Renewable energy sources have an intermittent character that does not necessarily match energy demand. Such imbalances tend to increase system cost as they require mitigation measures and this is undesirable when available resources should be focused on increasing renewable energy supply. Matching supply and demand should therefore be inherent to early stages of system design, to avoid mismatch costs to the greatest extent possible and we need guidelines for that. This paper delivers such guidelines by exploring design of hybrid wind and solar energy and unusual large solar installation angles. The hybrid wind and solar energy supply and energy demand is studied with an analytical analysis of average monthly energy yields in The Netherlands, Spain and Britain, capacity factor statistics and a dynamic energy supply simulation. The analytical focus in this paper differs from that found in literature, where analyses entirely rely on simulations. Additionally, the seasonal energy yield profile of solar energy at large installation angles is studied with the web application PVGIS and an hourly simulation of the energy yield, based on the Perez model. In Europe, the energy yield of solar PV peaks during the summer months and the energy yield of wind turbines is highest during the winter months. As a consequence, three basic hybrid supply profiles, based on three different mix ratios of wind to solar PV, can be differentiated: a heating profile with high monthly energy yield during the winter months, a flat or baseload profile and a cooling profile with high monthly energy yield during the summer months. It is shown that the baseload profile in The Netherlands is achieved at a ratio of wind to solar energy yield and power of respectively Ew/Es = 1.7 and Pw/Ps = 0.6. The baseload ratio for Spain and Britain is comparable because of similar seasonal weather patterns, so that this baseload ratio is likely comparable for other European countries too. In addition to the seasonal benefits, the hybrid mix is also ideal for the short-term as wind and solar PV adds up to a total that has fewer energy supply flaws and peaks than with each energy source individually and it is shown that they are seldom (3%) both at rated power. This allows them to share one cable, allowing “cable pooling”, with curtailment to -for example-manage cable capacity. A dynamic simulation with the baseload mix supply and a flat demand reveals that a 100% and 75% yearly energy match cause a curtailment loss of respectively 6% and 1%. Curtailment losses of the baseload mix are thereby shown to be small. Tuning of the energy supply of solar panels separately is also possible. Compared to standard 40◦ slope in The Netherlands, facade panels have smaller yield during the summer months, but almost equal yield during the rest of the year, so that the total yield adds up to 72% of standard 40◦ slope panels. Additionally, an hourly energy yield simulation reveals that: façade (90◦) and 60◦ slope panels with an inverter rated at respectively 50% and 65% Wp, produce 95% of the maximum energy yield at that slope. The flatter seasonal yield profile of “large slope panels” together with decreased peak power fits Dutch demand and grid capacity more effectively.
Airborne wind energy (AWE) is an emerging renewable energy technology that uses kites to harvest winds at higher altitudes than wind turbines. Understanding how residents experience a local AWE system (AWES) is important as the technology approaches commercialization. Such knowledge can help adjust the design and deployment of an AWES to fit locals' needs better, thereby decreasing the technology's burden on people. Although the AWE literature claims that the technology affects nature and residents less than wind turbines, empirical evidence has been lacking. This first community acceptance study recruited residents within a 3.5 km radius of an AWE test site in Northern Germany. Using structured questionnaires, 54 residents rated the AWES and the closest wind farm on visual, sound, safety, siting, environmental, and ecological aspects. Contrary to the literature's claims, residents assessed the noise, ecological, and safety impacts similarly for the AWES and the wind farm. Only visual impacts were rated better for the AWES (e.g., no shadows were perceived). Consistent with research on wind turbines, residents who rated the site operation as fairer and the developer as more transparent tended to have more positive attitudes towards the AWES and to experience less noise annoyance. Consequently, recommendations for the AWE industry and policymakers include mitigating technology impacts and implementing evidence-based strategies to ensure just and effective project development. The findings are limited to one specific AWES using soft-wing kites. Future research should assess community responses across regions and different types of AWESs to test the findings' generalizability.
