Lux Research projects wind to become the dominant source of carbon fiber demand in this decade.

With total installed capacity reaching 250 GW at the end of 2011, wind is the most prevalent source of renewable energy today. Furthermore, increasingly strict renewable portfolio standard programs–33% by 2020 in California, 20% in Europe, and 15% in China–provide significant impetus for the wind industry. However, the proliferation of effective wind installations heavily hinges on advanced coatings and composite materials that are critical for maintaining efficient operation.

A recent study conducted by 3M and the University of Illinois found that weathering damage to wind turbines decreases energy generation by over 20% per year, costing developers an estimated $131,000 annually in lost revenues. Functional coatings that offer enhancements in hydrophobic, anti-icing, and anti-drag properties can enhance efficiency and reduce operating and maintenance costs. For instance, researchers at Battelle announced in January 2010 that its carbon nanotube (CNT)-based coatings prevent ice build-up. The coatings, essentially giant resistors composed of CNT networks, heat up when current passes through, preventing ice from adhering and water from freezing. Meanwhile, companies such as GE, CG2 Nanocoatings, Luna Innovations, and Seashell Technologies are developing competitive, yet passive (requiring no energy), anti-ice coatings.

In addition to functional coatings that enhance operation, protective coatings that combat performance degradation by means of corrosion, wear, and fouling are key to maintaining efficient operation, particularly offshore. Currently, large and longstanding industries such as oil and gas and marine get the most attention in regard to protecting offshore structures and vessels. However, as renewable sources continue to play a larger part in the energy portfolio, coatings for offshore structures of wind farms (and wave and tidal power stations) will become increasingly important. Corrosion and fouling will be major concerns for any component that resides in the water, so material developers should keep these emerging segments in mind when designing new coatings.

The average offshore turbine size is expected to rise from currently 3 MW to about 6 MW in 2020. This progression to larger power ratings is logical because offshore turbine construction requires foundations on the sea floor and power transmission lines, which consequently inflate installation costs per unit and make larger turbines more economical. Larger turbines mean bigger blades, thus necessitating use of lighter and stiffer materials that highlight the need for advanced composites.

The most commonly used structural materials in turbine blades are glass fibers in an epoxy resin. Many consider carbon-fiber reinforced plastics (CFRPs) the obvious choice for next-generation blades. In fact, Lux Research projects wind to become the dominant source of carbon fiber demand in this decade, growing at an average CAGR of 26% from 12,500 metric tons in 2011 to 97,600 metric tons in 2020. However, recent significant progress by nanocomposite developers makes this a more interesting game. For instance, startup Applied Nanotech is developing hybrid composites incorporating both glass fiber (about 1/5 the cost of carbon fiber) and multi-walled, carbon nanotube (MWNT) reinforcements in a vinyl ester resin (cheaper than epoxy but with lower performance). The materials have already demonstrated 31% and 20% improvements in flexural strength and modulus compared with the glass-fiber reinforced plastic (GFRP) analog. MWNT-reinforced GFRPs may make a more logical choice for wind-turbine developers if they are able to meet next-generation performance criteria at a lower cost than CFRP. Regardless, advancements in composite design essentially give material developers a palette of resins, reinforcing fibers, and nanomaterial fillers to work with to create the best price and performance for a given application. WPE

By: Ross Kozarsky, Lead Analyst of Advanced Materials team at Lux Research, www.luxresearchinc.com

Windpower Engineering & Development

While carbon fiber and nanomaterials tend to gain all the hype, other advanced structural materials such as magnesium and advanced high-strength steel (AHSS) will have a greater impact on efficient energy use, according to a Lux Research report. Lightweighting has quantifiable savings — in aviation, a 1-lb. reduction is worth a $100 to $300 premium – but each material presents its own challenges, requiring careful choices.

While AHSS remains the leader, carbon-fiber reinforced plastics (CFRPs) can offer greater benefits, and aluminum alloys occupy the middle ground. Magnesium is the lightest structural metal, though it is hobbled by concerns about availability, and titanium’s cost continues to inhibit adoption outside of a few high-end applications, according to the report.

“Meeting the rising energy demand while minimizing environmental impact and maintaining economic growth and opportunity is one of the most important issues of the 21st century — and using current energy reserves more efficiently will no doubt play a critical part,” said Ross Kozarsky, Lux Research Analyst and the lead author of the report titled, Structural Navigation: Optimizing Materials Selection in Automotive and Aerospace.

