Transportation of Hydrogen: Hydrogen Usage

Abstract

For large-scale hydrogen use for alternative fuel problems, hydrogen transportation must be solved. Hydrogen can be transported as compressed gas, liquid, or bound in carriers. The chapter describes current transportation technologies—gaseous hydrogen via pipelines or special trucks, and liquid hydrogen in cryogenic tanks. The potential of using existing natural gas pipelines is analyzed; the need for modern pipeline material complex research is emphasized. Transportation in solid or liquid carriers, disadvantages and advantages of transportation methods, and problems and ways to solve them are analyzed. Hydrogen facilitates the conversion of low-grade crude oils into high-energy transport fuels by catalytic cracking and desulfurization. Ammonia production, essential for fertilizers and explosives, relies heavily on hydrogen synthesis from nitrogen and hydrogen. Methanol and dimethyl ether fuels offer alternatives to hydrogen storage and transportation, while liquid hydrocarbon fuels from coal and biomass utilize hydrogen in conversion processes like Fischer-Tropsch. Proton exchange membrane and alkaline fuel cells depend on hydrogen for electricity generation in transportation. Additionally, hydrogen serves as a reductant in metallurgy, with advancements in direct iron reduction and green steel initiatives driving sustainable practices in the steel industry. These applications underscore in modern processes and its potential for addressing energy and environmental challenges.

1. Introduction

The environment has suffered from the greenhouse gas emissions (CO₂, NO₂, CH₄, and O₃) that result from burning natural resources (natural gas, coal, and oil), which cause global warming. Moreover, these natural resources will soon run out due to their finite availability in nature. Hence, a new way of producing energy that is clean and sustainable is needed to ensure future energy security, which requires a gradual shift away from natural resources. To address these challenges, various renewable energy sources such as wind, solar, and nuclear have been investigated recently. However, these sources cannot meet the global energy demand due to weather and location limitations. In addition, this energy is not always accessible and requires transportation. Therefore, hydrogen has been the focus of extensive research as an energy carrier. Also, this energy is not always available and needs to be solved in terms of transportation as well as production and storage issues.

Hydrogen is the most plentiful element in the universe; it has high energy efficiency and is eco-friendly [1, 2]. Hydrogen is the energy carrier [2, 3, 4], which means it can store and deliver electrical energy through chemical reactions instead of combustion [5]. It can also be easily implemented in transportation to fuel cars, heat homes, and many other applications [6]. Its byproduct is only water and heat. Hydrogen has a higher energy content per mass (120 MJ/kg) than 44 MJ/kg for gasoline [7, 8]. However, hydrogen needs to be produced in a cost-effective way before it can be used in a practical form for application. Hydrogen is not naturally available in nature. Therefore, it needs to use a primary energy source, such as non-renewable energy sources like fossil fuel and renewable energy sources like solar energy, wind energy, and biomass. Also, hydrogen can be used instead of secondary energy sources like electricity or heat. In addition to the production and storage issues, the hydrogen that is produced must be transported safely for future use. Therefore, various features need to be considered, such as its high flammability limit in the air (4–74%) [9] compared to gasoline vapor (1.4–7.6%) and natural gas (5.3–15%). Also, its high explosion limit in the air (H₂ = 18.3–59%) compared to gasoline vapor (1.1–3.3%) and natural gas (5.7–14%). In addition, its low ignition energy (0.02 MJ) [9] compared to gasoline vapor (0.20 MJ) and natural gas (0.29 MJ) has to be controlled. Finally, its lower boiling point (−253°C) and low density in the liquid state (70.8 g/L) [10] compared to gasoline vapor (37e205°C) with a density of 700 g/L and natural gas −162°C) with a density of 423 g/L, require additional safety measures for hydrogen fuel.

Hydrogen is a versatile and clean energy carrier that can be used for various applications. It is the simplest and most abundant element in the universe, but it is not naturally available in a pure form on Earth. Hydrogen can be stored and transported in different ways, such as in pressurized or cryogenic tanks, pipelines, or blended with natural gas. Hydrogen can also be converted into electricity or heat through fuel cells or combustion or used as a chemical feedstock for many industries. Some of the benefits of hydrogen are that it has a high energy density, it produces no harmful emissions when used, and it can be integrated with renewable energy sources. However, some of the challenges of hydrogen are that it requires high capital costs, it has safety issues due to its flammability and low density, and it has a low efficiency of conversion and storage [11, 12, 13, 14]. Therefore, hydrogen is a promising energy carrier that needs further research and development to overcome its technical and economic barriers. According to the safety guideline, hydrogen can be transported traditionally in gaseous or liquid form in the pressurized or cryogenic tank. Also, finding a suitable means to transport hydrogen is a crucial part of the hydrogen economy. There are various means of hydrogen transport such as pipeline, blending natural gas, and cryogenic liquid tankers. Therefore, this chapter will try to summarize the state of the art of primary hydrogen transportation methods and uses of hydrogen. Also, identify the most promising techniques to improve hydrogen usage and transportation developments.

2. Transportation of hydrogen

Determining an effective mode of hydrogen transportation is a crucial step for implementing hydrogen fuel across diverse industrial applications. The transportation of hydrogen requires a thorough understanding of its properties to prevent potential explosion and leakage incidents. Given that hydrogen can exist in different states based on temperature and pressure, the transportation methods vary.

At low temperatures, hydrogen assumes a solid state with a density of 70.6 kg/m³ at −262°C, while at higher temperatures, it transforms into a gas with a density of 0.089 kg/m³ at 0°C and 1 bar. In the region highlighted in blue in Figure 1, between the triple point (13.8 K) and the critical point (33 K), hydrogen exists in a liquid state with a density of 70.8 kg/m³ [15]. At standard temperature (25°C) and 1-atm pressure, hydrogen is a gas, and its low critical temperature (T_c = 33 K) is attributed to the strong repulsion interaction between H₂ molecules. Consequently, storing and transporting H₂ necessitate addressing the challenge of the large volume occupied by hydrogen gas. For instance, 1 kg of H₂ at standard temperature and atmospheric pressure fills a volume of 11 m³. While the Joule-Thompson effect causes a pressure reduction in natural gas leading to a temperature drop of 0.5°C, hydrogen experiences an increase in temperature of 0.35°C for each rise in bar pressure. Therefore, the development of a hydrogen transportation system requires careful consideration of various conditions to ensure safety during transportation. Various methods for hydrogen transportation have been proposed, with the most common ones being compressed gas cylinders, cryogenic liquid tankers, pipelines, and blending with natural gas.

