Development of Technical Regulations for Fuel Cell Motorcycles in Japan—Hydrogen Safety

Article Development of Technical Regulations for Fuel Cell Motorcycles in Japan—Hydrogen Safety

Eisuke Yamada 1,* and Takehiko Mashiba 2,3

1 Japan Automobile Research Institute, 1328-23 Takaheta, Osaka, Shirosato, Ibaraki 1328-23, Japan 2 Japan Automobile Manufacturers Association, Inc., 1-30 Shiba Daimon 1-chome, Minato-ku, Tokyo 105-0012, Japan 3 Suzuki Motor Corporation, 300 Takatsuka, Minami-ku, Hamamatsu, Shizuoka 432-8611, Japan * Correspondence: [email protected]; Tel.: +81-29-288-7871

Received: 21 March 2019; Accepted: 2 July 2019; Published: 9 July 2019

Abstract: Hydrogen fuel cell vehicles are expected to play an important role in the future and thus have improved signiﬁcantly over the past years. Hydrogen fuel cell motorcycles with a small container for compressed hydrogen gas have been developed in Japan along with related regulations. As a result, national regulations have been established in Japan after discussions with Japanese motorcycle companies, stakeholders, and experts. The concept of Japanese regulations was proposed internationally, and a new international regulation on hydrogen-fueled motorcycles incorporating compressed hydrogen storage systems based on this concept are also established as United Nations Regulation No. 146. In this paper, several technical regulations on hydrogen safety speciﬁc to fuel cell motorcycles incorporating compressed hydrogen storage systems are summarized. The unique characteristics of these motorcycles, e.g., small body, light weight, and tendency to overturn easily, are considered in these regulations.

Keywords: fuel cell; hydrogen; motorcycle; standardization

1. Introduction Recent environmental and energy safety issues have resulted in a significant change in the transportation sector: The replacement of fossil fuels by alternative energy sources. As a clean fuel and energy carrier, hydrogen is a promising alternative energy source. Hydrogen fuel cell vehicles (HFCVs) are expected to play an important role in the future and thus have improved significantly over the past years [1,2]. The first commercial hydrogen fuel cell car was launched in 2014 in Japan [3]. However, hydrogen fuel cell motorcycles are still in their developmental stages. Since battery-powered electric motorcycles have already been provided by several manufacturers and are rapidly becoming popular in recent years [4], commercialization and widespread use of fuel cell motorcycles are also expected. Several concepts for fuel cell motorcycles have been designed. Metal hydride canisters are widely used for hydrogen-fueled scooters in Taiwan [5,6]. The canisters are designed with quick connectors to allow easy replacement. A hybrid scooter with a plug-in battery and a hydrogen fuel cell has been researched in the UK [7]. Two metal-hydride canisters are used for the hybrid scooter. Alternatively, small containers for compressed hydrogen gas have been researched and developed in Japan. Recently, a fuel cell motorcycle incorporating a compressed hydrogen storage system has been developed by Suzuki [8]. The fuel cell motorcycle, equipped with an air-cooled fuel cell unit, obtained Japanese type approval in August 2016. It is the first vehicle of its type in Japan. The fuel cell motorcycle was tested on the public roads of Japan [9] and the UK [10]. Figure1 shows the fuel cell motorcycle being refueled with compressed hydrogen gas at a hydrogen station in Japan. In this case, Japanese hydrogen fueling regulation JPEC-S 0003(2012) was applied to refuel the motorcycle after

World Electric Vehicle Journal 2019, 10, 48; doi:10.3390/wevj10030048 www.mdpi.com/journal/wevj World Electric Vehicle Journal 2019, 10, x FOR PEER REVIEW 2 of 6 World Electric Vehicle Journal 2019, 10, 48 2 of 6 In this case, Japanese hydrogen fueling regulation JPEC-S 0003(2012) was applied to refuel the motorcycle after the fueling safety has been confirmed [8]. Furthermore, a new hydrogen fueling methodthe fueling for safety fuel cell has beenmotorcycles conﬁrmed incorporatin [8]. Furthermore,g compressed a new hydrogenhydrogen fuelingstorage method systems for is fuel under cell developmentmotorcycles incorporating [11]. compressed hydrogen storage systems is under development [11].

