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WALID Report Summary

Project ID: 309985
Funded under: FP7-NMP
Country: Germany

Periodic Report Summary 2 - WALID (Wind Blade Using Cost-Effective Advanced Composite Lightweight Design)

Project Context and Objectives:
The power generated by off-shore wind turbines is proportional to the rotor plane area of the blade. However, the weight of large blades and the harsh conditions in which they operate puts the materials used under considerable strain, leading to shorter operational life. WALiD (Wind Blade Using Cost-Effective Advanced Composite Lightweight Design) will combine design, material and process innovations in an integrated approach. Using advanced thermoplastic composites, the project will develop cost-effective, lightweight, durable and recyclable blades with improved environmental resistance in off-shore conditions, leading to the following advantages:

i. Improved design of the blade root, connection concept and tip: strain analysis on the blade will enable high-performance thermoplastic composites to replace thermosetting composites, saving cost and weight
ii. Replacement of the shell core with thermoplastic foam materials: the density of the core material can be modified to the specific load, optimising the weight/stability profile. Further cost and weight savings will result from processing (elimination of the cutting process, no infiltration of resin into empty spaces)
iii. Improved modular concept of shear web design: replacement of thermosets by thermoplastic composite structures to ensure lightweight, load optimised design
iv. Development of fibre-reinforced thermoplastic coating, improving environmental resistance, anti-icing properties and durability against abrasion combined with a new predictive simulation model

The material development is supported by structural and material simulation of the new concepts as well as a defined testing programme to ensure they meet industry requirements. Case studies will be created demonstrating Life-Cycle Analysis and economic benefits of the new solutions. Finally, demonstration parts for the new technological concepts will be created in order to highlight the potential for full scale production to industrial end-users.

Project Results:
The WALiD consortium has developed and validated materials and construction concepts to reduce the weight and improve the recyclability of wind blades. These include new concepts for the root and shear web, and for the connection of the root. A recent result is the performance of a load calculation for a 90m blade to evaluate the new concepts in these dimensions. The simulation showed a huge weight saving (> 25 %) in this section. The concepts will be further tested in a dynamic test set-up to evaluate the durability.

Activities in the area of material development have included process modification (tape production, tape lay-up). New tape materials have been developed using different types of polymers and fibres. A new version of hybrid type materials consisting of newly developed glass fibres and carbon fibres has also been developed, and laminate plates have been produced and tested to provide data on mechanical properties for the simulation model.

Thermoplastic grades and fillers have been selected for foaming trials. The foaming trials have been conducted on pure resins (mainly PET) with intensive work on the material modification. A new die concept has been developed and tested that allows a high expansion ratio of the foam. The incorporation of nano-scaled fillers to further strengthen the material has been investigated. The foamed materials have been investigated with respect to density, cell size and compressive behavior. A calculation of the final weight showed that a saving of 50 % is possible in this section using concepts developed in WALiD.

Shear web concepts, and their interaction with the spar cap, have been detailed. Different designs and concepts have been investigated, including their manufacture using the robot lay-up of
thermoplastic-reinforced tapes. Especially the simulation of the lay-up process was a major step to evaluate the feasibility of the concepts with the current machine set-up.

The combinations with glass fibre and carbon fibre are currently being tested prior to further development.

WALiD has also developed a predictive model for erosion resistance. Based on a new droplet impingement test different material formulations could be tested.

The potential thermoplastic coatings have been investigated as well as ionomeric coatings and Diels-Alder modification of polyurethane (PU) to make PU thermoplastic. A film shows especially promising results for the erosion resistance.

PBT has been selected as the base material, and glass fibres as well as CNTs and other nanoparticles are being trialed.

Major work has also been carried out to develop the concept of the demonstrators, show-casing the capabilities of the project. A virtual blade demonstrator shows the overall concept of the blade. Physical demonstrators such as the blade root and connection, structural foam and shear web are being developed and simulated. Further test specimens for the root connection concept are under discussion, and a concept has been developed.

Throughout the project, standards have been reviewed to ensure that the new materials and processes conform to current standards. Many of the material-specific details in the standards relating to the design and manufacture of turbines were written with only state-of-the-art thermosetting materials in mind, but many of the design principles can be used with all material technologies.

With regards to ‘Life Cycle Assessment’ and economic evaluation, data has been collected and the scope of the study has been defined. Alongside all of the above activities, a thorough dissemination of the project aims and results has been carried out through the distribution of press releases and ezines, attendance and seminars, conferences and exhibitions, postcards and posters, a project video and the project website. For example, a talk was given on the ITHEC in Bremen.

Potential Impact:
The WALiD project will combine design, material and process developments using thermoplastic composites to create cost-effective, lightweight and recyclable blades which will be demonstrated by industrial end-users.

Wind energy is generally considered to be the most promising renewable energy source and to achieve higher energy output off-shore wind turbine parks are considered one of the best approaches. However, in order to increase the technological and economic efficiency of these large scale wind turbines with blade lengths up to 90m, a number of hurdles must be overcome – weight/performance ratio, environmental condition and high load conditions.

The global market for offshore wind turbines is expected to account for 11% of all the installed rotor blades in the market, whereas in 2012 this represented less than 1%. While the general composition of rotor blades utilised in onshore and offshore wind turbines are similar in terms of design, structure and composition; it is the larger size of the rotor turbine blades used in offshore applications which is the major difference. With a drive towards reducing costs and increasing energy output, increasing blade sizes look set to become the norm in the foreseeable future.

According to recent research, the global wind turbine blade market is expected to almost double between 2011 and 2016 from an estimated €5.7 billion to €10.9 billion. Considering a total requested funding of €3,964,797, the multinational consortium, by capturing only 0.5% of the smallest market prediction, produce results worth up to €28.5 million in 3 to 5 years.

Currently, most of the wind rotor blade market share is captured by only a few large organisations, however, it is the prediction of this consortium that the rapid growth of the blade market will bring forward new opportunities for state of the art composite materials, creative product development and innovative strategies which in turn can help develop a tangible competitive advantage in the marketplace for projects such as WALiD.

To quantify more specifically the economic impact of the WALiD results to the partners in the consortium, a range of demonstrators will be identified through which exploitation of the WALiD technology and materials will be targeted. This will define the market pull for WALiD as well highlight to potential industrial end-users the commercial relevance and potential for full scale production.

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