Is the H2 Economy realizable in the foreseeable future? Part II: H2 Storage, Transportation, and Distribution

Depósito de Investigación de la Universidad de Sevilla https://idus.us.es/ This is an Accepted Manuscript of an article published by Elsevier in International Journal of Hydrogen Energy, Vol. 45 (41), on August 2020, , available at: https://doi.org/10.1016/j.ijhydene.2020.05.241 © 2020 Elsevier. En idUS Licencia Creative Commons CC BY-NC-ND 1 Is the H2 Economy realizable in the foreseeable future? Part II: H2 Storage, Transportation, and Distribution Hassan Nazir1, Cindrella Louis2, Sujin Jose3, Jyoti Prakash4, Navaneethan Muthuswamy5,6, Marthe Buan6, Cristina Flox6, Sai Chavan4, Xuan Shi4, Pertti Kauranen6, Tanja Kallio6, Gilberto Maia7, Kaido Tammeveski8, Nikolaos Lymperopoulos9, Elena Carcadea10, Emre Veziroglu11, Alfredo Iranzo12* and Arunachala Kannan4* 1US-Pakistan Center for Advanced Studies in Energy (USPCAS-E), National University of Sciences and Technology, Islamabad 44000, Pakistan 2Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015, Tamil Nadu, India 3School of Physics, Madurai Kamaraj University, Palkalai Nagar, Madurai 625021, Tamil Nadu, India 4The Polytechnic School, Ira A. Fulton Schools of Engineering, Arizona State University, Mesa, AZ 85212, USA 5Department of Chemical Engineering, Norwegian University of Science and Technology, Sem Sælands vei 4, N-7491 Trondheim, Norway 6Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, FI-00076 Espoo, Finland 7Institute of Chemistry, Federal University of Mato Grosso do Sul, University City, Senador Filinto Müller Avenue no. 1555, 79074-460 Campo Grande-MS, Brazil 8Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia 9Fuel Cells and Hydrogen Joint Undertaking, Avenue de la Toison d'Or 56-60, B-1060 Brussels, Belgium 10National Center for Hydrogen and Fuel Cells, National R&D Institute for Cryogenics and Isotopic Technologies – ICSI Ramnicu Valcea, 4 Uzinei Street, 240050, Romania 11Editor-in-Chief, International Journal of Hydrogen Energy, USA 12School of Engineering, Universidad de Sevilla, Camino de Los Descubrimientos, s/n, 41092, Sevilla, Spain Abstract The goal of the review series on the H2 economy is to highlight the current status, major issues, and opportunities associated with H2 production, storage, transportation, distribution and usage in various energy sectors. In particular, Part I discussed the various H2 (grey and green) production methods including the futuristic ones such as photoelectrochemical for small, medium, and large-scale applications. Part II of the H2 economy review identifies the developments and challenges in the areas of H2 storage, transportation and distribution with national and international initiatives in the field, all of which suggest a pathway for establishing greener H2 society in the near future. Currently, various methods, comprising physical and chemical routes are being explored with a focus on improving the H2 storage density, capacity, and reducing the cost. H2 transportation methods by road, through pipelines, and via ocean are pursued actively in expanding the market for large scale applications around the world. As of now, compressed H2 and its transportation by road is the most realistic option for the transportation sector. Keywords: H2 Storage; Transportation; Distribution; Economy; Energy *Corresponding Authors: [email protected] and [email protected] *Manuscript Click here to view linked References 2 Table of Contents Table of Contents .............................................................................................................................. 2 1. Introduction ............................................................................................................................... 3 2. H2 Storage Methods .................................................................................................................. 5 2.1 Physical Storage methods ....................................................................................................... 6 2.1.1 Compressed ...................................................................................................................... 7 2.1.2 Liquefied and Cryo-compressed ...................................................................................... 7 2.2. Material Based Storage ................................................................................................... 