Figure 1. AA fuel cell motorcycle at a hydrogen station in Japan.

To make fuel cell motorcyclesmotorcycles commercially availableavailable all over the world, it is important to establish appropriateappropriate technicaltechnical regulations regulations for for these thes vehicles.e vehicles. Although Although the the technical technical regulations regulations for thefor theelectrical electrical safety safety of motorcycles of motorcycles have beenhave publishedbeen published as United as United Nations Nations Regulation Regulation (UNR) No.(UNR) 136, No. the 136,technical the regulationstechnical regulations for hydrogen for safety hydrogen of motorcycles safety haveof motorcycles not been published. have not Additionally, been published. Global TechnicalAdditionally, Regulation Global (GTR)Technical No. Regulation 13 and UNR (GTR) No. 134, No. which 13 and are UNR international No. 134, technicalwhich are regulations international for technicalhydrogen-fueled regulations vehicles for incorporatinghydrogen-fueled compressed vehicles hydrogen incorporatin storageg compressed systems, excluding hydrogen motorcycles, storage systems,have been excluding published. motorcycles, Most of these have regulations been published. are considered Most of to these be applicable regulations to are fuel considered cell motorcycles to be applicableincorporating to fuel compressed cell motorcycles hydrogen incorporatin storage systems.g compressed However, hydrogen there are storage parts ofsystems. these regulations However, therethat cannot are parts be of safely these applied regulations to fuel that cell cannot motorcycles be safely due applied to some to fuel characteristics cell motorcycles that are due unique to some to characteristicsthese vehicles. that It is necessaryare unique to to modify these vehicles. these regulations It is necessary for fuel to cell modify motorcycles. these regulations for fuel cell motorcycles.The characteristics unique to motorcycles include their small body, light weight, and tendency to overturnThe easily.characteristics National unique regulations to motorcycles taking these includ characteristicse their small into body, account light have weight, been and established tendency in Japan.to overturn A new easily. international National regulation regulations on hydrogen-fueledtaking these characteristics motorcycles incorporatinginto account compressedhave been establishedhydrogen storage in Japan. systems A new based international on Japanese regulation regulations on hydrogen-fueled was also established motorcycles as UNR incorporating No. 146 in compressed2019. In this paper,hydrogen several storage technical systems regulations based on specific Japanese to motorcyclesregulations whichwas also are established different from as UNR No. 146 134 in are 2019. summarized. In this paper, several technical regulations specific to motorcycles which are different from UNR No. 134 are summarized. 2. Regulations 2. RegulationsIn this section, some technical regulations different from that for four-wheeled vehicles are summarized.In this section, These regulationssome technical were regulations established indiff Japanerent after from discussions that for four-wheeled with Japanese vehicles motorcycle are summarized.companies, stakeholders, These regulations and experts. were established in Japan after discussions with Japanese motorcycle companies, stakeholders, and experts. 2.1. Capacity of Hydrogen Containers 2.1. CapacityIt is clear of thatHydrogen a small Containers vehicle, e.g., a motorcycle, must have hydrogen container(s) smaller than that of four-wheeled vehicles. Considering the container capacity of conventional gasoline motorcycles, It is clear that a small vehicle, e.g., a motorcycle, must have hydrogen container(s) smaller than the reasonable maximum container capacity for fuel cell motorcycles is considered to be around 20 L. that of four-wheeled vehicles. Considering the container capacity of conventional gasoline Additionally, the hydrogen volumetric concentration inside a garage caused by permeation from motorcycles, the reasonable maximum container capacity for fuel cell motorcycles is considered to be the container should be maintained to be less than 1%, as stated in the rationale of GTR No. 13. around 20 L. Therefore, it is necessary to consider a small garage for motorcycles instead of using a large garage for Additionally, the hydrogen volumetric concentration inside a garage caused by permeation four-wheeled vehicles. from the container should be maintained to be less than 1%, as stated in the rationale of GTR No. 13. According to survey results, the smallest garage used to house motorcycles is approximately Therefore, it is necessary to consider a small garage for motorcycles instead of using a large garage 3.56 m3. This garage is 2.2 m in length, 0.9 m in width, and 1.8 m in height. The upper limit of for four-wheeled vehicles. permeation rate per liter from a compressed hydrogen storage system (P ) and the lower volumetric air According to survey results, the smallest garage used to house motorcyclesl is approximately exchange rate for a garage per hour (r) are 46 mL/h/L and 0.03 /h, respectively, which are obtained from 3.56 m3. This garage is 2.2 m in length, 0.9 m in width, and 1.8 m in height. The upper limit of GTR No. 13. These values are used to calculate the capacity of 330 L in GTR No. 13. It is reasonable to permeation rate per liter from a compressed hydrogen storage system (𝑃) and the lower volumetric World Electric Vehicle Journal 2019, 10, 48 3 of 6 use the same procedure for a fuel cell motorcycle with a similar compressed hydrogen storage system. Therefore, the following equation holds to maintain the volumetric concentration in the smallest garage to be less than 1%: rVg Vm < 23.2L, (1) 100Pl where Vm is the compressed hydrogen storage capacity for a fuel cell motorcycle and Vg is the smallest garage capacity (3.56 m3). Therefore, it is a reasonable requirement that 23 L is the maximum capacity for fuel cell motorcycles. This requirement is stated in Japanese regulations.