Figure 1.

Various states of hydrogen under different temperature and pressure conditions [15].

Transporting hydrogen to its intended destination poses challenges due to its status as the least dense gas and its flammability when combined with even small amounts of air. The low volumetric energy density of hydrogen makes its transportation, storage, and eventual delivery to the point of use potentially costly. Safety concerns also arise in this process. Currently, hydrogen is predominantly conveyed from its production site to the utilization site either through pipelines or over the road, utilizing liquid tanker trucks or gaseous tube trailers and special carriers.

2.1 Pipelines

It is worth noting that throughout the operational history of hydrogen pipeline systems in North America and Europe, no issues related to hydrogen embrittlement or safety have been reported [16]. However, the considerable capital investments required for pipeline construction make this method the most costly and feasible only for consistent and significant hydrogen consumption scenarios, where the pipeline construction expenses can be recouped within an acceptable timeframe.

The recommended pressure for the primary transportation of hydrogen, considering its physicochemical properties, is in the range of 7–14 MPa [17]. For instance, in the USA, hydrogen pipelines operate within the range of 3.5–10 MPa [18]. Distribution networks, with smaller pipe diameters, operate under lower pressure conditions (in the USA, p = 0.03 to 1.4 MPa [18]). However, gas stations and power plants require higher inlet pressures, suggesting that the pressure in distribution networks should be higher than in natural gas distribution lines, falling within the range of 1.4–2.8 MPa [18].

In low-pressure pipelines (0.1 MPa and below), the gas speed is 10 m/s, while in main pipelines (6 to 8 MPa), it is twice as high [17, 19]. With identical pipe diameters and pressure drop, the flow rate of hydrogen is nearly three times higher than that of methane. The specific cost of hydrogen transportation decreases with an increase in distance. For example, when the distance increases from 8 to 100 km, the cost decreases by an order of magnitude.

The construction costs for new hydrogen gas pipelines are relatively high, with labor and material expenses constituting around 70% of the total construction costs. Consequently, current priorities include developing new metallic, non-metallic, and composite materials, along with advancing technologies for applying thin barrier coatings to pipe surfaces.

The internal coating is designed to diminish the surface concentration of hydrogen on steel. Research on hydrogen diffusion in a multilayer pipe, featuring an internal coating based on reinforced polyamide, and external coatings made of polyurethane, has indicated that existing polymer and fiberglass materials may not extend the service life of pipelines by more than 10 years.

Reinforced plastic pipelines present a promising alternative to steel pipelines in terms of technical characteristics and cost. Typically, they consist of (1) an internal impermeable barrier pipe or liner, (2) a protective coating, (3) an intermediate coating, (4) composite layers made of glass or carbon fibers, (5) an external barrier layer, and (6) a protective coating (Figure 2). These pipes exhibit high compressive strength, can endure longitudinal deformations, facilitating their transport, and can be wound on large diameter reels (Figure 3). The multilayer design can incorporate sensors for real-time condition monitoring.

Figure 2.

Diagram of a multilayer plastic pipe (a) Fiberspar LinePipe, LLC and the fiber winding stage (b) [20].

Figure 3.

Fiberspar LinePipe [21].

Polymer materials like polyethylene, polyamide, and polyvinylidene difluoride can be used for liners, and the hydrogen permeability of these materials determines the potential hydrogen leakage from the pipeline. Although most tests are conducted on films, the results may not universally apply to actual liners. Comparisons of permeability measurements for high-density polyethylene samples used in pipes and liners with published data for films indicate that the hydrogen losses from such pipelines are expected to be minimal—less than 0.1% of the transmitted volume [20]. The total capital investment for a polyethylene pipeline of this nature is approximately equivalent to that of a pipeline made of 16-inch steel pipes [22].

The pipeline system serves as a transportation network for natural gas or oil, connected by compressor stations, city gate stations, and storage facilities. Particularly suitable for large power plants (around 1000 metric tons/day), pipelines offer a cost-effective option [23]. Compressor stations utilize the heat from the transmission system to maintain consistent gas flow rates and pressures, meeting the specified requirements. The pipeline network encompasses both onshore and offshore components, covering transmission, transportation, and distribution pipelines. Utilizing pipelines for hydrogen transport is viewed as the most efficient means for extensive delivery and utilization as an energy carrier, presenting various advantages.

Hydrogen transportation through pipelines proves to be the most cost-effective for large-scale power plants, with a savings of $2.73 per kg of hydrogen transport [24]. Additionally, large-scale pipeline transport is considered the most environmentally friendly method of hydrogen delivery [24]. The pipeline’s longevity, spanning several decades, contributes to its reputation for safety and reliability, given that most pipelines are buried underground. This minimizes the likelihood of accidents due to leakage, explosions, or environmental interference, avoiding disruptions and traffic on roads. Despite the significant initial capital investment for pipeline installation, subsequent maintenance and operation costs are comparatively low. Moreover, existing pipelines can transport pure hydrogen, and new pipelines for hydrogen delivery can be manufactured using low carbon steel.

