Hydrogen Production Methods: Renewable and Non-renewable

Introduction

Hydrogen is a versatile energy carrier that can significantly contribute to a sustainable energy future. It can be produced through various methods, which are broadly categorized into renewable and non-renewable. This article explores these methods, their chemical reactions, current status, environmental impact, and the concept of hydrogen colors, along with the demand and supply dynamics.

Renewable Methods

1. Electrolysis:
• Water Electrolysis: Uses electricity to split water into hydrogen and oxygen. When powered by renewable energy sources like wind or solar, it produces green hydrogen.
• Chemical Reaction: 2H2O(l) -> 2H2(g) + O2(g)
• Current Status: Commercially available and increasingly used, especially in regions with abundant renewable energy.
• Environmental Impact: When powered by renewable energy sources, electrolysis produces green hydrogen with minimal environmental impact. However, the production of the necessary renewable energy infrastructure (e.g., solar panels, wind turbines) can have significant environmental footprints, including resource extraction, manufacturing emissions, and waste generation [1].


2. Photocatalytic Water Splitting:
• This method utilizes sunlight to directly split water molecules into hydrogen and oxygen.
• Chemical Reaction: 2H2O(l) + photocatalyst -> 2H2(g) + O2(g)
• Current Status: Still in the research and development phase, with potential for large-scale sustainable hydrogen production.
• Environmental Impact: This method has the potential for low environmental impact if the photocatalysts used are non-toxic and abundant. However, the technology is still in development, and large-scale implementation could face challenges related to material sustainability and efficiency [1].


3. Biomass Gasification:
• Biomass gasification converts organic materials into hydrogen, carbon monoxide, and carbon dioxide through high-temperature reactions.
• Chemical Reaction: Biomass + O2 + H2O -> H2 + CO + CO2
• Current Status: Used in pilot projects and small-scale applications, with ongoing research to improve efficiency and reduce costs.
• Environmental Impact: Biomass gasification can reduce waste and utilize renewable resources, but it can also produce greenhouse gases (GHGs) and other pollutants if not managed properly. The sustainability of this method depends on the source of the biomass and the efficiency of the gasification process [2].

Non-renewable Methods

1. Steam Methane Reforming (SMR):
• Reacts natural gas with steam to produce hydrogen and carbon dioxide.
• Chemical Reaction: CH4 + H2O -> CO + 3H2
• Current Status: Widely used and commercially viable but emits significant CO2. When combined with carbon capture and storage (CCS), it is termed blue hydrogen.
• Environmental Impact: SMR is a major source of CO2 emissions, contributing significantly to climate change. The process also consumes large amounts of water and energy [3].


2. Coal Gasification:
• Converts coal into hydrogen, carbon monoxide, and carbon dioxide.
• Chemical Reaction: C + H2O -> CO + H2
• Current Status: Used in some industrial applications, with high CO2 emissions unless coupled with CCS.
• Environmental Impact: This method produces high levels of CO2 and other pollutants, including sulfur oxides and nitrogen oxides. It also involves significant land use and water consumption, making it one of the least environmentally friendly hydrogen production methods.


3. Nuclear Thermochemical Water Splitting:
• Uses high temperatures from nuclear reactors to split water into hydrogen and oxygen.
• Chemical Reaction: 2H2O -> 2H2 + O2
• Current Status: Experimental stage, with potential for large-scale hydrogen production without CO2 emissions.
• Environmental Impact: While this method does not produce direct CO2 emissions, it involves the risks associated with nuclear energy, including radioactive waste and potential accidents. The environmental impact depends on the safety and sustainability of the nuclear energy source [4].

Hydrogen Colors

Hydrogen is often categorized by color codes based on its production method:

• Green Hydrogen: Produced using renewable energy sources.
• Blue Hydrogen: Produced from natural gas with carbon capture and storage.
• Gray Hydrogen: Produced from fossil fuels without carbon capture.
• Brown/Black Hydrogen: Produced from coal.
• Pink Hydrogen: Produced using nuclear energy.

Demand and Supply of Hydrogen

Demand

The global demand for hydrogen is growing rapidly, driven by its potential in various sectors such as transportation, industry, and energy storage. Here are some key statistics:

• Current Demand: In 2021, the global demand for hydrogen was approximately 94.3 million metric tons per annum (Mtpa) [5].
• Projected Demand: By 2030, the demand is expected to nearly double, reaching around 100 Mtpa [6]. By 2050, clean hydrogen demand could range between 125 and 585 Mtpa, depending on the scenario [7].
• Sectoral Demand: Currently, most hydrogen is consumed in the chemicals and refining sectors. However, new applications in heavy industry, long-distance transport, and energy storage are expected to drive future demand [6].

Supply

The supply of hydrogen is currently dominated by non-renewable methods, but there is a growing shift towards renewable production. Nearly all hydrogen produced today is gray hydrogen, derived from fossil fuels without carbon capture. The production of clean hydrogen (green and blue hydrogen) is increasing. By 2050, clean hydrogen could account for up to 73-100% of total hydrogen demand [7]. To meet the growing demand, significant infrastructure development is required. This includes the establishment of refueling stations, hydrogen pipelines, and advancements in hydrogen production technologies.

Conclusion

Hydrogen production is vital for a sustainable energy future, with renewable methods like water electrolysis and biomass gasification offering low-carbon solutions, while non-renewable methods such as Steam Methane Reforming dominate current supply but pose significant environmental challenges. The "hydrogen colors" framework emphasizes the importance of production pathways, with green hydrogen being the most sustainable. As global hydrogen demand grows, transitioning to clean hydrogen requires advancing renewable technologies, scaling infrastructure, and fostering supportive policies. By focusing on innovation and sustainability, hydrogen can play a key role in decarbonizing industries and achieving a low-carbon energy future.

References

• [1] A. I. Osman et al., “Hydrogen production, storage, utilisation and environmental impacts: a review,” Environ Chem Lett, vol. 20, no. 1, pp. 153–188, Feb. 2022, doi: 10.1007/s10311-021-01322-8.
• [2] WG-5 Environment, “ENVIRONMENTAL IMPACTS OF HYDROGEN PLANTS.” EUROPEAN INDUSTRIAL GASES ASSOCIATION AISBL, 2018.
• [3] S. G. Nnabuife, C. K. Darko, P. C. Obiako, B. Kuang, X. Sun, and K. Jenkins, “A Comparative Analysis of Different Hydrogen Production Methods and Their Environmental Impact,” Clean Technol., vol. 5, no. 4, pp. 1344–1380, Nov. 2023, doi: 10.3390/cleantechnol5040067.
• [4] A. Ozbilen, I. Dincer, and M. A. Rosen, “Environmental evaluation of hydrogen production via thermochemical water splitting using the Cu–Cl Cycle: A parametric study,” International Journal of Hydrogen Energy, vol. 36, no. 16, pp. 9514–9528, Aug. 2011, doi: 10.1016/j.ijhydene.2011.05.067.
• [5] “Hydrogen demand worldwide from 2019 to 2021, with a forecast for 2030.” [Online]. Available: https://www.statista.com/statistics/1121206/global-hydrogen-demand/
• [6] “Global Hydrogen Review 2024, IEA, Paris,” IEA. [Online]. Available: https://www.iea.org/reports/global-hydrogen-review-2024
• [7] G. Chiara, “Global Energy Perspective 2023: Hydrogen outlook.”