The potential of Type IV composite tanks in H2 filling stations and distribution, coupled with targeted cost reduction and emerging technologies for tank recertification and monitoring. #氢#Function
Cummins and NPROXX's joint venture H2 investment is increasing. Type IV storage tank manufacturer NPROXX is now a 50/50 joint venture with Cummins. Cummins has also acquired major suppliers of fuel cells and hydrogen electrolyzers. These 500 mm diameter and 2,200 mm long cars/heavy tanks produced by NPROXX can store H2 under a pressure of 350 bar. Image source: NPROXX
Part 1 of this series explores the significant expected growth of hydrogen fueled vehicles that require Type IV carbon fiber reinforced polymer (CFRP) storage tanks to store hydrogen (H2) as compressed gas. H2 can be burned directly or used in a fuel cell to generate electricity. Water and heat are the only emissions. As the world accelerates its transition to zero-emission transportation and industry, H2 is a key driver. However, the large amount of carbon fiber required to produce the millions of storage tanks required for these jobs may not be able to meet fuel cell vehicle (FCV) and infrastructure goals in time.
Other possible obstacles to the growth of Type IV tanks include the cost of carbon fiber and CFRP tanks and the lower storage density compared to cryogenic tanks, which are mostly metal. New storage tank manufacturers and French automotive Tier 1 suppliers Plastic Omnium (Lavallois) and Faurecia (Nanterre) have set goals to reduce the cost of Type IV storage tanks by 30-75% by 2030, while increasing storage efficiency to 7 % above. As CW demonstrated at the Tech Days Hydrogen event held in May, new technologies are being developed to help these efforts, starting with Cevotec (Unterhaching, Germany)’s Fiber Patch Placement (FPP) technology to reduce tank tops In the CFRP time and cost, to Cygnet Texkimp (Northwich, UK) 3D winding to reduce fiber damage, composite sensor integration expert Com&Sens (Belgium Eck) proposed on-site tank monitoring.
In Part 2, other markets for H2 refueling stations (HRS) and tubular trailers for distribution are discussed, including the use of fiberglass in Type IV storage tanks. The issues of cost and storage efficiency, recertification of storage tanks and the use of sensors for recertification, and optimization of production and health monitoring are also discussed.
The ambitious roadmap for H2 powered cars and trucks will require the construction of a large number of HRS. A report from H2stations.org in February 2021 stated that there will be 107 HRS in operation in 2020, the highest one-year total so far. With the addition of seven more in January 2021, 560 HRS is now operating globally, and plans to add 225 sites have been made. The Hydrogen Energy Commission’s February 2021 "Hydrogen Insights" report estimated that by 2030, 10,300 HRS will be required to achieve the FCV target.
CFRP tanks are being used in HRS. For example, Hexagon Composites (Alesund, Norway) supplies Resato (Assen, The Netherlands) with storage tanks for the large HRS in The Hague, and NPROXX sells two HRS storage tanks to the regional bus operator RVK (Cologne, Germany).
Figure 1. The elements of a hydrogen refueling station (HRS) are a schematic diagram of the elements of a hydrogen refueling station (HRS). Type IV composite pressure vessels can be used in tube trailers to transport H2 to the site and/or cascade storage tanks for on-site buffer storage. Image source: CW
Hydrogen is supplied to HRS via tube trailers, liquid tankers or pipelines, and can also be generated on-site using a steam methane reformer (SMR) or electrolysis unit (Figure 1). Type IV CFRP tanks can be used for tube trailers to transport H2, and can also be used for on-site buffer storage.
At the CW Tech Days event in May 2021, Kelley Owen, Chief Operating Officer of PowerTap Hydrogen (Irvine, California, USA) explained that each PowerTap HRS will use SMR units to produce 1,250 kg of H2 from natural gas per day. Fuel cell vehicle refueling and 700 bar fuel tank. In cooperation with Andretti Group, PowerTap will install HRS in selected Andretti Group gas stations and diesel stations in California.
Figure 2. High-quality on-site storage space. The rough design of HRS using a steam methane reformer and a Type 1 steel tank for buffer storage requires 25 x 35 feet of storage space. Image source: PowerTap Hydrogen
These HRS devices must be suitable for the current station area and are already occupied by gasoline and diesel pumps, convenience stores, etc. Owen said that PowerTap’s buffer storage will include two sets of tanks: 24 medium pressure (500 bar, 20 inches in diameter, 34 feet long) and 30 high pressure (900 bar, 16 inches in diameter, 35 feet long) rolled steel tube cylinders. Approximately 25 x 35 feet of storage space (Figure 2). Irving explained that the reason for choosing Type I steel pipes is that the cost of Type IV composite storage tanks is 30-35% higher, increasing the cost of the storage tank from US$1.2 million to US$1.6 million, which will consume each HRS typical More than half of the $3 million budget.
