In directly addressing the question, ‘can flax replace E-glass as a reinforcement for structural composites?’, this manuscript adopts a novel comparative case study approach to investigate the manufacture and mechanical testing of full-scale 3.5-m composite rotor blades (suitable for 11kW turbines) built from flax/polyester and E-glass/polyester.The resin transfer moulded flax blade is 10% lighter (fibre mass saving of 45%) than the identical construction E-glass blade. Static flap-bending tests, conducted in accordance to certification standards, confirm that like the E-glass blade, the flax blade satisfies the structural integrity requirements under ‘normal operation’ and ‘worst case’ loading. It is consequently claimed that flax is a potential structural replacement to E-glass for similar composite small wind turbine blade applications.The failure root bending moment and corresponding tip displacement of the flax blade are 11.6kNm and 2300mm, respectively. The blades exhibit distinctly different load–deflection curves and failure modes. The mean flexural rigidity of the flax and E-glass blades are estimated to be 24.6kNm2 and 43.4kNm2, respectively. It is interesting to find that although flax fibres and their composites are generally recognized for their stiffness, a flax blade cannot compete against an E-glass blade in terms of stiffness

The adverse effect of the use of fossil fuels on the environment and public health has given rise to a sustained renewable energy research and development. An important component of global renewable energy mix is the use of loose biomass, including agricultural and forestry residues, to produce solid fuels in the form of briquettes. Briquettes play a significant role in bioenergy mix in developing and developed countries. The production of biomass briquettes often entails the collection, transportation, storage, processing, and compaction of loose biomass that meet specific quality parameters. The densification process often involves the addition of binders to improve the cohesive strength of the briquette material. This paper surveys recent literature from 2012 to 2021 to establish the current state of research on the use of binders in briquette production; and reviews current parameters used in assessing the quality of biomass briquettes with focus on mechanical and handling properties. While a number of quality parameters were identified, their assessment methodologies varied widely in the literature, thus necessitating standardization for comparability purposes. The review also includes factors affecting the wide production and adoption of biomass briquettes in most developing economies and proposes ways of overcoming the bottlenecks.

The effect of fibre volume fraction on the physical and tensile properties of aligned plant fibre composites (PFCs) produced via vacuum infusion has been investigated. There is no clear correlation between fibre volume fraction and porosity. However, low fibre content PFCs are prone to intra-yarn voids, while high fibre content PFCs are prone to inter-yarn voids. This is due to changing resin flow dynamics with increasing fibre content.The tensile behaviour of PFCs with increasing fibre content is similar to that of conventional fibre reinforced plastics (FRPs). Interestingly, the non-linear stress–strain response of plant fibres has been transferred to the composites.Fibre content and tensile properties are found to be linearly related, as per the rule of mixtures. A void content of up to 4% is found to have minimal effect on the tensile properties of PFCs. The minimum and critical (vf,crit) fibre volume fractions for aligned flax and jute–polyester composites are found to be substantially higher than conventional aligned FRPs; vf,crit for jute–polyester and carbon–polyester is 8.1% and 2.4%, respectively. A simple model has also been developed to approximate the theoretical maximum obtainable fibre volume fraction of PFCs reinforced with staple fibre yarns. The absolute theoretical maximum fibre content is found to be 58.9%, which agrees with experimental values in literature. A high vf,crit (∼10%) and low vf,max (∼45%) implies that the range of useful fibre volume fractions for PFCs containing staple fibre twisted yarns is only 35%