Hydrogen, a carbon-free fuel, has the potential to aid global nations in achieving eight of the 17 Sustainable Development Goals (SDG). The shortcomings associated with H2 transportation and storage can be mitigated by using NH3 as hydrogen carrier because of its better safety, physical, and environmental properties. However, to achieve the global climate target, green ammonia production must be incremented by four times (688 MT) from the current level. Hence, understanding of advanced green NH3 production and storage technologies, along with the factors that influence them becomes necessary. It also aids in identifying the factors hindering green H2 and NH3 production, which can be resolved by promoting research. At the same time, drafting policies that encourage green H2 and NH3 production can abet in overcoming the bottleneck faced by the industry. Presently, green ammonia production can be made feasible only when the renewable electricity cost is less than $20/MWh and carbon price of $150/t of CO2 emissions is levied. Approximately 80 % of the energy consumed during NH3 is spent on H2 generation; therefore, it is necessary to enact policies that promote green H2 production globally. Producing green H2 can aid in mitigating ∼90 % of the greenhouse gases emitted during NH3 manufacturing thereby facilitating to reduce the carbon footprint of H2 carrier and decarbonize NH3 industry.

Microalgae cultivation is gaining interest as a sustainable alternative to the conventional wastewater (WW) treatment and nutrient recovery. Current study presents a comprehensive life cycle assessment (LCA) of microalgae cultivation in distinct wastewaters. Two different microalgae species in three different wastewaters were compared for sustainability performance in six scenarios. LCA was conducted using SimaPro (v9.3.0.3) and ReCiPe 2016 Midpoint method. The findings of the study reveal that global warming potential ranged between −678 and − 1357 g CO2eq./m3. Chlorella sp. cultivated in dairy WW shown higher environmental performance across the scenarios with GWP of −1357 g CO2eq./m3. The average global warming potential (GWP) of single-pot microalgae-based wastewater treatment got reduced by 240 %. The key inference of this study is that cultivation of the microalgae as single-pot treatment system not only helps in environmental sustainability but also holds significant promise for combating climate change as negative emission technology (NET).