Rick Rashilla, senior vice president of research and development at Hexagon Composites in Lincoln, Nebraska, said: "There is no doubt that the price of steel tanks is much lower than that of composite tanks. But in some applications, composite tanks are a good solution. For example. Some of our customers in Europe have installed such storage tanks on the roof of hydrogen stations, compressors or other equipment to reduce the overall footprint. This is possible because the IV tanks are very light. Although the cost of metal tanks Lower, but usually requires ground installation, and because of their weight, you can only stack them so high, while composite tanks can be stacked higher, reducing storage space."
However, compared with steel tanks, is the diameter or pressure of composite gas cylinders limited? “The wall thickness of any pressure vessel must increase as pressure and size increase,” explains Brian Yeggy, chief engineer of the R&D department at Hexagon Composites in Lincoln, Nebraska. A fuel tank with a pressure of 700 bar. "At present, Hexagon’s largest storage tank has a diameter of 580 mm/22.8 inches, a length of 3.3 meters/10.8 feet, and can be stored at 500 bar. It also has a 1,000 bar, 20-inch diameter fixed storage cylinder. "This is not The limitation of our technology is the requirement of our customers," Yeggy said. "We have expanded the composite tank to 42 inches in diameter and 51 feet in length for storage at 250 bar. "
"The higher the pressure," he continued, "the composite material looks more attractive, but because of the need for higher wall thickness, the higher the cost of the entire system regardless of the material." Composite tanks meet HRS requirements What is the capacity, up to 10 pressurization cycles per day, and a lifespan of 15 years? "This is equivalent to a maximum of 55,000 cycles," Yeggy said. "According to the standard of 45,000 cycles, most of our products have passed 15 to 30 years of certification, and can be guaranteed to fill up to 150% overflow without failure. We also tested several 27 inches in diameter and pressure The 379-bar storage tank has been cycled for 110,000 times without failure [Fig. 3]. We have a 14-inch diameter cylinder with a pressure of 380 bar. The cylinder has been tested for 1 million cycles, and every cycle is in 150% of its working pressure. Therefore, I am not worried that the IV storage tank can meet the cycle range required by the hydrogen refueling station."
Figure 3. Type IV tank handling refueling cycle Fatigue test data for selected Hexagon Composites Type IV compressed gas cylinders show that composite materials can handle the fatigue of pressurized cycles regardless of tank size and working pressure. Image source: Hexagonal Composite
Tubular trailers represent another market for composite gas cylinders—that is, the distribution or transportation of hydrogen from production sites to HRS or industrial sites. This is the main market for Hanwha Cimarron Composites (Seoul, South Korea), Hexagon and NPROXX (Heerlen, Netherlands). At Hexagon, this market is expected to account for more than 40% of the company's revenue in 2021. "For hydrogen, most of our distribution cylinders have a pressure of 350 bar and tend to be 500 or higher," said Hexagon's Rashilla. "Because of the need to get more hydrogen on board, there will probably be 700 bar cylinders; but it will always balance the cost of getting there."
“It all starts with hydrogen and infrastructure,” explains Michael Himmen, NPROXX managing director and head of sales. The growth of H2 powered vehicles requires gas stations, which in turn rely on fuel transportation. "We may have design clauses for ships and containers in the next two years." Here, the term "container" refers to the way the transport module is packaged. For example, Hexagon's X-STORE module for 500 bar H2 transportation includes a 10, 20, 30, or 40-foot-long metal frame trailer with 22, 52, 82, or 103 IV cylinders, which can hold 240, 565, 890 or 1,115 kg H2. NPROXX has similar products. Cimarron Composites explained in a feature article on H2 pressure vessels in CW 2020 that its Neptune 517-bar IV tank has a diameter of 30 inches and a length of 19 feet. It can fit 9 containers into a standard 20-foot container. H2 of less than 600 kg is twice this amount in a 40-foot container.
