Brightening Tomorrow Together 2024

While renewable energy is a blessing, large-scale hydropower generation often leads to significant environmental disputes, sometimes with unimaginable consequences. Micro-hydropower systems serve as a solution to this predicament. This chapter explores the attributes of micro-hydropower systems, their environmental footprints, and advantages. It further discusses how these systems can be integrated with other forms of renewable energy. The chapter also examines the policy and regulatory structures that oversee micro-hydropower generation, underscoring the significance of capacity enhancement in this sector. The content offers a thorough understanding of how micro-hydropower can contribute to sustainable development while mitigating environmental damage. This chapter sheds light on micro-hydropower systems, emphasizing their environmental friendliness, synergy with other renewable energy sources, and the necessity for supportive policies and capacity building for sustainable energy progression.

This paper presents the results of various applications of solar energy in the field of thermo-fluids engineering, specifically in the following 3 topics: energy storage, cooling, and water desalination. In the first part, the result of using PCM (phase change materials) for storage solar energy as sensible and latent energy in conjunction with nanoparticle-laden fluids is presented. It is seen that for medium-temperature range energy storage, the materials and geometry can be adjusted in order to tune the charging and discharging processes at much higher efficiencies. The second part of the paper presents results of low-cost cooling techniques which avoid the use of high-energy consuming VCR (vapor compression refrigeration) cycles, and instead use solar energy as the driving force, leading to more environmental friendly cooling solutions. In the third and final part of this paper, the solar energy-driven desalination process of membrane distillation has been presented in detail. Here, the main parameters of concern are the distillation flow rate as well as the overall GOR value (Gained Output Ratio). It is observed that solar-driven desalination processes can avoid the use of high grade energy (such as electricity) and can instead be operated using low grade energy source such as solar energy.

Soybean peroxidase (SBP) is a promising enzyme for wastewater treatment due to its ability to catalyze the oxidation of aromatic compounds, leading to the formation of precipitable polymers. This study investigates SBP's efficacy in removing p-, o-, and m-cresol from water. Experimental optimization using a continuously stirred batch reactor achieved 98, 97, and 100% removal efficiencies for p-, o-, and m-cresol, respectively. Optimal conditions were determined for each isomer at 1.0 mM: 0.4 U/mL SBP, pH 7.0, and 1.0 mM H₂O₂ for p-cresol; 0.7 U/mL SBP, pH 9.0, and 1.2 mM H₂O₂ for o-cresol; and 0.8 U/mL SBP, pH 8.0, and 1.1 mM H₂O₂ for m-cresol. These findings highlight SBP's potential for sustainable, efficient cresol removal in wastewater treatment, underscoring its relevance in both industrial and environmental applications.

As climate change advances, harmful algal blooms (HABs) are becoming prominent factors in water supply emergencies across the world, particularly during summers. Proliferation of HABs can make water sources temporarily unsuitable for water provision. These water supply emergencies worsen living conditions and can limit industrial and commercial activities, particularly those of greenhouse horticulture that have massive water dependency. This study investigates the effectiveness of hydraulic response measures in providing adequate water supply during such emergency periods. Different emergency scenarios were devised and applied, along with response measures, to a benchmark water distribution system (WDS) model to establish a relationship between response measures and longevity of water supply. EPANET, an open source WDS modelling software, was used to modify the WDS and to simulate the effects of the response measures. Results from this study will help water utilities to prepare and plan for such emergencies.

Nuclear energy's direct and hidden carbon footprint, including manufacturing and construction emissions, is lower than wind and solar. However, nuclear power plants require frequent and lengthy maintenance operations during which the plants’ auxiliary fossil-fuel generators support the grid. Such maintenance is costly. In addition, data indicates increased air pollution during such nuclear outages; thus, shortening such outages is financially and environmentally crucial. One very time-consuming maintenance procedure is de-icing the plant's ice condensers. The authors have developed a robot-controlled laser-based technology to carry out the de-icing task remotely and more efficiently using highly intensive radiation. Throughout this technology development effort, including testing its effectiveness in de-icing, a fascinating phenomenon was discovered. Water film atop melting ice was observed to boil homogeneously without contact with any superheated solid surface. This homogeneous boiling within melting ice was induced via radiation at a 10.6-micron wavelength and required a power intensity much lower than the values reported in the literature for thermocavitation in liquid water. This short article showcases this phenomenon, unprecedented in existing literature, through some preliminary images captured experimentally. The article also argues potential reasons for the reduced power intensity requirement of thermocavitation in melting ice versus a pool of liquid water.

