Old fan "huan" new machine: energy storage, cement, bridge, make clean energy more "clean"

"A large number of wind turbines put into operation by old wind farms have entered their 'twilight years', or quietly retired, or hurriedly buried, and the corresponding policy system and disposal technology reserve are still in a state of absence." Speaking of the current status of China's wind power blades after decommissioning, the person in charge of a wind power blade production enterprise is so emotional.

To some extent, that is true. In the tide of new energy, the harmless disposal of fan blades after retirement and the development of industrialization need to speed up. This is not an idle worry, but a forethought.

In China, the total number of scrapped wind power blades in 2018 was about 3,456 tons, and the total number of scrapped blades this year was about 5,424 tons. From the perspective of the service life of wind turbines, by 2025 or so, China will usher in a large wave of wind power blade scrapping tide. By 2030, more than 30,000 typhoon power units in China will be replaced, and by 2035 this number will exceed 90,000 units. Behind this string of data, are new problems that the wind power industry needs to overcome.

So, what are the harmless leaf treatment technologies?

1. What can wind turbines be decommissioned? Engineers have a brilliant idea to turn fan blades into Bridges

According to Kieran Ruane, a civil engineer who is a lecturer at Munster Technological University in Ireland and a member of Re-Wind, a wind power recycling research group, Wind turbine fan blades are mostly made of ultra-strong FRP glass fiber, with an average length of more than 150 feet (45.72 meters) and weight of more than ten tons, which is not easy to be decomposed, and if burned in an incinerator, it will cause air pollution, so most choose to occupy space for burial treatment. In order to turn the recycled wind turbine blades into a part of the infrastructure, nine months of engineering and material testing provided a solution for the design of the bridge.

Marcin Sobczyk, a developer at metal recycling company Anmet, revealed that the company has been developing ways to reuse wind turbine blades for seven years, starting with making wind turbine blades into outdoor furniture, and now hoping to turn fan blades into Bridges in order to expand its business footprint.

Sobczyk said that wind turbine blades have the characteristics of high strength, light, and durability for all-weather operation, although the design life of wind turbines is only 20 to 30 years, but after retirement, the fan blades also have decades of life, so Anmet company enhanced the strength of the recycled fan blades after three years of testing. So that it can be used like other Bridges for more than a century.

The world's first bridge made of wind turbine blades is located on the river in Szprotawa in western Poland, while the second fan blade bridge fell on the old railway in Midlerton and Jol in Ireland.

Bridges made of wind blades are cost-competitive with Bridges made of reinforced concrete, solve the problem of decommissioning wind power, and even reduce CO2 emissions, while also evaluating the condition of old blades in many more standardized ways and reusing fan blades.

2. What to do after the fan blade is scrapped? Don't worry, you can recycle cement

Now, a new environmentally friendly approach has emerged - recycling old fan blades to replace coal, sand and clay as cement fuel and raw materials. This approach also helps to reduce CO2 emissions in the cement industry.

Doesn't that sound like a surprise? GE Renewable Energy recently announced that it has signed an agreement with Veolia, an environmental services company, to recycle wind turbine blades. Under the agreement, Veolia will recycle most of the decommissioned blades while GE upgrades its turbines and renovates old wind farms.

Specifically, when GE upgrades its wind turbines and rebuilds old wind farms, Veolia recyles the removed blades, shredding them at its processing plant and then mixing the ingredients, such as fiberglass and balsa wood, to a cement manufacturing plant to produce Portland cement as an alternative to coal, sand and clay.

In contrast to traditional cement manufacturing processes, Veolia's cement kiln co-disposal technology allows industrial waste to be "transformed" into cement raw materials. On average, about 90% of the blades by weight will be recycled as raw materials for cement production, more than 65% by weight will replace raw materials originally added to the kiln to make cement, and about 28% by weight will replace coal to provide energy for chemical reactions occurring in the kiln.

The journey of a blade from the fan tower to the cement plant has several steps. First, in the process of retrofitting old wind farms, engineers replace old blades that may have been rotating for up to 20 years with longer, lighter and more efficient blades. The newly upgraded blades can help the wind turbines generate more energy each year, ultimately providing customers with more renewable energy.

The retired blades are about 120 feet long from root to tip, about the same length as a wing on the Airbus A380, currently the world's largest passenger jet. Workers would use a crane to break it into three sections and load it onto a truck, which would then drag it to a shredder, where powerful shredders would cut the large blades into smaller pieces.

At Veolia's processing plant, the small pieces of blade are finally cut into small pieces the size of pebbles, which the cement plant can mix with other materials and put into the cement kiln. From the time the fan blades are removed to the ground, to the time they are fully treated at the cement plant, it can take only a few weeks.

According to the environmental impact analysis conducted by Quantis, the net effect of leaf recycling through cement kiln collaborative treatment stands out among all recycling categories. Compared to traditional cement manufacturing, blade recycling reduces CO2 emissions in cement production by 27% and water consumption by 13%. In addition, by recycling every 7 tons of fan blades, cement kilns can avoid consuming nearly 5 tons of coal, 2.7 tons of silica, 1.9 tons of limestone and nearly 1 ton of additional mineral raw materials. Due in large part to the avoidance of coal consumption, this leaf recycling also produces net positive environmental benefits for human health, ecosystem quality and resource consumption. Cement produced from recycled leaf materials has the same characteristics and properties as cement produced by conventional methods and meets all applicable building standards.

