Hydrogen and Combustion Emissions: Atmospheric Pathways, NOₓ Impacts, and Clean Energy Futures

Dear Colleagues,

Hydrogen is increasingly recognized as a cornerstone in the transition to clean and low-carbon energy systems. However, its expanded production, distribution, and utilization—particularly through combustion applications—introduce significant environmental challenges that must be addressed. This Special Issue seeks to bring together interdisciplinary research exploring hydrogen’s role in atmospheric chemistry, with a focus on sustainable hydrogen technology, hydrogen emissions, combustion emissions, NOₓ formation, hydrogen leakage, and interactions with trace atmospheric species.

We invite contributions examining hydrogen-related emissions across production technologies (green, blue, or gray), their impacts on ozone and radical species, and the implications for air quality and climate. Both experimental and modeling are welcome, especially those that integrate life cycle assessments, emission monitoring, and environmental policy frameworks. Special attention will be given to studies addressing NOₓ emissions from hydrogen combustion and the broader climate alongside the ecosystem consequences of large-scale hydrogen deployment.

Aim and Scope

This Special Issue aims to explore the atmospheric implications of hydrogen production and combustion, particularly within the context of emerging clean energy technologies. As hydrogen becomes more widely adopted in transportation, industry, and power generation, it is essential to understand its full atmospheric impact—from NOₓ and trace gas emissions to long-term effects on air quality and climate forcing.

We seek to compile research that addresses the following:

• Hydrogen leakage and its atmospheric lifetime;
• Life cycle assessments of hydrogen production pathways with atmospheric considerations;
• Tropospheric and stratospheric chemistry are affected by hydrogen and its derivatives;
• Impacts of hydrogen infrastructure on local and regional air quality;
• Atmospheric modeling of hydrogen emission scenarios;
• The formation and environmental behavior of NOₓ and other combustion by-products from hydrogen and hydrogen-blended fuels;
• Radiative forcing implications and hydrogen’s global warming potential;
• Monitoring technologies for hydrogen and related emissions;
• Policy and regulatory strategies for managing hydrogen’s environmental footprint.

Importantly, this Special Issue is not limited to atmospheric or combustion emissions. We also welcome contributions that explore broader hydrogen fuel applications—such as dual-fuel systems, hydrogen blending with ammonia, methane, or biofuels, and engine performance and emission characteristics—with or without a specific atmospheric focus. Studies involving fuel design, emissions reduction strategies, renewable hydrogen integration, and combustion optimization are also encouraged.

By bringing together interdisciplinary research from combustion science, atmospheric chemistry, environmental policy, and clean fuel technology, this Special Issue aims to support the sustainable expansion of hydrogen energy systems in the pursuit of global decarbonization goals.

Dr. Omar I. Awad
Dr. Xiao Ma
Prof. Dr. Kumaran Kadirgama
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Atmosphere is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• atmospheric hydrogen
• combustion emissions
• NO_x emission
• hydrogen leakage
• green hydrogen emissions
• air quality impacts
• atmospheric chemistry
• hydrogen and climate interactions
• hydrogen capture
• sustainable hydrogen technology