Today, wind power occupies a dominant position in the field of renewable energy and has become one of the largest glass fiber reinforced composite materials markets in the world.
With the use of new materials, the optimization of the production process, and the improvement of blade design, the weight of the blade is further reduced and the overall performance of the blade is improved.
However, now that the blades are designed to be longer and longer, domestic and foreign manufacturers are eagerly looking for ways to reduce the structural weight of large wind turbine blades. Due to its excellent comprehensive performance, composite materials have become the preferred material for lightweight wind turbine blades.
Relevant data show that China's output of thermoset composites was 2.3 million tons in 2019, while composite materials for wind power blades were about 336,000 tons, accounting for 14.6% of the output of thermoset composites.
On November 5, at the "2020 China Composite Materials Industry Trend Development Conference" of the "Eighth International Composite Materials Technology Summit", Professor Wang Jihui of Wuhan University of Technology released the "Research Report on the Development of Composite Materials for Wind Power Industry". In the report, Professor Wang Jihui not only introduced in detail the overview of composite materials for wind power blades in China, but also analyzed the wind power market and the opportunities and challenges in the development of composite materials for blades.
Larger blades place higher requirements on materials
China is the world`s largest wind power market. Related data predicts that China’s onshore and offshore wind power installed capacity will maintain a rapid growth trend in the future. By 2030, China’s wind power will reach at least 800 million kilowatts, with an average annual compound growth rate of 12%. This means that the annual new installed capacity of wind power development in the future will be 2-3 times that of the present.
According to Professor Wang Jihui, large-scale blades are currently the mainstream trend of wind power development. The "Research Report on the Development of Composite Materials for the Wind Power Industry" shows that the future development trend of blades is mainly reflected in the larger single-machine capacity, longer blade length, lower cost, lighter materials and higher strength. The length of the future onshore wind power blades is mainly Mainly 70-90m (3-6MW), the length of offshore wind power blades will reach more than 100m (12MW+).
According to relevant data, in 2017, China used 3,060 tons of carbon fiber in wind power blades, all imported from abroad; in 2018, the use of carbon fiber in wind power blades was 8,000 tons, all imported from abroad; in 2019, the amount of carbon fiber in wind power blades was 13,800 tons, of which domestic carbon fiber was about 1800 tons.
In 2019, the global carbon fiber consumption of wind power blades accounted for 26% of the global carbon fiber, which shows that the consumption of carbon fiber in the wind power blade field is increasing rapidly.
The development trend of the wind power market is getting better, which will further stimulate the demand for carbon fiber consumption, which also means that the domestic carbon fiber industry has ushered in more development opportunities. With the increase in blade length, higher requirements have been placed on the manufacturing level of carbon fiber composite materials.
According to Professor Wang Jihui, core components such as blades and main bearings have become the bottleneck for the development of the wind power industry during the rush to install wind power installations in 2019-2020. This is mainly reflected in the tight supply of raw materials and rising prices. Among them, the amount of Balsa wood has increased sharply, resulting in prices. Soaring; and PET/HPE as a substitute for balsa wood, the demand for dosage is gradually increasing.
Carbon fiber main beam or completely replace glass fiber
Technological progress is inseparable from the support of new materials, and the same is true for blades.
It is reported that the blade is composed of three main materials: reinforcing fiber, resin matrix, and structural core material. The reinforcing fiber is required to have a high modulus, which can improve the stiffness of the blade; the resin matrix is required to have low viscosity, fast curing, low defects, and high molding efficiency; and the structural core material is required to improve the stability of the blade.
With the improvement of the performance of localized high-modulus and high-strength glass fiber, it provides strong support for the large-scale formation of onshore wind power blades. The rapid development of domestic enterprises such as ZGJS, SDTS, and CQGJ has promoted the scale of the wind power glass fiber industry to more than 6 billion, and China's glass fiber industry has achieved catching up with foreign companies.
"Onshore units have evolved from 2.xMW to more than 3.0MW, and cost reduction for blades is an inevitable trend at parity." Professor Wang Jihui said that the use of glass fiber pultrusion technology can increase the performance of glass fiber composites by more than 10%, which can effectively support Lu The development of large blades at a low price is an effective solution for onshore wind power blade composite materials.
Authoritative organizations believe that it is possible to improve and perfect the shortcomings of the carbon fiber application process, such as the conformability of the pultruded sheet, the folds of the prepreg, the wettability of the vacuum infusion, the reduction of costs and the enhancement of detection methods. Completely replace glass fiber.
"Carbon fiber pultruded sheet can give full play to the performance of carbon fiber, reduce the amount of carbon fiber in the blade, thereby reducing costs." At the press conference, Professor Wang Jihui also mentioned that the pultrusion process is simple, efficient, excellent in performance, low in quality, and high in raw material utilization. Features.
Finally, Professor Wang Jihui also talked about the recycling of composite material blades, and said that some domestic companies have started preliminary explorations in this field and gradually realized commercialization.