However, challenges persist in establishing a hydrogen pipeline infrastructure. Hydrogen gas in a pipeline may experience losses compared to other fuels, and the need for compressing hydrogen to high pressures (around 10–20 bars) to enhance delivery speed poses a logistical hurdle due to its low density (1/8th of natural gas). The porosity of polymer materials used in gas pipelines makes them unsuitable for delivering pressurized hydrogen, as hydrogen’s efficient escape, given its small size, poses safety risks. Furthermore, the embrittlement of pipeline steels and construction materials, leading to degradation and cracking, poses a risk of pipeline failure, dependent on material and operating conditions [25]. To address these issues, an alternative approach involving blending hydrogen with natural gas is proposed to mitigate risks and ensure a more secure distribution and delivery of hydrogen.

The first main hydrogen pipeline was put into operation in 1938 in Germany. This pipeline has been in operation for more than half a century without any accidents [19]. As of March 2023, Germany possessed the most extensive planned hydrogen transmission pipeline network in Europe, spanning a total of 3827 km [26]. Based on available information, the construction of hydrogen pipelines is gaining momentum, propelled by the increase in green hydrogen initiatives in China. A collective 1000 km of hydrogen pipelines are currently in the construction phase. This includes the development of two long-distance pipelines along with several shorter-distance pipelines [27].

Like natural gas currently, gaseous hydrogen has the capability to be transported through pipelines. The SoutH2 Corridor is a project that aims to connect to a “European Hydrogen Backbone” that will help Europe to achieve its green energy goals. The Backbone plan expects Europe to have 11,600 km of hydrogen pipelines by 2030 and almost 40,000 km by 2040 (Figure 4) [28].

Figure 4.

Map of Europe’s hydrogen pipeline plan until 2040 [28].

China is currently constructing all of Asia’s hydrogen pipelines, with three lines in the pipeline—Ulanqab Beijing, Shandong Hydrogen, and Ningxia Hui Autonomous Region Hydrogen. Additionally, there are plans for a hydrogen pipeline in the proposed India-Middle East-Europe Economic Corridor, targeting exports to the EU.

Over the past year, the Middle East has significantly increased its planned clean hydrogen capacity, the region has 83 low carbon or renewable hydrogen/ammonia projects with combined production of nine million metric tons hydrogen per year, S&P Global Commodity Insights’ data show, and aims to become a key exporter to other countries by 2030. Saudi Arabia aims to be the leading global hydrogen supplier, while the UAE and Qatar are actively enhancing their capacities to meet the growing global demand [28].

In North America, both the United States and Canada are considering the implementation of hydrogen pipelines. The U.S. currently possesses 2600 km of hydrogen pipelines, and its HyBlend initiative is investigating methods to repurpose existing natural gas pipelines for hydrogen transportation. These pipelines are in places where there are a lot of hydrogen users, such as oil refineries and chemical factories, especially in the Gulf Coast area.

Canada’s hydrogen initiatives involve a project in Quebec, anticipated to contribute to a 3% reduction in the province’s carbon emissions over the current decade.

Latin America’s significant potential for renewable energy positions it as a prominent provider of cost-effective, environmentally friendly hydrogen, according to the International Energy Agency (IEA). In the region, a total of 11 countries have devised strategies for hydrogen.

Chile aims to achieve the production of the world’s most economical hydrogen by 2030 and strives to be among the top three hydrogen exporters by 2040. Similar to the United States and numerous other nations, Chile is exploring the possibilities of utilizing its natural gas pipelines for the safe transportation of hydrogen or for blending hydrogen with natural gas [28].

The World Economic Forum’s Industrial Clusters initiative is establishing global hubs for hydrogen-related activities, fostering collaboration among stakeholders throughout the entire hydrogen value chain and uniting them around shared objectives. This initiative facilitates cluster members in accessing hydrogen from various producers, providing suppliers with a readily available pool of potential customers.

2.2 Compressed gas containers

Hydrogen gas is usually transported in cylindrical steel containers under pressure up to 20 MPa [19]. Such containers are delivered to the place of hydrogen consumption on automobile or railway platforms. Canadian company FIBA Canning Inc. offers various trailers with cylinders that can transport approximately 100 to 700 kg of hydrogen at pressures of 16–24 MPa (Figure 5) [29]. The cost of transporting compressed hydrogen by truck is quite high—slightly less than by pipeline, due to the low density of hydrogen.

Figure 5.

Transportation of compressed hydrogen gas [29].

Trailers for transporting hydrogen under pressure are effective in meeting the needs of small consumers, and the high cost of delivery can be offset by the absence of losses [30]. Currently, delivering hydrogen gas by trailer is the easiest way, especially in areas where there are no pipelines [30]. It is also convenient for delivery to fueling stations, where hydrogen trailers remain on site, without the need for permanent hydrogen gas storage infrastructure.

Recently, some researchers are also considering the option of delivering “cold gas” by trucks (trailers). For example, it is proposed to transport hydrogen gas at 35 MPa and 90 K in composite container pipes on trailers [31]. This will increase capacity and at the same time reduce liquefaction costs. The method is promising for delivering hydrogen to gas stations.

Depending on the required quantity, truck transportation is a feasible method for moving gaseous hydrogen in moderate amounts using compressed gas containers, such as cylinders or tubes pressurized within the range of 200–500 bar. In assessing the viability of hydrogen transportation by truck, factors such as transport capacity, tank weight, greenhouse gas emissions, and non-renewable energy consumption need careful consideration. For larger quantities, multiple pressurized gas cylinders or tubes are typically mounted on specialized trailers known as compressed gas hydrogen tube trailers, securely enclosed within protective frames for safety. The maximum transportable hydrogen load depends on the high weight of these cylinders or tubes. For example, a tube trailer equipped with steel cylinders can store up to 25,000 liters of hydrogen compressed to 200 bar, equivalent to 420 kg of H₂ [29].

To enhance the transported hydrogen quantity, lighter tank materials, such as composite materials for gas cylinders or tubes, are designed to handle higher pressures, allowing for the transportation of larger quantities of hydrogen per trailer. The cost-effectiveness of transporting hydrogen with tube trailers without liquefaction is evident, with a savings of $2.86 per kg delivered H₂ in small-scale power plants [30]. For instance, superlight cylinder materials made of carbon fiber composite with high-density polyethylene liners can accommodate up to 39,600 liters of hydrogen. These containers, pressurized to a maximum of 200 bar, can carry about 666 kg of H₂ [31].

