Hydrogen And Its Derivatives

Key Hydrogen Derivatives

The urgency of addressing climate change necessitates a rapid transition towards clean energy sources. Hydrogen, with its high energy density and zero carbon emissions at the point of use, has emerged as a front runner. However, its gaseous nature presents substantial hurdles in storage and long-distance transportation (volumetric density: 0.09 kg/m^3 compared to gasoline: 740 kg/m^3). Hydrogen derivatives bridge this gap, offering a more versatile and transportable form of clean energy.

The chemicals (mostly fuels) produced using green/ low carbon hydrogen, thus replacing the conventional hydrogen (grey, black hydrogen from fossil fuels) are called hydrogen derivatives. Additionally along with the clean (low carbon) hydrogen, wherever required, carbon dioxide (Co2) captured from the direct industry gas emissions, is used. (thus preventing C02 release to atmosphere again). These chemicals include primarily green ammonia, E-fuels, synthetic methane, synthetic methanol and others.

Several types of hydrogen derivatives are under development, each targeting specific applications with different production pathways however we will see the important ones as below mentioned. In some cases, like as mentioned above of using captured CO2 , plastic wastes are also used as inputs in the production process of derivatives.

Key Hydrogen Derivatives:

Green Ammonia (NH3): is the primary derivative, well proven, and several projects are on the way across the globe. Produced via the Haber-Bosch process, combining clean Hydrogen (using mainly green H2 produced by electrolysis of efficiency: 60-80%) with atmospheric nitrogen (N2). Green ammonia boasts a zero-carbon footprint, unlike conventional grey ammonia (responsible for ~1.8% of global CO2 emissions). Studies suggest a promising prospect for green ammonia production, with a recent catalysis study, published in Nature, demonstrating a scalable electrocatalyst achieving 83% Faradaic efficiency for NH3 synthesis at ambient temperature and pressure.

E-fuels (Electrofuels): Synthetic liquid fuels like methanol (CH3OH) or synthetic gasoline or jet fuel (various hydrocarbons). E-fuels are produced by combining clean (mostly green or low carbon) hydrogen with captured CO2 from direct industry emissions through various pathways like Fischer-Tropsch synthesis (overall process efficiency: 50-70%). They are fully compatible with existing transportation infrastructure but offer significantly lower lifecycle emissions compared to fossil fuels (e.g., lifecycle CO2 emissions of jet fuel from biomass-based Fischer-Tropsch synthesis: 70-90 gCO2e/MJ vs. conventional jet fuel: 85-95 gCO2e/MJ)

Synthetic Methane (CH4): Produced via methanation, which combines clean hydrogen (green or low carbon) with captured CO2. This clean alternative to natural gas can be injected into existing gas pipelines (methane volumetric density: 68 kg/m^3) for power generation, heating, and industrial applications. A Joule study, demonstrated a CO2 methanation process achieving a methane yield of 99% and a CO conversion rate exceeding 90%.

Synthetic Methanol (CH3OH):While often categorized as an E-fuel, methanol deserves a separate mention due to its diverse applications in transportation (fuel blending) and industrial processes. It can be produced via the combination of H2 and CO2 through various synthesis pathways.

Synthetic Kerosene: A crucial derivative for the aviation industry. It can be produced via various pathways.

Renewable Propane (r-Propane):A clean alternative to conventional propane (LPG), its potential for decarbonizing the LPG sector.

E-fuels like synthetic kerosene and r-propane offer viable solutions for decarbonizing aviation, maritime shipping, and heavy-duty transport where battery technology faces limitations.

Green ammonia can replace conventional ammonia in fertilizer production and other industrial processes, significantly reducing CO2 emissions ((responsible for ~1.8% of global CO2 emissions). Synthetic methanol can be a clean fuel source or feedstock for various industrial applications.

Synthetic methane can be integrated into existing gas grids, enabling the utilization of renewable energy sources for power generation and balancing grid fluctuations.

Conclusion:

The diverse range of hydrogen derivatives, each with specific properties and applications, unlocks the full potential of clean hydrogen for a de-carbonized future. Continued research and development efforts focused on cost reduction, infrastructure development, and supportive policies are crucial for their widespread adoption. As techno-economic considerations improve and LCA data strengthens, hydrogen derivatives are poised to play a transformative role in achieving a sustainable energy landscape.

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