Two alternatives for industrial decarbonization and transport
The future of renewable energy not only depends on how we generate it, but also on how we store it. The intermittency of the sun and wind forces us to seek efficient solutions to store that energy and use it when needed. In this context, renewable hydrogen and ammonia emerge as two promising options, but with distinct challenges.
Hydrogen: a versatile bet
Hydrogen is an energy carrier that can be produced through various methods. The most sustainable option, green hydrogen, is obtained via water electrolysis using renewable electricity (Hydrogen Europe, 2023). There is also blue hydrogen, generated from natural gas with CO₂ capture, and grey hydrogen, produced without emissions capture and still dominant in the market (ISPT, 2023).
Production and Storage
Green hydrogen is essential for the decarbonization of hard-to-electrify sectors such as steelmaking, the chemical industry, and heavy transport (Hydrogen Council, 2023). Its production via electrolysis remains costly, but efficiency improvements and declining renewable energy costs are expected to reduce its price over the next decade (H2eart for Europe, 2023).
There are three main methods for its storage and transport:
• Compressed gas: Stored at pressures up to 700 bar, requiring strong and expensive materials (ISPT, 2023).
• Liquid hydrogen: Maintained at -253°C, though liquefaction consumes between 25% and 30% of the energy content in the hydrogen (CAPCI, 2023).
• Metal hydrides: Offer greater safety, though with lower energy density and higher OPEX (Hydrogen Council, 2023).
Despite its versatility, hydrogen logistics are quite complex. Currently, only 10% of produced hydrogen is transported over long distances, while the rest is consumed at the production site (CAPCI, 2023)
Renewable ammonia: an alternative with existing infrastructure
Ammonia, a compound of hydrogen and nitrogen, has been used for decades in the chemical industry. It is produced through the Haber-Bosch process, which combines both elements at high pressure and temperature. If the hydrogen used comes from renewable sources, the result is green ammonia, with zero net CO₂ emissions (ISPT, 2023)
Storage and transportation advantages
Unlike hydrogen, ammonia is liquid at -33°C, which facilitates its handling. It can be transported using existing ships and pipelines, significantly reducing infrastructure costs. Currently, more than 150 ports worldwide handle ammonia (H2eart for Europe, 2023).
In addition, ammonia has a higher volumetric energy density than hydrogen: 12.7 MJ/L compared to 8.5 MJ/L, making it a more efficient energy carrier for long-distance transport (CAPCI, 2023).
However, converting ammonia back into hydrogen involves energy losses. The cracking process, which breaks ammonia into hydrogen and nitrogen, has an efficiency of 69% (ISPT, 2023).
Applications and Use Cases
Large-scale energy storage
Hydrogen and ammonia have great potential for storing renewable energy. Hydrogen is ideal for seasonal storage in underground caverns, while ammonia can be used as a carrier for hydrogen transport (H2eart for Europe, 2023)
Mobility and maritime transportation
The maritime transport sector is exploring ammonia as an alternative fuel. Companies such as Maersk and MAN Energy Solutions have developed engines that can operate on ammonia (Hydrogen Europe, 2023).
Hydrogen, on the other hand, is more suitable for land and air transport, especially in fuel cell vehicles (ISPT, 2023)
Conclusion
Both hydrogen and renewable ammonia are viable solutions for the energy transition. They both enable renewable energy storage and reduce dependence on fossil fuels. However, the choice between one or the other will depend on their specific application.
Hydrogen is more efficient for land mobility and industrial processes, but its storage and distribution remain a challenge, and its implementation will require significant infrastructure investments. In contrast, ammonia benefits from an established infrastructure and can serve as a hydrogen carrier, although its conversion is not fully efficient and results in energy losses.
As technologies evolve and costs decrease, it is likely that both solutions will coexist across different sectors. The development of supportive policies and infrastructure projects will be decisive in determining which energy vector plays a larger role in global decarbonization. Collaboration between governments and industries will be essential to accelerate the adoption of these technologies and achieve emission reduction goals in the coming years
References
[1] Hydrogen Council. (2023). Hydrogen in Decarbonized Energy Systems. Hydrogen Council.
[2] Hydrogen Europe. (2023). Clean Ammonia in the Future Energy System. Recuperado de https://hydrogeneurope.eu.
[3] ISPT. (2023). Clean Ammonia Roadmap. Institute for Sustainable Process Technology.
[4] CAPCI. (2023). Climate Action Programme for the Chemical Industry (CAPCI). Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH.
[5] H2eart for Europe. (2023). The Role of Underground Hydrogen Storage in Europe. Hydrogen Europe