Theoretically, wind can generate enough electricity to power all of human civilization. In 2017, wind power nameplate capacity reached 89 and 169.3 gigawatts in the United States and the European Union, respectively. That is enough to cover 10% of annual end-use electricity demand in the United States and 11.6% in the European Union. Moreover, both the United States and the European Union are expecting to double their production capacity by 2020. Although there is an attractive and fast-growing market for wind energy, realizing the full potential of wind will require more efficient, durable, and inexpensive turbines.
Challenges affecting the structural durability of wind turbine blades:
Although wind turbines are designed to have a lifetime of 20 years, they are unlikely to experience such a long lifespan. This is one of the major concerns for investors because blades represent 25% of the cost of a wind turbine (cost based on levelized cost of energy). Blades are continuously exposed to different types of mechanical impacts and sustain damage produced by weather conditions. Blades experience continuous delamination due to rain or ice adhesion, causing the erosion of the leading edge that results in an increase in drag and a decrease in lift, which can lead to a significant 9% power loss. All these types of damaging exposures affect the structural changes in the blades, which impacts their aerodynamics and, in turn, reduces the optimum amount of energy converted.
The design of blades becomes challenging because there must be an efficient compromise between structural capability, favoring thicker airfoils, and aerodynamic efficiency, favoring thinner airfoils. Thus, designers need to take into account how to optimize the aerodynamics of the blades, increase the length of the turbine, and then consider what would constitute the best materials needed to manufacture blades. Recently, designers have increased the length of blades in order to capture more wind power across snowy, desert, and offshore regions. Nonetheless, the problem of how to prevent rapid deterioration versus effective wind energy production still remains a major issue.
New technology is helping to redefine wind turbine blades:
Blades are fabricated using composite materials such as fiber-reinforced polymer composites, which include carbon, glass, or natural fibers. These materials often comprise up to 50% of the cost of a manufactured wind turbine blade. An inland turbine equipped with 60-meter-long blades and with an average weight of 20 tons (20,000 kilograms or 2,205 pounds) costs between $150,000 and $250,000 USD. Continuous research specifically targeting blades are competing to find optimal materials that can maintain low density and high stiffness for better performance and handling of blades and at the same time reduce costs.
As a result of new designs and materials:
- Turbines are getting bigger, taller, and more powerful. For example, the GE Haliade-X is an energy Goliath, with blades that can reach up to 351 feet — almost as long as a football field and almost 1.5 times taller than the Gateway Arch found in St. Louis, Missouri — capable of supplying electricity to 16,000 households.
- The Segmented Ultralight Morphing Rotor (SUMR) has been bio-inspired by palm trees, whose trunks survive hurricane-force winds by morphing and aligning with the direction of the wind. Thus, SUMRs can morph and sway with the wind and are capable of aligning with the blade path, reducing structural requirements.
- Gamesa has developed modular composite blades that make transportation on roads and installation easier.
- Sandia National Laboratories has used a 3D-printed mold to fabricate a wind turbine blade made of fiber-reinforced polymers. This technique applied at a larger scale will save time and money in fabrication and testing.
- The Leading Edge for Turbines (LEFT) project, financed by the UK government, is investigating the validity of aerospace technology applied to offshore wind turbine blades by developing a unique leading edge protection system based on nickel/cobalt alloy. This type of alloy has a high tensile and yield strength, offering an excellent opportunity for producing lightweight protection shields.
- VTT’s antiAGE project found a functional solution to the material problem with the help of artificial intelligence and 3D printing. AI will help to “visualize” fine-scale variations from an unlimited number of materials used in the fabrication of wind turbine blades that are imperceptible to human eyes. AI will help to determine the best materials for specific purposes. Likewise, manufacturing of highly tailored materials will be handled by 3D printing dictated by the AI’s material selection in any shape and will be cheaper than any traditional manufacturing technique.
A blade that can change shapes according to environmental responses?
One of the most recent developments in airplane wing construction that could also be used to fabricate wind turbine blades has been demonstrated by MIT and NASA engineers. Imagine the ability of a blade to morph or change shape as a response to any external stimuli (i.e., responding to different environmental conditions, improving interaction with other bodies). This active wing shaping makes use of composite lattice–based cellular structures. In other words, it is a wing that can be assembled from thousands of tiny identical cells covered with a thin layer of similar polymer material as the framework, which will allow the assembly system to deform the whole wing or parts of it. The result is a wing that is much lighter and that can generate automatic responses to changes in its aerodynamic loading conditions by shifting its shape (i.e., self-adjusting, self-reconfiguring). The building process of the experimental wings uses injection molding with polyethylene resin in a complex 3D mold and produces each part in just 17 seconds.
Wind is abundant, essentially inexhaustible, and one of the cleanest fuel sources that exists on this planet. During the last decade, there has been continuous growth of the wind energy industry, propelled by new advances in wind energy research. Most of the innovations presented here are the results of effective collaborative alliances between government laboratories, academia, and private companies. Exchanges of research and development expertise are helping to rapidly innovate wind energy technology.
