A systematic review of heat recovery from roads for mitigating urban heat island effects: current state and future directions

Heat recovery from roads is a promising technology to address the urban heat island effect. This review paper aims to provide a comprehensive analysis of the current state and future directions of heat recovery from roads to address the urban heat island effect while generating renewable energy. The study covers various aspects such as theoretical background, economic feasibility, environmental impact, and materials design techniques. A systematic search of relevant literature was conducted to analyze and synthesize different heat recovery systems’ efficiency, performance, and potential. The paper also discusses the economic feasibility and environmental impact of these systems, including installation and maintenance costs, revenue generation, and local ecosystem impact. The review explores the role of different materials, such as PEX pipe, asphalt mix, and carbon nanotubes, in improving heat harvesting systems’ efficiency. The paper concludes with a discussion of research gaps and future directions in the field of heat recovery from roads. This study provides a valuable resource for researchers, practitioners, and policymakers interested in sustainable and efficient energy system development

Planar laser-induced fluorescence and chemiluminescence analyses of CO2-argon-steam oxyfuel (CARSOXY) combustion

Strict regulations and acts have been imposed to limit NOx and carbon emissions. The power generation industry has resorted to innovative techniques to overcome such a low level of tolerance. Amongst those in the literature, CO2-argon-steam oxyfuel (CARSOXY) gas turbines have theoretically been proven to offer an economically sustainable solution while retaining high efficiency. Although theoretical studies have characterized CARSOXY, no experimental evidence has been provided in the literature. Therefore, this paper attempts to experimentally assess CARSOXY in comparison to a CH4/air flame. OH* chemiluminescence integrated with OH Planar Laser-Induced Fluorescence (PLIF) imaging has been utilized to study flame stability and flame geometry (i.e., the area of highest heat intensity (AOH¯¯¯¯¯¯Max center of highest heat intensity (COH¯¯¯¯¯¯Max)) over a range of working fluid Reynolds’ numbers and oxidizing equivalence ratios. In addition, the standard deviation of heat release fluctuations (σOH*/OH¯¯¯¯¯¯) has been utilized as the base-criteria to compare the stability performance of CARSOXY to CH4/air combustion. Moreover, turbulence-chemistry interactions have been described using Damköhler numbers and by plotting Borghi regime diagrams. This paper suggests a modified numerical approach to estimate Damköhler numbers and plot regime diagrams for non-premixed combustion by utilizing the Buckingham π theorem based on experimental observations and results. CARSOXY flames showed lower flame intensity than that of the CH4/air flame throughout the entire Re interval by approximately 16%, indicating higher heat release. The Damköhler numbers of the CARSOXY flame were also greater than those of the CH4/air flame in all conditions, indicating more uniform CARSOXY flames. It was found that the tendency of the CARSOXY flame of approaching the concentrated reaction zone is greater than that of the CH4/air flame

Window-windcatcher for enhanced thermal comfort, natural ventilation and reduced COVID-19 transmission

We investigate and test the effectiveness of a novel window windcatcher device (WWC), as a means of improving natural ventilation in buildings. Using ANSYS CFX, the performance of the window-windcatcher is compared to a control case (no window-windcatcher), in three different geographic locations (Cardiff, Doha and Amman) which are representative of three different types of atmospheric conditions. The proposed window-windcatcher has been shown to improve both thermal comfort and indoor air quality by increasing the actual-to-required ventilation ratio by up to 9% compared to the control case as per the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards. In addition, the locations with minimum velocities have been identified. Those locations correspond to the regions with a lower infection risk of spreading airborne viruses such as SARS-CoV-2, which is responsible for the COVID-19 pandemic

