We present the role of heat and electricity storage systems on the rapid rise of renewable energy resources and the steady fall of fossil fuels. The upsurge in renewable resources and slump in fossil ...fuel consumptions is attributed to sustainable energy systems, energy transition, climate change, and clean energy initiatives. The fast growth of renewables brings new design and operational challenges to transition towards 100% renewable energy goal. Energy storage systems can help ride‐through energy transition from hydrocarbon fuels to renewable sources. Nuclear fusion and artificial photosynthesis are the ultimate Holy Grails for permanent clean energy solutions. Plants harvest light and store it in chemical energy to regulate the food supply chain that may be a guideline for an energy transition from fossil fuels to renewables. Heat and electricity storage devices can account for the periodic nature of solar and wind energy sources. Solar thermal systems for water and space heating are also a viable solution for subzero temperature areas. This study presents the transition of world's energy prospect from fossil fuels to renewables and new advances in energy storage systems.
Halogenated hydrocarbons with high ozone depletion potential (ODP) were banned under Montreal Protocol (1987) due to their detrimental effects on ozone layer that shields the planet against ...ultraviolet radiations. The greenhouse gases (GHG) used in modern refrigeration, air conditioning, and heat pumping systems, are under Kyoto Protocol (1997)’s time-barred permission period. In order to reduce the depletion of ozone and reverse the climate change effects, the European Union legislation (2014) and Paris Accord (2016) are strongly emphasizing the phasing out of the use of harmful synthetic refrigerants. Choice of natural refrigerants makes no net addition of the greenhouse gases (GHG) in the environment. To retrofit and modify existing cooling and heating systems using natural refrigerants, extensive investigations are in progress worldwide. This work reviews timeworn, current and the next-generation refrigerants using Refrigerant Qualitative Parametric (RQP) quantification model to assist the refrigerant choice decision process. It is based on the ratio of arithmetic sums of actual parametric values of refrigerants normalized to equivalent ideal values. This model can help in choosing alternative refrigerants to replace CFCs by HCFCs or HFCs provisionally and finally replacing HCFCs or HFC to low GWP and ODP synthetic and natural refrigerants. A set of 16 refrigerants, both natural and synthetic, as an example, is computed for the standard Vapour Compression Cycle (VCC) based on the proposed model using REFPROP (NIST- 23 standard). The techno-economic parametric values of chosen refrigerants are taken from cited literature, ASHREA safety standards and international environmental legislations, laws and protocols. This paper reports the environment benign natural (CO2, NH3, HCs) and a few synthetic (R-152a, R-1234yf) refrigerants to be the optimal options.
•Refrigerants with ODP and high GWP were banned or facing time barred permission.•A Refrigerant Qualitative Parametric (RQP) quantification model is proposed.•Results show that natural and a few synthetic refrigerants are optimal options.
Summary
Refrigerants bearing high global warming potential (GWP) and ozone depletion potential (ODP) were outlawed or facing time‐beared permission under the Montreal (1987), Kyoto (1997) protocols, ...F‐Gas law (2015), Paris Accord (2016), and recent Kigali Amendment to Montreal Protocol (2019). In order to modify followed by the paradigm shift of existing heating and cooling systems, American Society of Heating, Refrigeration, and Air‐Conditioning Engineers (ASHRAE) envisaged natural and synthetic refrigerants (Synrefs) are under investigation globally. Carbon dioxide (CO2) is a popular natural refrigerant (Natref) replacing Synrefs used in commercial heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems globally. A rampant rise is observed in markets of Asia (Japan and China), North America (the United States and Canada), the Australian continent, and Africa (South Africa) by reaching 20 000 CO2‐stores around the globe. The European markets are leading the utilization of CO2 in the heat pump, and refrigeration, CO2 based markets estimate 14% of the total food retail stores (400 m2). Japan is the second leading market of CO2 heat pump and refrigeration with more than 10 200 CO2 condensing units. CO2 transcritical systems have a share of more than 10% in only European market (large stores); however, their share is less than 10% of total stores in other major markets of the world. New pump and compressor‐driven transcritical CO2 systems integrate ejectors, condensers, and booster systems to reduce energy consumptions, enhance efficiency, efficacy, and coefficient of performance. This article reports a critical review of the CO2 based heating, cooling, and refrigeration system and presents updated literature along with barriers and challenges on commercial use of Natref‐based heating and cooling applications worldwide.
