A comprehensive review on hydrogen production and utilization in North America: Prospects and challenges

Highlights

• The current status and future prospects of hydrogen production and utilization are discussed.

• Challenges and government regulations for hydrogen production in North America are addressed.

• High energy consumption and CO₂ emissions are the main challenges for conventional H₂ production.

• Hydrogen storage materials are still lacking in both volumetric and gravimetric density.

• Biohydrogen production needs further research and development before commercialization.

Abstract

Hydrogen is one of the most efficient and attractive energy carriers that can fulfill current and future energy requirements and address the drawbacks of conventional energy resources. Hydrogen as a fuel is nonmetallic, carbon-free, non-toxic, and has higher specific energy than gasoline (on a mass basis). Hydrogen production, storage, safety, and utilization are the four main aspects that should be considered in hydrogen energy-based systems. This review extensively analyzes the literature on fundamental, technological, and environmental aspects of various hydrogen applications and production techniques as well as theoretical and practical challenges. The global demand for hydrogen is mainly for its utilization in oil refineries (33%), chemical production (40%), metallurgical industries (3%), and the rest is in applications such as fuel, glass manufacturing, welding processes, and food industries. Natural gas, crude oil, coal, and electrolysis processes are the main feedstock sources for hydrogen production, with shares of 49, 29, 18, and 4%, respectively. Currently, hydrocarbon and alcohol reforming, gasification (coal and fossil fuels), and fossil fuel partial oxidation have the greatest shares of the hydrogen production methods. The main challenges for these methods are the high total energy consumption and carbon emissions to the environment. Water electrolysis technologies are still under development and can be combined with renewable energy resources, such as solar, geothermal, wind, and tidal to achieve eco-friendly technologies. Biohydrogen production through biological approaches such as direct and indirect biophotolysis, and photo and dark fermentation processes can be sustainable and promising technologies for bioenergy production worldwide. This review investigates the various thermochemical cycles for hydrogen production and presents the process flow diagram of each cycle. It discusses the different chemical and physical methods and materials for hydrogen storage. In fact, hydrogen storage materials are still lacking in both volumetric and gravimetric density, and in some cases, they do not have promising storage capacity. The current status of hydrogen production, available resources, various challenges in the field of hydrogen production, storage and transportation, and government regulations in North America are discussed.

Introduction

In 2012, the UN Secretary-General stated that “Energy is the Golden Thread.” Economic growth, social equity, and environmental sustainability of different societies depend on sustainable energy sources [1]. Nearly ten years later, most of the world's population is still living in a state of energy crisis and poverty, to the extent that a significant percentage of energy supplies comes from unsafe sources and highly polluting fuels and technologies [2]. After the creation of numerous programs and strict rules by the responsible organizations according to the key guidelines suggested by the Intergovernmental Panel on Climate Change (IPCC) in 2018 [3], a significant reduction in global GHG emissions has been reported to mitigate the global warming of 1.5 °C above pre-industrial levels. Fig. 1 shows the energy demand and the share of its growth for different regions [4]. The energy demand (million tonnes of oil equivalent (Mtoe)) is led by China (4060), the USA (2240), European Union (1540), and India (1540). These regions’ energy demand is expected to grow by31%, 1%, 0%, and 18%, respectively. Noteworthy, the energy demand growth for Southeast Asia, the Middle East, Africa, Brazil, and Eurasia is expected at 11, 10, 8, 55, and 5%, respectively (Fig. 1). Although fossil fuels supply around 80% of the world's energy demand, they considerably contribute to CO₂ emissions and global warming [5]. Therefore, the global transition from conventional to renewable energy resources is essential due to increased energy demand, lack of fossil fuels supply, difficult access to unconventional fossil fuels, and relatively high prices of fossil fuels, as well as to reduce CO₂ emissions. The smart and planned transition will provide an important foundation/platform for achieving decarbonization goals in dominant sectors and net-zero CO₂ emissions by 2050 [3].

