Theano Leventopoulou

• Leventopoulou, Theano; Jiang, Zhiyu & Dai, Jian (2026). Cost estimation of mooring systems for a floating photovoltaic concept, Innovations in Maritime Technology and Engineering. CRC Press. ISSN 9781042001194. doi: 10.1201/9781042001194-141. Fulltekst i vitenarkiv Vis sammendrag

  Floating photovoltaic (FPV) systems are rapidly gaining attention as a viable solution for large scale renewable energy deployment in offshore environments, where mooring systems represent a significant part of the overall installation cost. This study develops a weight-based cost estimation method to evaluate the economic feasibility of alternative mooring designs for FPV applications. This study develops a weight-based cost estimation framework to evaluate the economic feasibility of alternative mooring designs for FPV applications. The proposed methodology estimates total mooring cost as the sum of line material cost, additional component cost, and installation cost, with material cost calculated directly from the total mass of the mooring line. By relating cost to physical properties such as line length, diameter, and linear density, this approach provides a more realistic and transparent representation of manufacturing and material expenses than conventional cost-per-meter methods. Three different mooring configurations are examined: a baseline catenary system, a configuration with clump weight, and an anchorline system. Each configuration is assessed across multiple line diameters to capture variations in material usage and deployment requirements. Previous hydroelastic analysis showed that the clump-weight configuration leads to reduced mooring loads while still satisfying prescribed motion responses. These lower loads enable more efficient use of line material and components, which in turn reduces total system cost. A sensitivity study on the installation coefficient is also carried out to represent different offshore deployment scenarios. Results indicate that line material remains the primary cost driver, with component and installation costs also contributing significantly to total Capital Expenditures (CAPEX). Within the examined diameter range of 90–130 mm, the 110 mm diameter mooring line with clump weights achieves the most cost-efficient balance, offering minimal additional requirements and substantially lower total cost compared to anchor line systems. The findings demonstrate that a weight-based cost framework provides a practical and transparent tool for comparing mooring designs and can guide economical decision-making in future FPV developments.

• Leventopoulou, Theano; Dai, Jian & Jiang, Zhiyu (2026). Influence of mooring configurations on the hydroelastic responses of a floating photovoltaic array. Marine Structures. ISSN 0951-8339. 111. doi: 10.1016/j.marstruc.2026.104155. Fulltekst i vitenarkiv Vis sammendrag

  Floating photovoltaic (FPV) systems have gained increasing attention for offshore renewable energy generation. However, the deployment of these systems in open seas is associated with significant challenges due to wave-induced deformations and structural failures analysis accounts for the fluid–structure interaction and is essential for evaluating FPV systems. This study assesses the influence of mooring configurations on the hydroelastic responses of a prototype offshore FPV array, which consists of six interconnected floats. The three mooring configurations include tendon leg buoys with shared mooring, tendon leg buoys with shared mooring and clump weights, and catenary-shape anchor lines. The numerical study is carried out using a previously developed hybrid finite element and boundary element method. The floats are modeled as rectangular solid plates using Mindlin plate theory, and the modal expansion method is adopted to reduce computational time of the FPV array with 2724 degrees of freedom. We apply Irvine’s equations to analytically model the mooring lines connected to the fairleads, and then linearize the mooring stiffness. The modified stiffness matrices including hydrostatic stiffness, connection stiffness, and mooring stiffness are used in the hydroelastic analysis. A detailed sensitivity study is performed for the FPV array considering various mooring properties and wave periods. Among the three evaluated mooring configurations, the clump weight proved to be the most balanced solution. It offers a moderate increase in vertical mooring stiffness while keeping pretension loads relatively low, namely less than 150 kN and maintaining hydroelastic bending moments and plate deformations across the FPV array at modest levels, with the percentage difference in hydroelastic response remaining under 5%. This can be ascribed as a practical and cost-effective option for improving the structural integrity and motion performance of offshore FPVs.

• Leventopoulou, Theano; Dai, Jian & Jiang, Zhiyu (2025). Hydroelastic analysis of interconnected offshore floating photovoltaic floats. Journal of Offshore Mechanics and Arctic Engineering. ISSN 0892-7219. 147(6). doi: 10.1115/1.4068495. Fulltekst i vitenarkiv Vis sammendrag

  Floating photovoltaic (FPV) concepts have recently emerged as a promising solution for sustainable energy generation, gaining increasing market interest. Despite their potential, FPV systems face significant design challenges related to cost-effectiveness and structural integrity. For FPV arrays in offshore conditions, the structural and hydrodynamic performance of interconnected modules under wave action is a critical consideration, yet research in this area remains limited. This numerical study focuses on the frequency-domain hydro-elastic analysis of a novel FPV concept with semi-submersible floats and rope connections. Each float is simplified as a rectangular plate and modeled using the Mindlin plate theory. A hybrid boundary element-finite element method code is modified and verified to account for the connection stiffness between the floats. Subsequently, a case study is conducted for two and three interconnected plates in two orientations, considering realistic material properties for the connections. The analysis examines the bending moments, deformations, and stresses of the plates under various wave periods and headings. Additionally, the effect of connection stiffness on the responses of the floats is evaluated under varying wave periods. The findings indicate that softer connections mitigate adverse effects, and the differences in structural responses remain below 5% for connections with two material properties. While the system exhibits sensitivity to shorter wave periods, the maximum von Mises stress is well below the allowable yield stress. Overall, the hydroelastic response confirms the good structural integrity of the configurations. This study contributes to a fundamental understanding of modular floating systems under wave effects.

• Leventopoulou, Theano; Dai, Jian & Jiang, Zhiyu (2024). Hydroelastic analysis of floating photovoltaic floater under regular waves, Proceedings of ASME 2024 43rd International Conference on Ocean, Offshore and Arctic Engineering. Volume 4: Ocean Space Utilization.. The American Society of Mechanical Engineers (ASME). ISSN 9780791887813. s. 1–9. doi: 10.1115/OMAE2024-124497. Fulltekst i vitenarkiv Vis sammendrag

  The need for renewable energy is increasing and limited land space for installations has led to the rise of floating photovoltaic (FPV) systems, a promising and relatively new technology for harnessing solar power on water surfaces. Apart from the design and the construction of the FPVs, the hydroelastic problem posed by water waves on plate-like floating structures has a considerable value in the offshore application. This study focuses on the frequency-domain hydroelastic analysis of a recently proposed FPV concept with rope connection. In numerical modelling, each FPV float is simplified as a rectangular plate and modelled by using Mindlin plate elements considering only the vertical degrees of freedom. After a mesh convergence study, the FPV systems with one float and two interconnected floats are studied. Through parametric studies considering different wave headings, periods, and connector stiffness, we compare the distributions of displacement, and bending moments along the float for each system. This study serves as a reference for understanding the hydroelasticity effect of simple FPV systems under different environmental conditions and mechanical connections.

Se alle arbeider i NVA