The environmental impacts of hydrogen production can vary widely depending on the production energy source and process. This implies that the collection and management of sustainability data for hydrogen production globally is desired to ensure accountable development of the sector. Life cycle assessment (LCA) is an internationally recognized tool for environmental impact assessment. Integrating LCA in the holistic evaluation of the hydrogen value chain is desirable to ensure the cleanness and sustainability of the various available hydrogen production pathways. The objective of this review is to evaluate the methodology used in assessing the life cycle impact of hydrogen production including proposed documentation such as the guarantee of origin (GO) and certification schemes, and review case studies from Australia. An analysis of the sustainability strategies and schemes designed by the Australian government, aimed at mitigating climate change and promoting the hydrogen economy, was conducted. The case studies that were discussed identified the preferred available scaled routes of clean hydrogen production to be water electrolysis, which is based on technologies using renewable energy. Other dominant technologies which incorporate carbon capture and storage (CCS) were envisaged to continue playing a role in the transition to a low carbon economy. Additionally, it is critical to assess the greenhouse gas (GHG) emissions using appropriate system boundaries, in order to classify clean hydrogen production pathways. Harmonizing regulatory stringency with appropriate tracking of renewable electricity can promote clean hydrogen production through certification and GO schemes. This approach is deemed critical for the sustainable development of the hydrogen economy at the international level.

In Physics of Fluids, researchers model the way snow gathers on a roof based on snowflake size and distribution. The model considers how turbulence can affect recently landed snow and how wind can affect its gathering. Higher wind speeds will interrupt accumulation, reducing depth, but the effects of particle size on accumulation are all heightened under higher wind conditions — larger particles will be more resistant to the wind, and smaller ones will accumulate less.