2.2. Types of Hydrogen Containers Compressed hydrogen containers can be categorized into four types [12,13]. Type I and II are traditional steel containers that are primarily used for storing natural gas. Type III and IV are carbon fiber full-wrapped cylinders which have been developed and researched for use in HFCVs because their maximum allowable pressure is higher than that of Type I and II containers. Hydrogen gas stored in Type III and IV containers can be compressed up to 70 MPa, thereby enabling long-distance driving and making HFCVs comparable to conventional vehicles in this regard. Type III and IV containers will also be useful for the commercialization of fuel cell motorcycles. It is necessary to complete refueling of the hydrogen gas within few minutes for user convenience. However, the pressure in the container increases to 70 MPa from several MPa in few minutes. Such a high-pressure ramp rate induces a rapid increase in the temperature of the hydrogen gas inside the container. To avoid compromising the structural integrity of the hydrogen gas storage system, the temperature of this gas must be restricted to less than 85 ◦C[14,15]. To avoid temperatures higher than 85 ◦C inside the container during the refueling process at hydrogen stations, the supplied hydrogen gas needs to be pre-cooled. The temperature of the supplied hydrogen gas is gradually decreased by the pre-cooled system due to heat exchange through pipes, nozzles, hose, and other components in the hydrogen gas supply line. Therefore, the hydrogen gas at an initial filling is not sufficiently cooled. The ratio of the initial filling to the total filling inevitably becomes large in a small container. Therefore, there is great concern that the hydrogen gas temperature in a small container rises significantly compared to the gas temperature in a large container. Hiraki et al. experimentally investigated the temperature changes inside small Type III and IV containers during hydrogen filling [16]. The liner materials of the Type III and IV containers are metal and plastic, respectively. Since the heat capacity of the metal liner is large, an increase in the temperature of the hydrogen gas in Type III containers is moderate compared to the increase in the temperature of the hydrogen gas in Type IV containers. These experimental results show that the Type III container (with the metal liner) has a considerable thermal advantage with regard to hydrogen filling. It is difficult to refuel Type IV containers with hydrogen gas in a few minutes under high ambient temperature while maintaining the temperature of the hydrogen gas below 85 ◦C. From a safety point of view, it is appropriate to use Type III containers in fuel cell motorcycles for now. Therefore, Japanese regulations only permit Type III containers for use in fuel cell motorcycles.