Ammonia production plants - a review

Considering the global scientific and industrial effort to utilize ammonia as an alternative to natural gas combustion to run power plants, it is crucial to objectively assess the literature before adjusting or proposing new and advancing techniques in ammonia plants while considering a variety of factors. As a result, this paper assesses the global effort to improve existing ammonia plants and identifies progress by evaluating the currently available dataset to identify knowledge gaps and highlight aspects that have yet to be addressed. Based on the literature reviewed in this study, it was found that the majority of the efforts to advance ammonia plants mainly focus on reducing energy consumption, implementing alternative methods to extract the necessary hydrogen and nitrogen in the process, and changing the cycle arrangement and operating conditions to make the industrial plants more compact. However, regarding carbon reduction in the ammonia production process, it is clear that the effort is less significant when compared to the global scientific and industrial progress in other areas

Electrochemical reduction of CO2 into formate/formic acid: A review of cell design and operation

The release of carbon dioxide (CO2) into the atmosphere is threatening the environment and ecosystems, resulting in major challenges to sustainable development for modern industry. In this context, CO2 electrochemical reduction (CO2 ECR) is one of the most promising technologies to mitigate the effects of high CO2 content in the atmosphere. Electrochemical technology can convert CO2 into value-added chemicals including methanol, ethanol and formate. In this review, different mechanisms of CO2 electrochemical reduction into formate/formic acid are reviewed, highlighting the different cell designs. Also, the effect of cell design and operating parameters on the electrochemical reduction process are discussed. The review aims to highlight recent developments in the CO2 electrochemical cell design for formate production and provide guidelines for future advancements. Challenges of large-scale production and research gaps are also provided. 2023 The AuthorsThe authors would like to acknowledge the support of Qatar National Research Fund (a member of Qatar Foundation) through Grant # NPRP 12 C-33923-SP-102 (NPRP12 C-0821-190017). The findings achieved herein are solely the responsibility of the authors. Open Access funding provided by the Qatar National Library.Scopu

Preliminary design and analysis of a photovoltaic-powered direct air capture system for a residential building

To promote the adoption of Direct Air Capture (DAC) systems, this paper proposes and tests a photovoltaic-powered DAC system in a generic residential building located in Qatar. The proposed DAC system can efficiently reduce CO2 concentration in a living space, thus providing an incentive to individuals to adopt it. The ventilation performance of the building is determined using Computational Fluid Dynamics (CFD) simulations, undertaken with ANSYS-CFD. The CFD model was validated using microclimate-air quality dataloggers. The simulated velocity was 1.4 m/s and the measured velocity was 1.35 m/s, which corresponds to a 3.5% error. The system decarbonizes air supplied to the building by natural ventilation or ventilation according to the ASHRAE standards. Furthermore, the performance of the photovoltaic system is analyzed using the ENERGYPLUS package of the Design Builder software. We assume that 75% of CO2 is captured. In addition, a preliminary characterization of the overall system’s performance is determined. It is determined that the amount of CO2 captured by the system is 0.112 tones/year per square meter of solar panel area. A solar panel area of 19 m2 is required to decarbonize the building with natural ventilation, and 27 m2 is required in the case of ventilation according to the ASHRAE standard

Preliminary design and analysis of a photovoltaic-powered direct air capture system for a residential building

To promote the adoption of Direct Air Capture (DAC) systems, this paper proposes and tests a photovoltaic-powered DAC system in a generic residential building located in Qatar. The proposed DAC system can efficiently reduce CO2 concentration in a living space, thus providing an incentive to individuals to adopt it. The ventilation performance of the building is determined using Computational Fluid Dynamics (CFD) simulations, undertaken with ANSYS-CFD. The CFD model was validated using microclimate-air quality dataloggers. The simulated velocity was 1.4 m/s and the measured velocity was 1.35 m/s, which corresponds to a 3.5% error. The system decarbonizes air supplied to the building by natural ventilation or ventilation according to the ASHRAE standards. Furthermore, the performance of the photovoltaic system is analyzed using the ENERGYPLUS package of the Design Builder software. We assume that 75% of CO2 is captured. In addition, a preliminary characterization of the overall system’s performance is determined. It is determined that the amount of CO2 captured by the system is 0.112 tones/year per square meter of solar panel area. A solar panel area of 19 m2 is required to decarbonize the building with natural ventilation, and 27 m2 is required in the case of ventilation according to the ASHRAE standard

