Hydrogen Energy:
The Energy Carrier
of the Future
Hydrogen, as the most abundant element in the universe, stands out for its potential. Especially when compared to fossil fuels, with a notably high specific energy density, hydrogen energy takes its place among clean energy sources as a significant alternative energy carrier.
Properties of Hydrogen Energy
Hydrogen’s gravimetric energy density is 120 MJ/kg, a remarkably high value. This value is nearly three times that of gasoline, a widely used fossil-based fuel with an energy content of 44 MJ/kg [1].
For hydrogen to be used as a raw material or energy source, it needs to be obtained from various energy sources. Today, most of the hydrogen is produced from fossil fuels, particularly natural gas, through steam methane reforming. This production process results in significant carbon emissions. There is a color classification for hydrogen in the literature based on the energy source, production method and carbon dioxide emission level [2]. However, although different hydrogen colors are defined in different sources, the most common color descriptions found in most sources are given below:
Gray Hydrogen: Produced by steam reforming (SMR) of methane and does not use any carbon capture, utilization and storage processes during its production.
Blue Hydrogen: Produced by steam reforming (SMR) of methane and utilizes carbon capture, utilization and storage technologies.
Green Hydrogen: Produced by electrolysis of water using renewable electrical energy.
Turquoise Hydrogen: Produced by pyrolysis of methane and solid carbon (carbon black) is obtained as a by-product.
Apart from these main color classifications, there are also orange, pink, red, yellow, brown and black hydrogen [3].
Uses of Hydrogen
Hydrogen is one of the most promising energy carriers for the future. It can play a critical role in transportation, heating and electric power generation, especially in places where electricity is difficult to access. With stringent emission-limiting regulations and procedures in place today, the transition to hydrogen energy is increasing its popularity day by day. Hydrogen, which is the building block of ammonia, fertilizer, methanol and many polymers in the chemical industry, is also in high demand in the iron and steel industry, a hard-to-abate sector, where decarbonization is very difficult [4]. According to the International Energy Agency’s (IEA) “Global Hydrogen Review 2024” dated October 2024, hydrogen demand in 2023 reached 97 Mt (million tons), an increase of 2.5% compared to 2022. Sixty percent of the total industrial hydrogen consumption (outside of oil refining) of 54 Mt was used in ammonia production, 30% in methanol production, and 10% in the steel industry in Direct Reduced Iron (DRI) technology. In refineries, 43 Mt of hydrogen was used in various processes. In refineries, 43 Mt of hydrogen was used in various processes. Two thirds of the world’s hydrogen production is derived from natural gas. Hydrogen production from coal gasification accounts for 20% of the total global production. In addition, 15% of hydrogen worldwide is produced in refineries and the petrochemical industry. Although low carbon emission hydrogen production has grown rapidly in the last two years, it still accounts for less than 1% of global hydrogen production, less than 1 Mt per year. Most of the low-emission hydrogen production takes place in plants using fossil fuels and carbon capture, utilization and storage (CCUS) technology. Hydrogen production by electrolysis remains below 100 kt (kilo tons) in 2023 [5]. Although the rate of green hydrogen production with electrolyzer seems low due to the high unit cost of hydrogen today, this rate is increasing day by day with the changing balances in energy supply between countries, current approaches, regulations (EU Green Deal, CBAM-Carbon Border Adjustment Mechanism etc.) and technological developments in the decarbonization trend.
The Importance of Green Hydrogen
Green hydrogen produced using renewable energy sources is projected to play a critical role in reducing greenhouse gas emissions by replacing fossil fuels. Green hydrogen has the potential to reduce fossil fuel dependency by enabling decarbonization in sectors such as industrial applications (e.g. iron and steel production) and transportation (e.g. fuel cell vehicles). Therefore, green hydrogen is regarded as a vital component at the heart of future energy systems.
The Cost of Green Hydrogen and Future Prospects
The cost of green hydrogen can be evaluated in two main categories. The first of these, renewable energy production costs (solar and wind energy), is stated to have decreased by 59% from 2010 to 2022, according to the 2023 report published by the International Renewable Energy Agency (IRENA). Today, electricity generation via solar and wind energy is among the cheapest methods of renewable energy production in many regions of the world. The second category is electrolyzer costs, which are expected to decrease as the technology matures, in line with current regulations and strategies [6]. According to the “Global Hydrogen Review 2024” report published by the International Energy Agency (IEA) in October 2024, the cost of producing green hydrogen using electrolysis technology powered by offshore wind, onshore wind, and photovoltaic solar energy is estimated to reach $2/kg H2 by 2030, through the “Net Zero Emissions” (NZE) targets [5]. The U.S. Department of Energy (DOE) reported in 2024 that it aims to reduce the cost of green hydrogen production to $2/kg H2 by 2026 and $1/kg H2 by 2031 [7]. According to the data in the “Türkiye Hydrogen Technologies Strategy and Roadmap” published by the Ministry of Energy and Natural Resources in January 2023, it is predicted that the cost of green hydrogen production will fall to 2.4 $/kg H2 by 2035 and below 1.2 $/kg H2 by 2053 [8].
References
[1] Satyapal, S., Petrovic, J., Read, C., Thomas, G., & Ordaz, G. (2007). The US Department of Energy’s National Hydrogen Storage Project: Progress towards meeting hydrogen-powered vehicle requirements. Catalysis today, 120(3-4), 246-256.
[2] Van de Voorde, M. (Ed.). (2021). Hydrogen production and energy transition. Walter de Gruyter GmbH & Co KG.
[3] Incer-Valverde, J., Korayem, A., Tsatsaronis, G., & Morosuk, T. (2023). “Colors” of hydrogen: Definitions and carbon intensity. Energy conversion and management, 291, 117294.
[4] Zohuri, B. (2019). Hydrogen energy: Challenges and solutions for a cleaner future. Cham, Switzerland: Springer international publishing.
[5] IEA (2024), Global Hydrogen Review 2024, IEA, Paris https://www.iea.org/reports/global-hydrogen-review-2024, Licence: CC BY 4.0
[6] International Renewable Energy Agency (IRENA). (2023), Renewable power generation costs in 2022, International Renewable Energy Agency, Abu Dhabi: IRENA. Retrieved from www.irena.org/Publications/2023/Aug/Renewable-Power-Generation-Costs-in-2022
[7] U.S. Department of Energy (DOE). Hydrogen and Fuel Cell Technologies Office Multi-Year Program Plan. (2024). https://www.energy.gov/sites/default/files/2024-05/hfto-mypp-2024.pdf
[8] Republic of Türkiye Ministry of Energy and Natural Resources. (2023). Hydrogen Technologies Strategy and Roadmap. Retrieved from https://enerji.gov.tr/Media/Dizin/SGB/en/HSP_en/ETKB_Hydrogen_T_Strategies.pdf