Reducing emissions and increasing thermal efficiency in internal combustion engines have been the foremost goals of combustion research. The fuel spray development and subsequent chemical reaction processes heavily influence the combustion completeness concerning the surrounding environment and explicitly determine its suitable application as a fuel for combustion. Recently, strong efforts to mitigate the complete dependency on diesel fuel for heavy-duty internal combustion engines using alternative fuels made available by renewable feedstocks. The biofuel C₂H₆O isomers of dimethyl ether (DME) and ethanol are of interest for their simplistic chemical composition, ease of production, and opposite chemical applications wherein the autoignition temperature of ethanol is comparatively high. Nonetheless, the high fuel-borne oxygen can limit net soot formation and therefore is attractive as an alternative fuel to direct injection engines. In this work, high-pressure fuel sprays of ethanol and dimethyl ether reactions are empirically recorded using a pre-burn technique inside a constant volume chamber. The high-speed images were analyzed and processed for quantitative comparisons including the total effective coverage, light intensity, and chemiluminescence distribution of the sprays. The opposite reactivity characteristics among isomers were apparent as the natural chemiluminescence visibility became limited at a background temperature lower than 1546 K. The enhanced volatility of DME presented little challenge in high-intensity luminosity even under lower background temperatures. Furthermore, blue flame reactions were apparent with DME sprays in an increased oxygen content (15%) environment and extended mixing periods. The suitability of high-pressure ethanol spray reactions is constrained to elevated supply pressures and thermal environments to overcome mixing and ignition limitations.

Laminar flames have been thoroughly investigated, with detailed descriptions of the flame structure and mechanisms that drive the flame propagation process. Typically, the flame structure is described as unburned zone, preheat zone, reaction zone, and burned zone. Models based on this flame structure were developed to investigate the fundamental combustion mechanisms. Theoretically, an assumed outwardly propagating spherical flame has been used to determine the flame propagation speed, especially under elevated pressures, while the heat release of spherical premixed flame is less discussed but is important to real-world applications. In this paper, the heat release of spherical premixed flame is investigated via a combination of chamber pressure, shadowgraph imaging, direct imaging, and chemiluminescence of the flame. Three types of fuels, including hydrogen, methane, and propane were used to generate stoichiometric mixtures with three types of inert gases including nitrogen, argon, and helium gas. It is observed that the spherical flame kernel demonstrates a two-stage combustion behavior, with the first stage of flame propagation with little chemiluminescence emissions, and a second stage after flame occupies most of the chamber volume with high chemiluminescence emissions. This phenomenon is more obvious under higher background densities. By cross-referencing the test results from various test methods, it is discovered that the profile of light intensity generated by chemiluminescence agrees with chamber pressure the most, reflecting the actual heat release of the air–fuel mixture. Whereas the volume of the spherical flame kernel increases without causing significant changes in chamber pressure in the flame propagation stage. 3-D simulation was also performed using detailed chemical kinetics, and the test results support the empirical behavior of a delayed heat release as compared to the flame front propagation.

