Community Research and Development Information Service - CORDIS

H2020

SPARCARB Report Summary

Project ID: 642771
Funded under: H2020-EU.1.3.1.

Periodic Reporting for period 1 - SPARCARB (Lightning protection of wind turbine blades with carbon fibre composite materials)

Reporting period: 2015-01-01 to 2016-12-31

Summary of the context and overall objectives of the project

Wind turbines are often erected in remote areas of the world, off shore or in mountainous regions, to exploit better wind resources. In these areas, the cost of failures and repairs can be substantial, and increase the levelized cost of energy (LCOE) remarkably. Since blade failures due to lightning are known to cause the longest outage time and involve the largest repair cost, ensuring the lightning performance of the turbines and especially of the blades has become very important.
Modern wind turbine blades are to a large extent manufactured using Carbon Fiber Reinforced Polymers (CFRP) structural parts, due to the CFRP’s excellent mechanical tensile strength and stiffness, combined with a light weight. The use of CFRP decrease the weight of the overall rotor, and hence reduce the requirements for the remaining structure (drivetrain, nacelle structural parts, tower, foundation, etc.). By reducing all loads on the structure, the cost of the installed capacity can be minimized (CAPEX).
However, CFRP also exhibit highly an-isotropic electric and thermal conductivities, which require special attention in terms of lightning protection. The specific issues of concern include design of electrical bonding to CFRP, investigation of damage tolerance, resin chemistry to optimize thermal and electrical properties of the CFRP, guidelines on overall protection concepts, etc. The research project SPARCARB is dedicated to solve these challenges of enabling efficient lightning protection of wind turbine blades using these CFRP based materials.
Once the complete knowledge on the interaction between lightning and CFRP is achieved, and the knowledge is built into design guidelines and paradigms for blade manufacturing, blades can be designed to lower both CAPEX and OPEX of wind turbines. The reduced CAPEX will make future investment in wind plants more attractive, and the reduction in OPEX will ensure that the business case for investors remains attractive for the lifetime of the turbines. Both are important to ensure integration of more green energy into our system, and SPARCARB will via the generated knowledge assist in this process.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The work conducted in the first 24 months of the project have focused on recruiting the right candidates for the ESR positions, since the project is highly multidisciplinary and requires skills within mechanical and electrical engineering, material science, overview of complex manufacturing processes, etc. The first three ESRs were recruited from September 2015 to January 2016, and these ESRs have now spent 12months+ at the University of Southampton to follow their academic courses and training as described in their research plans. Secondly, interaction with the industrial beneficiary 'Global Lightning Protection Services A/S' as well as the industrial partner organisations, have given the ESRs a unique understanding of the industrial challenges in large scale blade manufacturing, and designing blades in compliance with the lightning environment.
Specific achievements are:
1 - A baseline CFRP material have been been defined to ensure the research and tests are conducted on realistic materials.
2 - The resin chemistry have been investigated, and efforts have been made to improve properties using different additives.
3 - Thermal, electrical, chemical and combined properties have been measured, to fully understand and model the complex processes involved in lightning interaction with CFRP.
4 - Several impulse current and arc entry tests have been completed by the ESRs on representative panels in both the SOTON laboratories as well as the GLPS lightning laboratory.
5 - Lightning induced structural damages have been investigated by means of CT scans and similar methods, and the damage mechanisms vs. the lightning impact have been described and modeled.
6 - Arrangements for the secondments scheduled in May/June 2017 and February/March 2018 have been made.
The project has been slightly delayed due to the late recruitment of ESR1, ESR3 and ESR4, hence some of the project milestones have not yet been completed. The recruitment of ESR2 is expected in March 2017, where the technical effect on the overall SPARCARB project is minimised by effectuating suitable mitigation plans. To compensate for the delay of ESR2, the supervisory team and ESR4 have adopted a decoupled modelling strategy, by which the thermal-electrical and mechanical damage models are decoupled, and where the former provides input for the latter. Initial thermal-electrical models have been developed that predict the temperature evolution, which is being used to estimate the location and volume of damaged CFRP, as well as the particular type of damage.
In general the project is in good shape, and both beneficiaries and the ESRs look forward to put the academic findings into an industrial context in the upcoming placement at GLPS (commencing February 1st 2017).

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Considering the location of wind turbines, the risk of harming humans or livestock can be substantial. In several cases pieces/components, even entire blades, have been detached from wind turbines because of lightning induced damage. This governs both blades made of pure fiberglass (GFRP) but also blades where structural components are replaced by carbon fiber composites (CFRP). SPARCARB is tailored to provide the knowledge on CFRP and its interaction with lightning, and explicitly how to optimize the material and the lightning interaction to secure a reliable and safe operation.
In this sense, blades with improved lightning performance does not only save operational cost and downtime for the turbine owner, but is also considered far safer than today’s blade designs.
The specific results being achieved within SPARCARB are listed in the following:
1. Clear protection strategy for CFRP blades and the formulation of a process guideline from initial structural design to safe lightning design. This is an overall goal for SPARCARB involving all four ESRs.
2. The properties of the CFRP composite material is characterized by ESR1, leading to an important discussion on the role of thermal and electrical properties vs. lightning performance. The research challenges the perception of electrical conductivity being the dominant parameter for lightning immunity, and it seems as if ESR1 is approaching a breakthrough in the importance of thermal properties as well.
3. Investigation and formulation of the matrix resin, and how to enhance especially thermal and electrical properties. By including Graphene Oxide Nano fillers, we believe to change the view on the isotropy of CFRP remarkably. The work is driven by ESR3.
4. Well defined damage description - which failure modes exists for the CFRP material against the various stresses induced by lightning. By knowing the limits, it is easier to design cost efficient without excessive engineering margins in one end, or over testing in the other. The results are improved design paradigms, mostly driven by ESR4

With its dedicated research team and the excellent list of partner organizations hosting the ESRs during their secondments, SPARCARB will provide an extensive outlook into means of optimising the CFRP material and its integration with the lightning environment. These results will be of technical benefits of blade manufacturers, financial benefits of future operators of wind turbine blades, and general benefits for the society experiencing cost of energy from renewable sources.
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