8 2.2.1. Physisorption................................................................................................................... 9 2.2.2. Chemisorption ............................................................................................................... 10 2.3. H2 Storage Challenges ......................................................................................................... 15 3. H2 Storage, Transportation and Distribution .......................................................................... 17 3.1 Seasonal storage at production and delivery sites ................................................................. 19 3.2 Transport ............................................................................................................................... 21 3.2.1 Road transport ................................................................................................................ 22 3.2.2 Pipeline .......................................................................................................................... 25 3.2.3 Ocean transport .............................................................................................................. 26 3.3 Distribution ........................................................................................................................... 29 4. Conclusion .............................................................................................................................. 30 References ....................................................................................................................................... 33 3 1. Introduction Large-scale energy generation from renewable resources will be required for a transition towards a net zero-carbon footprint society. H2 is known to be a key component to enable the integration of large-scale renewables, and also to become a major energy carrier able to transport and distribute the energy throughout sectors and regions as well as acting as a buffer to improve the resilience of the energy systems. Part I of this series [1] is focused on H2 production methods that will be available for massive and clean productions in the future energy scenario featuring H2 as an energy vector in the residential, industrial, transportation, and commercial sectors [2]. For making the H2 economy commercially viable, H2 should be stored, transported, and distributed for power and/or heat generation on-demand for various applications [3]. A very recent publication highlights outlook on the future prospects and recent research on H2-based Energy Storage through the H2 Technology Collaboration Program of the International Energy Agency [4]. Various studies have been conducted on the integration of renewable energy systems with H2 storage as well; to achieve the net-zero-emission energy systems [5,6] and sustainable development goal [7]. With the H2 utilization technologies (fuel cells) becoming more affordable, energy storage in batteries can be replaced through electrolyzers/H2 storage due to higher efficiency, reliability and performance. Hence, integration of the H2 storage in the H2 value chain along with renewable energy sources such as solar, and wind is the most promising approach [8]. Currently, the cost of the H2 system is higher compared to battery system but the recent research activities on the H2 value chain for various applications are expected to make them competitive by 2030 [5,9]. In Part II of the series, H2 storage, transportation, and distribution are reviewed in detail with a major focus on the technological and commercial point of view towards the H2 4 economy. In addition, the review provides the insight of intercontinental large scale H2 transportation. In fact, H2 could be distributed by blending (up to 15%) it with natural gas and using the existing infrastructure, with required modifications to the online monitoring for ensuring safety. Higher H2 concentrations will require retrofitting or replacement of the existing infrastructure. The economic feasibility of a progressive H2 deployment will become clear only if large-scale H2 production, distribution, and transportation are adopted for various applications [10]. In this context, it is very critical for the energy industries, local and federal agencies, educational institutions and non-profit H2 advocates/organizations to work together in establishing a robust storage and distribution systems for the seamless transition towards the H2 economy. 