In the case of transporting liquid organic hydrogen carriers (LOHC), trucks wait during the unloading and loading process, requiring only one trailer per truck. However, storage tanks are necessary at the hydrogenation and dehydrogenation sites for the liquid organic hydrogen carriers. Additionally, the LOHC delivery chain is reported to significantly enhance the economics of long-distance road transport [31].

2.3 Cryogenic liquid tankers

Various alternatives, including the transport of liquid hydrogen, have been suggested to address the challenges associated with compressed gas containers. Hydrogen, in liquid form, can be conveyed using trucks or other transportation modes. In contrast to compressed gas container, a liquid hydrogen trailer has the advantage of carrying more hydrogen due to the higher density of liquid hydrogen compared to hydrogen in a gaseous state. However, before storage in large insulated tanks at the liquefaction plant, gaseous hydrogen undergoes liquefaction by cooling it below −253°C through a process known as the liquefaction process [32]. The truck responsible for transporting liquid hydrogen is referred to as a liquid tanker. The effectiveness of thermal insulation significantly impacts the tank’s operational parameters and operating costs [33].

Nevertheless, the road shipment of liquid hydrogen and its dispensing at a vehicle filling site add costs ranging from $2.42 to $1.40 per kg of H₂ to the production costs. Additionally, approximately 40% of energy is lost during the liquefaction process [34]. Furthermore, there is a loss of stored hydrogen through evaporation or boil-off of liquefied hydrogen, which is more pronounced when using a small tank with large surface-to-volume ratios. Lowering the liquefaction cost for hydrogen can have a positive impact on its shipment cost via truck, ship, or rail, and can also be advantageous for storage at plant sites to prevent plant shutdowns. This approach holds promise for near-term investments, particularly as the shipment plan can be a potential investment in the early stages of fuel cell vehicle introduction. The hydrogen boil-off point is a critical consideration during its delivery [35].

The creation of cryogenic complexes for hydrogen liquefaction, its long-term storage and transportation by railways and highways began in the 1960s of the last century in connection with the use of liquid hydrogen as fuel for rocket and space systems [36].

Hydrogen liquefaction is a very energy-intensive process and, therefore, expensive, but transportation costs for liquid hydrogen are minimal. The technology of hydrogen transportation by road, including safety measures, has been sufficiently developed. In the USSR, tank trucks TRZHV-20 (capacity 20 m³) and TRZHV-24 (24 m³) were created to transport liquid hydrogen over long distances [17]. Currently, JSC “Cryogenmash” produces custom-made tank cars with a capacity of 25 and 45 m³ for the transportation of liquid hydrogen (Figure 6) [36, 37].

Figure 6.

Automobile tank of JSC “Cryogenmash” for liquid hydrogen transportation [37].

The tank is equipped with sophisticated systems for refueling and dispensing liquid hydrogen that meet Russian and European safety requirements and include a set of safety valves, rupture membranes, purge lines with pure nitrogen gas or vacuuming before refueling with hydrogen. In addition, the tank is equipped with effective wave dampers.

When transporting liquid hydrogen in tank trucks, losses caused by continuous evaporation of hydrogen and due to the performance of technological operations are inevitable. During one-time cooling of a tanker truck, up to 15% of hydrogen is lost from the volume of the tank, and cooling is carried out at least two times a year. Losses due to imperfections in the vacuum thermal insulation of the tank are 0.5%/day from its volume. Taking into account the fact that not all hydrogen is taken from the tank (a certain amount of liquid hydrogen remains for cooling), then for a tank with a capacity of 4.5 tons, the losses are about 8.2 tons/year.

At each refueling of the tanker, there are losses associated with the evaporation of the first portion of hydrogen. According to estimates, this is ~4%, that is, with a weight of 4.5 tons, they amount to ~180 kg. The losses for creating a pressure drop between the liquefaction plant and the capacity are approximately 1.5% [17].

Tanks for liquid hydrogen are made either cylindrical or spherical. Large containers are usually made spherical to reduce evaporation losses.

Liquid hydrogen is transported by tankers to a distance of more than 1.6 thousand km.

BMW specialists have created several prototype models of cars powered by liquid hydrogen fuel stored in special cylinders, in which the loss of hydrogen mass by evaporation is reduced to 1.5%/day [38]. BMW considers liquefied petroleum gas to be the most convenient type of fuel for promising cars.

Railway transport for the transportation of liquid hydrogen is used rather sparsely. In refrigerated railway tanks, hydrogen losses are about the same as in tank trucks. At present, JSC Cryogenmash offers customers high-speed hydrogen tanks with a capacity of 100 m³. The tanks are equipped with a reinforcement cabinet and devices that ensure the safety of transportation [37].

Kawasaki Heavy Industries in Japan has developed a ship capable of holding 160,000 m³ of liquefied hydrogen, equal to 11,200 tons, making it similar in size to a typical liquefied natural gas (LNG) carrier. This vessel would be 128 times larger than the tank on Kawasaki’s Suiso Frontier, which transported the world’s first liquefied hydrogen cargo from Australia to Japan in February.

Prior to this, only within the framework of the NASA space program, liquid hydrogen for refueling launch vehicles was transported on a special barge at a distance of about 100 km. However, the USA, Japan, South Korea and other countries have extensive experience in transporting liquefied natural gas in tankers. This experience will certainly be used in the creation of marine tankers for the transportation of liquid hydrogen.

2.4 Blending with natural gas

The incorporation of hydrogen into a natural gas pipeline network is considered a method for delivering pure hydrogen to the market. To extract hydrogen from natural gas closer to the end-use point, various separation and purification technologies have been employed. Three techniques—pressure swing adsorption (PSA), membrane separation, and electrochemical hydrogen separation—can be utilized to extract hydrogen from hydrogen-natural gas blends. It is noted that blends containing less than 5–15% hydrogen (volume) typically pose minor issues, dependent on site-specific pipeline conditions and natural gas compositions. However, blending in the range of 15–50% hydrogen requires more substantial modifications, such as converting large household appliances or enhancing compression capacity along the distribution path for industrial users [39].

