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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 ( T out ), 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Distribution Flexible Alternating Current Transmission System (DFACTS) devices are evolving technologies to mitigate voltage sags, swells, flickers and harmonics during transient and steady state operations. Power electronics and communication technologies have made the conventional grid smart and artificial intelligence based algorithms even smarter but simulation studies based notion of applying the FACTS devices to damp the small or large scale power swings to improve steady state or transient stability looks like an unreliable notion. Modern FACTS devices include SVC, STATCOM, SSSC, UPFC, UPQC, DVR, TSC and TSR. Use of STATCOM, SSSC and UPFC requires a real time reference which suffers communication delay limitation. STATCOM and SSSC produce 4PU to 5PU high voltage and current impulses which are high enough to puncture insulators to compromise insulation coordination. Operation of STATCOM and SSSC renders protective relays ineffective and pollute the power quality. Best control systems clear 0.1 to 2Hz oscillations in the range of 2.5 to 7 seconds and protective relays operate in range of 0.05 to 0.5 seconds to clear faults. Power engineers believe the FACTS devices destabilize the power system due to their own presence therefore their use with some snubbing circuits may be limited to generation and distribution sides. [ABSTRACT FROM AUTHOR]

Power grids are undergoing deregulation, privatization, and decentralization worldwide. The smart grid allows the integration of clean power renewable energy technologies to the utility grid through mini, micro, and nano grids. Conventional centralized power grids used to rely on fossil fuel-fired power plants which are being replaced worldwide with solar, wind, small hydro, geothermal, biomass, wave, and alternative energy technologies. Installed solar and wind power generation capacity has surpassed 1300 GW in 2020. Solar and wind powers rise during the day and fall during the evening. Consumer demand increases steadily during the evening and peaks after sunset when solar generation becomes zero and wind power falls substantially. Decentralized smart grid faces duck curve limitation on the integration of renewable energy technologies as centralized utilities used to face the peak-hours issue. Smart grid operators have no effective solution of load peaking after sundown except keeping fossil fuel-fired plants on standby to ride through the duck curve. We present a solution to the duck curve problem by integrating smart load shedding devices in micro and nano grids to adjust their demand frugally during peak hours to support the national grid. Information and communication (ICT) technologies that enabled the internet of things (IoT) have been attempted to facilitate smart load shedding in nano grids. ICT enabled voltage transformers (VT) and current transformers (CT) supply signals to heuristic rules based multifunction smart relaying system. Smart meters, instrument transformers, and status monitoring field devices generate a massive amount of data. The research designed an IoT and LabVIEW based software platform to carry out demand-side management. Under frequency (UF) and under-voltage (UV) relaying functions were used to conduct load shedding in nano grids. This nanoscale demand-side management experiment paves the way to ride through utility-scale duck curve setback. This PT/CT data based economic solution performs at nanoscale same as ABB PML 630 load shedding controller. This UF and UV relaying based multifunction relay starts shedding loads when frequency falls below <1% and voltage below 10% of rated values. Our load shedding scheme has successfully functioned on nanoscale 5 kW system. The future study section proposes to integrate big data technologies in-home energy management system (HEMS) through extract, transform and load (ETL) pipeline to import data from PT/CT and circuit breakers (CB) integrated smart meter to transform it according to requirement by loading data into Hadoop "big data" processing platforms for utility-scale load management with help of day-ahead load and weather-dependent renewable power generation forecasting techniques. [ABSTRACT FROM AUTHOR]

The unfettered rise in electricity demand due to overpopulation, industrialization, and lack of adequate generation augment stress on utilities' ability to serve their customers. The situation usually worsens when the demand exceeds production. The peak demands are catered by operating expensive spinning reserves or resort to blanket load shedding by utilities during the peak hours. The first option increases the cost of electricity which is undesirable whereas indiscriminate load shedding is also unacceptable. Utility companies practice direct control methods such as utility integrated control over consumer loads during peak hours to minimize the gap between supply and demand. We present a frequency and voltage relaying based demand side management (DSM) scheme to reduce the load on 11 kV distribution feeders during peak hours without resorting to blanket load shedding. In this scheme, an energy management system (EMS) employing Underfrequency and Undervoltage (UFUV) relays is implemented at consumers' premises instead of 220 kV distribution substations stations. This system monitors the power system's vital signals, voltage and frequency, to manage load. The EMS controller automatically detects the frequency and voltage changes in the system and responds to respective loading patterns. The dynamic voltage (v), current (i) and frequency (f) signals are acquired from zero crossing detectors and power sources are analyzed and stored. The transducer with output voltage range in millivolt (mv), signal conditioning techniques are applied to match data acquisition range (0–10V). The predefined range are computed with dynamic values to send tripping signal to control device. In order to counter sag, swell or minor deviation a 2–3 cycles time delay is added in calculations. The integration of the proposed DSM system has shown up to 97% power supply reliability. Efficient energy management reduces Green House Gas (GHG) emissions, which is a significant step towards cleaner production. • The peak electric energy demand leads to peak carbon emission in electric utilities. • Future energy mix consist of intermittent renewable energy sources quest for load management by utilities. • Proposed DSM system employs UVUF relays-based system for nano grid. • Successful automation in a residential building is achieved using IDMT. • The integration of the proposed DSM system has shown up to 97% power supply reliability. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]