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The concept of Digital Twin (DT) is widely explored in literature for different application fields because it promises to reduce design time, enable design and operation optimization, improve after-sales services and reduce overall expenses. While the perceived benefits strongly encourage the use of DT, in the battery industry a consistent implementation approach and quantitative assessment of adapting a battery DT is missing. This paper is a part of an ongoing study that investigates the DT functionalities and quantifies the DT-attributes across the life cycles phases of a battery system. The critical question is whether battery DT is a practical and realistic solution to meeting the growing challenges of the battery industry, such as degradation evaluation, usage optimization, manufacturing inconsistencies or second-life application possibility. Within the scope of this paper, a consistent approach of DT implementation for battery cells is presented, and the main functions of the approach are tested on a Doyle-Fuller-Newman model. In essence, a battery DT can offer improved representation, performance estimation, and behavioral predictions based on real-world data along with the integration of battery life cycle attributes. Hence, this paper identifies the efforts for implementing a battery DT and provides the quantification attribute for future academic or industrial research.

AbstractIn the design of concentrator photovoltaic modules, numerous components need to be optimised to achieve the highest performance of the complete system while simultaneously maintaining low costs for the manufacturing processes. In this paper, we present a systematic analysis of different designs of concentrator photovoltaic modules using mirror optics to concentrate the solar radiation by a factor of 1000 with passive heat dissipation. Module designs based on 4 different arrangements for the optics are investigated: on‐axis, asymmetrical, and Cassegrain with and without tertiary optics. Each design is optimised for high thermal, optical, and electrical performance via finite element method, ray tracing, and network simulations. Concepts for manufacturing are also proposed. The 4 specific designs are evaluated and compared in a systematic benefit analysis. In this analysis, 9 criteria are defined to describe the module performance and manufacturability. To quantify the benefit of each module design, utility values—a score to provide a value to the benefit—and weighting factors are defined. With this systematic analysis, the strengths and potential for optimisation are identified, and the different designs are compared. In addition, the potential for improvement is discussed surveying the different criteria.

Polyethylene terephthalate (PET) bottles are widely used as packaging material for natural mineral water. However, trace levels of acetaldehyde can migrate into natural mineral water during the shelf life and might influence the taste of the PET bottled water. 2-Aminobenzamide is widely used during PET bottle production as a scavenging agent for acetaldehyde. The aim of this study was the determination of the migration kinetics of 2-aminobenzamide into natural mineral water as well as into 20% ethanol. From the migration kinetics, the diffusion coefficients of 2-aminobenzamide in PET at 23 and 40°C were determined to be 4.2 × 10(-)(16) and 4.2 × 10(-)(15) cm(2) s(-1), respectively. The diffusion coefficient for 20% ethanol at 40°C was determined to be 7.7 × 10(-)(15) cm(2) s(-1), which indicates that 20% ethanol is causing swelling of the PET polymer. From a comparison of migration values between 23 and 40°C, acceleration factors of 9.7 when using water as contact medium and 18.1 for 20% ethanol as simulant can be derived for definition of appropriate accelerated test conditions at 40°C. The European Union regulatory acceleration test based on 80 kJ mol(-1) as conservative activation energy overestimates the experimentally determined acceleration rates by a factor of 1.6 and 3.1, respectively.

AbstractIn this contribution a fluid kinetic energy harvester excited by vortex induced vibration (VIV) is proposed. In terms of describing and verifying the interaction between the structural and the fluidic domain, a two-way Fluid Structure Interaction (FSI) simulation has been carried out. In order to optimize the harvester, different designs have been investigated to improve the performance. Subsequently, a demonstrator setup for testing the manufactured harvester has been assembled. The experimental results were compared with that of FSI-simulations. By applying the optimized harvester structure, the vortex induced pressure could be enhanced 4 times compared to convetional structures. The results show that the VIV energy harvester deliver 1μW power output under 2 m/s air flows.

This paper empirically investigates factors driving the adoption of energy-efficiency measures by small and medium-sized enterprises (SMEs). Our analyses are based on cross-sectional data from SMEs which participated in a German energy audit program between 2008 and 2010. In general, our findings appear robust to alternative model specifications and are consistent with the theoretical and still scarce empirical literature on barriers to energy-efficiency in SMEs. More specifically, high investment costs, which are captured by subjective and objective proxies, appear to impede the adoption of energy-efficiency measures, even if these measures are deemed profitable. Similarly, we find that lack of capital slows the adoption of energy-efficiency measures, primarily for larger investments. Hence, investment subsidies or soft loans (for larger investments) may help accelerating the diffusion of energy-efficiency measures in SMEs. Other barriers were not found to be statistically significant. Finally, our findings provide evidence that the quality of energy audits affects the adoption of energy-efficiency measures. Hence, effective regulation should involve quality standards for energy audits, templates for audit reports or mandatory monitoring of energy audits.

With the share of intermittent renewable energies within the electricity system rising, balancing services from dispatchable power plants are of increasing importance. Highlighting the importance of the need to keeping fuel costs for flexible power generation to a minimum, the study aims to identify favourable biogas plant configurations, supplying biogas on demand. A cost analysis of five configurations based on biogas storing and flexible biogas production concepts has been carried out. Results show that additional flexibility costs for a biogas supply of 8h per day range between 2€ and 11€MWh(-1) and for a 72h period without biogas demand from 9€ to 19€MWh(-1). While biogas storage concepts were identified as favourable short term supply configurations, flexible biogas production concepts profit from reduced storage requirements at plants with large biogas production capacities or for periods of several hours without biogas demand.

This paper investigates the impact of energy policy and the regulatory environment on the deployment of technologies based on renewable energy sources in Germany and presents a model to forecast future renewable energy technology diffusion. Our concept is based on the development of a composite indicator for renewable energy diffusion with a focus on wind energy (onshore) and photovoltaic. The approach has three major components: in-depth, semi-structured interviews with renewable energy developers and energy sector stakeholders to identify the major drivers and barriers (determinants) for renewable energy diffusion in the case study country; an EU-wide, questionnaire-based survey to understand the relevance (weights) of the individual determinants; and an analysis of past renewable energy diffusion patterns resulting in the deduction of a model for short-term renewable energy technology diffusion forecasts. Results demonstrate the substantial impact of economic and non-economic framework conditions on the diffusion of photovoltaic and wind energy in Germany. Furthermore, the use of composite indicators for renewable energy technology diffusion analyses proves to be a promising approach.

The field of energy forecasting has attracted many researchers from different fields (e.g., meteorology, data sciences, mechanical or electrical engineering) over the last decade. Solar forecasting is a fast-growing sub-domain of energy forecasting. Despite several previous attempts, the methods and measures used for verification of deterministic (also known as single-valued or point) solar forecasts are still far from being standardized, making forecast analysis and comparison difficult. To analyze and compare solar forecasts, the well-established Murphy-Winkler framework for distribution-oriented forecast verification is recommended as a standard practice. This framework examines aspects of forecast quality, such as reliability, resolution, association, or discrimination, and analyzes the joint distribution of forecasts and observations, which contains all time-independent information relevant to verification. To verify forecasts, one can use any graphical display or mathematical/statistical measure to provide insights and summarize the aspects of forecast quality. The majority of graphical methods and accuracy measures known to solar forecasters are specific methods under this general framework. Additionally, measuring the overall skillfulness of forecasters is also of general interest. The use of the root mean square error (RMSE) skill score based on the optimal convex combination of climatology and persistence methods is highly recommended. By standardizing the accuracy measure and reference forecasting method, the RMSE skill score allows-with appropriate caveats-comparison of forecasts made using different models, across different locations and time periods.