This paper redefines hydrogen colour codes based on carbon dioxide emissions. It highlights that there are several colour codes, which disregard the carbon dioxide emitted in the hydrogen production process (e.g., electrolysis with renewable energy, steam reforming of natural gas, coal gasification, etc.). Some colours are used interchangeably for different technologies, while many colour codes do not assign a colour for all possible production pathways. Therefore, the existent framework is misleading and lacks scientific underpinning of colour labelling (e.g., green, blue, grey, black, yellow, purple, turquoise, etc.). This paper builds upon the work of Nikolaidis and Poullikkas and provides a qualitative assessment of the colour codes used to label various technologies. Based on a comparative analysis of the latest research and analysing hydrogen colour codes, this paper inquires whether there is or not, a common understanding of the hydrogen production pathways that lie behind each hydrogen “colour”. This paper finds that there are major inconsistencies regarding the colours used, especially for technologies using fossil fuels as an energy source, but nuclear energy has also been found to have discrepancies in labelling. At the same time, there is only one colour used to describe a wide range of technologies using renewable energy (i.e., green). However, if carbon dioxide emissions of the corresponding production technology were visually represented using a predefined colour-code, the hydrogen produced with fossil fuels would have a less diverse colour range, than current colour palettes would suggest. Rather than being “grey” and “blue”, coal, oil and gasbased hydrogen appear to be different shades of “brown” and “black”. This finding illustrates that these technologies emit more carbon dioxide emissions than an initial labelling would suggest, which raises the question whether any colours of hydrogen, other than its “green” versions, is compliant with the objectives of the Paris Agreement.

Green hydrogen receives attention across academia, governments, and practitioners as a technical solution to decarbonize economic sectors, yet its large-scale deployment faces significant barriers and depends on effective policy incentives. There is little research examining how actors perceive barriers and incentives. Understanding such perspectives is key to designing impactful policies. This study investigates actors’ perceptions of barriers and incentives and how these vary across organizational characteristics, gender, managerial role, and Romanian market exposure. An online survey conducted in 2025 collected responses from diverse stakeholders across the European hydrogen value chain (N = 236). Responses were analyzed using Chi-square, Mann–Whitney U, and Kruskal–Wallis tests, as well as Pearson’s correlations. Results show that “high capital costs”, “regulatory uncertainty”, and “lack of infrastructure” are seen as the most critical barriers, while “financial subsidies”, “regulatory mandates”, and “public policies” are the preferred incentives. Statistically significant differences emerge for “public acceptance” and “limited market demand” across organizational roles and types, and for “public–private partnerships” among respondents with Romanian market contact. By showing that barriers and incentives are not only structural, but also shaped by individual and organizational characteristics, this study highlights conceptually that green hydrogen policies must consider diverse business perspectives to be successful.

This paper analyses the global project database on hydrogen production from the International Energy Agency (IEA)...

Mitigation of greenhouse gasses heightens attention on hydrogen as a crucial element in the global energy transition, while combating climate change. Building on previous analyses of hydrogen projects compiled by the International Energy Agency (IEA), this paper provides an updated and comprehensive analysis of this database while delving deeper into the intricacies of hydrogen products and their economic end-uses. Given the availability of alternative technologies in some sectors, it is crucial to understand the nuances of hydrogen projects, particularly in "hard-to-decarbonize" or "hard-to-abate" sectors such as iron and steelmaking, where the key benefit of using green hydrogen is to reduce greenhouse gas emissions from the process and energy use. Therefore, this paper’s objective is to provide insights into the distribution, technologies, and trends of hydrogen projects produced with renewable power, while unraveling the diverse products of these projects and identify the sectors benefiting most from them. Employing a rigorous statistical data analysis, a dataset encompassing approximately 2000 hydrogen projects worldwide is scrutinized. These questions guide the investigation: a) What is the distribution of hydrogen projects across different countries globally? b) What are the key trends in technology choice over time? c) What are the key trends of hydrogen projects using renewable energy? d) What are the primary products of green hydrogen projects? e) Which end-use sectors are benefiting from the “green” hydrogen products the most? The findings reveal a spectrum of internationally pursued hydrogen-derived products, ranging from hydrogen to ammonia and beyond. Moreover, they provide insights into industries that stand to gain from innovation, including mobility, ammonia production and other industrial applications. This paper significantly contributes to the understanding of “green” hydrogen products, and their end-uses. Governments and businesses can leverage this knowledge to make informed policy and investment decisions in a rapidly evolving market.