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Wind turbines are usually clustered in wind farms which causes the downstream turbines to operate in the turbulent wakes of upstream turbines. As turbulence is directly related to increased fatigue loads, knowledge of the turbulence in the wake and its evolution are important. Therefore, the main objective of this study is a comprehensive exploration of the turbulence evolution in the wind turbine’s wake to identify characteristic turbulence regions. For this, we present an experimental study of three model wind turbine wake scenarios that were scanned with hot-wire anemometry with a very high downstream resolution. The model wind turbine was exposed to three inflows: laminar inflow as a reference case, a central wind turbine wake, and half of the wake of an upstream turbine. A detailed turbulence analysis reveals four downstream turbulence regions by means of the mean velocity, variance, turbulence intensity, energy spectra, integral and Taylor length scales, and the Castaing parameter that indicates the intermittency, or gustiness, of turbulence. In addition, a wake core with features of homogeneous isotropic turbulence and a ring of high intermittency surrounding the wake can be identified. The results are important for turbulence modeling in wakes and optimization of wind farm wake control
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De energietransitie van fossiele naar duurzame energie krijgt brede maatschappelijk aandacht. Er zijn projecten voor het plaatsen van zonnepanelen en windturbines. Dit betreft zowel nationale projecten (zoals windparken op de Noordzee en de discussies over waterstof) als kleinere lokale projecten in huizen in woonwijken en bedrijfsgebouwen op bedrijventerreinen. Netcongestie is een recente ontwikkeling, wat betekent dat het elektriciteitsnet niet meer genoeg transportcapaciteit heeft om afspraken te kunnen maken voor nieuwe aansluitingen. Netcongestie beperkt de uitbreiding en vestiging van nieuwe bedrijven in sterke mate. De opschaling van de installatie van duurzame bronnen zoals zon- en windenergie wordt er door onmogelijk. Dit leidt tot een sterke vermindering van de toekomstige economische activiteiten en brengt het halen van duurzame-energiedoelstellingen in gevaar. Op korte termijn is volledig fysieke versterking van het net onmogelijk door gebrek aan mankracht en trage vergunningsprocedures. Een tussentijdse oplossing is het optimaal benutten van de netcapaciteit door de werkelijke vraag en aanbod te meten en beter op elkaar af te stemmen. In deze aanvraag stellen wij een onderzoeksaanpak voor om op lokaal bedrijventerreinenniveau deze sturing, vanuit een nauwe samenwerking tussen de netbeheerder, de parkorganisatie en de lokale (MKB) bedrijven op een bedrijvenpark, vorm te geven. Dit verkennend onderzoek begint met het in kaart te brengen van lokale (energie-)behoeftes en oplossingsmogelijkheden op laagspanningsniveau. Dit gebeurt door de informatie van slimme meters en de laagspanningstrafo’s momentaan uit te lezen en met AI de te verwachtte belasting te bepalen. Als bekend is wat de lokale regelmogelijkheden zijn, kan er met de bedrijven worden nagegaan hoe het huidige laagspanningsnet beter kan worden benut voorafgaand aan grote netverzwaring. Wij inventariseren hoe de opties en de voordelen voor de ondernemers op een begrijpelijke manier kunnen worden gepresenteerd, bijvoorbeeld met behulp van een dashboard.
Het project "CompEfficient" onderzoekt het verbeteren van energie-efficiëntie in de productie van composietmaterialen, gebruikt in transport en bouw, zoals vliegtuigen, auto’s, treinen, en windturbines. Composieten zijn gunstig door hun lichtgewicht en sterke mechanische eigenschappen die bijdragen aan lagere CO2-emissies. Dit onderzoek focust op zowel biobased als hoogwaardige thermoplastische composieten, waarbij traditionele fabricagemethoden veel energie vereisen, resulterend in relatief hoge CO2-uitstoot. Geleid door Hogeschool Inholland, met industriële partners Eve Reverse en Cato Composites, streeft dit eenjarige project ernaar energie-efficiëntie te verhogen door het persproces - waarbij materialen worden verwarmd en gevormd - te optimaliseren. Dit omvat het verminderen van energieverlies bij het verwarmen en het drukzetten van materialen. Het project zal bestaande pers- en verwarmingsmethoden evalueren en nieuwe technologieën evalueren en testen in een labomgeving, met als doel het energieverbruik te minimaliseren terwijl de productkwaliteit gehandhaafd blijft. De verwachte uitkomsten zullen bredere implicaties hebben voor de industrie door bij te dragen aan duurzamere productieprocessen en het verminderen van de milieu-impact van de composietproductie. Deze innovaties zullen niet alleen van belang zijn voor de betrokken bedrijven maar kunnen ook internationaal worden toegepast, gezien de groeiende vraag naar energie-efficiënte en milieuvriendelijke productiemethoden. Dit project biedt een kans om de voetafdruk van de composietindustrie aanzienlijk te verminderen en ondersteunt de overgang naar meer duurzame industriële processen.
TU Delft, in collaboration with Gravity Energy BV, has conducted a feasibility study on harvesting electric energy from wind and vibrations using a wobbling triboelectric nanogenerator (WTENG). Unlike conventional wind turbines, the WTENG converts wind/vibration energy into contact-separation events through a wobbling structure and unbalanced mass. Initial experimental findings demonstrated a peak power density of 1.6 W/m² under optimal conditions. Additionally, the harvester successfully charged a 3.7V lithium-ion battery with over 4.5 μA, illustrated in a self-powered light mast as a practical demonstration in collaboration with TimberLAB. This project aims to advance this research by developing a functioning prototype for public spaces, particularly lanterns, in partnership with TimberLAB and Gravity Energy. The study will explore the potential of triboelectric nanogenerators (TENG) and piezoelectric materials to optimize energy harvesting efficiency and power output. Specifically, the project will focus on improving the WTENG's output power for practical applications by optimizing parameters such as electrode dimensions and contact-separation quality. It will also explore cost-effective, commercially available materials and best fabrication/assembly strategies to simplify scalability for different length scales and power outputs. The research will proceed with the following steps: Design and Prototype Development: Create a prototype WTENG to evaluate energy harvesting efficiency and the quantity of energy harvested. A hybrid of TENG and piezoelectric materials will be designed and assessed. Optimization: Refine the system's design by considering the scaling effect and combinations of TENG-piezoelectric materials, focusing on maximizing energy efficiency (power output). This includes exploring size effects and optimal dimensions. Real-World Application Demonstration: Assess the optimized system's potential to power lanterns in close collaboration with TimberLAB, DVC Groep BV and Gravity Energy. Identify key parameters affecting the efficiency of WTENG technology and propose a roadmap for its exploitation in other applications such as public space lighting and charging.
