2pm, 9th June 2016, IDL Boardroom.
Prof. Lawrence C. Bank, Dist.M.ASCE, F.ACI, F.IIFC, City College of New York.
Recycling GFRP composite materials – a looming wind power sustainability problem
The rapid growth in wind energy technology in the last 15 years has led to a commensurate rapid growth in the amount of FRP materials used in this industry. One wind blade of a typical 2.5 MW turbine is 50 m long blade, contains approximately 8 tonnes of FRP material, and costs about $150,000. Unlike FRP materials used in ot
her industries, such as, marine, construction and transportation, turbine blades have a well–defined lifespan. They are expected to be taken out of service after approximately 20 years due to fatigue life limits; and may even be replaced before that time. By 2035, 705,200 tonnes of blades will need to be disposed in the US from the turbines installed between 2000 and 2015.
This translates to a global total of 4.2 million tonnes. It is clear that innovative concepts at all scales, from materials, to parts, to whole structures need to be developed to recycle these GFRP blades that do not include landfilling or incineration and contain very little material of value. Work at CCNY is currently addressing a number of these different scales.
On the materials level, the use of production waste FRP parts is being studied as a replacement for coarse aggregates in concrete. As a precursor to obtaining materials from wind blades, recent experimental investigations have used waste pultruded GFRP reinforcing bars. Rebars ranging from 6 mm to 25 mm in diameter were cut into cylindrical aggregate–sized pieces and used as a replacement for the natural coarse aggregate at percentages of 5, 10, 40 and 100%. Test cylinders were cast and tested for compressive strength and tensile (splitting) strength. Strength data are presented and compared with ACI and EU predictions. An analysis of failure modes and failure surfaces as a function of the replacement percentages is provided. In addition, the electricity consumed (in kWh) to cut of the FRP aggregate pieces is discussed and a brief discussion of life–cycle assessment (LCA) needed to address the economic and environmental trade–offs with this down–cycling method is provided. The significance of these results on the possible use of aggregate pieces from waste wind blade pieces is discussed, as well as needs for future research in this area.
Lawrence C. Bank is a Professor in the Department of Civil Engineering at the Grove School of Engineering at the City College of New York (CCNY) of the City University of New York (CUNY). From 2010 to 2013 he was Vice President and Associate Provost for Research and Sponsored Programs at CCNY. From 2008 to 2010, and again from 2014 to 2015, Dr. Bank was a Program Director at the US National Science Foundation (NSF). Dr. Bank began his studies in the Schools of Architecture and Civil Engineering at the University of Cape Town, South Africa. He received his BSc degree from the Technion, Israel in 1980, and his MS and PhD degrees from Columbia University in New York in 1982 and 1985, respectively. He has previously been a Structural Engineer with Leslie Robertson and Associates (LERA) in New York and on the faculty at Rensselaer Polytechnic Institute, Catholic University and the University of Wisconsin. His research focuses on the mechanics and design of composite material structures, and on sustainable buildings and construction materials. He is the author of "Composites for Construction: Structural Design with FRP Materials" (Wiley, 2006).