The agreement between GE and Veolia is expected to recycle and reuse thousands of blades, contributing to the cement industry's decarbonization goals. In line with its decarbonization vision, GE Renewable Energy is committed to reducing the environmental impact of its products throughout their life cycle, including becoming carbon neutral by the end of 2020. The GE Renewable Energy Group business will collaborate with other partners along the value chain to drive sustainability through innovation.

3. Hou Xianglin team of the Institute of Coal Chemistry of the Chinese Academy of Sciences -- skillfully disassembling the "ultimate material" and "decommissioning" fans to turn waste into treasure

"This research can not only turn 'retired' fan blades into waste, but also apply to many high-end manufacturing industries to safely dispose of 'stubborn' solid waste." The Chinese Academy of Sciences, Shanxi Institute of Coal Chemistry recently came the good news, 311 research group researcher Hou Xianglin team after more than ten years of dedicated research, mastered the "dismantling" of the main material of the fan blade - thermosetting carbon fiber resin composite material method, to achieve green recycling, waste into treasure.

The shell of the wind turbine blade is often made of glass fiber reinforced resin, and the tip and blade are made of higher strength carbon fiber. The molecular structure of these composites is extremely strong and aerodynamic, making the blades lighter and longer, allowing the fan to absorb more wind energy. Among them, thermosetting resin accounts for about 30%, equivalent to the filling in concrete buildings, while carbon fiber, glass fiber, etc. account for about 70%, equivalent to the reinforcement in concrete, the combination of the two is indestructible. Commonly used carbon fiber composite materials are mainly composed of carbon fiber and thermosetting resin composite, with insoluble and non-melting characteristics, known as the "ultimate material", recycling value is high, but difficult to achieve.

The most critical issue is that from the perspective of the service life of wind turbines, China is about to usher in a large wave of fan blade scrap, with tens of thousands of units. "Not only fan blades, but also many high-end manufacturing industries are using this composite material, which has high economic value if it can be recycled." Foreign research teams have carried out relevant studies one after another, but have not made much progress." Researcher Hou Xianglin further introduced that ordinary thermoplastics, such as plastic film in farmland, have a linear molecular chain structure that takes 200 to 400 years to degrade naturally, while the molecular chain of thermosetting resins is a rigid three-dimensional network structure. In other words, composite materials based on thermosetting resins, although the recycling value is high, but can not be naturally degraded, disassembly is even more difficult.

Hou Xianglin's team prospectively carried out research on thermosetting resins, hoping to open up a path for the recovery of a large number of thermosetting polymer materials that are about to be "retired". On the basis of many years of previous research, researchers such as Deng Tiansheng and Wu Shaodi, members of Hou Xianglin's team, selected the best performance from more than ten catalysts and obtained the key data of the test, which was the first in China to "disassemble" its molecular structure under relatively mild conditions to form a long chain thermoplastic polymer or resin synthetic monomer. This method is currently more in line with the recycling economy of the good method of reuse, the recovered resin products can be made into epoxy asphalt, and then further treatment can get bisphenol A, etc., the market price of thousands of yuan or even tens of thousands of yuan per ton, the economic benefits are very considerable.

According to reports, this research has achieved satisfactory results in the laboratory stage, ready for pilot scale. Overall, the degradation rate of epoxy resin is greater than 99%, and the recovery rate is greater than 95%. The carbon fiber recovery rate is greater than 96%, the fiber strength loss is less than 5%, and the strength index and modulus of the recovered carbon fiber monofilms are almost the same as the original fibers, which can be said to directly change the solid waste back to the raw material. "We are confident that the laboratory results will eventually be connected with actual production, and more valuable chemicals will be extracted to create greater environmental and economic benefits," Hou said.

4. New scenarios for gravity energy storage or abandoned fan blades

Recently, Italian Energy company Enel Green Power and Swiss energy storage company Energy Vault signed a cooperation agreement, claiming that they will jointly develop a gravity energy storage system made of decommissioned fan blades, which is also another exploration of the industry for the decommissioning of fan blades.

The joint statement shows that among all the components of wind farms, blades are the most difficult to recycle due to their special material properties. To this end, Enel Green Power and Energy Vault will jointly study waste wind turbine blades with a view to using them in gravity energy storage systems.

It is understood that the gravity Energy storage system is mainly developed by Energy Vault, and the technical principle is similar to the pumped storage system, the use of large solid materials as the gravity potential energy storage medium, the storage of excess power when elevated, and the release of power when needed. In July last year, the company's gravity energy storage system entered the commercial demonstration phase.

"The fan blade is mainly composed of glass fiber or carbon fiber and other materials, which has high material stability and material strength, and in the gravity energy storage system, the solid material produced by this material can effectively extend the system life and the cost is relatively low." Enel Green Power Executive Irene Fastelli.

According to the agreement between Enel Green Power and Energy Vault, the two parties have now analyzed the commercial feasibility of the method and will then study the feasibility of the application of the system in commercial power stations. If the project goes well, the results of the study on the commercial gravity energy storage power station will be available by the end of this year.

In fact, with the expiration of the life of the global wind farm decommissioning tide is gradually approaching, the industry has also accelerated the exploration of waste materials such as blades, in addition to the application of gravity energy storage system, the blade will be broken into building materials, leaf materials decomposition for recycling and other emerging ways are also more and more attention in the industry.