Energy transition requires actions from different sectors and levels, mainly focused on achieving a low-carbon and high-renewable integration society. Among the different sectors, the transport sector is responsible for more than 20% of global greenhouse gas emissions, mostly emitted in cities. Therefore, initiatives and analysis focused on electric vehicles integration powered by renewables is currently a desirable solution to mitigate climate change and promote energy transition. Under this framework, this paper proposes a multi-indicator analysis for the estimation of CO${}_2$ emissions combining renewable integration targets, reduction emission targets and realistic renewable resource potentials. Four scenarios are identified and analyzed: (i) current situation with conventional vehicles, (ii) replacement of such conventional by electric vehicles without renewable integration, (iii) and (iv) integration of renewables to fulfill emission reduction targets for 2030 and 2050 respectively. The analysis is evaluated in the state of Maine (United States). From the results, a minimum renewable penetration of 39% and 82%, respectively, is needed to fulfill the emission reduction targets for 2030 and 2050 by considering 100% conventional vehicle replacement. Different combinations of available renewable resources can reduce emissions by more than 35%.

The objective of this paper is to present an investigation of resistance welded thermoplastic joints using stainless steel wire mesh and polyethylene terephthalate (PET) with unidirectional E-glass fiber reinforcement. Five weld pressures and six heating element types were investigated to achieve high quality welds. Scanning electron microscope (SEM) images of welded heating element cross-sections were analyzed to provide a phenomenological description of the weld. Welded joints were also subjected to experimental lap shear evaluation and joint strengths were compared with values from the literature to assess the overall quality of welded joints. Characteristic B-basis strengths and corresponding SEM images are compared to lead to a recommended weld pressure of 345 kPa with a stainless steel wire mesh with 100 openings per inch.

A methodology for the design and optimization of a composite wind turbine tower for use on a floating offshore platform is presented. A composite turbine tower on a floating offshore platform not only has the potential to reduce maintenance and upkeep costs associated with the use of steel offshore but also has potential to reduce the tower mass and subsequently the support platform mass. The optimization problem is formulated to obtain a turbine tower that meets all strength and serviceability criteria and minimizes the tower mass. The optimization and design process link a number of dynamic analyses and finite element routines using a genetic algorithm. This work documents the optimization and design software and illustrates its use in various case studies for a 6 MW floating wind turbine system. Case studies include the optimization of a steel tower as a comparison to a composite material tower and the use of a cored, sandwich panel composite tower versus a solid composite tower. The results demonstrate that significant reductions in the tower mass are likely when comparing a steel tower with a composite tower. Also demonstrated for the platform and turbine configuration considered in this work is that the minimum mass tower design is driven towards a solid shell composite configuration, rather than a sandwich panel tower shell, in the face of reasonable design constraints.

Innovative floating offshore wind turbine (FOWT) platforms that deviate from the conventional semi-submersible, spar, and tension leg platforms (TLP) have become increasingly common due to the need to tap into the high wind energy potential located in deeper waters. One example is the hanging-mass concept, in which a suspended counterweight stabilizes a positively buoyant floater. This work presents a two-dimensional, nonlinear, multi-body model used to assess the influence of the counterweight mass and the suspension line stiffness on the system’s global performance, using linear stability analysis and time-domain simulations to conduct a parametric study. For example, the counterweight mass has a strong influence on the amplitude of rotational degrees-of-freedom. Corresponding natural periods may occur within the linear wave energy range for suitable counterweight sizes due to this strong influence leading to undesirable motions. High-frequency multi-body modes are also dependent on both the line stiffness and counterweight mass, which may result in high relative motion amplitudes and slack lines in certain conditions. Finally, the parametric study results contribute to preliminary hanging-mass FOWT design recommendations.

Floating offshore wind turbine (FOWT) hull technologies are evolving rapidly with many technically viable designs. However, a commercially dominant architecture has yet to emerge. Early hull designs including semisubmersible, spar, and tension leg platforms were largely derived from offshore oil and gas technologies but recent developments in the commercial application and optimization of FOWTs have resulted in a number of unique, FOWT-specific hull configurations. One hull design of interest includes the application of a moonpool to aid in mitigating platform motion in the presence of waves. A version of this annular hull has been deployed in France and Japan. In this paper, a 6-MW version of an annular hull is studied through experimental model testing and numerical analysis. The primary portion of this work involves testing a 1/100^th-scale model in the Harold Alfond Wind Wave Ocean Engineering Laboratory at the University of Maine. A secondary component of this work investigates the capability of Ansys AQWA, a typical commercial hydrodynamic software, to recreate the wave-induced motion of a FOWT hull containing a moonpool. An additional secondary component of this study compares the wave-only performance of the annular hull to experimental data obtained for the DeepCwind semisubmersible, spar and TLP to provide context for the measured response. The results obtained show that Ansys AQWA can adequately predict the gross response of the annular hull motion, and that the moonpool design tested often exhibits greater motion than the systems tested during the DeepCWind campaign.

Solid-sawn wood or wood composite beams may be reinforced with Fiber Reinforced Polymers (FRPs) on the tension side to increase their bending strength, stiffness and ductility. This paper describes results of an extensive full-scale physical testing program designed to verify the accuracy of a probabilistic model of reinforced glued laminated (glulam) beams. The testing program evaluated 90 glulam beams 130 mm wide x 305 mm deep x 6.7 m long reinforced in tension with E-glass FRP (GFRP). The beams were made using a random layup of L2 and better grade of Douglas Fir and Western Hemlock lamstock and were tested in four-point bending according to ASTM D198. The numerical model, called ReLAM (for Reinforced LAMinated beams), predicts the probability density functions (PDFs) of the Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) for a selected layup of reinforced glulam beams. The model utilizes a moment-curvature mechanics approach, Monte Carlo simulations, and internally calculates the volume effect in reinforced glulam beams from basic statistical mechanics principles. Both the laboratory testing and ReLAM showed that for the Douglas Fir layup tested, a GFRP tension reinforcement ratio of 3.3% increased the allowable bending strength F_b by 119%. ReLAM was found to be an accurate tool for predicting the bending strength and stiffness PDFs of reinforced glulams. These PDFs can be used in reliability-based design of FRP-glulams.