Progress in Life Cycle Assessment 2019

This preface introduces the contributions from young scientists and researchers participating in the 15th Ökobilanzwerkstatt in Stuttgart. It provides an overview of the growing relevance of establishing environmental aspects as a guideline in science, industry and politics. This results in an increased need to anchor life cycle assessments in the training of young scientists. Afterwards, the highlights of the Ökobilanzwerkstatt 2019 are presented and the topics of the publication in this book are introduced.

Estimates for the greenhouse gas emissions caused by maritime transportation account for approx. 870 million tonnes of CO₂ tonnes in 2018, increasing the awareness of the public in general and requiring the development of alternative propulsion systems and fuels to reduce them. In this context, the project HySeas III is developing a hydrogen and fuel cell powered roll-on/roll off and passenger ferry intended for the crossing between Kirkwall and Shapinsay in the Orkney Islands in Scotland, a region which currently has an excess of wind and tidal power. In order to explore the environmental aspects of this alternative, a life cycle assessment from cradle to end-of-use using the ReCiPe 2016 method was conducted, contrasting the proposed prototype developed within the project against a conventional diesel ferry and a diesel hybrid ferry. The results show that the use of hydrogen derived from wind energy and fuel cells for ship propulsion allow the reduction of greenhouse gas emissions of up to 89% compared with a conventional diesel ferry. Additional benefits are lower stratospheric ozone depletion, ionizing radiation, ozone formation, particulate matter formation, terrestrial acidification and use of fossil resources. In turn, there is an increase in other impact categories when compared with diesel electric and diesel battery electric propulsion. Additionally, the analysis of endpoint categories shows less impact in terms of damage to human health, to the ecosystems and to resource availability for the hydrogen alternative compared to conventional power trains.

This article applies the Well-to-Wheels (WTW) methodology in order to evaluate to which extent alternative fuels and powertrains can contribute to GHG emissions reductions within the heavy-duty segment of the European Union (EU). The analysis compares the WTW chain of diesel as the fossil benchmark to biodiesel, bio-methane, Power-to-Liquid (PtL) and Power-to-Gas (PtG) fuels, as well as catenary electric vehicles (CEVs) in heavy-duty tractor-trailers. The WTW analysis found that fuel and powertrain combinations from renewable energy sources offer a high potential for reducing GHG emissions as compared to diesel, however, the magnitude of the reductions significantly varies depending on feedstock and fuel type. Taking feedstock availability into account, the direct use of electricity in CEVs was identified as the most promising option for decarbonizing the heavy-duty long-haul sector, although the performance of CEVs depends on the extent to which the required energy comes from non-fossil resources.

The availability of low-cost renewable electricity from solar and wind energy provides an opportunity to use renewable hydrogen for aviation fuel production. The Power-to-Liquid (PtL) pathway provides a perspective to synthesize large amounts of sustainable jet fuels from H₂O and CO₂. The environmental performance of biofuel pathways can immediately be improved by the use of hydrogen from renewable energy. In the long-term perspective, it is conceivable that hydrogen can also be used directly as fuel in future hydrogen aircraft. We present an approach that allows comparative statements about the greenhouse gas balance of future hydrogen supply options for aviation. The model for direct hydrogen use takes into account the production of liquid hydrogen and its logistics. The reference cases are fuel production using renewable hydrogen in biorefineries and fuel production by PtL. We discuss future scenarios for an intensive use of hydrogen from renewable energy in aviation and evaluate the resulting environmental impacts.

In this study, the environmental burdens of polymer electrolyte membrane water electrolysis (PEMWE) producing hydrogen are analyzed with the help of a life cycle assessment (LCA). Three scenarios, which differ in the techniques applied for generating electricity for hydrogen production and the operation mode, are considered. Using electricity generated with the currently available generation structure leads to the GWP100 of 32.52 kg CO₂-eq per kilogram H₂, which leaves the plant with a purity of 99.9% at 35 bar and 333–335 K. These emissions are to a large extent caused throughout the plant’s operation but not during its production phase. Thus, currently a large proportion of the GWP100 results from electricity production. As electricity generation based on renewable energy continues to develop, the greenhouse gas emissions per kilowatt-hour electricity decrease. Consequently, the overall greenhouse gas emissions as well as those caused within the operation phase of PEMWE decline and the relative impact of the production phase grows. In case of operating the electrolysis plant exclusively with electricity originating from wind, the GWP100 of 0.93 kg CO₂-eq/kg H₂ results, of which more than one quarter is assigned to the production of the plant. Thus, the production phase of a PEMWE plant must be thoroughly considered when the share of renewable energy in electricity generation increases. Apart from the GWP100, other impact categories are analyzed. Comparing the three scenarios reveals that the application of renewable energy for electricity generation is beneficial for most impact categories. Nevertheless, ADP elements, FATEP inf., HTP inf. and ODP are negatively affected.

