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Case study: Challenges and possible measures in the future Norwegian distribution grid (CINELDI report 05:2024)
No full textThis case study aims to illustrate challenges and possible measures in a future Norwegian distribution grid in 2030-40. Based on official goals by the Norwegian government and the EU to decarbonize transport and increase the amount of distributed renewable energy production, we consider a future scenario where the distribution grid is subject to considerable increase in photovoltaic (PV) production and electric vehicle (EV) charging. If no action is taken, the expected changes in load and production will lead to violation of voltage limits and thermal overload on components. Through simulations, we show how these problems can be mitigated by using a combination of active measures in the grid and flexibility resources. The case study is built on tools and knowledge from CINELDI and affiliated research projects.Case study: Challenges and possible measures in the future Norwegian distribution grid (CINELDI report 05:2024)publishedVersio
Assessment of Anisotropic Elastic Parameters Using Laboratory Triaxial and In-Situ Pressuremeter Tests in Opalinus Clay
Get PDFOpalinus Clay is a stratified shale that exhibits anisotropic deformation properties. In this work, the transversely isotropic deformation parameters of Opalinus Clay are summarized from recent undrained triaxial test campaigns. Relatively consistent values are found for Poisson’s ratios representing different orientations, regardless of the lithofacies and the effective confining stresses used in the tests. Pressuremeter tests were performed at the Mont Terri Rock Laboratory in two boreholes perpendicular and parallel to bedding, respectively. The elastic moduli normal to the borehole wall (borehole moduli) are determined using unloading data obtained at multiple diametric caliper axes and exhibit strong anisotropy for the tests in the borehole parallel to bedding. The anisotropic borehole moduli are predicted based on Amadei and Savage’s (Int J Rock Mech Min Sci 28:383–396, 1991. https://doi.org/10.1016/0148-9062(91)90077-Y) analytical solution using the laboratory-derived Poisson’s ratios and the shear modulus derived from pressuremeter tests in the borehole perpendicular to bedding. The prediction overestimates the magnitude of the borehole moduli but underestimates their anisotropic ratio compared to that from pressuremeter measurement. Drilling a borehole parallel to the bedding of Opalinus Clay is known to induce a local borehole damage zone preferentially developed normal to bedding. The results from a finite element analysis that incorporates this local damage are in better agreement with the pressuremeter measurement.publishedVersio
Analytical Computation of the Maximum Power Point of Solar Cells Using Perturbation Theory
Get PDFTo compute the maximum power point (MPP) from physical parameters of the single-diode model (SDM), it is necessary to solve a transcendental equation using numerical methods. This is computationally expensive and can lead to divergence problems. An alternative is to develop analytical approximations which can be accurate enough for engineering problems and simpler to use. Therefore, this paper presents approximations for computing the MPP of single-junction solar cells. Two special cases are considered: (i) SDM with only series resistance, and (ii) SDM with only shunt resistance. Power series closed-form expressions for the MPP are obtained using perturbation theory and the Lagrange inversion theorem. Validation of the formulas is performed using experimental data from six different technologies obtained from the NREL database and comparing the results with the numerical solution of the SDM and three approximations from the literature. The results show an absolute percentage error (APE) of less than 0.035% with respect to the real MPP measurements. In cases with limited computational resources, this value could be further improved by using a higher- or lower-order power-series approximation.publishedVersio
On Model Assisted Measurements and Applications
Get PDFWith digitalisation comes the ability to obtain real time data such as e.g. pressure and temperature from processes and equipment continuously. The true value of these measurements does however not appear before combining the data with models and theoretical understanding. In this paper the combination of simulations, theoretical knowledge and measurements is explored and used to design online systems for monitoring off-gas flow through aluminium electrolysis pots and Gas Treatment Centre (GTC) lines. By developing CFD models and using the results from these, suitable positions for measuring differential pressure (Δp) can be found. Later the models, together with known physical principles, are used to establish correlations between measured Δp, temperatures, and flows. These relationships are then used to monitor the flow rates online and in real time, also providing information on the fluctuations in the systems and giving warnings if there are large deviations/changes due to e.g., equipment failure.publishedVersio
The potential of hydrogen-battery storage systems for a sustainable renewable-based electrification of remote islands in Norway
Get PDFRemote locations and off-grid regions still rely mainly on diesel generators, despite the high operating costs and greenhouse gas emissions. The exploitation of local renewable energy sources (RES) in combination with energy storage technologies can be a promising solution for the sustainable electrification of these areas. The aim of this work is to investigate the potential for decarbonizing remote islands in Norway by installing RES-based energy systems with hydrogen-battery storage. A national scale assessment is presented: first, Norwegian islands are characterized and classified according to geographical location, number of inhabitants, key services and current electrification system. Then, 138 suitable installation sites are pinpointed through a multiple-step sorting procedure, and finally 10 reference islands are identified as representative case studies. A site-specific methodology is applied to estimate the electrical load profiles of all the selected reference islands. An optimization framework is then developed to determine the optimal system configuration that minimizes the levelized cost of electricity (LCOE) while ensuring a reliable 100% renewable power supply. The LCOE of the RES-based energy systems range from 0.21 to 0.63 €/kWh and a clear linear correlation with the wind farm capacity factor is observed (R2 equal to 0.87). Hydrogen is found to be crucial to prevent the oversizing of the RES generators and batteries and ensure long-term storage capacity. The techno-economic feasibility of alternative electrification strategies is also investigated: the use of diesel generators is not economically viable (0.87–1.04 €/kWh), while the profitability of submarine cable connections is highly dependent on the cable length and the annual electricity consumption (0.14–1.47 €/kWh). Overall, the cost-effectiveness of RES-based energy systems for off-grid locations in Northern Europe can be easily assessed using the correlations derived in this analysis.publishedVersio
