What makes carbon fiber wind turbine blades good-looking and useful?

Hundred dollars per kilogram, or carbon fiber material is not only widely concerned by the wind power field, but also can reach the critical point of large-scale application.

20 years ago, Vestas in Denmark, China applied for a patent; 20 years later, the patent expiration butterfly effect may be transmitted to the entire industry, disturbing and even determine the future direction of wind power blade technology and market.

Some analysts judge, related pultrusion process carbon fiber main beam blade patent expiration will become a milestone event, set off a blade design optimization of small climax, if the price of carbon fiber materials and then keep pace with market demand, technology iteration and large-scale application of the big climax will be near. Judgment based on such a data: in recent years, the global wind power blade carbon fiber demand in about 30,000 tons, Vestas accounted for 20,000 tons, which is the power of the market, but also the power of the patent.

At the same time, because the blade design, manufacturing concept is different, after the expiration of the patent technology there are many pioneers have encountered and have not encountered the problem needs to be solved. Zhongfu Lianzhong deputy general manager Liu health to "wind energy" frankly: "These problems are not copied and copied can be solved, need us to constantly explore new knowledge, have their own core technology."

Then China's carbon fiber main beam blade in the end what has experienced, so that professional manufacturers in front of the good this kind of distracted and calm? The answer is the clear direction of technology development and strong market demand orientation, so that they never stop their own footsteps.

Test water active

The material for manufacturing wind power blade has been changing. From the initial lack of durability of wood, to the processing of difficult metal, until the application of glass fiber, a polymer composite material, to a certain extent to do the performance, cost and reliability of the balance. With the wind turbine more and more large, blade more and more long, is known as the next generation of wind power blade key material carbon fiber, began to be promoted in the field of wind power.

This is a long and emerging material. As early as 1880 when Thomas Edison invented the electric lamp, the first natural plant fibers such as cotton, hemp and bamboo were carbonized and used as the filament of incandescent lamps. However, its widespread use in the field of aerospace and protection is already a century after it was invented, just a few decades ago.

"The blade is getting longer and longer, the requirements for material performance are increasing, carbon fiber is light in mass, high in strength and modulus, and is currently the preferred material for wind turbine blades." Some analysts believe: "carbon fiber application in the blade parts including part of the skin, leading edge, trailing edge, etc., at present the most applied part is the main beam of the wind power blade."

It is understood that the main beam will generally account for one-third of the overall weight of the blade, but is to support the whole blade of the key components. The use of carbon fiber main beam, can in the premise of maximum cost savings, to ensure the blade strength, reduce the overall weight.

Modulus is the ratio of stress to strain in a material under stress. The modulus of elasticity can be regarded as a measure of the material to produce elastic deformation of the degree of difficulty, the greater the value, so that the material to occur a certain elastic deformation of the stress is also greater, that is, the greater the material stiffness, also in a certain stress, the occurrence of elastic deformation of the smaller.

A domestic manufacturer of a blade E8 level glass fiber application performance test results show that the use of fiber infusion process of glass fiber 0 ° tensile and compressive modulus were 54GPa, 52GPa; carbon fiber is 120GPa, 115GPa. In addition to the strength has improved, carbon fiber main beam blade weight than glass fiber has also decreased. The weight of the main beam with high-mode glass fiber infusion is 3.6 tons; the weight of the main beam with carbon fiber pultrusion is only 1.4 tons. The weight of the whole blade can be reduced from 13.5 tons to 11.8 tons.

Blade strength enhancement superimposed on the weight reduction effect, the direct benefit is to reduce the whole load, in the design can further reduce the weight of the host, tower, etc., to achieve the whole machine cost reduction. Another idea is to further increase the diameter of the main engine wind wheel, so as to improve the ability of the unit to use low wind speed wind energy resources, improve power generation efficiency.

Therefore, our country whole machine and blade manufacturers have layout carbon fiber main beam blade. As early as 2014, Zhongfu Lianzhong launched the application of carbon fiber main beam of 75 meters blade, using vacuum import process. After that, this enterprise also adopts carbon fiber prepreg to manufacture carbon fiber main beam.

