• Energy Research
• other engineering and technologies close
• ETH Zurich close

Laboratory corrosion and scaling testing of metallic materials exposed in high temperature and pressure environments generally involves complex, multi-instrument measurement setups. Here, we present a setup including an autoclave that is instrumented for in-situ electrochemical testing and that contains a ZrO2-based solid-state pH electrode and devices for temperature control and solution stirring. We show results highlighting the importance of adequate pre-calibration of the pH measurement, due to the hysteresis depending on temperature sweep. Additionally, we illustrate how interfacing the autoclave and the electrochemical cell to measuring and controlling instruments, using different data communication interfaces, can create ground loops. These ground loop interferences can introduce significant errors in the measurement, such as a potential shift of >100 mV. In complex, multi-instrument setups, a complete understanding of ground loops may often be difficult. Thus, we recommend systematic checks to identify the ground loops and we propose measures to avoid them. Measurement, 155 ISSN:0263-2241 ISSN:1873-412X

SummaryThe German government has adopted a law that requires sewage plants to go beyond the recovery of phosphorus from wastewater and to promote recycling. We argue that there is no physical global short‐ or mid‐term phosphorus scarcity. However, we also argue that there are legitimate reasons for policies such as those of Germany, including: precaution as a way to ensure future generations’ long‐term supply security, promotion of technologies for closed‐loop economics in a promising stage of technology development, and decrease in the current supply risk with a new resource pool.

<p>High temperature aquifer thermal energy storage (HT-ATES) can play a key role for a sustainable interplay between different energy sources and in the overall reduction of CO<sub>2</sub>emission. In this study, we numerically investigate the thermo-hydraulic processes of an HT-ATES in the Greater Geneva Basin (Switzerland). The main objective is to investigate how to handle the yearly excess of heat produced by a nearby waste-to-energy plant. We consider potential aquifers located in different stratigraphic units and design the model from available geological and geophysical data. Aquifer properties, flow conditions and well strategies are successively tested to evaluate their influence on the HT-ATES economic performance and environmental impact. This was achieved using a new open-access, user-friendly and efficient code that we also introduce here as a possible tool for geothermal applications.</p><p> </p><p>The results highlight the importance of thorough numerical simulations based on more realistic exploitation when designing HT-ATES systems. We show that relations between thermal performance and the shape of the injected thermal volume are generally hard to derive when complex well schedules are imposed because the injected/produced volumes may not be equal. Despite more complex storage strategies to comply with legal regulations, the shallower group of investigated aquifers in this study remains economically more suitable for storage up to 90ºC. In average four well doublets will be required to store the yearly excess of energy. The deeper group of investigated aquifers, however, become interesting for storage at higher temperatures.</p>

Abstract Gate-to-gate process energy consumption is an important metric for sustainability as it affects both costs and environmental impact. As only little process information is available in early phases of chemical process design, a detailed energy consumption calculation is substantially restrained. Therefore, a reliable estimation of energy consumption in early phases of process design is an important alternative. In this work, an index representing process energy consumption was evaluated and tested for 14 organic solvent case studies. By using simplified process models the indices were calculated and compared to literature values for gate-to-gate energy consumption. The predictability of the process energy consumption on the basis of this indicator, including possible modifications in its original definition, was evaluated with the Pearson's and Spearman's correlation coefficients. The results further validated the use of the EI (energy index) in its original form as a proxy indicator of the process energy consumption for decision making in early stages of process design. For assessing the production of new classes of chemicals the EI should be evaluated as shown in this paper in order to establish its practicability. In certain cases an adjustment of the indicator categories may be necessary.

Most commercially used electrode materials contract and expand upon cycling. This change in volume influences the microstructure of the cell stack, which in turn impacts a range of performance parameters. Since direct observation of these microstructural changes with operando experiments is challenging and time intensive, a simulation tool that takes a real or artificially generated 3D microstructure and captures the volumetric changes in a cell during cycling would be valuable to enable rapid understanding of the impact of material choice, electrode and cell design, and operating conditions on the microstructural changes and identification of sources of mechanically-driven cell aging. Here, we report the development and verification of such a 3D electrochemical-mechanical tool, and provide an example use-case. We validate the tool by simulating the microstructural evolution of a graphite anode and a Li(Ni,Mn,Co)O2 cathode during cycling and comparing the results to X-ray tomography datasets of these electrodes taken during cycling. As an example use case for such a simulation tool, we explore how different volumetric expansion behaviors of the cathode material impact strain in the cell stack, illustrating how the material selection and its operation impact the mechanical behavior inside a cell.

Medium and heavy-duty battery electric trucks (BETs) may play a key role in mitigating greenhouse gas (GHG) emissions from road freight transport. However, technological challenges such as limited range and cargo carrying capacity as well as the required charging time need to be efficiently addressed before the large-scale adoption of BETs. In this study, we apply a geospatial data analysis approach by using a battery electric vehicle potential (BEVPO) model with the datasets of road freight transport surveys for analyzing the potential of large-scale BET adoption in Finland and Switzerland for trucks with gross vehicle weight (GVW) of over 3.5 t. Our results show that trucks with payload capacities up to 30 t have the most potential for electrification by relying on the currently available battery and plug-in charging technology, with 93% (55% tkm) and 89% (84% tkm) trip coverage in Finland and Switzerland, respectively. Electric road systems (ERSs) would be essential for covering 51% trips (41% tkm) of heavy-duty trucks heavier than 30 t in Finland. Furthermore, range-extender technology could improve the trip electrification potential by 3–10 percentage points (4–12 percentage points of tkm).

Abstract We propose a general classification of all the modes of a given thermoacoustic system into two sets: one of acoustic origin and one of intrinsic thermoacoustic (ITA) origin. To do this, the definition of intrinsic modes, traditionally based on anechoic boundary conditions, is reformulated in terms of the gain n of the Flame Transfer Function (FTF). As a consequence of this classification, we show how theoretical results for the estimation of all thermoacoustic modes can be derived in the limit n → 0, for both axial and annular combustors, independent of the acoustic boundary conditions. Starting from this limit and using standard continuation methods while increasing n, all the eigenvalues of interest in a given domain in the frequency space can be identified. We also discuss how thermoacoustic modes of acoustic and ITA origin can interact, and in some cases coalesce generating exceptional points (EPs). Although all EPs found have negative growth rates, in their vicinity thermoacoustic eigenmodes have very large sensitivities and exhibit strong mode veering. We demonstrate how, in some cases, mode veering is responsible for the occurrence of thermoacoustic instabilities, and propose a numerical method to identify EPs. All the theoretical results are numerically verified using two generic thermoacoustic configurations.