06/28/2024
HYDROGEN CARRIER
Hydrogen is a promising clean energy carrier, but its transportation poses significant challenges. To address these challenges, various hydrogen carriers have been developed, each with its advantages and disadvantages. Here, we'll explore three well-known energy carriers: ammonia, Liquid Organic Hydrogen Carriers (LOHCs), and liquid hydrogen.
Ammonia
Ammonia (NH3) is a chemical that can store and transport hydrogen. It's produced through ammonia synthesis, where hydrogen and nitrogen react to form liquid ammonia. This liquid is stored in tanks, making it easy to transport. When the ammonia reaches its destination, it's broken down into its components, releasing hydrogen and nitrogen.
Pros:
1. Ammonia has been used in various industries for a long time, and the infrastructures for ammonia synthesis are abundant.
2. Ammonia can be stored in slightly refrigerated tanks at -33°C or at ambient temperatures under a pressure of 8-10 bar, making storage and transportation relatively straightforward and affordable.
Cons:
1. The process of cracking ammonia is still relatively new and not energy-efficient.
2. After cracking, additional steps are required to purify the hydrogen for use.
3. Ammonia is a toxic substance that, if it leaks, may have a negative impact on air, soil, and water quality, as well as human health.
Liquid Hydrogen (LH2)
Liquid hydrogen is a promising mode of transportation, as it has a higher energy density than gaseous hydrogen. To transform gaseous hydrogen into liquid hydrogen, the gas is cooled to -252.9°C. It can then be transported and stored in its liquid form, provided it's well-insulated. When needed, the liquid hydrogen is made gaseous again with an evaporator.
Pros:
1. Liquid hydrogen is not merged with any other substance, so chemical reactions and purification steps are not necessary, retaining the optimal quality of the hydrogen.
2. It's a very climate-change-friendly fuel, releasing only water when burned.
Cons:
1. Extreme cooling requires a lot of energy, and superior quality insulation is necessary to maintain the extremely low temperature.
2. A small amount of boil-off gas cannot be prevented over time.
Conclusion
Each hydrogen carrier has its advantages and disadvantages. Ammonia is a well-established energy carrier with abundant infrastructure, but its process is still relatively new and not energy-efficient. LOHCs are relatively inexpensive and safe, but their production causes extra CO2 emissions. Liquid hydrogen is a promising mode of transportation, but it requires extreme cooling and insulation. As the world moves towards a green hydrogen economy, it's essential to consider the pros and cons of each carrier to determine the most suitable option for large-scale hydrogen transportation.
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