Mechanical response of cement and shale admixtures under cyclic triaxial loading monitored by in-situ synchrotron micro-computed tomography
Get PDFUnderstanding the mechanical behaviour of natural soils as mixed with cement for stabilization is crucial for civil engineering developments. The response of cement-soil admixtures when subjected to cyclic loads is a largely unexplored topic, despite the importance of understanding fatigue in these ubiquitous construction materials. We present cyclic loading experiments on Portland cement mixed with fragmented shale fragments using triaxial testing, monitored with synchrotron-based μCT. Through digital volume correlation (DVC), the temporal evolution of the displacement, volumetric, and von Mises equivalent strain fields were obtained. We observed in detail the fatigue damage evolution during cyclic loading and found that following high-strain deformation of the much softer shale fragments, the ultimate failure of the samples occurred in the adjacent cement matrix. The failure mechanism under periodic stress and its relevance for accelerated laboratory testing of slow degradation long-term processes are of key importance to technical infrastructure, including subsea CO2 storage.publishedVersio
Impact of the Offshore Wind Development Plans in the North Sea on the Decarbonization of the European Energy System
Get PDFLarge amounts of offshore wind (OW) power are expected to be installed in the North Sea in the next decades with countries aiming for a total of 300 GW by 2050 as stated in the Ostend declaration. This scale-up will help achieve the decarbonization of the European energy system. However, it is unclear how the introduction of such large volumes of OW will impact the power system, the energy system and the profitability of the OW developments. This paper investigates these issues. A capacity expansion planning model of the European energy system is used to compare cases with limited OW investments, free investments and investments in OW fixed to the targets for 2040. It finds that large amounts of OW mainly reduce the installation of onshore wind, PV and nuclear while causing a total system cost increase across the horizon of about 1%. The offshore grid layout has little impact on the return on investment (ROI), with slightly higher ROIs for meshed offshore grids. Meeting the OW targets increase their ROI by forcing investments to be made at an earlier date, allowing production in periods with higher electricity prices.Impact of the Offshore Wind Development Plans in the North Sea on the Decarbonization of the European Energy SystempublishedVersio
Optimal experimental design for identification of hydrodynamic loading models
Get PDFHydrodynamic model-scale experiments are an intrinsic part of the design of marine structures, as they enable validating and calibrating the involved hydrodynamic numerical models. Such seakeeping experiments are generally conducted using a simple spring-based mooring system, with fixed properties throughout the tests. In the context of cyber-physical testing, the marine structure is kept in position in the laboratory by a virtual mooring system, the properties of which can be adjusted on the fly. This paper provides an algorithmic approach for maximizing the information gain from the test by optimizing the mooring stifness and damping parameters that define the experiment. The method is verified with synthetic data generated for the INO Windmoor 12MW floater, and is shown to be robust to noise and unmodeled effects.publishedVersio
Telling av syklister og elsparkesyklister med og uten Kunstig intelligens (KI). Erfaringer med nye teknologier og økt kunnskap om bruk av elsparkesykler
Get PDFRapporten undersøker bruken av nye teknologier for å telle syklister og elsparkesyklister og samler inn empiri om bruk av private og delte elsparkesykler på ulike plasser i Trondheim. Prosjektet har som mål å øke kunnskapen om metoder for å kvantifisere bruken av elektriske sparkesykler, samt danne er bilde av fordelingen mellom private og delte elsparkesykler. Funnene viser at det valgte KI-baserte kameraet presterer godt over lengre perioder, men har noen avvik i kortere tidsintervaller. Feilregistreringer oppstår ofte når trafikanter dekker hverandre eller når fotgjengere går med sykkel. Med tanke på fordelingen mellom delte og private elsparkesykler, er det delte som dominerer, spesielt i byområdet utenfor Midtbyen. Registrering av tilgjengelige elsparkesykler i utleie-apper gir en god indikasjon på bruken av delte elsparkesykler, selv om metoden har noen begrensninger knyttet til representativitet og ressursbruk. Rapporten konkluderer med at KI-teknologi har potensial til å forbedre datainnsamling for myke trafikanter, men understreker viktigheten av manuell kontroll og videre utvikling av algoritmer for å øke nøyaktigheten.publishedVersio
Characterization of pure and admixed brown trout (Salmo trutta) populations of high conservation value in the upper Danubian contact zone using ddRADseq genotyping
Get PDFIncreasing rates of hybridization and introgression in managed populations of freshwater fish are a major threat to the long-term viability of native species. The conservation challenge begins with identifying native gene pools. For brown trout (Salmo trutta Linnaeus, 1758) in the Upper Danube drainage, this task is complicated by the presence of both naturally and anthropogenically induced admixture of highly divergent lineages (Atlantic and Danubian). Herein, a ddRADseq protocol was used to type 377 individuals from 24 populations in the Upper Danube in Austria and Germany, and from reference populations from adjacent drainages and commercial hatcheries. High genetic differentiation at small geographic scales was found among pure Danubian-lineage populations, especially in the Kalkalpen National Park (Austria). In the Upper Danube drainage of Germany, as well as in the Rhine and Elbe drainages, brown trout populations were predominantly of Atlantic-lineage origin – as were those of all commercial hatcheries. Most populations, however, showed various degrees of admixture between Danubian and Atlantic lineages, hypothesized to be the result of both natural and anthropogenic processes. We highlight the conservation value of pure Danubian-lineage populations, and the challenges promoting conservation of naturally admixed populations, while discouraging continued stocking and admixture via management activitiespublishedVersio