At standard temperature and pressure (STP), hydrogen (H₂) gas is combustible, odorless, and tasteless. In the Earth’s atmosphere, H₂ gas occurs naturally only in low concentrations (about 1 ppm); but it is the third most plentiful element on the earth’s surface [6], [7]. Among the renewable energy resources (solar, hydro, wind, biomass, ocean thermal energy conversion (OTEC), and geothermal energy), H₂ can serve as fuel, energy carrier, and storage medium [8]. Hydrogen is an acceptable sustainable energy carrier with zero harmful emissions and reasonable renewability. It offers important advantages; it has high energy conversion efficiency, can be produced from abundant and accessible sources such as water, and can be stored as a liquid or gas, or in combination using various solid and liquid materials such as hydride storage materials. Moreover, it can be converted to different energy forms and has greater higher and lower heating values (HHV and LHV, respectively) than conventional fossil fuels [9]. Hydrogen has significant social benefits because it can supply clean, efficient, trustworthy, and inexpensive solutions to various energy sectors [10]. The main physical properties of hydrogen and its comparison with other fuels are summarized in Table 1 [11].

Thermal, electrolytic, or photolytic processes can produce H₂ using abundant natural gas, water, coal, and biomass. Clean H₂ can be produced from versatile domestic resources such as coal gasification [12], [13], [14], [15], [16], [17], natural gas [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], nuclear power [32], [33], [34], [35], [36], [37], [38], [39], and renewable energy resources such as solar [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], geothermal [50], [51], [52], [21], [53], [54], [55], [56], [57], wind [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], biomass [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], hydro [78], [79], [80], [81], [82], and OTEC [83], [84], [85], [86], [87], [88], [89]. Diverse experimental and theoretical methods for hydrogen production make the H₂ economy very likely soon, and it can be produced on a large or small scale using whatever resources are available and stored until needed. The main feedstocks for current global hydrogen production are natural gas, crude oil, coal and electrolysis processes with the shares of 49, 29, 18, and 4%, respectively [90]. Although some governments and societies are not focusing on H₂ fuel, it is expected that they will consider it short due to its unique and potential features. These features include its abundance, renewability, cleanliness, and flexibility as an energy source to support zero-carbon energy strategies [92].

Recently, Farsi et al. [91] used a lab-scale copper-chlorine cycle for sustainable H₂ production; the set-up can produce hydrogen up to 100 L/h. Hamza et al. [92] used Bi₂(CrO₄)₃ to produce H₂ by photocatalytic water splitting; 522.44, 174.15, and 88.24 μmol/g/h of H₂ were produced under UV, AM 1.5, and visible irradiations, respectively. Sheikhbahaei et al. [93] designed and fabricated a reactor for H₂ production using solar energy and aluminum. A maximum H₂ production rate and reactor coefficient of performance (COP) were 420 mL/min and 1261 mL H₂ per 1 g of Al, respectively. Ying et al. [94] carried out the electrolysis of HI solution (HI-I₂-H₂O) in an experimental setup for H₂ production. They produced about 300 mL H₂ after 1 h. Xu et al. [95] investigated H₂ production through a thermochemical water sulfur–iodine splitting cycle using hydriodic acid. They used several commercial proton-exchange membranes (PEMs) and reported that about 700 and 300 mL H₂ can be generated for 100 and 50 mA cm⁻² current densities at 60 °C, respectively. Tahir et al. [96] experimentally investigated the influence of various parameters on H₂ production using methanol-phenol mixture steam reforming (M−PSR). They carried out a comprehensive thermodynamic analysis and evaluated various possible reactions using Gibbs free energy. The optimum operating parameters were temperature (700 °C), pressure (atmospheric pressure), and methanol-phenol-steam feed molar ratio (0.1:0.9:20). Anzelmo et al. [97] employed a Pd-Au membrane reactor for high-purity H₂ production through a natural gas steam reforming process. The membrane showed a near-infinite ideal selectivity for hydrogen-Argon separation, and the hydrocarbon conversion and hydrogen recovery were higher than 80% at 450 °C and 300 kPa.

