Pollutant reporting protocols for low-carbon and carbon-free fuels combustion: a review on current challenges and progress
File(s)
Published version
Author(s)
Ripoll Kameid, Nicolás
ApSimon, Helen
Type
Journal Article
Abstract
This review examines existing pollutant reporting protocols and their corresponding emission metrics, focusing on their suitability for assessing pollutant emissions from carbon-free (hydrogen and ammonia) and low-carbon fuels (synthetic dimethyl ether and methanol) from an air pollution perspective. Meeting global decarbonisation targets has introduced technical challenges to the reporting of pollutants, with ammonia, hydrogen, dimethyl ether, and methanol, being the most discussed energy carriers for implementation in the transport and heat sectors, as well in hard-to-decarbonise industries such as cement and steel. Moreover, existing standards and methods were developed in a hydrocarbon-led environment, and, in most cases, are not suitable for providing comparable emission values in fuel-flexible operations. A key point of this study is the discussion on the challenges of using concentration-based emission metrics for the combustion of carbon-free and low-carbon fuels. An overview of the existing studies establishing the theoretical framework to support this discussion is also provided. A comparative analysis of existing emission metrics and standards enables a clear overview of the challenges encountered when using carbon-free and low-carbon fuels. Migrating existing standards to performance-based metrics linked to process outputs has been consistently shown to provide the fairest emission metric in fuel flexible scenarios. However, the use of appropriate conversion factors for concentration-based emission metrics has been reported as the path of least resistance for existing European standards. Finally, this review offers a general overview, to both the combustion and air pollution communities, on the challenges associated with properly reporting pollutant emissions in an ever-changing energy landscape.
Date Issued
2025-04-04
Date Acceptance
2025-03-19
Citation
International Journal of Hydrogen Energy, 2025, 143, pp.550-560
ISSN
0360-3199
Publisher
Elsevier BV
Start Page
550
End Page
560
Journal / Book Title
International Journal of Hydrogen Energy
Volume
143
Copyright Statement
© 2025 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Identifier
10.1016/j.ijhydene.2025.03.295
Publication Status
Published
Date Publish Online
2025-04-04