Note: This is the first article of a four-part series covering plastics in wind energy (1) trends, (2) material advances, (3) process technologies and (4) applications.
Oil and natural gas prices and environmental forces are all key wind energy drivers. But the fact that wind energy has the highest rate of return among the various sources of alternative energy is attracting new "players" into the energy sector.
As the prices of traditional oil and gas increase, demand for alternative energy supply also increases. Conversely, falling prices for oil and natural gas reduce demand for alternatives. Hydraulic fracturing has significantly reduced the spot price of natural gas since 2008 and is playing a role in wind energy economics, particularly in the U.S.
Within the global wind power arena, the wind turbine industry has become one of the world's largest markets for plastic composites. According to recent data from the World Wind Energy Association (WWEA), 14 gigawatts (GW) of wind capacity were added worldwide by the end of the first half of 2013 to reach 296 GW. In the second half of 2013, an additional capacity of 22 GW were projected to be erected worldwide, bringing new annual installations to 35.7 GW, significantly less that the 44.6 GW added in 2012.
The total installed wind capacity was expected to reach 318 GW by the end of 2013, enough to provide almost 4 percent of the global electricity demand. This expected decrease in new installations is mainly due to an abnormal U.S. situation, and experts expect that wind markets worldwide will be able to recover from the 2013 decrease and set a new record in 2014.
Five wind energy countries, China, USA, Germany, Spain and India represent together 73 percent of the global wind capacity. In total, four countries installed more than 1 GW in the first half of 2013 — China (5.5 GW of new capacity), the U.K. (1.3 GW), India (1.2 GW) and Germany (1.1 GW). In 2012, only three countries had a market volume of more than 1 GW.
Today, about 83 countries have commercial wind power installations, with 24 of these countries passing the 1 GW level.
In terms of technology, the latest trend in wind energy is toward larger, lighter blades to capture more wind and lower rotational inertia. Wind intercepted by the turbine is proportional to the square of its blade length. However, the maximum blade length of a turbine is limited by both the strength and stiffness of its material. The industry is looking to material advances in resin and fiber as well as processing technologies to enable development of longer light turbine blades.
New technology is being developed to build larger turbine blades while eliminating the need for molds and the transportation problems typical with large blades. Researchers are developing fabric blades built by tensioning architectural fabric over spars and ribs of a wind-blade space frame. Fabric-based blades could allow for new designs, including blades that change shape to accommodate changing wind conditions.
Intelligent blades that adapt to wind conditions will provide a leap in energy yield. Various researchers are exploring how to apply wireless sensor technology onto wind turbine blades to better predict changes in wind and adjust the turbine's operation, optimizing energy yield and minimizing loads on the structure.
Vertical-axis wind turbines (VAWTs) are being developed for large-scale offshore wind turbine applications. Sandia National Laboratories is conducting comprehensive research into the viability of VAWTs for offshore use.
Electrical energy storage capability will be increasingly important to grid stability as electricity production via wind and solar gain market share. Technical innovation will make wind and marine more competitive with other forms of energy. Design, development and testing of a myriad of marine energy devices remain mainly in the research and development stage.
Efforts to improve design and performance, reduce costly maintenance procedures and extend plant-operating lifetimes under the harsh marine environment present many opportunities for plastics development. Wind and wave/tidal developments hold much promise to help meet the growing global energy demand with innovations in plastics playing a key role.
Thermoplastics promise wind energy opportunities despite issues. Short mold-cycle times, ease of repair and recyclability continue to make thermoplastics attractive to blade manufacturers, in spite of multiple issues such as processing on a large scale, thermoplastic composites' static and fatigue properties, moisture uptake and cost.
The Wind Blade Using Cost-Effective Advanced Composite Light-Weight Design (WALiD) consortium is looking to replace thermoset composites with thermoplastic composites in certain components of offshore wind turbine blades. The four-year project started in March 2013 proposes the introduction of thermoplastic composite materials into the blade root, tip, shell core and shear web.
Goals of the WALiD project are to:
- Improve design of blade root, connection concept and tip — Strain analysis on the blade will enable high-performance thermoplastic composites to replace thermosetting components, saving costs and weight.
- Replace the shell core with thermoplastic foam materials — The density of the core material can be modified to the specific load, optimizing the weight/stability profile to enable faster processing via automated processes.
- Improve modular concept of shear web design — Replacement of existing thermosets by thermoplastic composite structures to ensure a lightweight, load-optimized design.
- Develop fiber-reinforced thermoplastic coating — Improving the blade's environmental resistance, anti-icing properties and durability against abrasion.
The WALiD consortium, which will commit a total of 5.1 million euros to the project, is comprised of 11 European organizations including:
- Fraunhofer Institute for Chemical Technology and Windrad Engineering GmbH from Germany;
- Smithers Rapra and Smithers Pira Ltd from the United Kingdom;
- TNO Netherlands Organization for Applied Scientific Research, PPG Industries, Fiber Glass BV, and NEN from Netherlands;
- APT Archimedes Polymer Technologies from Cyprus;
- Norner AS from Norway;
- Comfil ApS from Denmark;
- Loiretech SAS; Coriolis Composites SAS from France.
Expected benefits from the project are:
- Weight reduction in the blade
- Economical savings
- Increased durability of blades
- Excellent recyclability after blade lifetime (20 years)