From theoretical aspects of hydrogen production, diverse studies have been performed. Bockris and Uosaki [98] proposed a theoretical photoelectrochemical process to produce H₂ in 1977. They admitted that the characterization estimation of the process is difficult due to the lack of earlier theoretical and experimental studies. Shayan et al. [99] performed a computational study and compared H₂ production rate/performance while using different gasification agents. Namely, they used air, oxygen-enriched air, oxygen and steam. The results revealed that steam and oxygen have a higher rate of hydrogen production compared to air and oxygen-enriched air. [102] Bhatt and Lee [100] examined the performance of various nano photocatalysts from theoretical perspectives to modify large band gaps and band edge positions of the current photocatalysts used for H₂ production. They focused on the theoretical study related to the modified nanostructured photocatalysts by co-catalysts or dopants to investigate the impacts of band gaps and band edge positions of the photocatalysts for hydrogen production via water splitting. Penchini et al. [101] theoretically investigated the performance of a 200 W solid oxide electrolyzer stack for H₂ production. They presented a thermodynamic theoretical study for the cell electrolyzer by considering the heat and mass balance of the stack at different operating conditions. Their results revealed that the Faraday efficiency of the cell strongly depends on the water utilization and slightly on the hydrogen content in the inlet stream. Wang et al. [102] examined the various structures of nitrogen-saturated porous Mo₂C for H₂ production. They showed that the catalytic property of Mo₂C depends on the concentration of doped-N atoms which can enhance the Mo₂C catalytic properties and decrease its hydrogen absorption ability. Saidi and Jahangiri [103] systematically evaluated the performance of a catalytic membrane reactor through an ethanol steam reforming process for hydrogen production. The results of Ethanol steam reforming over a Co/Al₂O₃ catalyst in a catalytic Pd-Ag membrane reactor indicated that continuous removal of hydrogen from the retentate is necessary to achieve high performance of the reactor. Ghasemzadeh et al. [104] simulated and compared the performance of a water gas shift reaction in a silica membrane reactor and a Pd–Ag reactor. The performance of the silica membrane reactor was 5% lower than that of the dense type. Fernandez et al. [105] designed various nickel-based molecular electrocatalysts with pendant amines to maximize the turnover frequency and minimize the overpotential for hydrogen production. They focused on the proton-coupled electron transfer (PCET) process and found that PCET needs lower overpotential and decreases the energetic penalty for the nitrogen to reach the nickel center for proton transfer.

This review investigates the importance of H₂ in different applications, different production techniques, existing technical and non-technical challenges, and effective tips/guidelines. It answers questions such as, what is the current status and importance of H₂ compared to other conventional fuels? What are the different applications of H₂? What are the different methods of H₂ production, the materials they require, their fundamentals, advantages, disadvantages, challenges, and importance? What are the safety and economic challenges of H₂? What are the political prospects, protective regulations, and structural frameworks of different governments regarding the importance of H₂, its production methods, and its future?

The production of hydrogen is important based on a study by McKinsey; it was estimated that by 2030, the U.S. hydrogen economy could yield $140 billion and support 700,000 jobs [106]. Approximately 70 million metric tonnes of hydrogen are being produced globally every year for use in oil refining, ammonia production, steel manufacturing, chemical and fertilizer production, food processing, and metallurgy [107]. Based on the prediction, the yearly global hydrogen demands in 2050 are about 18.3 Mt for ammonia production, 40.8 Mt for synfuel production, 62.9 Mt for industrial applications, 26.6 Mt for building applications, 66.5 Mt for transport applications, 55 Mt for power generation, and 16.9 Mt for refining applications [108]. Compared to the previous investigations, the main contribution of the current review is the presentation of a comprehensive overview of all common and new hydrogen utilization and production approaches. In addition, the main challenges, advantages, disadvantages and drawbacks of the various techniques are discussed. It should be noted that the current review includes the key findings of both experimental and modeling research investigations. To the best of our knowledge, there is no such a systematic review on the production, sources, and use of hydrogen with focus on North America in the open sources. Indeed, this manuscript summarizes the current status and future prospects of hydrogen and its importance in the human energy basket and describes the different uses of hydrogen from the perspective of fuel and energy carriers in the first section. Later, it elaborates on various methods of hydrogen production, materials required in each method, mechanisms of production methods, advantages and disadvantages of each method, and some key practical and theoretical aspects. Then, it briefly describes various environmental, economic, and safety aspects of hydrogen production and utilization. The final section discusses the most important hydrogen issues from the viewpoints of production methods, sources required for the production, and the protective and structural laws of governments regarding hydrogen fuel in North American countries.