Figure 4. Type IV glass fiber storage tank. Compared with carbon fiber composite material, the type IV storage tank is lower in cost, but lighter than steel (orange square in the picture above). Image source: UMOE Advanced Composites
Umoe Advanced Composites (UAC, Kristiansand, Norway) also aimed at H2 gas transmission, but without carbon fiber. Instead, the company produces Type IV cylinders made with industry-standard T4 plastic linings, and are packed with fiber-wound glass fiber/epoxy resin combinations. UAC currently offers modules from 200 to 350 bar and will expand to include 450 and 500 bar storage tanks in 2022. As explained by UAC CEO Øyvind Hamre at CW’s Hydrogen Technology Day event, glass fiber reinforced polymer (GFRP) tanks provide the same capital expenditure (CAPEX) as steel tanks, but with a 70% weight reduction ( Figure 4). At the same time, GFRP reduces capital expenditures by 50% compared with CFRP cylinders, but the weight is higher. In May 2021, UAC announced the establishment of a new factory in China with a joint venture company to expand its production capacity from 10,000 to 20,000 cylinders (1,700-2,000 liters) per year by 2022. At the same time, it will increase its production capacity in Norway to 4,000 cylinders/year.
As explained in the introduction to Part 1 of this series, besides cost, another key issue for Type IV tanks is storage density—that is, how much H2 can be stored in a given volume. The key index here is called weight, weight or mass ratio, which is defined as the mass of stored H2 divided by the mass of the storage tank or storage system. The 2019 review of the hydrogen storage system listed the weight densities of Type I, II, and III storage tanks as 1.7%, 2.1%, and 4.2%, respectively. This metric can also be referred to as storage density or efficiency. For Type IV storage tanks, Toyota (Toyota City, Japan) set a benchmark value of 5.7% for its 700 bar storage tanks in 2014 due to a 20% reduction in CFRP by optimizing the filament winding mode. These generally include toroidal windings along the cylinder, small-angle windings across the cylinder and the top of the circle, and large-angle windings at the boundary between the toroidal and low-angle windings. Toyota devised a method to eliminate large-angle spiral windings, which previously accounted for 25% of laminates. Instead, the shape of the liner is flattened to achieve lamination by loop winding in the border area. Toyota also concentrated the ring winding on the inner layer with the highest stress. One of Faurecia's claimed advantages in its CFRP IV tank is the >7% weight ratio.
In 2019, NPROXX, a 50/50 joint venture with Cummins (Columbus, Indiana, USA), launched a 700 bar IV storage tank with a storage density of 6.4%, while Iljin Hysolus (Bongdong-eup, Lampang, South Korea) The production of fuel cell passenger vehicles for Hyundai Nexo averages 6.3%. "For us, the key is how you handle the carbon fiber and the degree of damage to the fiber during the winding process," points out Himmen of NPROXX. "This actually determines how much carbon fiber you use in the fuel tank."
Yeggy said that the H2 tank manufactured by Hexagon Composites is now split into Hexagon Purus, and its storage efficiency is between 5% and 7%. "We have been conducting research to improve storage efficiency, but the lighter the tank you make, the more precise it must be, and the greater the loss tolerance," he pointed out. "And cost is an important factor. If you don't consider cost, then I can build a design on paper and increase storage efficiency by 10%. But to achieve this goal, it will cost more than the vehicle it is in."
Although reducing the cost of storage tanks has always been a goal of the U.S. Department of Energy (DOE) program, Faurecia has claimed that by 2030, it will reduce the cost of H2 storage systems by 75%, from 1,300 euros each. To 315 euros. Kg H2 is stored. Plastic Omnium's goal is to reduce costs by 30%. NPROXX agrees with the latter. "Based on the number of tanks produced by 2030, our analysis is that we can reduce costs by 25-30%," Himmen said. However, he acknowledged that carbon fiber accounts for 60% of the cost of storage tanks-the DOE cost model shows that higher output does not significantly reduce fiber prices. Rashilla of Hexagon Composites stated that Hexagon has cooperated with the US Department of Energy on various tank and carbon fiber cost reduction projects, and pointed out that other projects may be carried out in the near future.
Rashilla points out that another way to reduce costs is through Hexagon's Digital Wave business unit, which uses modal acoustic emission (AE) to inspect tanks at the end of their regulatory life and analyze tank integrity to provide additional services. Modal AE uses advanced electronics and sensors to improve sensitivity and data. "Extending the life of the cylinder is a great way to reduce costs and emissions," Rashilla said. "This has been proven in carbon fiber composite gas cylinders for firefighters. We have also completed this work for the first production batch of compressed natural gas tanks, whose service life will end in 2010-2015. Digital Wave The test can verify that the tank is not damaged and that it is likely to have an'X' lifespan."
