What is green ammonia?
Ammonia, NH3, is a widely used chemical and one of the world's "big four" chemical productions. It has been traditionally used as a fertiliser but is being increasingly seen as a fuel source for a carbon-free future.
However, ammonia production still creates a significant amount of greenhouse gases—about 1.8% of the world's carbon dioxide emissions come from ammonia production. The process must be decarbonised to sustain its existing role in a net zero future. Green ammonia is ammonia made in a carbon-free way using renewable energy.
One way of making green ammonia is to combine hydrogen, created by the electrolysis of water, with nitrogen, extracted from the air, in a Haber-Bosch reactor – with the whole process being powered by renewable energy. This more environmentally friendly process sits in contrast to grey/brown, blue and turquoise ammonia.
Grey, also known as brown, ammonia is made from methane, water and air using Steam Methane Reforming (SMR) to produce the hydrogen. This process not only uses a lot of energy but also significant amounts of carbon dioxide are produced during the SMR process.
Blue ammonia is produced using the same conventional method as grey/brown ammonia but the by-product of carbon dioxide is captured and stored. Finally, turquoise ammonia uses pyrolysis to convert methane into pure carbon and hydrogen, which is then reacted with nitrogen to make ammonia.
Opportunities for Green Ammonia
With the development of new technologies, ammonia has the potential to:
- Support the National Grid to run on renewable power
- Help hard-to-decarbonise transport sectors
- Support the hydrogen economy
Green ammonia can be cost competitive with grey and blue ammonia as:
- Renewable energy prices are dropping
- Carbon emission prices will increase
- Gas prices are increasingly volatile
A video giving information about Green Ammonia can be found at the bottom of this page, and further information can be found in a Royal Society Briefing Paper.
R&D Requirements for Green Ammonia
There are three broad areas of research and development for Green Ammonia
- Production
- Storage and distribution
- Utilisation
Production-
- Accommodate intermittent renewable energy input
- Investigate alternatives to the Haber-Bosch process
- Engineering innovation to increase efficiency
- Investigate different production scales
- Health, safety and environmental considerations
Storage and distribution-
- Lower cost vessels
- Maritime and port infrastructure
- Supply chain stakeholder clustering
- Fuel handling, distribution and re-fueling systems
- Health, safety and environmental considerations
Utilisation-
- Ammonia reciprocating engines
- Ammonia gas turbines
- Ammonia aviation engines
- Ammonia fuel cells
- Ammonia cracking to supply hydrogen
- Health, safety and environmental considerations
UKRI Activity in Green Ammonia
The ASPIRE project will demonstrate a 150 kW flexible green ammonia plant that will be powered uniquely by an array of solar panels and a small wind turbine. The demonstration employs an electrolyser to generate hydrogen, an air separator to generate nitrogen, and a synthesis loop centred around a segmented synthesis reactor. The design permits a high turndown of the ammonia generation rate and fast response to changes in set point, making it possible to track an intermittent renewable power source and generate green ammonia in proportion to the available power.
The demonstration plant due to be built in 2024 aims to prove that a commercial-scale version of the technology, i.e. 10-200 MW, could achieve a green ammonia price of less than £1000/tonne and a carbon output of 0.18 kgCO2/kgNH3. The ASPIRE project is funded by the Department for Energy Security and Net Zero and the consortium includes STFC, Johnson Matthey, the University of Bath, and Frazer Nash Consultancy
Other green ammonia research
STFC's Energy Research Unit's green ammonia projects include:
- ASPIRE - Flexible Green Ammonia Synthesis
- REV (Renewable Energy Vector Simulation tool) - Feasibility studies for offshore production of ammonia
- REACH (Renewable Energy Ammonia CHarging) - Demonstration of a direct Ammonia fuel-cell for zero carbon charging or back-up power
- HPAC (High-Pressure Ammonia Cracker) - Demonstration of high-pressure ammonia cracking for the purpose of preparing combustible mixtures for use in Ammonia burning gas turbines and reciprocating combustion engines
- Design of an efficient Ammonia cracker for generating pure hydrogen for PEM fuel cells
Thank you to our sponsors
This includes the Department for Energy Security and Net Zero, the Engineering & Physical Sciences Research Council, and the Science and Technology Facilities Council.
Video
Contact information
If you have any further questions, please contact Dr Tristan Davenne from STFC's Energy Research Unit at tristan.davenne@stfc.ac.uk.
The Energy Research Unit is a part of the Science and Technology Facilities Council's Technology Department. Find out more information about their capabilities on their website.