Over the last two decades, the tidal energy industry has laid the groundwork for creating commercially viable tidal power generation projects to strengthen sustainable energy policies around the world. At the end of 2021, the cumulative installation of tidal stream technology that has been deployed in Europe reached 30.2 MW, where the majority of the installations are by small and medium-sized companies. Due to a growing demand among investors related to the global tidal energy industry, the reliability and safety of operational-stage tidal energy systems’ components are becoming increasingly important. In this context, companies, universities and research institutes are focusing on conducting large- and small-scale tests of tidal turbine elements to validate their projected design life, and major attention is being given to assessing the structural integrity of turbine blades. This review paper focuses on structural tests that have been reported for axial flow tidal turbine blades manufactured using composite materials around the world, highlighting the testing standards, equipment and instrumentation required. Overall, this review article discusses the state of the art in the structural testing of tidal turbine blades. In addition, it highlights the global concerns and research gaps to ensure the long-term sustainability of axial flow tidal turbine blades. In addition, the information contained in this article will be useful for formulating a smooth and reliable mechanism to enhance the evaluation process of the structural properties of tidal turbine blades in the future.

The study compares the environmental impact of coal-fired electricity generation and solar photovoltaic (PV) systems for generating domestic-level electricity demand for Sri Lankan households. In Sri Lanka, the average roof size and power consumption of detachable houses were estimated to be 20-50m ² and 130kWh per month, respectively. The installation costs of on-grid, off-grid, and hybrid solar PV systems were then compared to determine the best system to install. Based on the country's economic situation and power outage trends, an offgrid solar PV system was chosen as the best solar system for domestic-level applications in Sri Lanka. Following that, a lifecycle assessment (LCA) was performed to compare the environmental impacts of using off-grid solar PV and coalpowered thermal power systems to generate 310kWh per month for 20 years. The LCA results revealed that the rooftop-installed solar PV system was the most environmentally friendly electricity generation method in Sri Lanka for domestic-level applications. The authors emphasized the significance of potential changes to the Sri Lankan National Energy Policy by implementing the NetZero vision at the local household level.

The structural testing of tidal stream turbines is critical for ensuring their reliability and performance, with testing procedures aligned to standards such as DNVGL-ST-0164 and IEC DTS 62600-3:2020. This research explores the structural integrity of tidal turbine blades, where a set of advanced instrumentation was employed during the testing program, including fibre bragg grating sensors for strain measurement, laser scanning vibrometers for dynamic performance analysis, digital image correlation systems, laser displacement sensors for displacement measurements, and infrared thermal imaging for temperature monitoring. The use of these advanced measuring tools improved the reliability of data collection, post-processing accuracy, and result representation, setting a new standard for structural testing of tidal turbine blades. The case study of ORPC’s 5m long crossflow turbine foil with a rotor diameter of 1.8m, tested under controlled dry laboratory conditions was used. Within this test, an unbalanced rotating mass was used to apply fatigue loading, achieving a groundbreaking milestone of 1.3 million fatigue cycles. This accomplishment represents a significant advancement in fatigue testing techniques. The approach proved more efficient than traditional servo-hydraulic actuators in applying fatigue loads, enabling faster test timelines while maintaining accuracy. Post-test inspections and analyses provided further insights into damage mechanism and material degradation. The damaged sections revealed shear fractures in the matrix materials, bond failures at the matrix-fibre interface, and fibre breakage in both the leading and trailing edges of the turbine foil. Additionally, tensile testing was performed on coupons extracted from undamaged areas of the foil to assess the effects of fatigue degradation. The comparison of strain results from the finite element model with both manufacturer-specified and experimentally derived material properties, using strain distributions identified during the structural testing program, offered valuable insights. This analysis enabled the study to develop a comprehensive understanding of blade performance and material behaviour under the given conditions. Moreover, this study aims to address critical gaps in current structural testing practices, particularly the operational stage impacts often overlooked in dry laboratory conditions and their effects on blade performance. It specifically examines how water absorption impacts the material properties and long-term durability of tidal turbine blades. The research also seeks to identify a methodology for integrating material testing outcomes with the effects of water absorption to develop a predictive framework for estimating blade lifespan in line with the operational status. By incorporating these findings, the industry can accelerate the development of affordable and sustainable tidal energy solutions, contributing to a cleaner and more resilient global energy portfolio.