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One way to implement a wind turbine in the sea is to use lattice structures. Since these structures are placed offshore, they must be able to withstand all kinds of loads. It is essential that the eigenfrequencies of the support structure do not correspond to the passing frequencies of the blades and any other dynamic actions. To avoid this the natural frequencies of the structure should be estimated during the design and the objective of this MSc study is the development of an easy to use finite element model to perform the modal analysis of an offshore wind support structure. It was built based on relevant inputs, defining the possible design of the lattice structure. Based on these parameters, the model can be adjusted and a high number of designs can be tested easily. The model is built in Matlab and consists of several modules, each one representing a different part of the design. The user has access to a main script to enter all necessary inputs. Then the program starts and a second function takes over. This second function is divided into five parts. The first, the definition of the geometry, creates the nodes and elements composing the structure. The second part concerns the creation of matrices characterizing the model. Each element is associated with two matrices: a local element mass matrix and a local element stiffness matrix. Each is computed in a local frame of reference, then rotated and assembled into two global matrices, representing the complete structure. Then, the equivalent stiffness characterizing the soil-piles interaction is calculated in the third part. Depending on the pile size and the soil properties, the equivalent stiffness is determined. Once the matrices completely describe the model, eigenvalues and mode shapes are calculated in the fourth part. The fifth part of the function is the plotting of the structure. The functionalities of the Matlab tool have been validated and thoroughly checked. Firstly, by comparing the analytical and numerical results of a simplified structure (a ...

With increasing decarbonisation and accessibility to our energy systems and markets, there is a need to understand and optimise the value proposition for different stakeholders. Game-theoretic models represent a promising approach to study strategic interactions between self-interested private energy system investors. In this work, we design and evaluate a game-theoretic framework to study strategic interactions between profit-maximising players that invest in network, renewable generation and storage capacity. Specifically, we study the case where grid capacity is developed by a private renewable investor, but line access is shared with competing renewable and storage investors, thus enabling them to export energy and access electricity demand. We model the problem of deducing how much capacity each player should build as a non-cooperative Stackelberg-Cournot game between a dominant player (leader) who builds the power line and renewable generation capacity, and local renewable and storage investors (multiple followers), who react to the installation of the line by increasing their own capacity. Using data-driven analysis and simulations, we developed an empirical search method for estimating the game equilibrium, where the payoffs capture the realistic operation and control of the energy system under study. A practical demonstration of the underlying methodology is shown for a real-world grid reinforcement project in the UK. The methodology provides a realistic mechanism to analyse investor decision-making and investigate feasible tariffs that encourage distributed renewable investment, with sharing of grid access.

Een samenvatting van het boek 'Sustainable Energy - without the hot air' van David J.C. MacKay. Professor MacKay is hoogleraar aan de Universiteit van Cambridge en Chief Scientific Advisor to the Department of Energy and Climate Change van de Britse regering. In het boek vergelijkt hij het gebruik van energie met de hoeveelheid energie die opgewekt kan worden met duurzame energie.

To cut down immense greenhouse gases emission and energy consumption in the rapidly urbanizing world, a holistic understanding and rethinking of our dynamic urban energy system are inevitable. Performing bottom-up building energy modelings at urban scale based on Geographic Information System (GIS) and semantic 3D city models could be a promising option to provide quantitative and integrated energy solutions. Nevertheless, input uncertainties either caused by limited data accessibility in most cities or parameters with stochastic variability (e.g. house occupancy profile) become one of the biggest obstacles to produce reliable and acceptable building energy modeling results. This study aims to address the heating demand simulation performance gap caused by input uncertainties. In this case study based on Amsterdam residential building stock, parameter importance ranking of the 14 simulation inputs are first derived according to the sensitivity analysis. The selected key uncertain parameters are then modeled in a probabilistic distribution way at postcode 6 level (approximately or slightly more than 10 buildings). Model calibration is based on the Bayesian approach and given six years (2010-2015) of gas consumption data to infer parameter posterior distributions. After the training phase, the calibrated annual heating demand simulation results of the validation years show significant improvement in modeling accuracy. Comparing the baseline and the calibrated simulation results, the averaged absolute percentage errors of energy use intensity (EUI) among at least 84 valid postcodes have decreased from 24.96% to 8.31% in 2016 and from 19.93% to 7.70% in 2017 respectively. The calibrated urban building energy model would be most interested by municipalities, urban planners, and engineering consultancies. It can be used to evaluate long-term energy supply and demand strategies, identify building renovation saving potential, perform large-scale building performance mapping, and carry out retrofit measures assessment. ...

This chapter describes the game `Remodel’. It has been developed in the Netherlands. It focuses on strategic decisions in regard to technological innovation and environmental regulation. The game stimulates the awareness of science and engineering students for the organisational and political context of their future professions.