"At present, Zhongfu Lianzhong's independently developed 76-meter carbon fiber prepreg main beam blade has produced 220 sets; the 90-meter carbon fiber prepreg main beam blade provided by an OEM with design has produced 44 sets." Liu health introduced: "Zhongfu Lianzhong is developing other carbon fiber utilization technology to manufacture 102m and 110m carbon fiber blades for the OEM."

Independent blade factory in increasing the carbon fiber main beam blade input, the whole machine merchant subordinate blade factory also does not fall behind. According to a complete machine dealer a blade field experts, the company in the research or under the line of 10 megawatts level above the blade, basic are in the main beam area used carbon fiber material, the upcoming 110 meters above the blade main beam also used this material.

In addition to the above-mentioned enterprises, gold wind technology, vision energy, ming yang intelligence, electrical wind power, China sea, east electric and other machine enterprise, in the material science and technology, time new material and other blade enterprise are in the development or has launched the use of carbon fiber material wind power blade, which is not lack of length more than 100 meters, mounted on a single machine capacity of 10 megawatts above the whole machine products.

High cost

"With the offshore wind turbine further large-scale, blade development to more than one hundred meters, the application of carbon fiber materials can make the blade and the overall benefits of the machine more and more obvious, the current one hundred meters offshore wind power blade are basically used in the carbon fiber main beam." Liu health mentioned.

The face of carbon fiber materials in the field of wind power blade applications increase, the demand for carbon fiber has also been increasing. Some statistical information shows that by 2016, wind power blade to 18,000 tons of demand to replace the aerospace, become the global carbon fiber market demand for the largest field. 2021, the global wind power blade carbon fiber use of 30,000 tons, China's wind power blade with carbon fiber demand of up to 20,000 tons, accounting for about 40% of the total national carbon fiber demand. By 2025, the global wind power blade carbon fiber demand will exceed 90,000 tons. During the "14th Five-Year Plan" period, the compound annual growth rate of global wind power blade carbon fiber market demand can reach 30%.

In the face of clear demand, whether a material or product can eventually achieve large-scale application, not only depends on its own performance, but also closely related to the cost. This also applies to the carbon fiber main beam blade.

"At present, the performance of domestic carbon fiber has basically been recognized by the wind power industry, but the price is too high leading to its cost performance is not high is a key factor affecting the further scale application of carbon fiber blade." Liu health said.

Compared with the exponentially improved performance and exponentially reduced weight, carbon fiber material 10 times higher price at the moment appears to be somewhat less competitive. "The most critical thing is of course the price and supply factors, which are related. Production capacity and technical level limits the cost of carbon fiber materials down, carbon fiber prices are currently in 150 yuan / kg above, glass fiber less than 15 yuan / kg, which greatly limits the amount of carbon fiber use." The above-mentioned experts in the field of the blade of the whole machine manufacturer believe that.Currently, wind turbine blades account for about 22% of the cost of wind turbine components, and are the second highest cost component. In the carbon fiber material prices rise at the same time, wind turbine prices have continued to decline in the past two years, driving the blade to show a downward trend in prices. This makes due to the use of carbon fiber main beam led to the blade cost increase, difficult to be accepted by the market.

The face of carbon fiber main beam high cost and patent protection, China manufacturers as early as 2 years ago carried out a "curve to save the country" action, a bold attempt to apply the pultrusion process in the manufacture of glass fiber main beam. The results found that the glass fiber pultruded main beam and glass fiber infusion main beam compared with a number of advantages, including high efficiency, low cost, good quality stability, and do not have to change the blade design, do not need the mold and auxiliary materials.

It can be said, pultruded glass fiber main beam has become the most powerful competitor of carbon fiber main beam blade, unless the cost of carbon fiber material can be certain to reduce, or pultruded glass fiber main beam technology development encountered a new bottleneck.