5 Figure 1. Schematic representation of the H2 storage, transportation, distribution and delivery showing the scope of the Part II of the review. The scope of Part II of the H2 economy review series can be visualized through the schematic representation in Figure 1. Once H2 is produced in either small or large scales, the industrial and transportation applications depend on the storage and transportation/distribution capability. H2 can either be compressed or liquefied and stored for small and medium scale applications or transported through pipelines (or by truck or ship tankers) for large-scale applications. 2. H2 Storage Methods H2 can be stored either in compressed (350 - 700 bar) or liquefied (-253 oC) or solid forms for enhancing the gravimetric density [11]. This section also discusses the advantages and specific 6 issues about the H2 storage options, the constraints related to materials, the important technological gaps, and the priorities and recommendations for further development. Figure 2. Classification of H2 storage methods and materials. As seen in Figure 2, H2 storage methods can be broadly classified into two, such as physical storage and material storage. While the physical storage system is based on the principle of compression and liquefaction, the material storage systems are many and offer a variety of utilization modes based on the service conditions. 2.1 Physical Storage methods Physical methods of H2 storage are based on either compression or liquefaction or the combination of both. 7 2.1.1 Compressed The most common and simple method of H2 storage is in its natural form. Worldwide, the prevalent refueling stations adopt the gaseous storage under high pressure, which finds application in stationary, vehicular and bulk transportation [12]. Storing H2 as high-pressure gas has the advantage of fast filling and high release rate, whereas the large space requirement and safety concerns are the main drawbacks of H2 storage in high-pressure tanks. The compressed form in carbon fiber composite pressure vessels at pressures ranging from 20 to 100 MPa is used when lightweight capacity is needed, and in metal pressure vessels if high capacity is required [13,14]. Underground H2 storage could also be a potential method and is discussed briefly in Section 3.1. 2.1.2 Liquefied and Cryo-compressed Storing liquid H2 achieves higher energy density per unit volume than compressed storage but the energy consumption is higher for liquefaction. Also, loss of H2 due to the boil-off phenomenon in vehicular applications needs to be minimized by insulating the container without any reduction in both the gravimetric and volumetric energy densities [15]. Cryogenic vessels are generally used for storing and transporting H2 for medical as well as industrial applications. Liquefaction of H2 at -253 oC is energy-intensive (40 % of H2 energy) compared to compressed H2 systems (10-15 % of H2 energy) [16]. Storage at -253 oC is achieved by vacuum insulated inner pressure vessel with an external casing. Cryo-compressed storage offers a synergy of both compressed gaseous H2 and liquefied H2 storage systems. While compressed H2 is stored at near-ambient temperatures, "cold" and "cryogenic" compressed H2 storage is carried out at a low temperature for realizing higher H2 densities. With a lower boil-off loss in liquefied H2 storage, storage density 80 g L-1 can be attained [17]. The performance of liquid H2 in terms of weight, volume, and cost are 2.0 kWh·kg- 8 1, 1.6 kWh·L-1, and $6 respectively, while those of various other storage technologies are given in Table 1 [18–22]. Table 1. Performance status of H2 Storage Systems (5.6 kg) and the targets [18–22]. H2 storage systems Gravimetric (kWh kg-1) Volumetric (kWh L-1) Cost ($ kW-1h-1 with 500000 units y-1) Liquified 2.0 1.6 6 700 bar compressed (Type IV) [18,19] 1.4 0.8 15 300 bar compressed (Type IV) 1.8 0.6 13 Cryo compressed (500 bar) [20,21] 2.3 1.4 18 Metal Hydride (NaAlH4/Ti) [22] 0.4 0.4 43 Sorbent (MOF-5, 100 bar, HexCell, LN2 cooling) 1.3 0.7 15 Chemical H2 Storage (AB- liquid) 1.5 1.3 17 2020 Target (DOE, USA) 1.5 1.0 10 2025 Target (DOE, USA) 1.8 1.3 9 Ultimate Target (DOE, USA) 2.2 1.7 8 2.2. Material Based Storage H2 storage through chemical systems is one of the ways in effectively meeting various transportation applications. However, there is no single chemical compound meeting all the required properties. The anticipated storage solutions require a breakthrough in material properties. This can be achieved by innovation in basic research which