British groups Sunborne Systems Ltd. and AFC Energy PLC have tested their ammonia crackers. Sunborne has indicated that it has tested its ammonia reactor at a scale equivalent to the consumption of internal combustion engines in motor vehicles. The U.K.'s National Physical Laboratory (NPL) has tested the technology developed by AFC and states that it produces hydrogen with a purity of 99.99%.
The test operation at the Sunborne demonstrator plant in Oxfordshire exceeded expectations, according to the company. The company said it has proven that the ammonia cracking reaction is capable of producing a fuel mixture that can power a 56-kW (75-hp) engine. The test program conducted at the Culham Science Centre showed that the reactor had high thermal efficiency and was suitable for higher-energy internal combustion engines and industrial applications, he said. Sunborne's goal, he said, is to extend the technology for maritime applications.
AFC, also based in the United Kingdom, has demonstrated its modular ammonia cracking technology. The demonstration, conducted at NPL, shows that the integrated cracking and purification system produces hydrogen with a purity level of 99.99%, it said. In the process, the ammonia residues in the hydrogen are below the permitted levels under the ISO 14687:2019 standard, according to the NPL. AFC plans to develop its technology for stationary power generation, marine propulsion and heavy vehicle refueling.
Sunborne reactor is retrofittable
The company was founded in 2021 by Reaction Engines, the UK Science and Technology Facilities Council (STFC) and cleantech venture investor Kiko Ventures. The company's goal, it says, is to develop an innovative, compact ammonia reactor technology that will enable decarbonization in heavy-load sectors such as shipping.
Combining Reaction Engines' heat management and heat exchange technology with STFC's cracking catalysts, the reactor converts from liquid ammonia to a mixture of hydrogen, nitrogen and "unsplit" ammonia. The reactor can be retrofitted into existing fossil fuel-fired systems and power generators.
As a next step, the company plans to conduct a larger demonstration. It aims to reach at least 1 MW by 2025.
99.99% Purity of the AFC Cracker
The AFC ammonia cracker can be used to "crack" ammonia into discrete hydrogen and nitrogen molecules. The hydrogen can then be consumed as fuel in fuel cells or combustion, while the nitrogen is released into the atmosphere (which is approximately 78% nitrogen) without carbon emissions.
Since unsplit traces of ammonia in hydrogen can damage a fuel cell, it is an important achievement that the ammonia cracker reactor meets the ISO standard for residual ammonia ("parts per billion" or "PPB") in hydrogen. Published in 2019 by the International Organization for Standardization (ISO), ISO 14687:2019 sets the international standard for the minimum quality characteristics of hydrogen and specifies the maximum allowable level of residual ammonia.
Achieving the ISO standard for hydrogen purity is a milestone in the capability of cracker technology, according to AFC. "Ammonia to power" could not only be used in stationary or marine applications, but also cracked ammonia could be used to fuel trucks and buses as an alternative to a distributed network of small electrolysers.