When transporting natural gas, approximately 0.3% of the pumped natural gas volume is consumed at compressor stations every 100–120 km to facilitate movement. To estimate energy costs for transporting hydrogen and natural gas through the same pipeline, accounting for the viscosities of hydrogen and methane at equal energy flows, let us analyze the power required for pumping N (W).

$$\text{N}={\text{V}}_{\text{o}}\Delta \text{p}=\frac{\pi }{4}{D}^{2}v\Delta p=\frac{\pi }{4}{D}^{2}v\frac{1}{2}\rho v^2\xi$$E1

where V_o – volumetric flow, m³/s; Δp – pressure drop, Pa; D – pipeline diameter, m; v – gas speed, m/s; $\rho$ – gas density, kg/m³; $\xi$ – resistance coefficient; Re = $\rho$vD/μ – Reynolds number; n = 0.25 – for turbulent gas flow in the pipe; μ – dynamic viscosity, Pa•s.

Energy flow through the pipeline (J/kg)

$$\text{Q}={\text{V}}_{\text{o}}\rho {\text{H}}_{\text{v}}$$E2

where H_V is the highest calorific value of the transported gas.

From Eqs. (1), (2) we obtain the ratio of power (energy consumption) required for pumping hydrogen and methane Eq. (3):

$$\left(\frac{N_{H_2}}{N_{C{H}_4}}\right)={\left(\frac{N_{H_2}}{N_{C{H}_4}}\right)}^n{\left(\frac{{\rho }_{C{H}_4}}{{\rho }_{H_2}}\right)}^2{\left(\frac{H_{\text{v}}{}_{C{H}_4}}{H_{\text{v}}{}_{H_2}}\right)}^{3-n}$$E3

Due to the low density of hydrogen, the flow rate needs to be increased by about three times. While the increase in flow resistance is partially offset by viscosity differences, transmitting an equivalent amount of energy in the form of hydrogen through a pipeline demands approximately 4.6 times more energy than natural gas (Figure 7) [40]. During transportation, only 70–80% of the original hydrogen will be transferred over distances ranging from 2.5 to 4 thousand km.

Figure 7.

Dependence of gas consumption for pumping on distance.

Li et al. [41] conducted a numerical investigation on the Joule-Thompson (J-T) coefficient of natural gas at different hydrogen blending ratios, demonstrating a roughly linear decrease in the J-T coefficient of the natural gas-hydrogen mixture with increasing hydrogen blending ratio. Their findings also indicated a 40–50% reduction in the J-T coefficient when the hydrogen blending ratio reached 30% (mole fraction) compared to that of natural gas. Zhou et al. [42] reported on the hydrogen-blended gas-electricity integrated energy system, emphasizing the superiority of hydrogen blending in the upper line of the natural gas network over the lower line. They found that a concentrated hydrogen blending strategy is more effective than a dispersed one. Wu et al. [43] summarized recent research on the hydrogen-induced failure of high-strength pipeline steels in hydrogen-blended natural gas transmission. Zhang et al. [44] established a mathematical model for Hydrogen-Blended Natural Gas (HBNG) transportation, exploring the influences of hydrogen blending on hydraulic and thermal characteristics of natural gas pipelines and networks. Their results indicated that hydrogen blending could reduce pipeline friction resistance and increase volume flow rate. Additionally, they observed performance degradation of centrifugal compressors with increasing hydrogen blending ratio, leading to a shift in the operating point toward higher volume flow rates and lower pressure [44]. According to the European Naturally project [39], introducing hydrogen into the natural gas network holds potential advantage.

Utilizing the existing network of natural gas pipelines for hydrogen transport is a crucial aspect of the future hydrogen economy. Presently, the Unified Gas Supply System (UGSS) of JSC NC “QazaqGaz” possesses a significantly greater energy transmission capacity than power transmission networks and is fundamentally prepared to receive hydrogen and its mixtures with other flammable gases. The UGSS, the world’s largest gas transportation system, is a unique technological complex encompassing gas production, processing, transportation, storage, and distribution facilities. It ensures a continuous gas supply cycle from the well to the end consumer. The group of companies of JSC “NC “QazaqGaz” operates gas pipelines with a total length of about 76 thousand km. Including 20 thousand km of main gas pipelines with an annual capacity of up to 267.8 billionm³ and gas distribution networks with a length of about 56 thousand km, transportation gas is provided by 42 compressor stations and 238 gas injection units [45]. Consequently, most conditions necessary for hydrogen transportation have already been established. However, the UGSS is currently fully loaded, and the use of the existing gas pipeline network seems feasible only during the transition period to the hydrogen economy. To use a mixture of hydrogen and natural gas, creating cost-effective and efficient technologies for gas separation and hydrogen purification will be essential.

Experimental studies investigating the possibility of transporting hydrogen using steel pipelines designed for natural gas [41] revealed that hydrogen losses from the system are 3–3.5 times greater than the volume of natural gas losses. However, given that the heat of combustion of hydrogen is approximately three times greater, the energy losses are roughly equivalent. Notably, during the 6-month experiment, there were no instances of self-ignition due to hydrogen leakage through fittings, and the materials of the pipelines and seals remained unchanged.

Nevertheless, the potential hydrogen embrittlement of steel structures remains a focal point of concern [15, 30, 46]. The current natural gas infrastructure may not be suitable for transporting and distributing hydrogen due to the utilization of insufficient quality metals in these systems. To draw definitive conclusions about the suitability of existing gas transmission systems for pumping hydrogen, comprehensive research and development are necessary to study the materials of modern gas pipelines. This research is crucial, especially considering that energy transmission through a gas pipeline in the form of hydrogen over distances of 2–3 thousand km is 2–4 times more economical than energy transmission through power lines. Additionally, pumping hydrogen through pipeline transport offers the advantage of accumulating and storing hydrogen in underground and above-ground facilities under pressure, delivering it to consumers at the required time and quantity.