"I think the industry still lacks data," Himmen said. “Type IV ships will not be inspected until the first 10 years of service. But what exactly happened to the integrity of the pressure vessel at that time, do you really have the data to understand? We participated in an EU plan to create these data. We provided A large number of storage tanks and equipped them with various sensors to determine the life impact of temperature, pressure cycling, aggressive refueling, and in-service use and abuse on the integrity of the storage tank. The goal is to obtain before we put the sensor in the composite material More knowledge, because I first want to know what to measure and compare with to determine the quality of the pressure vessel."
Despite future efforts, one area where NPROXX is currently integrating sensor technology is in its production process.
Figure 5. Fiber optic sensors for optimizing tank production, monitoring and design. Com&Sens uses fiber Bragg grating (FBG) fiber optic sensors embedded in or on the composite tank to sense strain and temperature during filament winding, testing, and operation. These sensors can verify the pressure of the FE model, provide structural health monitoring and tank integrity measurement for re-certification. Image source: Com&Sens
During CW's H2 Technology Day, Com&Sens demonstrated how to use embedded fiber Bragg grating (FBG) fiber optic sensors to optimize composite tank production and on-site health monitoring. The FBG fiber optic line can be co-wound from the spool because the H2 tank laminate is being wound by the fiber. The length of each optical fiber ranges from 1 to 100 meters, with a maximum of 20 sensing points, and the minimum spacing is 1 cm.
Eli Voet, co-founder of Com&Sens, said: “Each sensing point is located in the optical fiber to measure at any discrete position within the hoop or spiral layer of the composite laminate.” During the operation of the patented point connection technology, these points will be interrogated, so that a large number of'smart' tanks can be used." He explained that the FBG embedded in the laminate senses the redistribution of strain within the material. "These sensors can be used for production process optimization, allowing understanding and digitizing process parameters that were previously impossible to measure," Voet adds. "Capturing system-wide stress, strain, and temperature measurements during curing, fatigue cycles, and burst testing will help designers validate finite element models and optimize, for example, the use of materials in future designs. But perhaps the most promising The application is to conduct life cycle and structural integrity monitoring during storage tank operations, thereby increasing acceptance and confidence in hydrogen technology." For example, Voet demonstrated the ability to produce storage tanks with a “digital fingerprint” and then based on the fingerprint Recertification of storage tanks to extend service life.
According to the Hydrogen Insights report of the Hydrogen Energy Commission in 2021, 75 countries have formulated zero-emission strategies, and more than 20 countries have announced a ban on the sale of internal combustion engine (ICE) vehicles by 2035. In addition to H2, battery electric, solar and other alternative fuels will be part of the solutions needed to achieve these goals. However, people are paying more and more attention to and increasing government support for H2. Net zero emissions by 2050 have been the mantra for avoiding climate disasters, but many countries are working hard to achieve their goals by 2040 or earlier. is it possible?
Dahl of Hexagon Purus Maritime said: "Not only do you have to reconsider the vehicle architecture, you also have to rethink the entire operating business model." "Of course, there is a hesitation-who will preempt and take risks? It also requires a lot of investment. But those People who have goals and have the courage to achieve them will become leaders who move forward."
In addition to multiple zero-emission solutions, H2 storage will continue to have multiple solutions, and not all of them will rely on composite materials or carbon fiber. How will the composites industry respond to the rapidly emerging markets of H2 powered cars, trains, ships, and gas stations that are under development? Can the new carbon fiber make the storage tank have higher storage efficiency and lower cost? NPROXX’s Himmen said: “We have thought a lot about the ideal carbon fiber we want to use.” “It is expected that there will be such a large output. Obviously [expected] the consumption of carbon fiber will be higher, and I think the ideal carbon fiber has not yet been put on the market. ." But maybe it can. "You need subversion to make real changes," Dahl pointed out, "and 2050 is coming."
The third production line will produce an additional 2,500 tons of carbon fiber annually for industrial applications, infrastructure, and Type III and Type IV compressed natural gas and hydrogen pressure vessels.
BBG Gmbh & Co. KG has developed a mold for the manufacturer of Type IV CFRP tanks, which integrates automation and sensors to produce adjustable-length hydrogen storage tanks faster and cheaper.
The high-performance composite pressure vessel will be tested and verified later in 2021, and will be certified for distribution in the European and North American markets.
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