is essential for technological advancement. The challenges demand commercially viable, higher H2 storage capability, cyclic stability of the chemical systems that can be achieved by various smart nanoscale materials [23]. In order to increase the volumetric H2 storage, solid-state organic hydrides have huge potential through physisorption and chemisorption. Alloy or complex-type materials are also expected to demonstrate high H2 storage capability. Carbonaceous materials are applicable, as they possess large surface areas to adsorb H2, and their performance enhancement can be done by techniques such as Kubas interaction, spillover effect, functionalization, and with 15 limiting factors. Therefore, there is intense need for the development of environmentally benign, cost effective, easy to transport, convenient and reversible hydrogen storage systems. In this regard, Zou et al. reported ethylene glycol based LOHC system with a proven H2 storage capability of 6.5 wt. % and further development is in progress considering various key practical aspects [65]. LOHC could be one of the suitable candidates for terrestrial transportation and aviation industry [66], since it is economically advantageous as the existing infrastructure can also be employed for its transportation and delivery [67]. Currently, the major research and development focuses on the development of organic systems, which can generate H2 at relatively higher pressure at ambient temperature using less expensive catalysts with a reversibility of >97 %. 2.3. H2 Storage Challenges The US-DOE has established the targets for an on-board H2 storage system in terms of gravimetric/volumetric capacity, material cost, operating temperature, desorption temperature, and reusability of H2 storage medium for automotive applications and are shown in Table 4 [68]. A large variety of H2 storage materials such as borohydrides, chemical hydrides, metal hydrides, complex hydrides, zeolites, MOFs, etc. have been investigated for their applicability and efficiency as potential H2 storage materials. The ultimate aim is to develop a lightweight and compact H2 storage medium for meeting the DOE targets. Table 4. Overview of DOE targets towards solid-state H2 storage [68]. Storage parameter By 2020 Ultimate Gravimetric capacity (kg H2 kg-1) 0.055 0.075 Volumetric capacity (kg H2 L-1) 0.040 0.070 16 System cost ($ kg-1 H2) 333 266 Operating temperature (℃) 40 - 60 40 - 60 Delivery temperature (℃) 40 - 85 40 - 85 Cycle life (cycles) 1500 1500 H2 fill time for 5 kg (min) 3 - 5 4 - 5 The technical targets for the onboard H2 storage in the case of light-duty fuel cell vehicles (FCVs) are summarized in Table 5 [69]. Table 5. Technical Targets for onboard H2 Storage for Light-Duty FCV applications [69]. Parameter Unit 2020 2025 Ultimate System capacity (Gravimetric) kWh/kg (kg H2/kg system) 1.5 (0.045) 1.8 (0.055) 2.2 (0.065) System capacity (Volumetric) kWh/L (kg H2/L system) 1.0 (0.030) 1.3 (0.040) 1.7 (0.050) Storage system cost  Fuel cost $/kWh net ($/kg H2) $/gge at pump 10 (333) 4 9 (300) 4 8 (266) 4 Durability/ Operability:  Operating ambient temperature  Min/max delivery temperature  Operational cycle life (1/4 tank to full)  Minimum and Maximum delivery pressure from storage system  Onboard efficiency  “Well” to Powerplant efficiency ℃ ℃ Cycles bar % % -40/60 -40/85 1500 5 and 12 90 60 -40/60 -40/85 1500 5 and 12 90 60 -40/60 -40/85 1500 5 and 12 90 60 Charging/ discharging rates:  System fill time  Minimum full flow rate (e.g., 1.6 g/s target for 80 kW rated fuel cell power)  Average flow rate  Start time to full flow at 20 ℃ and -20 ℃  Transient response at operating temperature 10% - 90% and 90% - 0% (based on full flow rate) min (g/s)/kW (g/s)/kW s s 3-5 0.02 0.004 5 and 15 0.75 3-5 0.02 0.004 5 and 15 0.75 3-5 0.02 0.004 5 and 15 0.75 H2 quality (from storage) % H2 Meet or exceed SAE J2719 17 Dormancy time target (minimum from initial 95% usable capacity) Boil-off loss target (maximum reduction from initial 95% usable capacity after 30 days) Days % 7 10 10 10 14 10 Permeation and leakage, Toxicity, and Safety - Meet or exceed SAE J2579 Recycleability According to End-Of-Life Vehicle Directive 2000/53C The R&D gaps for H2 storage (liquid, solid, and gaseous forms) with respect to the technological status, best options that have to be addressed are given in Table 6. Evidently, the energy required to store H2 is a major challenge in all three modes (gas, liquid and solid), even though commercial systems are