In most vertical farms or plant factories with artificial lighting (PFAL), the major cost is the high energy consumption of lighting fixtures. This is not always the case in northern communities, such as Gjoa Haven, Nunavut, where a vertical farming system was deployed in October 2019 and has been operated since. With average winter temperatures below −30 °C, heating and ventilation costs often exceed lighting costs, and waste heat from light fixtures becomes a valuable energy input. A frequent criticism of PFAL systems in southern climates is the high cost of electricity and low efficiency of light fixtures to match readily available solar radiation. When the operation of PFALs was considered in remote and northern communities, which have minimal solar radiation in the winter months, instead the comparison was made between imported, gathered, and locally grown food sources. In such systems, the high ratio of heat to photosynthetically active radiation produced by artificial light sources provided a valuable heat source, rather than waste discarded to the environment. However, the latent heat produced by crop transpiration proved a challenge to conventional HVAC solutions, and the intermittent nature of traditional lighting strategies caused heating demand spikes. In 2022, a second vertical farming system was deployed to Gjoa Haven to address the challenges observed. The second system was used to grow a cucumber crop in winter 2023, achieving total energy use efficiency of 220.1 kWh/kg of fresh produce.

Rising anthropogenic CO₂ emissions contribute to the adverse effects of climate change as the current atmospheric CO₂ concentration exceeds 400 ppm. Fortunately, carbon capture, utilization, and storage (CCUS) methods are under development to reduce atmospheric CO₂ concentrations. Direct air capture (DAC) methods are of particular interest, as they enable CO₂ to be captured from any point in the atmosphere. A practical application of DAC is greenhouse enrichment, whereby captured CO₂ is used to raise CO₂ concentrations in greenhouses. This work reviews and discusses the integration of DAC in greenhouses, which serves the dual purpose of mitigating climate change and improving agricultural yields. DAC allows greenhouses to quickly achieve CO₂ concentrations as high as 1200 ppm, which is consistent with an enrichment factor of 3 (1200 ppm/400 ppm). This enrichment factor and optimal photosynthesis conditions allow various crops, including fruits and vegetables, to increase yields ranging from 21 to 61%, even when grown out-of-season. Furthermore, we compare different adsorbents to understand which are most practical for greenhouse enrichment. Results reported in the literature show that greenhouse enrichment requirements can be achieved using adsorbents that occupy 0.05% to 1.5% of the greenhouse volume. Moreover, a brief techno-economic analysis is presented to compare the benefits of different greenhouse adsorbents to other methods of providing CO₂ enrichment. The cost of DAC adsorbents ranges from about 34.68 to 120 USD/tonne of CO₂. Lastly, this paper reports on the limited research in greenhouse DAC regarding techno-economic assessments and life cycle analysis, as well as the optimization of numerous DAC systems and adsorbent properties.

The importance of agroforestry has never been more conspicuous and palpable as it is today. This is due to the prevalent situation of global warming and climate change which calls for nature-based adaptive and mitigation solutions which not only contribute to sustainable livelihoods but equally enhance environmental sustainability. Agroforestry fits squarely as a practice that enhances sustainable livelihoods while fostering environmental sustainability. The policy and governance framework for agroforestry is still lacking in many regards. This chapter undertakes an in-depth review of literature to understand the current situation while charting new empirical research pathways. Findings reveal that, agroforestry is crucial for sustainable livelihoods as it contributes to livelihood diversification through diverse benefits such as food, fuelwood, fodder, fruits, traditional medicines, fish, meat, milk, hides and skin, honey, poles, building materials, spices. Through these livelihood diversification benefits from agroforestry are added improvements in physical, natural, human and financial capital. The policy framework for agroforestry as a sustainable livelihood strategy is largely well developed in India and Nepal where there are National Agroforestry Policies. There are also global policies such as the UN Sustainable Development Goals (SDGs), Conventions such as the convention on biological diversity, United Nations Framework Convention on Climate Change (UNFCCC), and the convention to combat desertification which factor in agroforestry as a climate-smart and sustainable livelihood option. In terms of governance, countries in the global north have better governance mechanisms which promote agroforestry as a sustainable livelihood strategy. In the global south, besides countries like India and Nepal which have an advanced governance mechanism for agroforestry, the governance framework is poor is most countries in the global south. A better policy and governance framework will contribute to enhance agroforestry as a sustainable livelihood option across the world in general and the developing world in particular.