Energy storage and transportation are essential keys to make sure the continuity of energy to the customer. Electric power generation is changing dramatically across the world due to the ...environmental effects of Greenhouse gases (GHG) produced by fossil fuels. The unpredictable daily and seasonal variations in demand for electrical energy can be tackled by introducing the energy storage systems (ESSs) and hence mitigating the extra GHG emission in the atmosphere. Energy storage techniques can be mechanical, electro‐chemical, chemical, or thermal, and so on. The most popular form of energy storage is hydraulic power plants by using pumped storage and in the form of stored fuel for thermal power plants. The classification of ESSs, their current status, flaws and present trends, are presented in this article. The present state of fossil fuel reserves, their production, consumption, and as a consequence of these the CO2 emissions are also discussed. The primary energy carriers coal, oil and gas are not evenly distributed along the globe. Long distances are involved in transporting these energy carriers and transportation and delivery of these key resources to the prime customers is always necessary. The different methods to transport the energy from the source end to demand end is also discussed in this article. The assessment of various energy storage methods on the basis of several factors and present status and development of storage and transportation of energy in Pakistan is discussed.
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Water heating without greenhouse gas emissions is indispensable for sustainable development in low sun regions. The integration of solar energy in domestic water and space heating ...systems is a sustainable pathway. Kyoto and Montreal protocols have already banned the use of chlorofluorocarbons and hydrofluorocarbons and granted a time limited permission to hydrochlorofluorocarbons. Synthetic refrigerants outperform natural refrigerants, yet 196 countries agreed on phasing out these refrigerants under Paris Accord in 2015. Industries, researchers and policy makers are retrofitting existing heating and cooling systems to integrate natural refrigerants worldwide. In this regard, an evacuated glass tube solar water heating system is simulated in Transient Systems Simulation Program (TRNSYS®) using low global warming potential (GWP) refrigerants. Parametric analysis is carried out to determine optimal sizes and configurations of solar collectors, heat exchangers, tank volumes and heights for annual performance assessment of solar water heaters. The optimized model was dynamically simulated under diverse weather conditions of Pakistan (Karachi), Australia (Melbourne) and China (Beijing). Our results show an optimal selection of solar water heating system parameters using 6 m2 collector area, 0.42 m3 tank volume, and 1.2 m tank height fulfil single family dwelling heating demands. Moreover, use of low global warming potential hydrofluoroolefins(HFOs) R-1234yz and R-1234yf refrigerants shows even superior thermal performance. The highest annual solar fraction values were recorded for CO2 (0.720289) and R-410a (0.723428) under various weather conditions. Our findings show that use of synthetic refrigerants slightly improves the performance of system, however, giving weightage to environmental benefits the natural refrigerants take precedence over synthetic refrigerants. This research work recommends an adoption of natural refrigerants as an environmentally superior and sustainable option.
This work reports the observation of sunlight diffraction through empty spaces in between twigs and leaves in tree crowns. The diffraction patterns are dominated by red wavelength on front followed ...by the trail of rest of spectral bands of white light rainbow bursts. Tree crowns act as obstacles and apertures causing diffraction/ interference of solar rays. Separation between leaves and twigs (d) is a few inches and distance between crown and camera (D) is in range of a few meters. Empty spaces in tree crown are much longer than red to violet wavelengths in sunlight therefore scattering, dispersion, reflection, diffraction and interference effects cannot be ruled out. Tree crown deflects solar rays into narrow angles all around to enable interference inside camera lens to create grating structure diffracting light into regular patterns. Diffraction pattern look like red petunia flower having 3 × 3 rose petals. Motorola mobile phone camera was used to record the sunlight diffraction patterns. Mobile camera consists of small focal length (≈5 mm) lens, a fixed opening aperture and an image sensor. Lens consists of few plastic or glass elements and sensor consists of charge coupled device (CCD) or CMOS technology. These diffraction/ interference patterns have potential to increase efficiency of Next Gen solar cells. This paper describes possible theoretical background of light diffraction and multiple ray interference through tree twigs and leaves.
•Observed sunlight diffraction patterns resemble red petunias.•Conducted experiments on 1 × 2 to 2 × 3 size trees.•Nature-inspired photonic device efficiency boost.•Enhances potential for Next Gen solar cell efficiency.•Natural structures inspire photonic device improvements.
Growing population, depleting fossil fuels, economic expansions, and energy intensive life style demand are resulting in higher energy prices. We use energy as of heat and electricity, which can ...directly be obtained from sun using thermal collectors and solar cells. Solar thermal systems are gaining attention for water and space heating applications due to green aspects of solar energy. A solar thermal collector is a vital part of solar thermal energy system to absorb radiant energy from the sun. In this study, a solar water heating (SWH) system has been designed and simulated in the TRNSYS ® software using thermal and chemical properties of heat transfer fluids using REFPROP for dwellings located on ±31° latitudes (+31 Lahore in Pakistan and -31° Perth in Australia). We present an efficiency parametric optimization-based model for water and space heating. Simulation results for four types of solar thermal collectors are presented, and performance is analyzed on the basis of output temperature (Tout), solar fraction (f), and collector efficiency (η). This study evaluates the comparative performance of evacuated tube collector (ETC), flat-plate collector (FPC), compound parabolic concentrator (CPC), and thermosiphon-driven systems. Our findings conclude the evacuated glass tube collector achieves the highest solar fraction, i.e., 50% of demand coverage during August in Pakistan and February in Australia, with an overall average of 43% annually.
