This work explores the role of 3D concrete printing (3DCP) in achieving the relevant sustainable development goals (SDGs) that were set out by the United Nations. The study focuses on the recent progress and limitations of the three dominant types of cementitious mixtures, ordinary Portland cement (OPC), recycled aggregate-based cement, and geopolymers, and real-world applications for 3DCP. The study reveals that 3DCP has a significant advantage in terms of cost, with a potential to save around 78% and 60% of the costs associated with conventional construction methods and labor, respectively. Moreover, 3DCP consumes less water than conventional construction methods, with a water usage reduction of 20%. Additionally, it was found that 3DCP is on track to reduce the global energy utilization by 5% by the year 2025. Even though 3DCP bears a lower climate change impact, there is still work to be done to improve its sustainability.

Biological plants such as algae have a great potential of fixating CO₂ from flue gases or atmospheric air and converting it into useful biomass. This is because CO₂ is part of their photosynthesis process where the gas is an essential input ingredient. In this study, a closed system was designed for algae cultivation and carbon capture as a means to mitigate carbon emissions and at the same time assimilate biomass. Among species of saltwater microalgae there exist the Chlorella, Spirulina and Nannochloropsis among others. The latter was selected, as it is suitable for carbon capture because of its high carbon dioxide absorption characteristics, as well as its high oil content that is needed for the production of biofuel. To achieve this goal, the response of the algae was altered by generational mutations that were driven by environmental control of CO₂ concentrations, pH level, and temperature, in addition to the sufficient supply of nutrients. Two flow rates, 2 L/min and 5 L/min were used for the biomass measurements and carbon dioxide capture analysis, resulting in CO₂ removal efficiencies of 91.93%, and 65.43%, respectively. The benefit of the proposed system is twofold, first that it combines active carbon capture, which enhances algae growth. The algae is known to be able to thrive in harsh conditions of high temperature and high water salinity, which reflects favorably on the economy of the cultivation system as it does not require any expensive or energy intensive setups or treatments. This cultivation has a pronounced potential of biomass production that is left for a future study.

This paper introduces a comprehensive overview of various graphene production and deposition processes with a main focus on their utilization for energy harvesting and augmentation applications. A focused view on simple yet effective mechanical exfoliation techniques to produce graphene, and sometimes simultaneously deposit it. Two of these techniques, i.e. ball milling technique and compressed air blasting of graphite have been used and developed in our labs, respectively. The produced and deposited graphene via these methods is tested for energy harvesting enhancement in applications such as the spectral absorption enhancement of solar thermal collectors, electrode production for capacitive deionization, and as Nano-spacers in SERS applications for solar PV cells with an increase in 28% compared with Pt-based counterelectrode. The two mechanical production processes of graphene discussed are facile, economical and rapid, and is expected to bring solid-state graphene production a step closer to automation, a concept that is currently synonymous only with solution-based processes. These processes enabled the incorporation of a graphene layer on solar thermal collectors and this layer has exhibited 43% enhancement in efficiency than ones that did not have a graphene layer. Because of graphene eminence and its well-established place in many areas one of them being energy this is due to its unique thermal, mechanical, optical, electronic, and chemical properties. This paper will analyze the tools used for the synthesis of graphene and their throughput, cost and ease of use.