“The transportation sector commands nearly one-third of global energy demand, providing a vast swath of saving opportunity, and enhancing operating efficiency with lighter structural materials is one of the most promising avenues towards achieving this goal,” he added.

Lux Research analysts conducted decision-tree analyses to understand which materials flourish where — now and in the future — and help automotive and aerospace companies, and guide suppliers and material developers to the best opportunities. Among their findings:

·        AHSS is the cost and availability leader. At an average price of $1.70/kg, AHSS is the cheapest advanced structural material and available in plenty. Its affordable price is a significant advantage for high-volume vehicles, but properties aren’t as dazzling as some other materials, and its limited ductility and welding pose problems.

·        Aluminum is often the best short-term bet. Aluminum is second only to steel in cost and availability because of the scale brought by global giants like Alcoa, Rio Tinto Alcan and Rusal. Its alloys occupy the middle ground on the overall structural materials spectrum and in many uses is the best material to use in the short term without disrupting manufacturing paradigms.

·        Aerospace is decades ahead of automotive in CFRP. While new aerospace models like Airbus’ A350 and Boeing’s 787 Dreamliner employ over 50% CFRP by weight, on average polymer composites constitute less than 2% of an automobile’s total weight. This dichotomy in penetration has resulted in Boeing and Airbus enjoying longstanding relationships with major carbon fiber suppliers such as Toray, Teijin, Mitsubishi Rayon, Hexcel, Cytec and Formosa.

The report, “Structural Navigation: Optimizing Materials Selection in Automotive and Aerospace,” is part of the Lux Research Advanced Materials Intelligence service.

Lux Research 
www.luxresearchinc.com 

Windpower Engineering & Development

The company has developed products that meet low VOC requirements and have short curing times, which means more efficient production. And we’re currently working on other exciting projects for wind towers.” All this means lower production costs for wind turbine and tower manufacturers. A key element of the company’s strategy is a willingness to customize products for the wind industry and offer onsite technical support.

Hempel’s product portfolio for wind turbines consists of products based on epoxy, polyurethane, zinc silicate and polyaspartic, as well as a range of waterborne anti-corrosive products. Besides adhering to industry standards, the company’s protective coatings are durable, provide ultra-violet (UV) stability, and are abrasion-resistant.

Hempel
hempel.com

Windpower Engineering & Development

The turbine mainshaft has been analyzed in nCode DesignLife for its fatigue life. The software has been certified by GL Renewables Certification.

“The certificate proves that the software is suitable for the calculation of fatigue life of forged and cast structural machinery components of wind turbines, “says Mike Woebbeking, Vice President and Head of Certification Body, GL Renewables Certification. It assures users that their component designs can be analysed in conformity with GL RC’s Guideline for the Certification of Wind Turbines 2010.

This includes fatigue analysis under complex real-world loading conditions specified in GL RC’s guidelines or IEC 61400-1 international standard. The evaluation is based on parallel calculations of intermediate and final results considering different stress hypotheses and influence factors for survival probability, cast quality, surface finish, and mean-stress correction.

The software, nCode DesignLife, for fatigue analysis, works well with large models and realistic loading schedules. The developer says its advanced fatigue solver lets wind turbine manufacturers identify when and where failure could occur in a casting using complete loading duty cycles representing the full 20-year loading events experienced in service.

HBM-ncode
www.hbm.com/nCode

GL Renewables Certification
www.gl-group.com

Windpower Engineering & Development

Wind turbine blade manufacturer GBT USA (Global Blade Technology) announced in mid-September 2011 it would be opening a production plant in the U.S. has seen quite a bit of growth in the last four months. In that short time, GBT USA has secured two major blade production projects on the floor and is gearing up to start production on more. The company says it has increased the size of its U.S. team to include engineers, team leaders, and production staff. It expects to see the first blades rolling out the doors in April 2012. The Evansville, Indiana facility will have the space to produce molds and wind turbine blades in excess of 80-m long in a 45,000 ft² production floor.

Global Blade Technology
www.gbtholding.com

Windpower Engineering & Development

Building upon the recently developed sizing technology applied to Advantex SE2020, the HiPer-tex W2020 is also engineered for epoxy polymer systems used in resin infusion or prepreg processes.

