The markets: Renewable energy (2018)

The market for composites in wind turbines, comprising mainly nacelles and rotor blades, totaled US$7.2 billion in 2015 and is expected to grow at a CAGR of 9.3% to reach US$12.2 billion by 2021. 

Wind energy continues to dominate in this segment and remains, far and away, the world’s largest market for glass-fiber-reinforced composites. It’s also competing with other heavy users, such as the aerospace industry, for carbon fiber as blades get longer and blade builders look for ways to lightweight the massive structures without performance sacrifices. Wind turbine blades remain a key market segment for composites. According to a report titled Wind Turbine Composites Material Market: Global Trends & Forecast to 2020 by MarketsandMarkets (Magarpatta City, India and Seattle, WA, US), the market for composites in wind turbines, comprising mainly nacelles and rotor blades, totaled US$7.2 billion in 2015 and is expected to grow at a CAGR of 9.3% to reach US$12.2 billion by 2021, thanks especially to increasing demand in China, India, South Korea and Japan. 

The wind industry consultancy MAKE (Chicago, IL, US and Aarhus, Denmark) estimates that roughly 650,000 wind turbine blades will be produced between 2017 and 2025, with a 12-15% increase in the average rotor diameter. “Blade lengths continue to increase,” says MAKE partner Dan Shreve, “offering an enormous market opportunity for blade OEMs and their strategic materials providers.”

In the US, wind power is booming, and that despite facing year three of a five-year phase-down of the Production Tax Credit on which the industry was once dependent for its financial security. More than 900 utility-scale turbines (fitted with 2,700 composite blades) were installed in the first quarter of 2017, totaling 2,000 MW of capacity. This is the US wind industry’s strongest start since 2009, according to a new report released by the American Wind Energy Assn. (AWEA, Washington, DC, US).

“We switched on more megawatts in the first quarter than in the first three quarters of last year combined,” says Tom Kiernan, CEO of AWEA, at the release of the U.S. Wind Industry First Quarter 2017 Market Report. Growth continued strong throughout 2017.

 The roster of US wind projects under construction and in advanced development as of the end of the third quarter of 2017 had reached 29,634 megawatts (MW), the highest level since this statistic was first measured at the beginning of 2016, according to AWEA’s U.S. Wind Industry Third Quarter 2017 Market Report, and wind power is competing for and winning the business of a growing set of major utilities and Fortune 500 brands.

With year-over-year construction and advanced development activity up 27%, wind’s strong growth reflects a new status quo. Wind power now has a place in the energy mix of some of America’s largest companies. The combined pipeline of 29,634 MW of wind capacity includes 13,759 MW now under construction and 15,875 MW in advanced development, defined as not yet under construction, but having signed a power purchase agreement, proceeding under utility ownership, or announcing a firm turbine order. Within the pipeline, new third quarter activity represents 4,248 MW of capacity entering advanced development and 638 MW beginning construction.

In the US, many observers believe that wind farms will function competitively as the PTC fades out, but at least one materials supplier has anticipated the need to improve those chances. Although the cost of building and operating wind turbines has decreased significantly over the past two decades, Covestro’s (Leverkusen, Germany) Kim Harnow Klausen says, “Blades are still 25-35% of the total wind turbine cost.”

Klausen is the head of Covestro’s program to develop polyurethane (PU) as an optimized matrix resin to replace epoxy in composite wind blade production. Begun in 2009, the
program produced a demonstrator glass fiber/PU spar cap for a 45m long wind blade, using resin infusion in 2015. “We have now made the first polyurethane wind blade in Asia, a
37.5m long blade for a 1.5-MW wind turbine in China,” says Klausen. For this blade, all of the components — spar, web, root and shell — were infused using Covestro’s PU resin. “We are also going to make a larger blade this year,” he adds. 

Why polyurethane? “The resin we have developed is 10-25% stronger than epoxy,” Klausen claims. PU also offers inherently lower viscosity — below 100 cps at 25°C — for faster infusion, as well as a faster cure and less exotherm during cure vs. epoxy, vinyl ester (VE) and polyester systems. Further, as blade length increases, so does the need for improved properties and fatigue performance, as well as fabrication speed. The benefits of a change from epoxy to polyurethane were compiled in a 2012 presentation by Usama Younes at Sandia National Laboratories (Albuquerque, NM, US), based on multiple investigations of PU with glass and carbon fiber, including resin infusion molding of a thick, glass/PU root ring for a 42m-long wind blade:

  • 34% less time required for infusion of thick (50-ply) laminates. 
  • >17% greater tensile strength. 
  • Almost double the interlaminar fracture toughness. 
  • 30% lower stress crack growth rate. 
  • Better adhesion to glass fiber. 

In 2017, plans were afoot for additional work toward a demonstration of a complete blade and commercialization in the 2018 timeframe.  

Even the wind energy blade market, as successful as it has been with conventional molding processes, is, like other markets served by composites, giving additive manufacturing a look in the tooling area. In 2016, wind blade maker TPI Composites (Warren, RI, US) received a contract from Sandia National Laboratory (Albuquerque, NM, US) to fabricate a limited number of 13m-long wind turbine blades for testing. Given that conventional machined plug and layup tooling processes can take 6 to 12 months, TPI worked with ORNL to 3D print modules from carbon fiber/ABS, then connected these and applied several layers of fiberglass/epoxy and a finish coat to manufacture the tools in less than half the time usually required and at lower cost. The tools include integrated hot-air heating channels, which replaced the typical resistive electric wire heating system.

Although wind energy still captures the spotlight, and rightly so, the means to convert the power of incoming/outgoing tides and ocean currents are also attaining commercial status. One example in 2017 was Portland, ME, US-based Ocean Renewable Power Co.’s deployment of its commercial-scale TidGen ocean tidal energy power system in Western Passage, at the mouth of the Bay of Fundy, one of the world’s most powerful tidal flows, on the border between eastern most Maine and New Brunswick, Canada. ORPC’s 5-MW, 15-device, all-composite tidal turbine system should have the capability to generate low-cost electric power for all of Downeast Maine. Within 8-10 years, ORPC expects to have 100-120 MW of similar systems in place not only off the coast of Maine but also offshore of Alaska as well. What made the story an especially standout effort was news of a sister system, the RivGen system, a two-turbine unit supported by a chassis with a pontoon support structure that enables installers to tow it into position and then acts as a foundation when it is sunken and deployed on a riverbed. A RivGen on the Kvichak River adjacent to remote Igiugig, Alaska now provides that town power at much lower price than was paid previously when electric power generation was dependent on diesel fuel. 


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