Propelling the Future of Renewable Energy

As part of National Composites Week, today we are highlighting how Hexcel is propelling the future of renewable energy.

As the world population continues to grow, there is a major push to replace fossil fuels with renewable energy sources such as wind, which is an infinite resource and creates minimal environmental impact. Hexcel has supported wind turbine production worldwide for more than 25 years with excellent know-how in composite materials and process enhancing as well as environmentally friendly production processes.

Wind turbines convert the wind’s energy into mechanical power, which in turn is fed into generators to that are linked to the power grid network to supply homes and businesses with electricity. These turbines are not small. The blade on a wind turbine can stretch up to 241 feet long -- that is two-thirds the length of a U.S. football field. These turbines must operate through decades of use in all sorts of weather, so they must be tough enough to handle the environmental influences while still performing optimally. This requires innovative composite materials to construct the bulk of the turbine blades. Hexcel has provided lightweight, long-term, proven glass and carbon fiber reinforced epoxy resin composites with demonstrated high fatigue resistance needed to construct these enormous efficient blades for more than 20 years. Hexcel specializes in the development and manufacture of carbon fiber, non-crimp fabrics, fiber-reinforcements, prepregs, laminates including pultruded elements, and polyurethanes. Hexcel set up prepreg manufacturing plants in Windsor, Colorado and Tianjin, China to manufacture prepregs for wind blades, complementing our existing plant in Neumarkt, Austria that pioneered the production of glass prepregs for wind turbine blades for our customer Vestas in the 1990s.

Hexcel’s tailor-made wind energy products include various reinforcement materials (unidirectional, biaxial or multiaxial weaves, fabrics, fleeces and kits) impregnated with different types of thermosetting epoxy resins, which are produced on an industrial scale in variable widths and lengths. Additionally, fully cured glass and carbon laminates can be supplied, pre-shaped and ready-to-use for the manufacture of blades in variable lengths and widths.

One of the main considerations in making the manufacturing process more efficient is the curing temperature of the composite. The high curing temperatures (greater than 212˚F in some cases) of some commercial composites are a major disadvantage, since a considerable amount of energy is released by the exothermic curing reaction, resulting in a temperature rise within the composite part. Hexcel has developed the HexPly® M79 prepreg, which cures at temperatures as low at 158˚F with a shorter cure time, while maintaining the same strength properties as conventionally cured composites. This less exothermic reaction allows for the production of thick parts without risking superheating when curing.

Hexcel’s HiMax™ multiaxial fabrics are fantastic reinforcements that allow wind turbine manufacturers to process multiple layers of unidirectional fibers, with each ply placed in a different orientation or axis in a single fabric. HiMax™ non-crimp fabrics using E-glass, high modulus glass and carbon fibers are also available in a wide range of unidirectional, biaxial and triaxial constructions. HiMax™ fabrics have applications throughout the turbine, from the stitched carbon fiber UDs used in the main structural elements, to glass fabrics and hybrids for blade shells and nacelles. There are also specialist applications such as lightweight fabrics for heated leading edge de-icing zones.

Hexcel has also launched a range of HexPly® surface finishing prepregs and semi-pregs for wind turbine blades and marine applications. Providing a tough, durable and ready-to-paint surface without using in-mold coats, these products shorten the manufacturing cycle and reduce material costs. HexPly® XF2(P) prepreg is optimized for wind blades and has a ready-to-paint surface, straight from the mold, saving at least two hours of total manufacturing cycle time.

Polyspeed® pultruded carbon laminates were developed for load-carrying elements in a blade structure and are manufactured with a polyurethane matrix that provides outstanding mechanical performance in terms of stiffness and durability. The blade manufacturing process is optimized, with increased throughput. The pultruded laminates are supplied in coils as continuous cross section profiles.