The emerging H2 economy has promoted the development of tanks for aircraft, ships, and natural gas transportation. #cleansky #feature #aramidfiber

Universal Hydrogen's dual-tank module uses a carbon fiber-wrapped pressure vessel to store 850 bar of hydrogen, provides a range of 400 nanometers for Dash 8 or ATR turboprops, and uses existing infrastructure for easy transportation and loading. Image source: General Hydrogen

Hydrogen has been used as a carbon dioxide-free alternative to fossil fuels for decades, and the growth of carbon fiber reinforced plastic (CFRP) pressure vessels for hydrogen storage is definitely increasing. But in 2020, hydrogen becomes a task, identified by the European Commission (EC) as a key priority of the European Green Agreement for achieving a sustainable economy and EU climate neutrality by 2050. The main events of aviation hydrogen include:

The viability of hydrogen as a fuel source—regardless of the industry—depends on the rapid development of various young but fast-developing transportation, delivery, and storage technologies. Commercializing these technologies is not easy, but they are being resolved. The following is a summary of some of the work being done.

Universal Hydrogen was co-founded in 2020 by Paul Eremenko, the former chief technology officer of Airbus SE (Leiden, Netherlands) and United Technologies (Farmington, Connecticut, USA), with the goal of providing hydrogen to help transition to hydrogen-powered aviation as an infrastructure come on. A key component is its fuel module, which includes dual H2 storage tanks in a carbon fiber reinforced polymer (CFRP) frame. "We will provide modules to the site as needed, so hydrogen storage infrastructure is not needed," explained JP Clarke, CTO of Universal Hydrogen. "These modules are simply loaded onto the plane like batteries or kitchen supplies."

The module was first developed for the 50-seat Dash 8 and ATR turboprop regional aircraft. These modules will have 7 feet long x 3 feet diameter tanks, use carbon fiber to contain H2 gas at 850 bar, reaching a density of 50 kg/m3, or use insulated metal tanks to contain liquid H2 (LH2) at standard pressure and temperature up to Density of 71 kg/m3. Although the LH2 tank has higher volumetric efficiency, the insulated but uncooled tank must be used within 42 hours because LH2 will evaporate if it is not kept at -253°C. "Both types of tanks will be located in a lightweight, structurally optimized composite frame that also has impact resistance and a certain load-bearing capacity," Clark said.

The H2 gas tank will include an impermeable polymer lining wrapped in a dry carbon fiber braid and a protective outer layer of Kevlar aramid fiber. "No resin needed," Clark explained. "The inner lining handles permeability, while the carbon handles the hoop and axial load, and the outer layer adds a frame to prevent damage; thereby reducing weight and thickness. This integrated fuel tank and frame design, coupled with mapping the function to each fuel tank layer, This allows us to make some major improvements in quality scores." 

The mass fraction is calculated by dividing the stored hydrogen mass by the mass of the entire module, so the larger the mass fraction, the better. "We have conducted very extensive trade studies on the mass fraction and volumetric efficiency of Dash 8 and ATR aircraft," Clark noted. "So you are looking at the volume and weight of the fuel and the capacity of these aircraft, achievable range and maximum take-off weight, weight distribution, etc. Using 850 bar of hydrogen, we can use a 45-minute reserve and approximately 550 nautical miles with the LH2 tank However, the average phase length of turboprop missions is about 300 nautical miles, so most of these flights can be accomplished with gaseous H2 systems using CFRP tanks."

Will Universal Hydrogen work with composite tank manufacturers? "Our strategy is to collaborate where it makes sense and stick to our core business," Clark said. He reiterated the focus of Universal Hydrogen: "We want to be a supplier of fuel and infrastructure. We will provide modules and send them where needed so that our partners can focus on the rest of the aircraft design and operation. Our goal is to become a promoter of hydrogen-powered aviation."

Like aviation, shipping is subject to regulations designed to reduce carbon dioxide and other greenhouse gas (GHG) emissions. Starting from January 2018, ships that load and unload cargo or passengers with a gross tonnage of more than 5,000 tons in European Economic Area (EEA) ports must monitor and report their carbon dioxide emissions. Furthermore, as part of the MARPOL Convention to reduce pollution from ships, the International Maritime Organization (IMO) has required that from January 2020, the sulfur content in fuel must be reduced from 3.50% m/m (mass to mass) to 0.50%. The International Maritime Organization also promised to formulate a preliminary greenhouse gas strategy and strive to reduce it by 50% from the 2008 level by 2050.

“The best possibility to comply with regulations is to initially switch to liquefied natural gas (LNG),” said Dr. Panayotis Zacharioudakis, managing director of Ocean Finance (Athens, Greece), a consulting company that promotes maritime sustainability and the coordination of EC projects. Members SuperGreen and SpaceTech4Sea. SuperGreen will create a sustainable green transportation system in Greece, including electric commuter boats and two hybrid LNG/electric catamarans, connecting the port of Piraeus with other ports in the eastern Mediterranean network. "For this project, we are using CFRP to build a high-speed ferry," Zacharioudakis explained. "If we use the most advanced metal liquefied natural gas tank, it will weigh 7 metric tons, which is equivalent to more than 70 passengers [100 kg of luggage per person]. Therefore, we must reduce the passenger capacity by 70 people."