Air pollution, climate change, and plastic waste are three contemporary global concerns. Air pollutants affect the lungs, green gases trap heat radiation, and plastic waste contaminates the marine ...food chain. Two-thirds of climate change and air pollution drivers are emitted in the process of burning fossil fuels. Pollutants settle in months, green gases take centuries, and plastics take thousands of years. The most polluted regions on the planet are also the ones that are greatly affected by climate change. Air pollutants grow in most climate-change affected areas, contributing to the greenhouse effect. Smog affects local and regional transboundary countries. The biggest greenhouse gas (GHG) emitters may not be the worst-hit victims because wind and water flow distribute green gases and plastic waste worldwide. The major polluters are often rich and developed countries, and the worst affected countries are the underdeveloped poor communities. Technologically advanced countries may help the developing countries in research into removing particulate matter, green gases, and plastic waste. Intergovernmental Panel on Climate Change (IPCC) and Paris Accord have emphasized on immeasurable efforts to encourage the conversion of pollution, green gases, and plastic waste into energy. Conversion of CO2 into petrol, GHG gases into chemicals, biowaste into biofuels, plastic waste into building bricks, and concrete waste into construction materials fosters a circular economy. This work reviews existing waste to power, energy, and value-added product conversion technologies.
Smog; pollutants; Green gases; Hydrocarbons; Fossil fuels; Value added products.
This paper addresses the use of nanogrid technology in resolving the issue of blanket load shedding for domestic consumers. This is accomplished by using different load management techniques and load ...classification and utilizing maximum solar energy. The inclusion of DC-based load in basic load and DC inverter load in regular load and scheduling of the burst load during the hours of maximum solar PV generation bring novelty in this work. The term “nanogrid” as a power structure remains ambiguous in various publications so far. An effort has been done in this paper to present a concise definition of nanogrid. Demand side load management is one of the key features of nanogrid, which enables end users to know major characteristics about their energy consumption during peak and off-peak hours. A microgrid option with nanogrid facility results in a more reliable system with overall improvement in efficiency and reduction in carbon emission. PV plants produce DC power; when used directly, the loss will automatically be minimized to 16%. The AC/DC hybrid nanogrid exhibits 63% more efficiency as compared to AC-only nanogrid and nearly 18% more efficiency as compared to DC-only nanogrid. Smart load shifting smoothens the demand curve 54% more adequately than during conventional load shifting. Simulation results show that real-time pricing is more economical than flat rate tariff for a house without DG, whereas flat rate results are more economical when DG are involved in nanogrids. 12.67%-21.46% saving is achieved if only flat rates are used for DG in nanogrid instead of real-time pricing.
•The Indus Water Treaty is a successful settlement of boundary water basin conflict.•Water, food and energy are intimately related in a nexus influencing each others.•This paper reports global water ...treaties and aftermath of Indus Water Treaty.
Water, energy and food nexus of Indus Water Treaty (IWT) is presented in the light of water governance. The water governance doctrine refers to social, economic, administrative and political systems influencing the transboundary water use and management. Water governance means who gets what water, when and how much, and who has the right to water related benefits. Indus Water Treaty is cited to be one of the few successful settlements of boundary water basin conflicts that has stood the test of times since last six decades. Riparian states have opportunities of harvesting water, power and agriculture by compliance to accords in letter and spirit. IWT restrains both (India) and lower (Pakistan) riparian from pulling out of accord from fear of deadly consequences. IWT is founded on World Bank’s professionally prepared comprehensive terms and conditions keeping in mind future regional developments. This treaty has given control of three eastern rivers (Ravi, Beas and Sutlej) to India and three western rivers (Indus, Jhelum and Chenab) to Pakistan. IWT gives both countries genuine share of eastern/western waters for domestic use, agriculture and electricity generation using Run-of-River Plants, subject to observing minimum level of water flow into lower riparian at Head Marala Barrage. Water, energy and food nexus of this treaty bonds upper and lower riparian to comply with water governance principles. Upper riparian diverted 34 million acre feet (MAF) water out of eastern rivers before entering into Pakistan and launched run-of-river power plants spree on western rivers in last two decades. Restricting water flow to lower riparian in the name of pond filling needs attention. Unrestricted use of water in run-of-river power plants is pointed out to be a limiting factor in Indus Water Treaty. Continuum of cooperation has room for collaboration under Indus Water Treaty. India and Pakistan can sort out disputes by dialogue, in light of rights and needs, rather Harmon Doctrine.
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