Basalt Fibre Reinforced HDPE for Wave Energy Converters
This project addresses the renewable energy technology challenge area, with the objective of establishing the technical feasibility of basalt fibre reinforced High Density Polyethylene (HDPE) as an advanced material for the primary structure of an ocean wave energy converter (WEC). HDPE offers a low cost structural material that is resistant to UV, corrosion and biofouling increasing the lifetime and reducing the maintenance requirements for a wave energy converter. While fibre reinforced HDPE has been previously investigated, the use of basalt fibres is novel and offers superior properties compared to a standard E-glass which is commonly used in fibre composite manufacture. Basalt fibre is also chemically inert and when combined with recycled HDPE potentially offers a high performance, low cost, green structural material for wave energy converters. In addition to the immediate application to WEC’s the material has application to other offshore energy generation technologies.
A current challenge for wave energy generation is to reduce the levelised cost of electricity (LCoE) generated, necessary to increase the competitiveness of WECs for energy generation. The use of fibre reinforced HDPE as a structural material offers an improved lifetime and reduced maintenance costs over conventional structural materials such as steel. This can significantly contribute to the necessary reductions in LCoE. Wave energy is an inherently low carbon source
of energy, and one objective of the project is to use recycled HDPE therby reducing the environmental impact of the manufacturing process. The UK is well placed to take advantage of wave energy generation, with the 2011 UK Renewable Energy Roadmap reporting that wave and tidal energy could generate 27GW by 2050.
Basalt fibre reinforced HDPE as an enabling technology for lower cost WEC devices contributes to all parts of the energy trilemma through reducing carbon emissions, reducing energy costs and providing security of supply through taking advantage of the UK’s wave resources.
The project will explore the potential of this material by investigating the influence of parameters such as the relative proportion of fibre and HDPE on the mechanical behaviour, development of a suitable material composition and verification of the ability of existing manufacturing processes to utilise the new material.
Composite development and optimisation led by Professor Karnik Taverdi
Brunel University aims to develop and optimise a suitable composite material manufactured with different fibre concentrations, fibre preparation, additives, coatings etc to investigate the influence of these parameters on relevant material properties. Mechanical testing and microstructural investigation will be used to measure material strength and stiffness, the fibre distribution within the material and the quality of the adhesion between the fibre and matrix materials. Co-rotating intermeshing twin screw extrusion technology will be used to compatibilise and combine fibres with the base polymer and the composite produced will be stranded and pelettised ready for further processing. The test samples will then be prepared primarily by injection moulding, if necessary compression moulding or rotational moulding techniques will also be used. Both virgin and recycled HDPE material will be investigated. The material composition that provides the best perforamce properties will then be used for the WEC application.
Structural Simulation and Modelling led by Dr James Campbell
In collaboration with partner Sea Energies, Brunel University will develop one or more representative structural models to allow the mass of a WEC using the novel material to be assessed. The model will be based on the material properties on best perfoming composite. The same models will be used to estimate the mass of steel and unreinforced HDPE versions of the same WEC. Along with the device mass for composite material this information will be used to estimate the gain in levelised cost of electricicty (LCoE) from using the new material.
Fig. 1. SeaEnergies wave energy converter (scale model) on trials off the coast of Ireland. Our research aims to replace the hull with recycled HDPE-basalt fibre composite offering a high performance, low cost, green material.