Manufacturers of wind turbine blades need each blade to be released from the mould perfectly. (Picture used under license from Shutterstock.com © cla78.)
Manufacturers of wind turbine blades need each blade to be released from the mould perfectly. (Picture used under license from Shutterstock.com © cla78.)


Part 1
of this feature discussed the functions of release agents. In Part 2 we discuss their use in wind turbine blade manufacture.

Complex systems

The design, development, testing and manufacture of release systems are complex. These systems must account for hundreds of variables in the manufacturing process and produce consistent results.

... release agents must be deliberately designed to tolerate a range of production variables and produce a ‘no surprises’ result at the plant.
 

Included in the set of variables is one very fundamental challenge: No two blade producers manufacture blades in the same way. There is no industry standard – no one set of requirements or guidelines that govern blade production. The procedures vary from company to company, as does every step in the manufacturing process.

Therefore release agents must be deliberately designed to tolerate a range of production variables and produce a ‘no surprises’ result at the plant. Chem-Trend engineers design its release systems to be adaptable and comprehensive enough to accommodate a multitude of variables: mould and blade designs, mould and blade materials, blade weights and sizes – even labour practices.

Chem-Trend has experts in the field to address the massive variation that exists in the wind industry. The company can even design and produce specialised release systems based on a manufacturer’s unique needs.

In a sense, every manufacturer is unique based on its geographic location and plant conditions. Today’s blade manufacturers are building their facilities close to wind farms, which are located in every part of the world. Co-location reduces shipping costs for the blade companies, as well as the risk involved in sending these enormous parts around the globe. The result: production facilities inhabiting every climatic condition imaginable. The plant environments vary in temperature and humidity from region to region, and shop to shop.

Ambient conditions have a great impact on the reactive materials and chemical changes that take place during the application process. Chem-Trend has developed in-house facilities to replicate these extreme weather conditions and test the capabilities of its release systems. In these simulated production environments, Chem-Trend engineers formulate new compounds to insure full manufacturing compliance, regardless if the plant is in Des Moines or New Delhi.

Release agents can be applied using a variety of techniques. Traditionally, manufacturers have used cloths or mops to apply the product to the mould. Some blade manufacturers are adopting a spray system and even automating the process using robotics. Unlike car makers, which use specialised booths to contain the spray process, blade producers must apply release agents right in the plant. That’s because a normal spray booth would be much too small to house today’s large blades. As such, the need for water-based release agents becomes ever more important to keep operators safe from chemical hazards.

Once a mould is treated using a complete release system, several blades can be produced off the tool, requiring only an occasional touch up coat in between. That’s only if the release system is applied as instructed by the manufacturer, and no shortcuts taken. However, the most important step in insuring the best result is preparing the mould itself. That means cleaning the surface thoroughly to remove any residue and inspecting the mould for damage or other imperfections before each use.

New blade designs

Each year, the wind industry seeks to make major improvements in turbine performance, including longer product lifespan and reduced weight. The quest to use new composite materials and create even larger blades is challenging to manufacturers that are already working to meet the increased industry demand for parts.

Wind energy – a growing, global market
Globally, the wind industry is expanding, especially into new markets such as Brazil and South Africa.

Wind has been the fastest growing source of electricity generation in the world for the last 25 years. Thanks to large untapped wind resources, industry analysts report wind power capacity grew 20% globally in 2012. China and the US topped the list of countries adding new turbines, with Germany, India and the UK following behind. Asia is the clear leader in generating wind energy, in front of North America and Europe. Even Africa, which trails all other geographic locations for wind production, installed its first large commercial wind farm. Experts are projecting that Africa will be a substantial new market and that wind production will be a driver of economic opportunity.

In the US, 29 states have established renewable portfolio standards that require electricity providers to obtain a portion of their power from renewable sources. This is just one factor fuelling the increase in wind capacity in recent years.

For the first time ever wind energy became the number one source of new US electricity generating capacity. Last year, nearly half of all new capacity came from wind. The US wind industry now totals 60,007 MW of cumulative wind capacity, according to the American Wind Energy Association (AWEA). That equates to more than 45,100 turbines providing enough electricity to power 14.7 million homes – roughly equivalent to every home in Colorado, Iowa, Maryland, Michigan, Nevada and Ohio combined.

The wind industry represents a growing market for global manufacturing. Of the top 10 wind turbine manufacturers, China represents nearly 29% of the world’s market share, followed by Germany, Denmark, Spain and the US. More than 550 manufacturing facilities across 44 US states make components for wind turbines. Along with physical expansion, the industry is developing new technologies that take the modern megawatt-scale wind turbines to the next generation. New turbine designs capable of efficiently handling a wider range of wind speeds are being developed to optimise the climatic conditions in specific regions.

For today, the industry has the wind at its back. According to the Global Wind Energy Council (GWEC), wind power could supply up to 12% of global electricity by 2020, creating 1.4 million new jobs and reducing CO2 emissions by more than 1.5 billion tons per year, more than 5 times today’s level.

The US Department of Energy reports the nation possesses sufficient and affordable wind resources to generate at least 20% of its electricity from wind by the year 2030. Nearly 70% of the equipment installed at US wind farms last year – including wind turbines and components like towers, blades, gears and generators – was made domestically. The wind industry is credited with employing 80,000 workers and boosting the nation’s economy by $25 billion.

(Source: The Quell Group.)

New turbines are reducing the total cost of wind energy. Towering turbines maximise the amount of wind power they can capture and produce up to three-times the capacity of smaller units built just a few years ago. They are also reducing the overall number of turbines necessary to generate a similar amount of power. The largest blade made to date exceeds 60 m and weighs nearly 40,000 lbs.

The industry is gaining the bulk of its efficiency through eliminating the cost associated with unnecessary weight. It is finding its answer through more robust, lighter weight materials and design.

All of these challenges present barriers of entry for companies considering joining the market. The overall risks and the enormous capital investment involved in blade production mean few manufacturers are able and willing to get into the game. With blades growing in size, tooling and facility costs are increasing, despite the increased demand for parts.

The issue of blade size may become a self-governing problem. Engineers argue the eventual limit imposed on the ultimate size of a blade – whether it is the cost of human error or the ability to manage the thickness and warpage variations that increase with scale. With a long blade configuration, there exists a greater risk of damaging structural loads on the turbine at higher wind speeds. Even the fundamental laws of physics – material fatigue – may come into play. But for now, the race to make a bigger blade is on.

Materials and blade size are not the only barriers to growth in the wind industry. Regional politics and policies, logistics, equipment, design and utility providers are also part of the mix. In Europe, for example, large manufacturers from all industries are faced with regulations limiting volatile organic compounds (VOCs) emissions. To help their customers become compliant, Chem-Trend is developing water-based rather than solvent-based release systems.

The manufacturing process is but one in a long line of complexities that exist and must be managed for economical production of wind power into the future. Release agent manufacturers are doing their part to help raise overall productivity, reduce cycle times and cut costs by developing solutions that adapt to new materials in all corners of the world. They are a strong link in the chain, enabling greater steps forward for affordable green energy. ♦

Further information

Chem-Trend, P.O. Box 860, Howell, MI 48844-0860, USA; tel: +517-546-4520; www.chemtrend.com/contact_us

Read Part 1 of this article here.


This article was published in the July/August 2013 issue of Reinforced Plastics magazine.

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