This paper describes the design of a self-scheduled current controller for doubly-fed induction generators in wind energy conversion systems (WECS). The design is based on viewing the mechanical angular speed as an uncertain yet online measurable parameter and on subsuming the problem into the framework of linear parameter-varying (LPV) controller synthesis. An LPV controller is then synthesized to guarantee a bound on the worst-case energy gain for all admissible trajectories of rotor speed in the operating range. Furthermore, this study investigates the robust performance of the LPV controller with respect to other bounded machine parameter variations and the impact of the stator voltage dips on the robustness of the control system. Two closed loop simulation models, one with a conventional control scheme and the other with an LPV control scheme, are developed for the control of the electrical torque and the power factor on the rotor side in order to compare the performance of the control systems. Some simulation results are given to demonstrate the performance and robustness of the control algorithm.

The building sector uses 40% of the primary energy worldwide. Energy demand in a non-residential existing building is rising due to higher comfort conditions, population growth and the enhancement of the building services. On the other hand, renewable energy technologies are every time more accessible for the built environment, especially the ones that use the sun as their primary energy source. The difference between that energy demand and that production of energy in existing buildings is causing a mismatch of energy that needs to be solved if problems such as an increase in the electricity bills, an oversized energy grid or the dependence on fossil fuels want to be avoided. Currently there is not research on how to reduce the mismatch in non-residential existing buildings; therefore, this research aims to be the beginning of the exploration of this topic. By matching the energy demand and the energy produced at any point of time within the building boundary, the building will be energy flat. During this research, the renovation of a case study building towards energy flatness was proposed. A three steps strategy was proposed to reduce energy demand, produce renewable energy and integrate a complementary energy system in existing buildings that want to be renovated towards a full energy balance and a renovation proposal of a case study building towards energy flatness. As a result, energy flatness in the renovation of non-residential existing buildings is limited to the extent of their physical and functional parameters which restrains the energy demand, production and distribution. Furthermore, the three steps strategy helped to reduce the energy mismatch and is relevant because the energy mismatch problem is going to be every time more visible in the built environment. ; Architecture, Urbanism and Building Sciences | Building Technology | Sustainable Design

To properly simulate the highly anisotropic turbulent engine flows, higher order turbulence model should be used to correctly reproduce flow physics inside the engine. The popular KIVA computer code has been modified to include the Reynolds-stress turbulence model (RSTM) for this purpose. The objective of this paper is to present our recent research on the use of RSTM and the KIVA code for engine flow simulation, which include gas turbine combustors and IC engines.

AbstractWind turbine design codes for calculating blade loads are usually based on a blade element momentum (BEM) approach. Since wind turbine rotors often operate in off‐design conditions, such as yawed flow, several engineering methods have been developed to take into account such conditions. An essential feature of a BEM code is the coupling of local blade element loads with an external (induced) velocity field determined with momentum theory through the angle of attack. Local blade loads follow directly from blade pressure measurements as performed in the National Renewable Energy Laboratory (NREL) phase IV campaign, but corresponding angles of attack cannot (on principle) be measured. By developing a free wake vortex method using measured local blade loads, time‐dependent angle of attack and induced velocity distributions are reconstructed. In a previous paper, a method was described for deriving such distributions in conjunction with blade pressure measurements for the NREL phase VI wind turbine in axial (non‐yawed) conditions. In this paper, the same method is applied to investigate yawed conditions on the same turbine. The study considered different operating conditions in yaw in both attached and separated flows over the blades. The derived free wake geometry solutions are used to determine induced velocity distributions at the rotor blade. These are then used to determine the local (azimuth time dependent) angle of attack, as well as the corresponding lift and drag for each blade section. The derived results are helpful to develop better engineering models for wind turbine design codes. Copyright © 2008 John Wiley & Sons, Ltd.

Globally one-third of all food that is producedfor human consumption is wasted (FAO, 2013). Although it happens across theentire Food Supply Chain, 53% of all food waste in Europe takes place withinconsumers’ households (Stenmarck et al., 2016). All this waste has seriousconsequences for the environment and if we want to achieve our ‘food waste reductionof 30% by 2025 and 50% by 2030’ (UN, 2020) more needs to be done. An assignmentwas formulated together, with the Delft based organization I Change, to developa product/service that facilitates consumer food waste prevention by addressingthe household routines. By reviewing consumers’ existing household routines andthe motives of their food-wasting behavior, it has been discovered thatconflicting goals are the main reason consumers are wasting food. On the onehand consumers are willing to reduce their food waste because it is a purewaste of money, ethically wrong and because they feel ashamed or guilty whendoing it (van Dooren & Mensink, 2018). On the other hand, consumers wastefood because they strive for convenience, want to be good providers by makingsure there is enough to eat and want to be prepared for uncertainties (e.g.:working overtime, unexpected guests) (Graham-Rowe, Jessop & Sparks, 2014). These food wasting motives have led to manyconsumers lacking the ‘good food habits’ needed to make both convenient andgood choices. These good food habitsinclude making shopping lists, setting up meals plans and checking stock beforegoing shopping. According to Ooijendijk et al. (2019) having and sticking to theseroutines can prevent up to 50% of the total amount of food consumers waste. Through an iterative design and test processEetkaartjes was developed. Essentially this product is a set of product categorylabels that consumers use in their fridge, freezer and/ or cupboards whichenables them to become better organized. Based on results from the testingphase it was concluded that through better organization, several of the previouslydiscussed lacking ‘good ...