available for targeted applications. Table 6. H2 Storage Technology Status, Options and R&D Challenges and Opportunities. Storage Mechanism Status Options R&D Challenges and Opportunities Gaseous H2 Commercially available, not too expensive C-fiber composite vessels (6-10 wt. % H2 at 350-700 bar) Fracture mechanics, safety, compression energy, reduction in volume, codes and standards. Liquid H2 Commercially available, but expensive Cryogenic insulated Dewar (~ 20 wt. % H2 at 1 bar and -253 °C) Energy intensive, dormant boil off, safety, codes and standards. Solid H2 Smaller units available, but exorbitantly expensive Potential options: Rechargeable hydrides, chemical hydrides, carbon, and other high surface area materials. Best option: Metal hydrides (potential for > 8 wt.% H2) Performance enhancement by catalysis, nano scaling, compositing or ionic substitutions and functionalization by heteroatom substitution. Weight, lower desorption temperatures, higher desorption kinetics, unfavorable thermodynamics, recharge /refueling time and pressure, thermal management, pyrophoric, cycle life, container compatibility, optimization, codes and standards. and high cost 3. H2 Storage, Transportation and Distribution 18 H2 production can take place in large and centralized plants from various energy resources [1]. However, transferring the H2 from the production site to the delivery site is challenging, especially when the energy source is in a remote area. Further, H2 production and user demand will vary with time. Therefore, the seasonal storage of H2 in large quantities at production and the closest H2 delivery sites will help to regulate the consumption and production processes. Figure 3. H2 storage and transportation – a logistic flow along with cost targets, for mobility applications [68]. In general, the H2 supply chain includes three main stages: (i) production and bulk/seasonal storage at the production site, (ii) transport, and (iii) bulk storage/seasonal storage at the delivery 19 site and delivery to the end-user. Figure 3 provides the logistic flow of transportation by tank and tube trailers of liquid and compressed H2 to the delivery sites [68,70]. The H2 pressure handled at each stage is different and hence the supporting technologies such as gaseous compressors, pumps, and pressure-reduction stations are required in each stage. Since H2 tends to cause embrittlement of metals (H2-assisted fracture), especially at higher pressures, more attention needs to be paid to the materials' compatibility. H2 has very low ignition energy of around 0.02 mJ to start the combustion reaction with 4-75 vol. % H2 in the air and even lower in the oxygen. Due to a higher diffusion coefficient of H2 in air, 0.61 cm2/s (0.05 cm2/s for gasoline and 0.16 cm2/s for methane), proper safety measurements should be implemented in each stage of the H2 supply chain for ensuring safety. Today, the industry is already handling H2 for many purposes on a large-scale including refineries or ammonia production. However, when it comes to handling H2 at a broader scale, important points to consider are how H2 can be transported efficiently, on time and safely. In addition, optimization models are important for infrastructure development, using the H2 supply and demand, and evolution of the H2 supply chain network in the near term, midterm and long terms [71]. As H2 distribution is new to the energy companies and existing infrastructure, it will be necessary for them to find good solutions for handling large quantities of H2 in order to be competitive in the future energy market. Since the market transformation is one of the main challenges therefore, enormous interdisciplinary opportunities and jobs emerge on the horizon for the associated community towards realizing H2 economy [72]. 3.1 Seasonal storage at production and delivery sites As discussed in earlier sections, H2 could be stored in different states (gaseous, solid, liquid, and dissolved in the organic solvent). Among them, storing H2 in a gaseous form is simplest in terms of infrastructure required and it is also the best-developed method at present [73]. The only 20 equipment required for gaseous H2 storage is a compressor and a pressure vessel [74,75]. For smaller quantities, the H2 gas is compressed (20 MPa) and stored in 50 L cylinders with end domes, similar to those used for any process gases [73]. The cylinders can be stored at environmental temperatures between -50 to 60 °C. Usually, the cylinders are made of steel which