3B’s technological expertise and manufacturing know-how delivers a high modulus glass with outstanding mechanical properties providing significantly greater strength and strain-to-failure than traditional E-glass. The HiPer-tex W2020 offers these properties in a typical unidirectional laminate (average glass volume fraction 60%):

• 54 to 56 GPa E-modulus
• 55 to 60 MPa transverse tensile strength
• 10 times longer lifetime in fatigue resistance versus traditional E-glass

Compared to blades manufactured with traditional E-glass, HiPer-tex W2020 achieves up to 10% weight saving for the same blade design and length. Alternatively, blade length can be extended by up to 6% while maintaining the same weight but offering up to 12% more energy output.

The material offers better wet-out therefore a more consistent laminate quality. A significantly improved resin-matrix adhesion provides higher shear strength and substantially greater interfibre strength when compared with existing high modulus fibre glass.

Onur Tokgoz, 3B wind energy global business leader: “3B is collaborating with the whole value chain in the wind industry sector to bring to market new cost competitive and high performance reinforcements which further push the limits of glass fibre-rotor-blade designs.”

3B-the fibreglass company
www.3b-fibreglass.com

Windpower Engineering & Development

Fibersim assists with support for conceptual designs, defining detailed laminates, simulating ply layup and generating manufacturing data feeds to verifying quality.

Fibersim software version 2012 reduces risk throughout the wind energy, aerospace, and automotive industries by optimizing design and manufacture of innovative, durable, and lightweight composite structures. The software, developed by Vistagy, was acquired by Siemens on December, 2011. Fibersim 2012 reduces uncertainty in the performance of composite parts by defining, communicating, and validating required fiber orientations throughout a product’s development, ensuring it meets specifications. By eliminating design interpretation errors, the new release reduces the risk of producing over-engineered parts that behave unpredictably, or are heavier and more costly than necessary.

The software assist with support for conceptual designs, defining detailed laminates, simulating ply layup and generating manufacturing data feeds to verifying quality. Fibersim works with industry-leading, 3D commercial CAD systems. A few benefits of Fibersim 2012 include:

• ·         Increased confidence in the way manufactured composite parts perform by providing a new Spine-Based Rosette. It allows defining fiber orientations along a path that can be validated throughout a development cycle. Maintaining fiber orientations in manufactured parts—whether an airframe stringer, an automotive C frame, or a 60-m wind turbine blade.
• ·         In 2010, the software introduces advanced material and process simulations for multilayered materials, including non-crimp fabric and ply forming simulations. Fibersim 2012 builds on these capabilities to simulate a greater number of materials and manufacturing processes used with the first-ever Spine-Based Simulation for parts produced using steered-fiber methods. Steering fibers along the path of a wind-turbine-blade mold will cause localized buckling and deformation. Identifying these issues early in the design cycle allows making decisions to ensure expected part strength in a timely and cost-effective manner.
• ·         The recent version allows the exchange of Multi-axial Material and Core data for the communication of two critical design components between analysts and designers. Accurate analysis of part stiffness and strength necessitates the inclusion of multi-axial and core materials commonplace in aerospace, automotive, and wind energy designs.

• The software simplifies composite development with intuitive tools for design and documentation for engineers with different levels of composites experience. The most challenging and time-consuming design task is capturing drop-off specifications for regions of varying thickness. Fibersim 2012 introduces Stagger Editor, a visual drag-and-drop method for capturing those specifications. Large panels, such as wings, have a significant number of different drop-off profiles. The Stagger Editor makes it easy to develop the profiles and reduce design errors.

Siemens PLM Software
www.siemens.com/plm.

Windpower Engineering & Development

“The HSP-7401 primer and AUE-50000 Series topcoat sets a new standard for efficiency and will significantly increase blade protection and durability while also lowering production and life-cycle costs,” says  Dave Chapman, PPG global marketing director, commercial coatings.

The coating series was developed through extensive global testing against a wide range of blade coating standards and specifications. The polyurethane primer and topcoat components were designed together. Using up to 60% less applied film than conventional polyurethane multicoats, they provide outstanding adhesion and flexibility. HSP-7401 primer delivers outstanding adhesion to the composite substrate, the primary attribute required in wind turbine blade finishing. It is quick-drying and may be topcoated in as little as 30 minutes.