In the current debate about Circular Economy (CE) many circularity measurements focus solely on material cycles and resource-efficiency. Hence, remanufacturing is per se seen as a sustainable End-of-Life (EoL) pathway. As CE-indicators do often not take the use-phase into account, that assumption is not necessarily true and the benefit questionable. This is why in this paper a remanufacturing indicator is introduced which evaluates if remanufacturing is a good EoL strategy for energy using products (EuP) from an ecologic and economic point of view, taking technical improvements and energy efficiency gains into account. We elaborate what matters when assessing remanufacturing, especially when a comparative assessment is conducted. The indicator is applied in a case study where remanufacturing of an old circulation pump is compared to using various new, more efficient pumps as substitutes in a 2nd Life Cycle. Thereby, a parameterized model is developed for the LCA and LCC assessment of the remanufacturing process. The main finding is that remanufacturing of EuP only makes sense when technology is mature. This is very distinct from an environmental perspective but applies also to the financial aspects.

Existing material selection methodologies do not account for effects that scaling has on the resulting environmental consequences. The impact of producing an emerging material using a lab-scale process is likely to differ significantly from the impact of mass-producing the same material at industrial scale. We propose a methodology, based on the established Ashby material selection process, that combines material selection with environmental impact assessment and takes into account the effects of scaling up material production processes for emerging materials. The approach adds additional steps for data collection, life cycle assessment and scaling to the pre-existing steps in Ashby’s methodology. It allows for the assessment of multiple environmental impact categories as well as a transparent way of handling underlying data uncertainty and variability. We review existing approaches of environmental material selection methodologies, derive requirements for a novel approach, present our concept methodology and demonstrate it using a case study example. Further refinement of the concept should primarily address the life cycle assessment and scaling steps.

The representation of gold-producing processes in common life cycle assessment (LCA) databases is insufficient. The biggest problems identified are the missing data for recycling of high-value scraps and for ASM and the estimations in industrial mining. The life cycle inventories (LCI) for the latter are based on corporate reports. The data available from the company figures are always incomplete and must therefore be scaled between the different mines. This process was defined in this work as Intersystemic-Data-Scaling (IDS). An analogy is presumed here between mines, although literature shows that there are differences in mines like ore types that affect the extraction processes and thus the LCI. In the present study all the assumptions and IDS were visualized in a world map. It was found that except for energy demand and production volumes there is no flow without IDS. Finally, the actual shares of the different gold routes in the world market were estimated using literature research. When compared to the market shares used in common life cycle databases it can be seen that there are big data gaps emphasizing the importance of further data collection for the life cycle datasets for the material gold.

The Life Cycle Assessment (LCA) of buildings is an important evaluation method for the environmental quality of a building and its impact on climate and environment. However, the efforts required are very high and cost-intensive. Whole-building LCAs are therefore usually only used as theoretical evidence after completion of a certified building. The potential for full environmental optimization in early project phases is therefore not used in practice. New digital planning methods such as Building Information Modeling (BIM) offer the possibility of integrating and linking much of the information required for a whole-building LCA when creating a digital building model, which should be incorporated by all participants in the planning right from the start. Technical, organizational and contractual prerequisites must be (further) developed so that a whole-building LCA can be applied earlier and more easily with the aid of the BIM method. Within the framework of this work, primarily issues and their technical improvements of the official German LCA database ÖKOBAUDAT and German green building certification systems BNB/DGNB are presented. Based on the open BIM standard of the IFC data model, current fundamentals will be examined to adapt ÖKOBAUDAT aiming to simplify BIM integrated calculation of whole-building LCAs. In this context, concrete recommendations for action to extend the IFC data model and ÖKOBAUDAT will be discussed.

With increasing energy performance requirements of buildings, new solutions and materials for thermal energy storage have been recently developed. In this regard, phase change materials (PCMs) proved to provide a good energetic performance, but their environmental potentials are still debated. In this work, a tool for environmental performance evaluation of PCM storage systems is presented. On the basis of a comprehensive collection of data coming from PCM producers, Life Cycle Assessment (LCA) analyses are carried out on material level. The integration of building energy simulations allows analyses on higher levels (component and building level). Afterwards, through comparisons among different systems the tool supports decision-making and enables optimization of PCMs storage system depending on location, building type, insulation level, and components specifications. Results proved that, despite their energy saving potentials, PCM storage systems showed not always a good environmental performance over the whole lifecycle. Main drivers are impacts from material production processes and low recycling rates. Thus, the development of such energy supply and storage concepts considering environmental life cycles has to be encouraged.

Rotary heat exchangers belong to the most efficient heat exchangers for gas streams. This technology is commonly used in power plants, paint shops and heating, ventilation and air conditioning systems. Yet an optimization taking into account both economic and ecological aspects is absent in literature. This work uses a simulation model developed at the Pforzheim University of Applied Sciences, combined with LCA and economic data to optimize rotors. From an environmental perspective, the use phase is where the bigger impacts take place. In the economical side, the use phase is also the most important. For the optimization, a commercial software for this purpose is used. The results show a conflict between the two possible optimization goals. Additionally data of two commercially available rotary heat exchangers from the Eurovent Database are also compared to the results from optimization via simulation and there is evidence that in some specific cases an improvement in the environmental or economical aspect can be done without compromising the other aspect.

