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.

Energy storage for medium- to large-scale applications is an important aspect of balancing demand and supply cycles. Hydropower generation coupled with pumped hydro storage is an old but effective supply/demand buffer that is a function of the availability of a freshwater resource and the ability to construct an elevated water reservoir. This work reviews the technological feasibility of hydropower generation and also pumped hydro storage and its geographical distribution around the world. There is also an emphasis on installations in the Middle East and North Africa (MENA) in terms of available capacity as well as past and future developments and expansions. A discussion is presented on a project taking place in the United Arab Emirates (UAE) in the Hatta region, which has a water reservoir that would be fit for utilization for pumped hydro storage applications. Once the project is commissioned in 2024, it will provide an estimated 2.06 TWh per year, helping the UAE achieve the goal of relying on 25% renewable energy resources in their energy mix by 2030. These results were obtained by using EnergyPLAN software to project the effect of utilizing various energy resources to face the expected demand of ~38 TWh in 2030.

The world has heavily relied on fossil fuels for decades to supply energy demands. However, the usage of fossil fuels has been strongly correlated with impactful problems, which lead to global warming. Moreover, the excessive use of fossil fuels has led to their rapid depletion. Hence, exploring other renewable and sustainable alternatives to fossil fuels is imperative. One of the most sustainable fossil fuel alternatives is biofuel. Microalgae-based biofuels are receiving the attention of researchers due to their numerous advantages compared with those obtained from other types of feedstocks. Hence, it is essential to explore the recent technologies for biofuel produced from microalgae species and define the possible challenges that might be faced during this process. Therefore, this work presents the recent advancements in biofuel production from microalgae, focusing on emerging technologies such as those using nanomaterials and genetic engineering. This review focuses on the impact of nanoparticles on the harvesting efficiency of various microalgae species and the influence of nanoparticles on biofuel production. The genetic screening performed by genome-scale mutant libraries and their high-throughput screening may assist in developing effective strategies for enhancing microalgal strains and oil production through the modification of enzymes. Furthermore, the barriers that limit the production of biofuels from microalgae are introduced. Even though microalgae-based biofuels are perceived to engage with low negative impacts on the environment, this review paper touches on several environmental issues associated with the cultivation and harvesting of microalgae species. Moreover, the economic and technical feasibility limits the production of microalgae-based biofuels.

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.