Cimarron Composites conducts low temperature tests on CFRP pressure vessels. Image source: Cimaron Composites

Why is the extra weight added? "Compared with diesel, LNG must be stored at a low temperature of -163°C, and metal tanks must use materials, structures, insulation and operating systems that meet the requirements of IMO for gas fuel or IGF specifications," Zacharioudakis said. For Ocean Finance, the extra weight was unacceptable, so it began to study possible solutions and found a report on the cryogenic tank Cimarron Composites (Huntsville, Alabama, USA) developed in cooperation with NASA .

"This is when we started the EASME (European Agency for Small and Medium Enterprises) SpaceTech4Sea project," Zacharioudakis said. "The idea is to modify aerospace technology for maritime applications." The third project partner is the Classification Society American Bureau of Shipping (ABS in Houston, Texas, USA), which will validate and approve the technology. In September 2019, ABS approved in principle (AIP) the conceptual design of Cimarron's ultra-light, low-temperature composite LNG storage tank. Since then, it has built and tested small and full-size tanks for certification. "They just finished the last test," Zacharioudakis said. "In more than two months, we will obtain the complete certification of the composite LNG storage tank for the marine market. Compared with the traditional metal tank, the tank will reduce the weight by more than 85%."

Although most of the details of the tank are proprietary, Tom DeLay, founder and president of Cimarron Composites, said it is made of carbon fiber and advanced thermosetting resin, using some resin infusion and wet fiber winding. "We have tested 25-inch and 40-inch diameter storage tanks, and are discussing with SuperGreen's CFRP ferry manufacturer for a storage tank with a capacity of 5 cubic meters [5,000 liters], which can be achieved with a storage tank with a diameter of 2 meters. Meters long.” Ocean Finance has seen the market for more than a thousand such tanks and will cooperate with Cimarron to establish automated production, possibly in Greece.

What about hydrogen? "Even if we completed these LNG projects, we started to pay attention to hydrogen," Zacharioudakis pointed out. "There is so much interest, activity and funding in Europe. However, one problem is that maritime regulations require storage tanks to provide LNG with a storage period of up to 15 days. The same is true for LH2." DeLay admits that it is LH2 (-253ºC, see above Text) It is much more difficult to develop storage tanks with low temperature capability than for LNG (-196ºC); one of the challenges is to find materials that can resist embrittlement and cracking. He is now collaborating with Ocean Finance to help complete a trade study to study the technical and economic factors of using liquid and gaseous H2 on ships.

Filament winding of Jupiter IV type CFRP pressure vessel. Image source: Cimaron Composites

It is worth noting that Cimarron Composites has developed a type IV CFRP tank for high-pressure storage of hydrogen and other gases. "Our original Jupiter tank was developed to transport most industrial gases, including hydrogen, at a pressure of 4,350 psi [300 bar]," DeLay said. "However, hydrogen is transported more efficiently at higher pressures, which is why we developed the 7,500 psi [517 bar] Neptune tank."

Transporting H2 gas by road, rail or sea. Neptune's high-pressure (517 bar) CFRP tank can transport 600 kg of H2 gas in a standard 20-foot container. Image source: Cimaron Composites

Both Jupiter and Neptune tanks have passed numerous tests required by UN ISO 11515 and are available in various diameters and lengths up to 26 feet. "These tanks were developed for transportation in standard modules by truck, rail or ship," Delay points out. "We found that 30-inch diameter has ideal packaging efficiency. Compared with large diameter steel cylinders, we can transport more hydrogen. At 19 feet long, we can fit nine tanks into a standard 20-foot container. Each tank weighs 67 kilograms. For hydrogen, we can transport 600 kg in a 20-foot container and 1,200 kg in a standard 40-foot container."

"We source carbon fiber from all major suppliers, including Toray [Tokyo, Japan], Mitsubishi Rayon [Tokyo], Teijin [Rockwood, Tennessee, U.S.] and Hyosung [Seoul, South Korea]," DeLay added, "but For Neptune, we have obtained the qualifications of three different suppliers at the same time. We use commercially available products to formulate our own resin, and very strictly control the fiber and resin content and the tension during filament winding and oven curing cycles to prevent thermal stress . All of these increase the mechanical performance of the tank."

Whether it requires cryogenic liquid storage or high-pressure gas storage, DeLay sees opportunities for growth. "We have spent many years developing our expertise," he said, "from rocket fuel tanks to the large storage tanks and transport tanks we are now developing and producing. A year ago, I was skeptical about hydrogen, thinking that the only The reason is the government's promotion. But now we have received very large orders and various requirements. We can see that many industries are investing heavily in hydrogen energy on a global scale, and the government is also supporting this development . It looks like we are ready to provide the right product at the right time."

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