Tristan Davenne, Ben Peters, and Richard Cowan attended the symposium to present their projects:

• ASPIRE:  Ammonia Synthesis Plant using Intermittent Renewable Energy.
• REACH: A Review of the Design and Testing of an Ammonia-Fuelled Solid-Oxide Fuel Cell System with Free Cracking from Waste Heat.
• HPAC: Design and testing of a high-pressure ammonia cracker.

Tackling the reliability of renewable energy

Ammonia is created by reacting hydrogen with nitrogen at a high temperature and pressure, in a reaction known as the Haber-Bosch process.

Conventional ammonia (aka grey ammonia) uses natural gas as the source of this hydrogen, leading to significant carbon emissions (specifically 1.8% of global greenhouse gases).

In contrast, green ammonia is made entirely from renewable energy, water, and air, with no direct carbon emissions.

So, why don't we make only green ammonia?

Grey ammonia is generated in large chemical plants running 24 hours a day, 7 days a week, and is typically seen as cheaper to make than the greener alternative.

However, it is interesting to note that, due to gas price volatility, grey ammonia prices did exceed projections for green ammonia prices for a short period in 2022.

Unlike conventional ammonia, the production of energy from renewable sources, like solar or wind, can vary from minute to minute, depending on factors such as cloud coverage or wind speed.

This poses a technical challenge for the realisation of green chemical processes: how to create a reliable system of production with a less than reliable source of energy.

The answer, according to our ERU, is flexibility- specifically the ability to respond in line with available renewable power.

The minds behind the ASPIRE project aim to demonstrate the viability of highly flexible green ammonia synthesis by building a small-scale plant on the ERU's test site at Rutherford Appleton Laboratory. 

The project, which was launched in early 2022, is a collaboration between STFC, the University of Bath, Jonson Matthey, and Frazer-Nash Consultancy. It also received funding from the Department for Energy, Security, and Net Zero.​

Solving the ammonia economy puzzle

ASPIRE focuses on just one piece of the 'ammonia economy' puzzle.  You cannot solve the challenges of producing ammonia without also figuring out a way to use it.

The ERU's HPAC and REACH projects work to address this challenge.

REACH, or the Renewable Energy Ammonia Charging system, investigates the use of an ammonia-fuelled solid-oxide fuel cell system (SOFC) with an integrated cracker.

Ammonia-fuelled fuel cells represent a possible option for the decarbonisation of off-grid, temporary, or emergency power systems.

Imagine travelling to a remote far-flung destination, unreachable by the electrical grid. You would need a reliable system for producing electricity, especially in an emergency.

Rather than relying on a polluting diesel generator, you could take a system like REACH – a stand-alone unit that uses ammonia to generate electricity.

HPAC, the High-Pressure Ammonia Cracker, on the other hand, is designed to replicate part of an ammonia-burning engine, breaking down some ammonia into hydrogen so that the fuel is compatible with different types of combustion.

This could be useful for shipping and transport, replacing or retrofitting heavy fuel oil engines that produce a large amount of carbon dioxide while shipping goods worldwide.

To learn more about green ammonia and the ERU's projects, please visit their website.​

Written by Cat Lewin-Williams.