Despite the numerous advantages of blending hydrogen with natural gas, higher blend levels pose considerable challenges in terms of pipeline materials, safety considerations, and modifications required for end-use applications. Evaluating the substantial costs associated with accommodating elevated hydrogen blends in a specific pipeline system is crucial, and these expenses must be carefully weighed against the benefits of incorporating hydrogen as a component in natural gas blends. Beyond a 50% blend level, more complex issues arise in multiple aspects, including pipeline materials, safety concerns, and the adjustments needed for end-use appliances or other applications [25].

Despite the promising results offered by hydrogen transportation, significant efforts are required to address various safety issues, such as material embrittlement and container leakage. Challenges include its wide flammability range and the minimal energy needed for ignition. These safety concerns present potential barriers that must be effectively addressed to fully open up the hydrogen market.

2.5 By carriers

Physical transportation of hydrogen is usually done in various high-pressure and cryogenic tanks made of different types of materials, which should not interact with the hydrogen or perform any other reactions. We mentioned above that the traditional transportation techniques for hydrogen are high-pressure gas cylinders and liquid hydrogen that belong to the category of physical transportation. There is a possibility of material-based hydrogen transportation consisting of chemical and physical carriers. Using these types of transportation methods, the existing infrastructure would avoid many problems associated with the delivery of hydrogen in gaseous or liquid forms and reduce costs. In chemical carriers, hydrogen molecules are split into atoms and integrated with the chemical structure of the material. Among all, metal hydrides (for example, LiAlH4) are the most famous group of materials that can be used for chemical carriers [47]. Metal hydride carriers have the ability to absorb and desorb hydrogen at either room temperature or through heating of the tank. The main challenges of chemical carriers’ materials are the cost, weight, and operating temperature, enhancing the charge-discharge rate and controlling the formation of unwanted gases during decomposition. Metal hydride carriers are also called “rechargeable” carriers; which are transported to a fuel station, where hydrogen is extracted from them, and then returned for a new refueling. Such carriers include, for example, metal hydrides. When using metal hydrides as carriers, it is advisable to use the same hydrides in the giving and receiving water system, then the heat released by the receiving system can be used to separate the water from the delivery system. A promising chemical carriers alternative is also LOHCs such as N-ethyl carbazole, methanol, dibenzyltoluene, toluene, and others, where the hydrogen is bonded chemically with hydrogen-lean molecules and is released through a catalytic dehydrogenation (Re. (4)) [48].

$${\text{C}}_{10}{\text{H}}_{18}\rightleftarrows {\text{C}}_{10}{\text{H}}_8+{\text{5H}}_2$$E4

These transportation options are attractive due to their easy manageability under ambient conditions, the transport and release processes do not emit CO₂, and the carrier liquid is not consumed and can be used repeatedly. These carriers are non-toxic and non-corrosive but have a low storage capacity which can limit their applications [49].

Alongside organic hydrogen carriers, ammonia is a compound where hydrogen is similarly bonded with a lean hydrogen molecule and released through dehydrogenation. Typically, hydrogen can be accumulated in ammonia through the conventional Haber-Bosch ammonia production process, which is responsible for around 85% of total worldwide ammonia production. The produced ammonia can then be transported through pipelines, tank cars, and tanker vessels. Thus, at normal temperature, ammonia liquefies at a pressure of 1.0 MPa and it can be transported through pipes and stored in liquid form (ammonia liquefaction temperature −239.76 K, critical temperature 405 K). After shipment, the hydrogen is released from ammonia through the catalytic decomposition process at a temperature of 527–627 K and atmospheric pressure (Re. (5)), which is a highly energy-intensive process. Therefore, efforts are necessary to improve their energy efficiency, reliability, and scalability [50].

$$N{H}_3=1/2{\text{N}}_2+3/2{\text{H}}_2$$E5

To produce 1 kg of hydrogen, 5.65 kg of ammonia is required.

Another approach to material-based transportation involves using porous materials as physical carriers. The most promising options include Metal-Organic Frameworks (MOFs) and porous carbon materials, such as carbon nanotubes. This technique offers advantages such as a large surface area, low binding energy for hydrogen, quicker charging and discharging rates, and cost-effectiveness. However, challenges persist, including the weight of the carrier materials, the need for low temperatures and high pressures, and limitations in both gravimetric and volumetric hydrogen density. Despite these challenges, both methods could enhance safety during transportation by allowing for lower accumulation pressures and manageable properties. Nonetheless, they may not be suitable for high-demand scenarios and are typically transported via roads.

It appears that various methods of transporting hydrogen will be employed during its development as an energy source, with different degrees of utilization. These methods may be combined and utilized at different stages of market development, depending on how hydrogen is produced.

During the initial phase of transitioning to a hydrogen economy, trailers equipped with specialized containers under pressure could be utilized since the demand for hydrogen would likely be relatively low, and this approach minimizes hydrogen loss during transportation.

The advantages and disadvantages of the main methods of transporting hydrogen are reduced to Table 1. Using cryogenic tankers for hydrogen delivery proves to be the most cost-effective for the average consumer, especially when transporting larger quantities of hydrogen compared to trailers with pressure containers, and it enables delivery to all geographical regions.

