N 58° 40‘ 2.87“ – E 9° 11‘ 35.087“

The decarbonization of ammonia

The decarbonization of ammonia production involves categorizing various production methods into brown, blue, and green ammonia. Brown ammonia is higher carbon ammonia produced from a fossil fuel feedstock, while blue ammonia is low-carbon ammonia produced using carbon capture and storage technology in the manufacturing processes. Green ammonia is zero-carbon ammonia produced using sustainable electricity, water, and air, with the same ammonia produced but with different carbon emissions from the processes.

Brown ammonia:

  • Higher carbon ammonia

  • Made using fossil fuel as the feedstock

Blue ammonia:

  • Low-carbon ammonia

  • Brown ammonia with carbon capture and storage technology
    applied to the manufacturing processes

Green ammonia:

  • Zero-carbon ammonia

  • Made using sustainable electricity, water, and air

Green ammonia production – using green
hydrogen from water electrolysis

Green ammonia production involves using green hydrogen obtained from water electrolysis. In this process, hydrogen is produced by the electrolysis of water, while nitrogen is obtained directly from air using an air separation unit, which accounts for 2-3% of the process energy used. Ammonia is then produced using the Haber-Bosch process, powered by sustainable electricity. However, the main challenge of this process is its cost, which is about 85% electricity. In most parts of the world, electricity is still significantly more expensive than natural gas. The International Energy Agency estimates that electrolysis is cost-competitive with steam methane reforming with carbon capture at electricity prices between 1.5 to 5.0 USD cents/kWh (1.2 to 4.0 GBP pence/kWh), and with steam methane without carbon capture at 1 to 4 USD cents/kWh (0.8 to 3.1 GBP pence/kWh), assuming gas prices between 3 to 10 USD cents/MMBtu (2.3 to 7.7 GBP pence/MMBtu). (The Royal Society, 2018; International Energy Agency, 2019)

Over the past decade, the cost of electricity in areas with abundant renewable potential has decreased dramatically. Auction prices for utility-scale solar installations in Morocco, Chile, and Saudi Arabia indicate that water electrolysis may already be cost-competitive with steam methane reforming with carbon capture and storage in areas with optimal renewable energy conditions (Kruger et al., 2018; International Renewable Energy Agency, 2017)6,7. Green ammonia production via electrolysis is currently operating at technology readiness levels (TRLs) 5-9, and the lowest current costs of green ammonia production are already competitive with blue ammonia. However, the present costs of ammonia production vary widely across different regions due to variations in fuel and feedstock costs. The lowest electrolysis costs come from locations where renewable electricity costs are the lowest, which, globally, is solar, from areas of high global horizontal irradiance and onshore wind. The use of ammonia for hydrogen transportation on a massive scale is possible due to its existing high degree of technological readiness and may play a key role in the supply chain (Ash & Scarbrough, 2019)8.

6. Kruger, K., Eberhard, A., & Swartz, K. (2018). Renewable Energy Auctions: A Global Overview.
Retrieved from http://www.gsb.uct.ac.za/files/EEG_GlobalAuctionsReport.pdf

7. International Renewable Energy Agency. (2017). Levelised costs of electricity (LCOE) 2010-2017.
Retrieved from www.irena.org/Statistics/View-Data-by-Topic/Costs/LCOE-2010-2017

8. Ash, N., & Scarbrough, T. (2019). Sailing on Solar: Could green ammonia decarbonise international shipping? Environmental Defense Fund.
Retrieved from https://europe.edf.org/file/399/download?token=agUEbKeQ

„Chemical energy can be stored
and transported using ammonia
as a medium.“

New zero-carbon uses
for green ammonia

Besides decarbonizing current uses of ammonia, the development
of green ammonia production has additional benefits, including:

  • Using ammonia as a medium to store and transport chemical energy. This energy can be released directly or through the full or partial decomposition of ammonia to release hydrogen. The hydrogen or ammonia-hydrogen mixture can then react with oxygen in the air to generate energy.

  • Using ammonia as a transport fuel by directly com-busting it in an engine or by a chemical reaction with oxygen in a fuel cell, which produces electricity to power a motor.

  • Using ammonia to store thermal energy through liquid-to-gas phase changes, solid-to-solid phase transformations, and absorption with, for example, water.

Storing and transporting sustainable energy

The flow of energy in a zero-carbon economy begins with generating primary electricity from sustainable sources. However, this energy needs to be either utilized instantly or stored. There are various ways to store and recover zero-carbon energy, including:

  • electrochemical storage in batteries,

  • physical storage in pumped hydroelectricity and compressed gases,

  • chemical storage in the form of zero-carbon electro fuels such as hydrogen or ammonia.

Each zero-carbon storage alternative has its benefits in terms of flexibility, efficiency, energy density, cost, scale, and longevity. While it is ideal to minimize energy transitions, factors such as energy and financial costs of storage and transportation must also be considered. For instance, storing and using hydrogen locally might be preferable if there is low-cost, large-scale gas storage (e.g., in salt caverns) available. Ammonia, with its high energy density and established global transportation and storage infrastructure, could provide a new, comprehensive sustainable energy storage and distribution solution worldwide. Compared to compressed or liquefied hydrogen, ammonia‘s ease of storing as a compressed or refrigerated liquid makes it a viable option for storing zero-carbon energy and transporting it by pipeline, road, rail, or ship.