The escalating climate crisis and unsustainable waste management practices necessitate integrated approaches that simultaneously address energy security and environmental degradation. Hydrogen, with its high energy density and zero-carbon combustion, is a key vector for decarbonization; however, conventional production methods are fossil-dependent and carbon-intensive. This systematic review explores biowaste-to-hydrogen (WtH) technologies as dual-purpose solutions, converting organic waste to clean hydrogen while reducing greenhouse gas emissions and landfill reliance. A comprehensive analysis of different conversion pathways, including thermochemical (gasification, pyrolysis, hydrothermal, and partial oxidation (POX)), biochemical (dark fermentation, photofermentation, and sequential fermentation), and electrochemical methods (MECs), is presented, assessing their hydrogen yields, feedstock compatibilities, environmental impacts, and technological readiness. Systematic literature review methods were employed using databases, such as Scopus and Web of Science, with strict inclusion criteria focused on recent peer-reviewed studies. This review highlights hydrothermal gasification and dark fermentation as particularly promising for wet biowaste streams, like food waste. Comparative environmental analyses reveal that bio-based hydrogen pathways offer significantly lower greenhouse gas emissions, energy use, and pollutant outputs than conventional methods. Future research directions emphasize process integration, catalyst development, and lifecycle assessment. The findings aim to inform technology selection, policymaking, and strategic investment in circular, low-carbon hydrogen production.

Hydrogen (H₂) production from biomass has emerged as a promising alternative to fossil-based pathways, addressing the global demand for low-carbon energy solutions. This study compares the environmental impacts of two biomass-based H₂ production processes, biogas reforming and agricultural residue gasification, through a life cycle assessment (LCA). Using real-world data from the literature, the analysis considered key system boundaries for each process, including biogas production, reforming, and infrastructure, for the former, and biomass cultivation, syngas generation, and offgas management, for the latter. Environmental impacts were evaluated using SimaPro software (Version 9.4) and the ReCiPe midpoint (H) method. The results revealed that biogas reforming emits approximately 5.047 kg CO₂-eq per kg of H₂, which is 4.89 times higher than the emissions from agricultural residue gasification (1.30 kg CO₂-eq/kg H₂), demonstrating the latter’s superior environmental performance. Gasification consumes fewer fossil resources (3.20 vs. 10.42 kg oil-eq) and poses significantly lower risks to human health (1.51 vs. 23.28 kg 1,4-DCB-eq). Gasification water consumption is markedly higher (5.37 compared to biogas reforming (0.041 m³/kg H₂)), which is an important factor to consider for sustainability. These findings highlight gasification as a more sustainable H₂ production method and emphasize its potential as an eco-friendly solution. To advance sustainability in energy systems, integrating socio-economic studies with LCA is recommended, alongside prioritizing agricultural residue gasification for hydrogen production.

Additive manufacturing (AM) of composite materials is promising to create customizable products with enhanced properties, utilizing materials like carbon fibers (CFs). To increase their circularity, composite recycling has been proposed to re-introduce the recovered components in AM. A careful evaluation of recycling is necessary, considering the sustainability and functionality (i.e., mechanical properties) of the recovered components. Thus, Life Cycle Assessment (LCA) is applied to estimate the environmental impacts of AM via Fused Filament Fabrication (FFF), using virgin or recycled CFs via solvolysis at a laboratory scale. This study aims to provide a detailed Life Cycle Inventory (LCI) of FFF and evaluate the sustainability of using recycled CFs in AM. For both virgin CF manufacturing and CF recycling, electricity consumption was the main contributor to environmental impacts. CF recovery via solvolysis resulted in lower impacts across most impact categories compared to AM with virgin CFs. Different scenarios were examined to account for the mechanical properties of recycled CFs. AM with 75% recycled CFs, compared to 100% virgin CFs undergoing landfilling, resulted in over 22% reduction in climate change potential, even after a 50% loss of recycled CF functionality. Overall, this study offers insights into the LCI of FFF and shows that CF recycling from composites is worth pursuing.

Poland is facing demanding challenges to achieve a sustainable energy mix in the near future. Crucial and tough decisions must be made about the direction of the national energy economy, safety, and environmental impact. Considering the electricity and heating demand forecast, this paper proposes an optimization model based on the Grey Wolf Optimizer meta-heuristic to support the definition of ideal energy mix considering the investment and operational costs. The proposed methodology uses the present energy mix in Poland (the most recent values are from 2017) to calibrate the model implemented in the EnergyPLAN tool. Afterwards, EnergyPLAN relates to an optimization process allowing the identification of the most convenient energy mix in 2040 in Poland. The values obtained are compared with those proposed by Polish public entities showing advantage regarding the global costs of the project nevertheless respecting the same levels of CO₂ and the energy import and export balance. The expected savings can achieve 1.3 billion euros a year and more than 8 million tonnes of CO₂ emission reduction. Sensitivity analysis considering the decrease of the global cost of renewables-based sources is also presented.

Standard methods for assessing the environmental impact of waste management systems are needed to underpin the development and implementation of sustainable waste management practice. Life cycle as...