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Green hydrogen; Electrolysis; Renewable energy; Hydrogen economy; Fuel cells; Energy storage; Sustainability; Decarbonization; Climate change; Electrolyzers

Introduction

In the face of rising global temperatures and a pressing need to reduce greenhouse gas emissions, the energy sector is witnessing a paradigm shift toward clean and renewable alternatives. Among these, green hydrogen has emerged as a promising candidate for addressing the intermittency of renewable sources and decarbonizing hard-to-abate sectors. Unlike grey or blue hydrogen, green hydrogen is generated via electrolysis using renewable electricity, resulting in zero direct CO₂ emissions [1]. The appeal of hydrogen lies in its versatility—it can be stored, transported, and used as a fuel or feedstock across multiple industries, making it central to the concept of a future hydrogen economy [2].

Description

Hydrogen production through water electrolysis involves splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂) using an electric current. The key technologies for this include alkaline electrolyzers, proton exchange membrane (PEM) electrolyzers, and solid oxide electrolyzers. Each has distinct advantages: alkaline electrolyzers are mature and cost-effective, PEM offers higher efficiency and compact design, and solid oxide systems operate at high temperatures, improving thermodynamic efficiency [3].

For green hydrogen to become viable, the electricity used must come from renewables such as solar, wind, or hydropower. This imposes both an opportunity and a challenge, as large-scale deployment of renewables must be synchronized with electrolyzer operations to ensure steady hydrogen output [4]. Recent innovations include modular electrolyzer systems, hybrid renewable-electrolyzer plants, and AI-based load management for optimizing performance in real-time [5].

Green hydrogen serves multiple applications. In transportation, it powers fuel cell electric vehicles (FCEVs), offering longer range and faster refueling compared to battery electric vehicles. In power systems, it functions as a long-duration energy storage medium, converting surplus renewable energy into hydrogen for later reconversion into electricity via fuel cells or turbines. Additionally, green hydrogen can replace fossil-derived hydrogen in industrial processes like steel manufacturing, ammonia synthesis, and refinery operations, drastically reducing emissions [6].

Results

Pilot projects across the globe are demonstrating the practicality of green hydrogen. For example, the HyDeploy project in the UK successfully blended hydrogen into a natural gas grid, while Japan’s Fukushima Hydrogen Energy Research Field uses solar power to produce hydrogen at scale [7]. Similarly, the Hydrogen Valley initiative in the EU is setting up integrated hydrogen ecosystems that connect production, storage, transport, and end-use.

On the technical side, electrolyzer efficiencies have seen significant improvements. The efficiency of modern PEM electrolyzers has reached over 70%, and ongoing materials research on catalysts, especially using earth-abundant metals like nickel and iron instead of platinum, is reducing costs [8]. Additionally, international cooperation is growing, with countries like Germany, Australia, and India establishing hydrogen roadmaps and bilateral agreements to promote technology sharing and trade [9].

However, economic barriers remain. The current cost of green hydrogen ranges from $4 to $6 per kilogram, significantly higher than grey hydrogen derived from natural gas at $1 to $2/kg. Achieving parity requires a combination of cheaper renewable energy, larger-scale production, and supportive policy measures such as carbon pricing, subsidies, and infrastructure development [10].

Conclusion

Green hydrogen holds the potential to revolutionize the energy landscape by providing a clean, flexible, and scalable fuel alternative. Though still in its early stages of adoption, the combination of technological advances, market demand, and policy momentum is accelerating its development. To fully realize its promise, integrated strategies involving investment in R&D, infrastructure, international collaboration, and public-private partnerships are essential. With these efforts, green hydrogen can play a pivotal role in achieving net-zero emissions and fostering a more sustainable and resilient energy future.