2.3. Thermally Activated Pressure Relief Device To immediately discharge compressed hydrogen gas in the event of a fire accident, it is required to install a thermally activated pressure relief device (TPRD) on the containers of HFCVs. Installing a TPRD is necessary for small and large containers. When the TPRD is activated, a hydrogen flame is formed immediately in the discharge direction. Therefore, it is important for first responders to identify the direction of the hydrogen gas discharge from the TPRD. In UNR No. 134 excluding motorcycles, the direction of the hydrogen gas discharge from the TPRD is specified. The hydrogen gas discharge to forward from the vehicle, or horizontally (parallel to road) from the back or sides of the vehicle is not permitted by UNR No. 134. World Electric Vehicle Journal 2019, 10, x FOR PEER REVIEW 4 of 6

World Electric Vehicle Journal 2019, 10, x FOR PEER REVIEW 4 of 6 gas discharge to forward from the vehicle, or horizontally (parallel to road) from the back or sides of World Electric Vehicle Journal 2019, 10, 48 4 of 6 the vehicle is not permitted by UNR No. 134. gas discharge to forward from the vehicle, or horizontally (parallel to road) from the back or sides of However, motorcycles are generally overturned in accidents. Thus, it is necessary to further the vehicle is not permitted by UNR No. 134. restrict the discharge direction. The direction of the hydrogen gas discharge is specified in Japanese However, motorcycles are generallygenerally overturnedoverturned in accidents.accidents. Thus, Thus, it it is necessary to further regulations. The hydrogen gas discharge from a TPRD attached to a fuel cell motorcycle shall not be restrict the discharge direction. The direction of th thee hydrogen gas discharge is speciﬁedspecified in Japanese directed in any orientation other than perpendicularly outward from the bottom of the body of the regulations. The The hydrogen hydrogen gas discharge from a TPRD attached to a fuel cell motorcycle shall not be vehicle, as shown in Figure 2. directed in any orientation other than perpendicularlyperpendicularly outward from the bottom of the body of the vehicle, as shown in Figure2 2..

Figure 2. Direction of gas discharge from a thermally activated pressure relief device. Figure 2. Direction of gas discharge from a thermally activated pressure relief device. Figure 2. Direction of gas discharge from a thermally activated pressure relief device. 2.4. Protection of Hydrogen Containers 2.4. Protection of Hydrogen Containers 2.4. ProtectionIf a fuel cell of Hydrogen motorcycle Containers incorporating a compressed hydrogen storage system encounters an accident,If a fuelit is important cell motorcycle to appropriately incorporating protect a compressed the onboard hydrogen container storage to avoid system container encounters rupture. anIf If a fuel cell motorcycle incorporating a compressed hydrogen storage system encounters an aaccident, motorcycle it is importantoverturns, to there appropriately is concern protect that theits onboardcontainer container might come to avoid into container direct contact rupture. with If a accident, it is important to appropriately protect the onboard container to avoid container rupture. If something.motorcycle overturns, there is concern that its container might come into direct contact with something. a motorcycle overturns, there is concern that its container might come into direct contact with Therefore,Therefore, Japanese Japanese regulations regulations state state that that the the co containerntainer shall shall not not be be in in contact contact with with the the road road something. surface,surface, or or even even in in direct direct contact contact with with any any othe otherr component component of of the the vehicle vehicle (with (with the the exception exception of of Therefore, Japanese regulations state that the container shall not be in contact with the road protectiveprotective devices), devices), in the event of a crash, rear-end collision, etc. surface, or even in direct contact with any other component of the vehicle (with the exception of Post-crashPost-crash fuelfuel system system integrity integrity is required is required for hydrogen-fueled for hydrogen-fueled vehicles incorporating vehicles incorporating compressed protective devices), in the event of a crash, rear-end collision, etc. compressedhydrogen storage hydrogen system, storage excluding system, motorcycles, excluding motorcycles, which is stated which in UNR is stated No. 134.in UNR In case, No. that134. theIn Post-crash fuel system integrity is required for hydrogen-fueled vehicles incorporating case,vehicle that crash the vehicle tests are crash not tests applicable are not to applicable the vehicle. to the The vehicle. vehicle The fuel vehicle system fuel shall system instead shall be instead subject compressed hydrogen storage system, excluding motorcycles, which is stated in UNR No. 134. In beto thesubject relevant to the alternative relevant accelerations.alternative acceleration Crash testss. areCrash not tests necessary are not for necessary motorcycles, for thereforemotorcycles, it is case, that the vehicle crash tests are not applicable to the vehicle. The vehicle fuel system shall instead thereforeappropriate it is to appropriate apply an alternative to apply an acceleration alternative test. acceleration test. be subject to the relevant alternative accelerations. Crash tests are not necessary for motorcycles, TheThe strength of thethe attachmentattachment of of the the container container shall shall be be verified verified by by the the alternative alternative acceleration acceleration test, therefore it is appropriate to apply an alternative acceleration test. test,where where a specific a specific acceleration acceleration is applied is applied to the containerto the container attached attached to the vehicle to the onvehicle a loading on a platform.loading The strength of the attachment of the container shall be verified by the alternative acceleration platform.The container The container shall remain shall attached remain toattached the vehicle to the with vehicle a minimum with a minimum of one attachment of one attachment point and point stay test, where a specific acceleration is applied to the container attached to the vehicle on a loading andwithin stay the within installed the installed location afterlocation the accelerationafter the acce test.leration The test. acceleration The acceleration values used values in the used test in were the platform. The container shall remain attached to the vehicle with a minimum of one attachment point testobtained were obtained from the from frontal the and frontal lateral and collision lateral collisio tests shownn tests inshown Figure in3 Figure. In the 3. frontal In the frontal collision collision test, a and stay within the installed location after the acceleration test. The acceleration values used in the test,motorcycle a motorcycle collided collided with the with side the of side a car. of Ina car. the lateralIn the lateral collision collision test, the test, car the collided car collided with the with side the of test were obtained from the frontal and lateral collision tests shown in Figure 3. In the frontal collision sidethe motorcycle.of the motorcycle. The collision The collis speedion indicated speed indicated in the figure in the is basedfigure onis based accident on statisticsaccident involvingstatistics test, a motorcycle collided with the side of a car. In the lateral collision test, the car collided with the involvingmotorcycles motorcycles in Japan over in Japan the past over 10 the years. past 10 years. side of the motorcycle. The collision speed indicated in the figure is based on accident statistics involving motorcycles in Japan over the past 10 years.

