• Energy Research
• DE close
• PL close
• RWTH Aachen University close

The dataset accompanies the Nature Energy publication by Figgener et al. (2024), Multi-year field measurements of home storage systems and their use in capacity estimation, DOI 10.1038/s41560-024-01620-9. In addition, we use the dataset in Figgener et al. (2024), Degradation mode estimation using reconstructed open circuit voltage curves from multi-year home storage field data, DOI 10.48550/arXiv.2411.08025 The ISEA / CARL of RWTH Aachen University measured 21 private home storage systems in Germany over up to eight years from 2015 to 2022. All these storage systems are combined with residential photovoltaic systems to increase self-consumption. The measured quantities published are system-level battery current, voltage, power, battery pack housing temperature, and room temperature. The sample rate is one second. The dataset consists of 106 system years, 14 billion data points, and 1,270 monthly files stored in 21 system folders. Use the data as follows:1. Download the data (Data_ID_01.zip to Data_ID_21.zip) and the belonging repository (Metadata_and_Code.zip) 2. Uncompress the files so that the uncompressed folders have the same name as the .zip files. 3. Copy all data folders in folder "Metadata_and_Code/00_Data/01_Operational_Data". Read and execute the file "StartUp_Read_and_Execute.m" and stay in this folder for any script you execute. In addition, a detailed description of the dataset and how to use it can be found in the supplementary information of the publication.

SF 6 self blast circuit breakers use the flow back of high pressure gas from the expansion chamber, which is generated by ablation of a PTFE-nozzle and the arc radiation to interrupt the arc. The interruption capability of SF 6 self blast circuit breakers depends on the pressure inside the switching chamber at current zero. During each fault current interruption, the arc radiation induces contact and nozzle ablation. The nozzle widening causes reduction of the pressure build-up and thus results in the reduction of the interruption capability. The objective of this work is to use a non-invasive method to assess the degree of nozzle ablation without opening the interrupter and to estimate the degradation of the interruption capability. In this work, the frequency response analysis is applied to detect the change in capacitance due to the change of the geometry inside the circuit breaker interrupter.

This paper reports on laboratory studies into the ac impedance spectra of nickel–metal hydride and nickel–cadmium batteries, aiming at finding out possible correlation between electrical parameters, extracted directly from the high frequency region, and the battery state-of-charge (SoC). Impedance diagrams were recorded immediately after interrupting the dc charge, or discharge, current. The study revealed that the series resonance frequency, at which the dynamic cell behavior switches from an inductive character (Z″>0) to a capacitive one (Z″<0), varied monotonously as a function of state-of-charge. This behavior was reproducible after intermittent charge and discharge. Half-cell measurements were also conducted to associate the cell impedance with either processes occurring at the positive or negative plates.

AbstractThe future European energy supply system will have a high share of renewable energy sources (RES) to meet the greenhouse gas emission policy of the European Commission. Such a system is characterized by the need for a strongly interconnected energy transport grid as well as a high demand of energy storage capacities to compensate the time fluctuating characteristic of most RE generation technologies. With the RE generators at the location of high harvest potential, the appropriate dimension of storage and transmission system between different regions, a cost efficient system can be achieved. To find the preferred target system, the optimization tool GENESYS (Genetic Optimization of a European Energy System) was developed. The example calculations under the assumption of 100% self-supply, show a need of about 2,500 GW RES in total, a storage capacity of about 240,000 GWh, corresponding to 6% of the annual energy demand, and a HVDC transmission grid of 375,000 GWkm. The combined cost for generation, storage and transmission excluding distribution, was estimated to be 6.87 ct/kWh.

Abstract A variety of novel, recyclable and reusable, construction materials has already been studied within literature during the past years, aiming at improving the overall energy efficiency ranking of the building envelope. However, several studies show that a delicate control of indoor climating elements can lead to a significant performance improvement by exploiting the building’s savings potential via smart adaptive HVAC regulation to exogenous uncertain disturbances (e.g. weather, occupancy). Building Optimization and Control (BOC) systems can be categorized into two different groups: centralized (requiring high data transmission rates at a central node from every corner of the overall system) and decentralized 1 (assuming an intercommunication among neighboring constituent systems). Moreover, both approaches can be further divided into two subcategories, respectively: model-assisted (usually introducing modeling oversimplifications) and model-free (typically presenting poor stability and very slow convergence rates). This paper presents the application of a novel, decentralized, agent-based , model-free BOC methodology (abbreviated as L4GPCAO) to a modern non-residential building (E.ON. Energy Research Center’s main building), equipped with controllable HVAC systems and renewable energy sources by utilizing the existing Building Management System (BES). The building testbed is located inside the RWTH Aachen University campus in Aachen, Germany. A combined rule criterion composed of the non-renewable energy consumption (NREC) and the thermal comfort index – aligned to international comfort standards – was adopted in all cases presented herein. Besides the limited availability of the specified building testbed, real-life experiments demonstrated operational effectiveness of the proposed approach in BOC applications with complex, emerging dynamics arising from the building’s occupancy and thermal characteristics. L4GPCAO outperformed the control strategy that was designed by the planers and system provider, in a conventional manner, requiring no more than five test days.

Planning the air-terminations for a structure to be protected the use of the rolling-sphere method (electro-geometrical model) is the best way from the physics of lightning point-of-view. Therefore, international standards prefer this method. However, using the rolling-sphere method only results in possible point-of-strikes on a structure without giving information about the probability of strikes at the individual points compared to others.

Acetic acid bacteria such as Gluconobacter oxydans are used in several biotechnological processes due to their ability to perform rapid incomplete regio- and stereo-selective oxidations of a great variety of carbohydrates, alcohols, and related compounds by their membrane-bound dehydrogenases. In order to understand the growth physiology of industrial strains such as G. oxydans ATCC 621H that has high substrate oxidation rates but poor growth yields, we compared its genome sequence to the genome sequence of strain DSM 3504 that reaches an almost three times higher optical density. Although the genome sequences are very similar, DSM 3504 has additional copies of genes that are absent from ATCC 621H. Most importantly, strain DSM 3504 contains an additional type II NADH dehydrogenase (ndh) gene and an additional triosephosphate isomerase (tpi) gene. We deleted these additional paralogs from DSM 3504, overexpressed NADH dehydrogenase in ATCC 621H, and monitored biomass and the concentration of the representative cell components as well as O2 and CO2 transfer rates in growth experiments on mannitol. The data revealed a clear competition of membrane-bound dehydrogenases and NADH dehydrogenase for channeling electrons in the electron transport chain of Gluconobacter and an important role of the additional NADH dehydrogenase for increased growth yields. The less active the NADH dehydrogenase is, the more active is the membrane-bound polyol dehydrogenase. These results were confirmed by introducing additional ndh genes via plasmid pAJ78 in strain ATCC 621H, which leads to a marked increase of the growth rate.

The Grid 4 Vehicles project (G4V) has analyzed the effects of a mass integration of electric and plug-in hybrid electric vehicles (EV and PHEV) into some distribution grids in Europe. A consortium consisting of six European research institutions and six European utilities has developed a methodology to investigate the effects of EV and PHEV in distribution grids and has proposed different options for intelligent and “grid-friendly” EV charging. This paper introduces the algorithms used for grid calculation, describes intelligent charging methodologies and demonstrates the most significant results of these calculations.