainability assessment of ten different transformation strategies for Germany. Applying multi-criteria decision analysis reveals that both ambitious (80%) and highly ambitious (95%) carbon reduction scenarios can achieve top sustainability ranks, depending on the underlying energy transformation pathways and respective scores in other sustainability dimensions. Furthermore, this research highlights an increasingly dominant contribution of energy systems’ upstream chains on total environmental impacts, reveals rather small differences in macroeconomic effects between different scenarios and identifies the transition among societal segments and climate impact minimization as the most important stakeholder preferences.

Increasing the share of renewable energies in electricity and heat generation is the cornerstone of a climate-friendly energy transition. However, as renewable technologies rely on diverse natural resources, the design of decarbonized energy systems inevitably leads to environmental trade-offs. This paper presents the case study of a comprehensive impact assessment for different future development scenarios of a decentralized renewable energy system in Germany. It applies an adapted ecological scarcity method (ESM) that improves decision-support by ranking the investigated scenarios and revealing their main environmental shortcomings: increased mineral resource use and pollutant emissions due to required technical infrastructure and a substantial increase in land use due to biomass combustion. Concerning the case study, the paper suggests extending the set of considered options, e.g., towards including imported wind energy. More generally, the findings underline the need for a comprehensive environmental assessment of renewable energy systems that integrate electricity supply with heating, cooling, and mobility. On a methodical level, the ESM turns out to be a transparent and well adaptable method to analyze environmental trade-offs from renewable energy supply. It currently suffers from missing quantitative targets that are democratically sufficiently legitimized. At the same time, it can provide a sound basis for an informed discussion on such targets.

Background Given the multitude of scenarios on the future of our energy systems, multi-criteria assessments are increasingly called for to analyze and assess desired and undesired effects of possible pathways with regard to their environmental, economic and social sustainability. Existing studies apply elaborate lists of sustainability indicators, yet these indicators are defined and selected by experts and the relative importance of each indicator for the overall sustainability assessments is either determined by experts or is computed using mathematical functions. Target group-specific empirical data regarding citizens’ preferences for sustainability indicators as well as their reasoning behind their choices are not included in existing assessments. Approach and results We argue that citizens’ preferences and values need to be more systematically analyzed. Next to valid and reliable data regarding diverse sets of indicators, reflections and deliberations are needed regarding what different societal actors, including citizens, consider as justified and legitimate interventions in nature and society, and what considerations they include in their own assessments. For this purpose, we present results from a discrete choice experiment. The method originated in marketing and is currently becoming a popular means to systematically analyze individuals’ preference structures for energy technology assessments. As we show in our paper, it can be fruitfully applied to study citizens’ values and weightings with regard to sustainability issues. Additionally, we present findings from six focus groups that unveil the reasons behind citizens’ preferences and choices. Conclusions Our combined empirical methods provide main insights with strong implications for the future development and assessment of energy pathways: while environmental and climate-related effects significantly influenced citizens’ preferences for or against certain energy pathways, total systems and production costs were of far less importance to citizens than the public discourse suggests. Many scenario studies seek to optimize pathways according to total systems costs. In contrast, our findings show that the role of fairness and distributional justice in transition processes featured as a dominant theme for citizens. This adds central dimensions for future multi-criteria assessments that, so far, have been neglected by current energy systems models.

Energy storage is currently a key focus of the energy debate. In Germany, in particular, the increasing share of power generation from intermittent renewables within the grid requires solutions for dealing with surpluses and shortfalls at various temporal scales. Covering these requirements with the traditional centralised power plants and imports and exports will become increasingly difficult as the share of intermittent generators rises across Europe. Pumped hydropower storage plants have traditionally played a role in providing balancing and ancillary services, and continue to do so. However, the construction of new plants often requires substantial interventions into virgin landscape and bio-habitats; this is often fiercely opposed by local citizens. Utility-scale lithium ion batteries have recently entered the energy scene. Albeit much smaller than most pumped hydropower plants, they can also provide the required balancing and ancillary services. They can be constructed on brownfield sites as and where needed, to support the move towards increasingly decentralised energy systems. Although they are seen by some as a more environmentally friendly option, they do cause impacts relating to the consumption of limited natural resources during the production stage. Addressing initially technological capacity of pumped hydropower storage and utility-scale battery to meet the required services, a simplified LCA will be performed to examine the environmental impacts throughout their life cycles. This includes two sensitivity analyses. Issues addressed in this paper include also methodological issues relating to comparability and those parameters that are pivotal to the LCA result.

PURPOSE: The life cycle assessment of silicon wafer processing for microelectronic chips and solar cells aims to provide current and comprehensive data. In view of the very fast market developments, for solar cell fabrication the influence of technology and capacity variations on the overall environmental impact was also investigated and the data were compared with the widely used ecoinvent data. METHODS: Existing material flow models for silicon wafer processing for microelectronic chips and solar cells used for engineering and planning formed a starting point for this analysis. The models represent an average of widely used processes and associated process equipment. The resulting input/output tables formed the data basis for the life cycle assessment. This is a cradle-to-gate investigation, consisting of primary gate-to-gate data for wafer processing. The upstream processes of the necessary inputs were supplemented with data from ecoinvent v2.0. Subsequent manufacturing steps, utilization, and waste disposal of the final products were not included. The software used for creating the inventory and impact assessment was Umberto version 5.5. The Impact 2002+ method was applied for impact assessment. RESULTS: For both semiconductor and solar cell fabrication, energy consumption and upstream chemicals production are most relevant for the overall potential environmental impact when only the gate-to-gate processes are considered. The upstream process for wafer production is dominant in solar cell fabrication, but exerts little influence on semiconductor fabrication. In the case of semiconductor fabrication, a comparison with the present ecoinvent dataset “wafer, fabricated, for integrated circuit, at plant” shows large differences. CONCLUSIONS: In the case of silicon solar cells, the results of this study and the ecoinvent data are very similar and the impact of different fabrication processes appears to be minor.

This paper highlights specific challenges of applying LCA within an integrated resource efficiency analysis in the chemical industry and gives particular attention to allocation procedures. In a company case different allocation rules were applied. The results pointing in opposite directions clearly show that on the basis of product-related assessment any reliable derivation of resource efficiency potentials is possible. One approach to avoid these problems, are scenarios comparisons on overall system level. If material flow models mapping (non-linear) procedural dependencies realistic, different scenarios can be calculated and compared in economic and ecological revenue and effort changes without allocation and linearization become necessary.