AUE-50000 is an extremely erosion-resistant, weather-resilient polyurethane topcoat that offers the smoothness and protection from environmental attack elements required in wind blade applications. The system is also VOC-compliant to 420 g/l. The two components balance performance properties that deliver long-term, low maintenance asset protection in any operating environment including challenging desert and offshore situations. PPG has been producing coatings for wind turbine blades for more than 30 years.

PPG Commercial Coatings
www.ppgcommercialcoatings.com.

Windpower Engineering & Development

A view of cable slices shows the conductors (metallic) and insulation (white) and jacket (black).

Variables include:

• Wind farm specifics

• Cable length and cost

• Installation cost

• Predicted cable life and failures

• Cost per failure

• Dielectric losses

• Discount rate and tax rate

When comparing life-cycle costs, it’s important to know that all cables are not created equal. For most power transmission and distribution needs, high-voltage or medium-voltage cables typically are specified. They are often installed underground or underwater (submarine) and connect the wind farm to the grid. Power cable components usually consist of several different materials, including cross-linked polyethylene (XLPE), ethylene propylene rubber (EPR), and water tree-retardant XLPE (TR-XLPE). However, not all cable materials deliver the same results. Hence, testing data and manufacturing standards are needed to predict performance. It is critical that wind developers are aware of how various materials perform in power-cable applications.

For instance, field studies over 30 years of use show that TR-XLPE cables from Dow exhibit little or no wear. This is due to jacketing and insulation materials resistant to moisture intrusion. Industry accepted tests estimate their lifespan at more than 40 years. This kind of performance is in line with wind-farm developers who are targeting a similar lifespan. Lab and field testing of cable components performed by independent institutes such as Georgia Tech’s National Electric Energy Testing Research and Applications Center (NEETRAC) also should be considered. Specifically recommended is the Cable Design Aging Test, NEETRAC project 97-409.

When considering cable materials, initial cost, dielectric losses, and predicted reliability can lead to significant economic differences for the wind farm owner and or utility over the lifetime of the cable. Factors that influence material selection include:

Water intrusion can negatively impact power cable performance or damage them beyond repair. Insulation and semiconductive shield materials may significantly slow water-tree growth. This is seen in cables aged in actual field conditions or under laboratory-aging conditions such as an Accelerated Water Treeing Test (AWTT). Testing protocols such as ICEA S-94-649 were established to distinguish XLPE and TR-XLPE insulation and semiconductive shield materials under accelerated aging conditions. The test above compares standard TR-XLPE to Dow’s next-generation TR-XLPE demonstrating improved performance.

• End user specifications

• Mechanical and environmental

stress resistance

• Ease of installation

• Results of electrical tests: accelerated

aging and dielectric performance

These factors also should be considered in developing cable standards for the wind industry. Just as industry specifications are written for utility applications, wind-energy specifications should also be established to improve consistency, performance, and reliability of wind-farm collectors. Investors, developers, independent power providers, utilities, equipment, cable and material suppliers, and others should collaborate to reach the energy goals that may soon find their way into legislation.

Until then, wind-farm developers should consider specifying cables that meet or exceed current power industry minimum standards. This will help ensure the use of durable materials, quality manufacturing processes, and high performance, which support and sustain system reliability. WPE

By: Damien M. Polansky, North America Market Manager Dow Electrical & Telecommunications www.dow.com/electrical/market/wind.htm

Windpower Engineering & Development

Polywater Clear RTV is UV stable, VOC compliant, non-flammable, non-yellowing, non-shrinking, and offers a maximum temperature usage of 400º F.

Polywater RTV Silicone seals voids and seams on outside electrical apparatus such as meters, boxes, light fixtures, and conduit penetrations to keep them weatherproof.

The RTV Silicone is said to be well suited for numerous external sealing needs. The material is packaged in a 10.3 ounce (305 ml) caulking tube for easy dispersal, and has a re-sealable cap to minimize waste.

Polywater Clear RTV is UV stable, VOC compliant, non-flammable, non-yellowing, non-shrinking, and offers a maximum temperature usage of 400º F. Its waterproof formula allows for 25% movement, contains 100% silicone, and is great for electrical apparatus and solar applications. The material meets industry specifications including FDA CFR 177.2600, USDA Rating P-1; MIL-A-46106, ASTM C920-Type S, NS, Class 25, TT-S-001543A, and TT-S-00230C.

American Polywater
www.polywater.com/rtv.aspn

Windpower Engineering & Development