is cheap, and they can withstand H2 pressures up to 200 bar, holding 0.9 kg of H2. This type of cylinder is useful in small scale applications where low amounts of H2 are required. For storage of larger amounts, H2 can be compressed at 165 bar and stored in spherical vessels with a capacity of about 2000 m3 holding 29700 kg of H2. This is equivalent to the electrical energy of 989 MWh (41 MW for 24 h) with an energy density of 33.33 kWh·kg-1 H2. The power required for a city with a population of 1M is 1500 MW for countries such as the Nordics, USA, and Australia. Therefore, the equivalent need is around 37 spherical vessels of 2000 m3 capacity, whereas a storage vessel with the same capacity of 2000 m3 can hold up to 142000 kg H2 in liquid form at - 253 °C and 1.013 bar. This is 4.8 times more than for compressed H2 gas at 165 bar. The largest liquid H2 tank is spherical (diameter: 20 m; volume: 3800 m3) for storing ~230000 kg, for space shuttle application in the USA [73]. This tank could provide electrical energy of around 319 MWh. A small percentage of stored liquid H2 will be lost (2-3 % in smaller and ~0.2 % in larger and smaller containers per day, respectively) due to evaporation (boil-off) [73]. Furthermore, there is an increased risk of vessel failure since the materials become brittle at low temperatures. Besides challenges in maintaining the liquid vessels, it is also very costly to install, along with other concerns such as lack of technical manpower for commissioning and maintenance. Consequently, the energy price will be high and not suitable for commercial applications. 21 Another possibility to store H2 in larger volumes at a reduced price is storing underground such as in salt caverns, aquifer, salt domes, and human-made cavities [76]. The optimal seasonal storage pressure in a cavern is generally 175-200 bar, whereas the capacity is in the range of million m3. This is a much more efficient, low-cost, and flexible system than installing many small storage vessels. H2 produced continuously from wind/solar energy can be stored underground in huge quantities. The stored H2 can later be transported whenever there is demand in the market facilitating the demand and supply process continuously. This is safer than working in smaller batches where there is a risk of running out of H2 in the storage. Caglayan et al. [77] estimated the potential of H2 storage in salt caverns for Europe to be 84.8 PWhH2, with Germany having ~40%. Pure H2 gas has been stored in three caverns in Teesside, UK, since 1972 operated by Sabic Petroleum [78]. The volume of each cavern is about 70000 m3 at 24 bar. The possible working gas capacity is 0.83 million kg, which is equivalent to ~ 1.3 GWh. There are also two caverns for storing H2 in the USA at Clemens and Moss bluff with volumes of 580000 and 566000 m3, pressure 70-135 bar, and 55-152 bar operated by Conoco Phillips and Praxair, respectively [78]. These caverns can store 2.56 and 3.72 million kg H2 with the energy equivalent of 3555 and 5166 MWh, respectively. This is enough for powering a city with one million people in the USA. However, storing H2 underground is demographically limited, as it is difficult to find suitable underground storage places near utility sites. 3.2 Transport H2 can be transported in gas, liquid, or metal hydrides form via road, pipeline or ocean. Compressed H2 gas can be transported from site to site in small quantities and short distances [79]. For long distances and a large amount of H2, using pipelines could be a better method. 22 Liquid H2 can largely be transported over long distances via road or ocean, while Low-pressure H2 stored in metal hydrides can only be transported in a small quantity over a short distance. Figure 4. (a) Compressed H2 in Tube-Trailers, (b) Metal hydrides H2 storage, (c) Liquid H2 storage, (d and e) H2 transportation via pipeline, and (f and g) LH2 or LOHC transportation via ocean. 