Transportation method	Advantages	Disadvantages
Hydrogen gas
Pipeline transport	Highest cost-effectiveness for large volumes of hydrogen No thermodynamic limitations to reduce transportation costs Low power consumption Transportation safety Environmentally friendly Use of existing pipelines systems for natural gas and oil Accumulation and storage in underground gas storage facilities under pressure and supply through gas pipelines to consumers at the right time in the right quantity	Large investments in the construction of special pipelines Very high transportation costs for small volumes Complex and expensive procedure for obtaining permits for land acquisition, construction, etc. The need for comprehensive R&D to study the hydrogen resistance of existing pipe steels, the features of underground gas storage facilities, the creation of new materials, fittings, compressors, etc.
Container transportation	No hydrogen loss No need to create storage infrastructure at the point of consumption	Suitable only for small consumers High cost of transportation
Liquid hydrogen
Cryogenic tanks	High energy density and small volume Relative cheapness and efficiency of cryogenic tanks Minimizing the need for compression at points of consumption	High power consumption and high cost Impossibility of reducing cost when long-term use Difficulty in handling cryogenic liquids
Bound hydrogen
Carriers	Minimum cost of transportation in the future Use of existing infrastructure Moderate pressures and temperatures in the system delivery Possibility of reducing storage costs	Difficult to use on site due to the need for transformation for unloading Increased energy consumption Possibility of impurities entering hydrogen gas Availability of idle range of the carrier for recharging The need to conduct comprehensive R&D, including ensuring safety and impact on the environment

Table 1.

Main methods of transporting hydrogen.

Pipeline systems are best suited for transporting hydrogen to areas with high demand, especially as more production facilities connect to the network. Economic considerations will always influence the preferred method of delivery. For instance, establishing gas distribution lines in urban areas may pose challenges. A typical delivery scenario might involve transmitting hydrogen via a pipeline from a central plant to a terminal, from which further delivery could occur via trailers, cryogenic tanks, or cargo transport vehicles.

When selecting hydrogen transportation methods, safety considerations must be taken into account. Significant risks include potential disruptions to power supplies for large populations due to technogenic disasters, systemic accidents, or deliberate acts such as terrorism. Therefore, employing cutting-edge technologies, such as durable pipeline materials and remote-controlled sensors, for constructing new underground pipelines is particularly pertinent. This approach would necessitate implementing pipeline patrol programs (potentially different from those for natural gas), safety regulations for excavation, and other measures. Transporting hydrogen through underground pipelines is preferable in terms of ensuring the safety of the population, especially in the face of potential terrorist threats.

3. Hydrogen usage

Hydrogen, the most abundant and simplest element in the universe, is primarily found on Earth in compounds form with other elements. For instance, it combines with oxygen to create water (H₂O) and with carbon to form hydrocarbons, which are present in fossil fuels and various other resources. Although hydrogen has been utilized in chemical and industrial applications for over a century, recent investments by both markets and governments in hydrogen as an energy source have sparked increased interest in hydrogen production. When hydrogen is combusted, it mainly emits water vapor, making it a crucial component in efforts to reduce greenhouse gas emissions. Additionally, hydrogen is seen as a key solution for storing energy generated from conventional sources such as renewable energy, natural gas, and nuclear power. The International Energy Agency’s (IEF) 2023 Global Hydrogen Outlook (GBO – 2023) reported that the Global hydrogen use reached 95 Mt. in 2022, and which is nearly 3% increased from their revised estimate for 2021 [51]. Hydrogen use has grown mainly in all countries except Europe. The only reason for the decline in the use of hydrogen in Europe was attributed to the Russian invasion of Ukraine because as a result of the war, European chemical plants reduced production volumes, which led to a 6% reduction in the use of hydrogen in Europe. However, there was a strong growth of 7% in North America and the Middle East. China remains the world’s largest consumer of hydrogen with a 0.5% increase in hydrogen use (Figure 8). Areas of wide hydrogen uses are briefly as follows:

Figure 8.

Usages of hydrogen across various sectors and regions, both historically and within the context of the net zero emissions by 2050 scenario, 2020–2030 [51].

3.1 Oil refining

Hydrogen plays a crucial role in the refining of petroleum, aiding in the desulfurization and catalytic cracking of long-chain hydrocarbons. Approximately one-quarter of global production is dedicated to converting low-grade crude oils (particularly from tar sands) into high-energy transport fuels like gasoline and diesel. The process involves converting heavy aromatic feedstock into lighter alkane hydrocarbon products under intense pressures (7000–14,000 kPa) and high temperatures (400–800°C), using hydrogen and specialized catalysts [52]. Moreover, hydrogen is essential for eliminating impurities such as sulfur from these fuels. In 2022, the use of hydrogen in oil refining exceeded 41 million metric tons, surpassing the previous peak in 2018. The most significant rise in year-over-year demand originated from North America and the Middle East, collectively representing over 1 million metric tons, or approximately 75% of global growth in 2022 [51].

3.2 Production of ammonia

The production of ammonia through the synthesis of hydrogen and nitrogen, accounting for approximately 180 million metric tons per year or 1 petawatt-hour, constitutes more than half of the global demand for pure hydrogen. Of the 53 Mt. of hydrogen used in industry in 2022, about 60% was for ammonia production [53]. This process relies on the Haber-Bosch method (Re. (6)). Primarily, ammonia is utilized for agricultural fertilizers, with a portion being employed, in the form of ammonium nitrate combined with diesel fuel, for mining explosives. Additionally, it can be utilized as a transportation fuel or subjected to cracking to yield hydrogen for fuel purposes. The Haber process uses 3–5% of the world’s natural gas to produce the hydrogen, and the nitrogen is extracted from the air by cooling it [54]. Looking ahead, ammonia could play a significant role in hydrogen storage and transportation, as discussed in upper sections. It also holds potential as a fuel source. In Japan, initiatives are underway to explore the co-firing of ammonia with coal in boilers and with natural gas in combustion turbines [55]. Moreover, ammonia shows promise as a maritime fuel, requiring only minor modifications for use in ship engines, and it can also be utilized in certain fuel cell technologies.

$${\text{N}}_2+3{\text{H}}_2\rightleftharpoons 2\text{N}{\text{H}}_3\text{Δ}\text{H}-92\text{k}\text{J}/\text{m}\text{o}\text{l}$$E6