Effect of Hydrogen Bond Donors and Acceptors on CO2 Absorption by Deep Eutectic Solvents

The effects of a hydrogen bond acceptor and hydrogen bond donor on carbon dioxide absorption via natural deep eutectic solvents were studied in this work. Naturally occurring non-toxic deep eutectic solvent constituents were considered; choline chloride, b-alanine, and betaine were selected as hydrogen bond acceptors; lactic acid, malic acid, and fructose were selected as hydrogen bond donors. Experimental gas absorption data were collected via experimental methods that uses gravimetric principles. Carbon dioxide capture data for an isolated hydrogen bond donor and hydrogen bond acceptor, as well as natural deep eutectic solvents, were collected. In addition to experimental data, a theoretical study using Density Functional Theory was carried out to analyze the properties of these fluids from the nanoscopic viewpoint and their relationship with the macroscopic behavior of the system, and its ability for carbon dioxide absorption. The combined experimental and theoretical reported approach work leads to valuable discussions on what is the effect of each hydrogen bond donor or acceptor, as well as how they influence the strength and stability of the carbon dioxide absorption in deep eutectic solvents. Theoretical calculations explained the experimental findings, and combined results showed the superiority of the hydrogen bond acceptor role in the gas absorption process, with deep eutectic solvents. Specifically, the cases in which choline chloride was used as hydrogen bond acceptor showed the highest absorption performance. Furthermore, it was observed that when malic acid was used as a hydrogen bond donor, it led to low carbon dioxide solubility performance in comparison to other studied deep eutectic solvents. The cases in which lactic acid was used as a hydrogen bond donor showed great absorption performance. In light of this work, more targeted, specific, deep eutectic solvents can be designed for effective and alternative carbon dioxide capture and management

State of the Art in Humidified Gas Turbine Configurations

This research investigates the most modern approaches to water treatment and recovery in power plants because of the scarcity of water sources and the significance of those sources in enhancing the performance of power-generating cycles. Gas turbines, which use mixes of air and water as the working fluid, provide superior efficiency, high specific power outputs, and reduced investment costs compared to combined cycles. Several different cycles for humidified gas turbines, including cycles of direct water injection, cycles of steam injection, and evaporative cycles that include humidity control towers, have been proposed. Despite this, only a few of these cycles have been put into practice, and even fewer are available for purchase on the market. This work aims to analyze the research and development literature on humidification-based gas turbines and highlight the cycles that have the most significant promise for the long run. In addition, work on development that still has to be carried out in order to deploy humidification-based gas turbine cycles is advised. This article may also be used as an overview of the research and development work that has taken place on humidification-based gas turbines over the course of the last thirty years

Evaluating the Food Profile in Qatar within the Energy–Water–Food Nexus Approach

Finding a balance between the capacity for production and the rising demand for food is the first step toward achieving food security. To achieve sustainable development on a national scale, decision-makers must use an energy, water, and food nexus approach that considers the relationships and interactions among these three resources as well as the synergies and trade-offs that result from the way they are handled. Therefore, this paper evaluates the Energy–Water–Food Nexus Profile of Qatar at a superstructural level by applying the Business-As-Usual (BAU) storyline; thus, trends of past data have been used to provide future projections to 2050 using the statistical prediction tools such as the compound annual growth rates of food demand (CAGRFD), international supply (CAGRFI), and the average local food supply change factor (c¯). Once the BAU storyline has been generated, the source-to-demand correlations have been defined for each food category. Such correlations include the annual and average ratios of the local food supply to the total demand (i.e., αi and α¯) and the ratios of the local food supply to the international supply (i.e., βi and β¯). In addition, as an effort to identify the required action to reach food self-sustainability, the additional local food supply to achieve (xi,add) and its ratio to the local demand (γ) have been defined. The highest average ratio of the local food supply to the total demand (αi) was found for the meat category, which was estimated to be 48.3%. Finally, to evaluate the feasibility of attaining food self-sustainability in Qatar, the water consumption (Vw,i) and its corresponding required energy for each food category have been estimated