For the mitigation of climate change a switch to renewable energies in combination with battery storage and high efficient technologies, such as combined heat and power is necessary. To assess the environmental impacts of an electricity system model of a residential district, a Life Cycle Assessment is conducted. Different approaches of impact assessment methods are applied and compared. Based on the assumptions made, the use of a battery storage cannot always be recommended due to its dependence on the expected lifetime and capacity utilization in general. When the full cycle life of a battery storage is reached and the consumed electricity originates from photovoltaic an environmental advantage compared to the German electricity mix is created. Consequently, battery storage application can reduce the climate change potential in the conducted analysis up to −26%. A disadvantage is the introduction of a higher resource consumption compared to the German electricity mix. Noticeable is only a slight decrease in the fossil energy demand due to the utilization of natural gas by the combined heat and power plant. Furthermore, there is a displacement of mining or extraction of fossil fuels towards Russia, USA and Rest of World, which may influence the security of supply.

Sustainability assessment for emerging technologies is a prerequisite for sustainable process and product development. Life Cycle Assessment (LCA) is an accepted method for quantifying and assessing the potential environmental impacts of product systems. In general, an LCA is conducted on mature technologies or an industrial scale. Nevertheless, the design or development stage provides important information on potential environmental impacts and is rated to determine the grand part of environmental impacts of new technologies and products. In this study, practice-oriented recommendations for LCA practitioners and other project partners of inter-disciplinary and inter-organizational R&D projects are derived in order to enhance the integration and implementation of LCAs in technical R&D projects. The observations are presented as three main recommendations: Create common knowledge, consider LCA as part of the R&D and adapt and revise. LCA at the R&D stage can contribute to enhanced knowledge sharing and, most importantly, can support the entire R&D project by generating information on the environmental performance of the new processes and products and revealing the window of opportunity for sustainable process and product development.

Carbon offsets as an additional measure to mitigate climate change are on the agenda in recent years. This study analyzes the three carbon offsetting programs (the Clean Development Mechanism, the Verified Carbon Standard and the Gold Standard) with the largest market shares by systematically comparing their standard documents with environmental Life Cycle Assessment (LCA) standards (ISO 14067 and ISO 14040/44). The programs’ most important methodologies are assigned to the sectors forestry, renewable energy, energy efficiency, industrial gas, and waste. We analyzed each sector for its compatibility with LCA using a criteria evaluation scheme to answer the main question, whether the methodologies provide guidance on life cycle emission accounting and what uncertainties they face. The offsetting standards differ from LCA standards due to different analyzed systems, system boundaries and purposes of their methods. Furthermore, offsetting methods always apply scenario analysis. Environmental impacts apart from greenhouse gases are not quantified, rather environmental impact assessments of heterogeneous quality are applied. We find that the approaches in the analyzed carbon offsets are incompatible with the LCA approach, mainly because they always involve scenario analysis, do not include all life-cycle phases and do not account for additional (negative) environmental and social impacts that project activities related to carbon offsets may cause.

This article discusses the comparability of Life Cycle Assessments (LCAs) and the central role of the application purpose in a study review. According to ISO 14040, an LCA study design emerges in continuous reference to the “intended application”. Goal and scope, case-specific assumptions, as well as methodological freedoms, should be justified by their significance for the specific application purpose, e.g. for process optimization or for advice on a political issue. In contrast, our systematic review of 58 LCA studies shows that LCAs hardly name applications, and more generally, applications are difficult to reconstruct. This lack of transparency makes the LCA methodology attackable through meta-studies that ignore the problem-oriented and case-specific approach. Since these studies are valuated for different purposes by a diverse set of actors, quantification in any study that does not represent the context and purpose of its generation can disguise as much as it can enlighten. Therefore, we propose what a study should look like that is problem-solving, concrete and yet provides transferable results for other studies.

Biodiversity is a complex and intangible field and a general applicable quantification methodology is yet to be established. Neither indicator systems on the influence on species richness or ecosystem services nor the assessment of the amount of human influence lead to a reliable quantification method. A new approach developed by Lindner in 2016 assesses the difference between a reference situation with the current situation through land use by combining expert knowledge with fuzzy logic and constructing trajectories of biodiversity impacts of case-specific indicator categories through interviews with a group of specialists. In this paper, the method is adjusted for the evaluation of the biodiversity impact of grazing sheep. A set of indicators was constructed, weighted and individually assessed together with sheep farming experts. The established indicators include the change of biodiversity through grazing sheep, the optimal grazed area, the optimal grazing period, the influences on the soil and the humus layer, the impact of machinery use, the importance of transhumance as well as the influence of other species like goats within the herd. An extensive sheep farm from the Swabian Alb, Germany and a semi-extensive sheep farm from the Rhön Mountains, Germany, were assessed for exemplarily testing the method. The assessment presented results assigning the more extensive sheep farm a higher biological as it was excepted. The set of indicators appears applicable for similar farms in similar regions. A point of further inquiry is to underline positive effects and benefits of grazing sheep on biodiversity observed in other studies.