3.3 Production of methanol and DME fuels

Given the problems of storage and transportation of hydrogen itself, as well as the radical change of fuel cell cars, methanol (CH₃OH) can be obtained by reacting hydrogen gas with atmospheric CO₂ gas (Re. (7)) [56]. Methanol has several own potentials. First, dimethyl ether (DME) can be obtained from methanol, which is made by dehydrating several methanol molecules (Re. (8)). It is a gas but can be stored under low pressure as a liquid. Second, methanol is preferred for gasoline engines, dimethyl ether (CH₃-O-CH₃) for diesel engines [57]. Methanol and DME production is at relatively low temperature. Third, the energy density of methanol and DME is 16 MJ/L and 18–19 MJ/L, respectively, which is lower than petroleum-based fuel, but usable and easy to store.

$$C{O}_2+3{\text{H}}_2\Rightarrow \text{C}{\text{H}}_3\text{O}\text{H}+{\text{H}}_2\text{O}\text{Δ}\text{H}-49.5\text{k}\text{J}/\text{m}\text{o}\text{l}\text{a}\text{t}25^{°}\text{C}$$E7

$$2\text{C}{\text{H}}_3\text{O}\text{H}\Rightarrow \text{C}{\text{H}}_3\text{O}\text{C}{\text{H}}_3+{\text{H}}_2\text{O}\text{H}23\text{k}\text{J}/\text{m}\text{o}\text{l}$$E8

3.4 Liquid hydrocarbon fuels

Coal and biomass have long served as the foundation for liquid hydrocarbon fuels, relying on hydrogen for their conversion [58]. Originating in 1920s Germany, the Fischer-Tropsch process, primarily coal-based, fueled a significant portion of Germany’s World War II efforts and later became instrumental in South Africa’s oil production, notably by Sasol. This process, requiring substantial hydrogen, catalyzes carbon monoxide to yield liquid hydrocarbons, now facilitated by coal gasification. Approximately 14,600 tons of coal yield 25,000 barrels of synfuel “oil”, alongside 25,000 tons of CO₂. Nuclear power offers avenues for enhancement: nuclear hydrogen sources coupled with process heat could boost hydrocarbon output and slash CO₂ emissions, while a hybrid system utilizes nuclear electricity for water electrolysis, yielding hydrogen for coal gasification. Conversely, biomass undergoes hydrotreating or Fischer-Tropsch processing to produce liquid biofuels, demonstrating sustainable alternatives in liquid fuel production [59].

3.5 Fuel cells

Hydrogen is predominantly utilized in fuel cell electric vehicles (FCEVs) for transportation purposes. Unlike conventional batteries, fuel cells generate electricity through a chemical reaction using external hydrogen fuel and oxygen from the air. Proton exchange membrane (PEM) fuel cells, the primary type used in cars and heavy vehicles, operate at temperatures of around 80–90°C [60]. They offer high volumetric power density and long life but require high-purity hydrogen and costly noble metal catalysts, typically platinum. Although they theoretically achieve about 60% efficiency in converting chemical energy to electrical energy, practical efficiency is approximately half of that. Alternatively, alkaline fuel cells (AFCs) operate at around 200°C, boasting efficiency above 60%. Developed since the 1960s, AFCs have been employed by NASA in space missions due to their reliability [61]. They are cost-effective, utilizing non-noble metal catalysts and tolerating less-pure hydrogen from ammonia cracking. However, commercialization is limited by CO₂ poisoning, which leads to insoluble carbonate formation.

3.6 Reductant for metallurgy

Metallurgical coke, primarily carbon, plays a crucial role in steelmaking as a reductant, yet advancements in utilizing natural gas for direct iron reduction are emerging to mitigate CO₂ emissions [62]. Currently, blast furnaces, fueled by coke, dominate steel production, while electric arc furnaces (EAFs) and direct-reduced iron (DRI) methods are gaining traction. EAFs, predominantly powered by electricity, offer synergy with nuclear energy, while DRI, facilitated by hydrogen, presents an avenue for clean production. The steel sector accounts for a substantial portion of global hydrogen usage, with green steel initiatives, such as hydrogen in Europe’s vision and projects like HYBRIT in Sweden, driving innovation. Plans for green steel production in Australia and Russia underscore the industry’s shift towards sustainable practices [63], utilizing electrolysis and renewable energy sources to meet hydrogen demands and reduce carbon footprint.

4. Conclusion

In the realm of transportation, transporting hydrogen via tube trailers without the need for liquefaction proves to be more economically efficient, resulting in a savings of $2.86 per kilogram of delivered H₂ in smaller-scale power plants. The issue of hydrogen boil-off during transport stands out as a critical concern. The extent of embrittlement largely hinges on factors such as the material composition of the pipeline and the prevailing temperature and pressure conditions. Furthermore, the embrittlement of pipeline steels and other construction materials can lead to deterioration in mechanical properties and the development of cracks, ultimately resulting in pipeline failures. Additionally, it is observed that blending hydrogen into the upper line of the natural gas network yields superior results compared to blending it into the lower line. Moreover, a strategy focusing on concentrated hydrogen blending outperforms a dispersed approach.

Hydrogen stands as a pivotal element in various industrial processes and emerging technologies, playing a vital role in sectors ranging from oil refining to metallurgy and transports. Its versatility as an energy carrier enables its use in the desulfurization and catalytic cracking of petroleum, as well as in the production of essential chemicals like ammonia and methanol. Moreover, hydrogen facilitates the synthesis of liquid hydrocarbon fuels from coal and biomass, offering sustainable alternatives for the future. In the realm of transportation, hydrogen fuel cells present an efficient and clean solution, though challenges remain in terms of infrastructure and cost-effectiveness. Furthermore, hydrogen’s significance in metallurgy, particularly in steel production, highlights its potential to drive the transition toward greener industrial practices. With ongoing advancements and initiatives aimed at harnessing its potential, hydrogen emerges as a key player in the pursuit of a more sustainable and low-carbon future. Consequently, these challenges have the potential to disrupt the distribution and delivery of hydrogen. Therefore, the successful realization of a hydrogen-based economy is contingent upon the ability to identify the most promising areas for future advancements in hydrogen transportation, usage, production, and storage.