3.2.1 Road transport 3.2.1.1 Truck Trailers that are customized to carry stacked long gas cylinders as shown in Figure 4a are called tube-trailers [70]. The storage pressure range for each cylinder is from 200 to 300 bar and is currently limited to a maximum 250 bar by the Department of Transportation, USA [80]. Trucks hauling these tube-trailers are currently used by industrial gas companies to transport compressed H2 gas over short distances (200-300 km), and a trailer can carry from 2000-6200 m3 H2 [70]. The 23 amount of H2 carried is thus in the range of 180 - 540 kg, depending on the number of tubes. This represents 1-2 % of the total mass of a truck of ~40 tons. Current trailers utilize Type 1 cylinders with ~1 wt. % H2 storage capability due to the heavier steel. Composite materials based vessels can store ~550 kg of H2 at 250 bar, thus up to 720 kg of H2 can be transported per trailer [80]. Metal hydrides based containers can be used for transporting H2 by directly loading onto a truck or railcar (Figure 4b) to the customer/end-user sites, where it can be exchanged with the empty hydride containers [75,81,82]. The advantage of this transportation method is that the existing logistics infrastructure can be used where there is no need for using pressure for transportation and storage. Further, the hydrides require heat to release H2, and the chance of accidental H2 release is therefore minor. Thus, H2 stored in metal hydrides is less hazardous to transport compared to compressed H2 or LH2 transportation. However, the H2 stored in this system has low gravimetric densities (1 to 7 wt. %), and it will, therefore, be very expensive to transport. As described above, the LOHC technology enables H2 storage under ambient conditions and hence high pressure or highly-insulated tanks are not required [83]. In this context, the LOHC can use the currently existing transportation mode for fossil fuels such as road oil tankers, tank trucks, pipelines, rail trucks, tanker ships, etc [84]. However, the storage density of H2 in LOHC is 6 - 8 wt. %, therefore, the net storage capacity is still a major controlling factor. Furthermore, unlike a gasoline tanker, the LOHC trailer has to be returned to the chemical plants for catalytic hydrogenation [84]. 24 3.2.1.2 Liquid H2 tankers Currently, trailers customized to carry a single long cylinder, otherwise called tankers (Figure 4c) are used to transport the LH2. The trucks hauling the tankers with LH2 are referred to as cryogenic tanker trucks or liquid tanker trucks. Liquid tanker trucks operating at atmospheric pressure have volumetric capacities of about 50000 - 60000 L and can transport up to 4000 kg H2 with a truck mass of ~40 tons, which represents ~10 wt. % of the total mass of the truck [70]. The particulars of road H2 delivery are given in Table 7 [85] and shows that LH2 tanker trucks can transport 10 times more H2 in terms of weight capacity than the tube-trailers with compressed H2. This transport mode is thus more economical than transporting H2 in gaseous form. H2 storage capital costs and operating costs are given in Table 8 [85]. Transporting H2 in liquid form requires a liquefaction plant; which is capital-intensive, in addition to the liquefaction process being costly. Furthermore, the liquefaction process, the transport time and the utilization time (end-use or delivery time) must be timely scheduled to avoid excessive H2 boil-off. The H2 evaporation rate depends on the container size/shape/insulation and time of storage and is typically of the order of 0.2 % per day for a 100 m3 container [70]. However, the H2 boil-off may not be an issue if the storage time is not longer than a week or two. Table 7. Road H2 delivery estimations [86]. Cryogenic tanker truck Tube trailer Load (kg) 4000 300 Net delivery (kg) 4000 250 Load/unload (h per trip) 4 2 Boil-off rate (% per day) 0.3 - Truck utilization rate (%) 80 80 Truck/tube ($/module) 450000 100000 Undercarriage ($) 60000 60000 Cab ($) 90000 90000 Table 8. Capital cost ($) and operating cost (energy) for H2 storage. Capital cost ($) Operating Cost (kWh/kg) 31 will take effect. For realizing the H2 economy, mathematical modeling for techno-commercial aspects, technological development of components and systems, advanced manufacturing, large scale adoption of demonstration projects, and energy management with cybersecurity need to be pursued in parallel. Usage and application of H2 based technologies will be reviewed in Part III of the H2 Economy review series in decarbonizing various markets. 32 Acknowledgment AMK would like to thank The J. William Fulbright Foreign Scholarship Board and The Bureau of Educational and Cultural Affairs of the US Department of State for the “Distinguished Chair Award” as well as Aalto University, Espoo, Finland for financial support. 33 References [1] Nazir H, Luis C, Jose S, Prakash J, Muthuswamy N, Buan M, Flox C, Chavan S, Shi X, Kauranen P, Kallio T, Maia G, Tammeveski K, Lymperopoulos N, Carcadea E, Veziroglu E, Iranzo A, Kannan AM. 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