Figure 3. Collision tests between motorcycles and cars. Figure 3. Collision tests between motorcycles and cars. The collision tests providedFigure 3. the Collision acceleration tests between values motorcycles to verify the and strength cars. of container attachment. The acceleration values in the direction of travel (forward and rearward direction) and in a direction World Electric Vehicle Journal 2019, 10, 48 5 of 6 that is horizontally perpendicular to that of travel (left and right) were 426 (43.5 g) and 617 (63 g) m/s2, respectively. These acceleration values are considerably large because motorcycles are light in weight. In UNR No. 134, acceleration values in the direction of travel and in a direction that is horizontally perpendicular to that of travel are 20 g and 8 g, respectively, for vehicles of category M1, which are power-driven vehicles having at least four wheels and used for the carriage of passengers and comprising not more than eight seats in addition to the driver’s seat.

3. Conclusions The Japanese technical regulations for hydrogen-fueled motorcycles, which are diﬀerent from those for four-wheeled vehicles, were summarized. The unique characteristics of motorcycles, such as their small body, light weight, and tendency to overturn easily, were considered in these regulations. After thorough consideration, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) enacted and published safety regulations for hydrogen fuel cell motorcycles in February 2016 [17]. Then, the Ministry of Economy, Trade and Industry (METI) enacted and published technical regulations for compressed hydrogen containers for motorcycles in May 2017 [18]. Technical regulations on hydrogen safety for fuel cell motorcycles, including those mentioned above, have been proposed internationally. After the discussion, the new UNR No. 146 (Hydrogen and fuel cell vehicles of category L) was enacted in January 2019 [19].

Author Contributions: Investigation, E.Y. and T.M.; writing—original draft preparation, E.Y.; writing—review and editing, E.Y. and T.M. Acknowledgments: The authors gratefully acknowledge the work of the Fuel Cell Motorcycle working group of JAMA. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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