Global Electricity Demand Research Articles

Review on Performance Enhancement of Photovoltaic/Thermal–Thermoelectric Generator Systems with Nanofluid Cooling

Photovoltaics (PVs) are an effective technology to harvest the solar energy and satisfy the increasing global electricity demand. The effectiveness and life span of PVs could be enhanced by enabling effective thermal management. The conversion efficiency and surface temperature of PVs have an inverse relationship, and hence the cooling of PVs as an emerging body of work needs to have attention paid to it. The integration of a thermoelectric generator (TEG) to PVs is one of the widely applied thermal management techniques to improve the performance of PVs as well as combined systems. The TEG utilizes the waste heat of PVs and generate the additional electric power output. The nanofluid enables superior thermal properties compared to that of conventional cooling fluids, and therefore the performance of photovoltaic/thermal–thermoelectric generator (PV/T-TEG) systems with nanofluid cooling is further enhanced compared to that of conventional cooling. The TEG enables a symmetrical temperature difference with a hot side due to the heat from PVs, and a cold side due to the nanofluid cooling. Therefore, the symmetrical thermal management system, by integrating the PV/T, TEG, and nanofluid cooling, has been widely adopted in recent times. The present review comprehensively summarizes various experimental, numerical, and theoretical research works conducted on PV/T-TEG systems with nanofluid cooling. The research studies on PV/T-TEG systems with nanofluid cooling were reviewed, focusing on the time span of 2015–2021. This review elaborates the various approaches and advancement in techniques adopted to enhance the performance of PV/T-TEG systems with nanofluid cooling. The application of TEG with nanofluid cooling in the thermal management of PVs is an emerging research area; therefore, this comprehensive review can be considered as a reference for future development and innovations.

Green ammonia could produce climate-friendly ways to store energy and fertilize farms

Curbing climate change goes hand-in-hand with decarbonizing energy production. But how can communities continue to meet the global demand for electricity without releasing more CO2? A cadre of chemists says one solution may be hiding in an unlikely source: ammonia—the pungent, clear, nitrogen-rich gas, or liquid, that’s most often used as an agricultural fertilizer. Most of the ammonia produced in the world goes to crops, with the rest ending up in plastics, explosives, fabrics, and other materials. Ammonia is appealing as a means of storing and transporting energy, and it could offer a way to package and store hydrogen. But the conventional process for making ammonia at plants like this one involves liberating hydrogen from the hydrocarbons in fossil fuels and hence results in CO2 emissions. Image credit: Shutterstock/saoirse2013. But to researchers looking for carbon-neutral energy, ammonia makes an appealing fuel. Made of nitrogen and hydrogen, it burns without releasing carbon. [In 2014, Japanese researchers unveiled the first turbine powered by ammonia combustion (1).] Ammonia is also appealing as a way to store energy that’s transported from where it’s made to where it’s needed. And some researchers say that ammonia could be used to package and store hydrogen, which could be readily cracked out of the liquid or gas and used in fuel cells. And yet, several challenges remain if ammonia is to help with the globe’s massive carbon emissions conundrum. The conventional process for making ammonia involves liberating hydrogen from the hydrocarbons in fossil fuels, often methane, which adds CO2 to the atmosphere. By some estimates, ammonia production is responsible for roughly 2% of fossil fuel use, worldwide, and releases more than 400 millions of tons of CO2, representing more than 1% of total annual global emissions of the greenhouse gas. Those numbers …

Peak Shaving with Battery Energy Storage Systems in Distribution Grids: A Novel Approach to Reduce Local and Global Peak Loads

The growing global electricity demand and the upcoming integration of charging options for electric vehicles is creating challenges for power grids, such as line over loading. With continuously falling costs for lithium-ion batteries, storage systems represent an alternative to conventional grid reinforcement. This paper proposes an operation strategy for battery energy storage systems, targeted at industrial consumers to achieve both an improvement in the distribution grid and electricity bill savings for the industrial consumer. The objective is to reduce the peak power at the point of common coupling in existing distribution grids by adapting the control of the battery energy storage system at individual industrial consumer sites. An open-source simulation tool, which enables a realistic simulation of the effects of storage systems in different operating modes on the distribution grid, has been adapted as part of this work. Further information on the additional stress on the storage system is derived from a detailed analysis based on six key characteristics. The results show that, with the combined approach, both the local peak load and the global peak load can be reduced, while the stress on the energy storage is not significantly increased. The peak load at the point of common coupling is reduced by 5.6 kVA to 56.7 kVA and the additional stress for the storage system is, on average, for a six month simulation, period only 1.2 full equivalent cycles higher.

Global power and energy scenario during COVID-19 pandemic: Lessons from lockdown

Technology is advancing progressively at a very sharp rate in every phase of the commercial and economic issues, where energy plays a vital role in hi-tech enrichment. After continuous and multi directive research, human is efficient enough to put their steps on the peak of all imaginable pitches. But a human cannot fight against the environment in all instances. COVID-19, or Corona Virus, is such a type of environmental pandemic. Due to a large spread rate of COVID-19, the human society of the entire Globe is getting affected within a very small period. During its first and second wave, it collapses maximum countries health, economic structures along with the electrical sector. Many countries have enforced the ‘lockdown’ to their citizen for minimizing the community spread rate, which directly affects the energy sector. Standing in this scenario, this study focuses on the significant effect of COVID-19 on the energy sector of the Globe, especially in India. This paper also demonstrates that how several countries are trying to secure their power sector in this pandemic situation.

Thermal Storage for District Cooling—Implications for Renewable Energy Transition

The utilization of air conditioning in public and private buildings is continuously increasing globally and is one of the major factors fueling the growth of the global electricity demand. The higher utilization of renewable energy sources and the transition of the electricity-generating industry to renewable energy sources requires significant energy storage in order to avoid supply–demand mismatches. This storage-regeneration process entails dissipation, which leads to higher energy generation loads. Both the energy generation and the required storage may be reduced using thermal energy storage to provide domestic comfort in buildings. The development and utilization of thermal storage, achieved by chilled water, in a community of two thousand buildings located in the North Texas region are proven to have profound and beneficial effects on the necessary infrastructure to make this community independent of the grid and self-sufficient with renewable energy. The simulations show that both the necessary photovoltaics rating and the capacity of the electric energy storage system are significantly reduced when thermal storage with a chilled water system is used during the air conditioning season.

Influences of Small Hydroelectric Plants on the genetic differentiation of Neotropical freshwater fish populations: a case study

ABSTRACT In view of the growing global demand for electricity, many countries have been looking for ways to diversify production. However, in countries such as Brazil, hydroelectric power plants still constitute the predominant generating source, occupying important drainage systems, such as the Upper Paraná River. At the same time, hydroelectric dams are among the main sources of impacts on freshwater fish, interfering, for example, in the genetic distribution of populations. Although the same could be expected from Small Hydroelectric Plants, very little genetic information has been obtained along Neotropical drainages. Based on this, the present study analyzed the DNA (microsatellite loci) of non-migratory fish species (seven) upstream and downstream of three Small Hydroelectric Plants in the Upper Paraná River basin, obtaining information about the genetic distribution of fish populations in this scenario. In general, the data suggest that populations have been genetically subdivided by Small Hydroelectric Plants and that other factors, such as the number of Small Hydroelectric Plants along a drainage and connectivity with long free stretches, could also influence genetic differentiation levels, which provides information of great relevance to global discussions about the impacts of hydroelectric power plants, as well as for the implementation and management of projects.

Optimal design and energy management of an isolated fully renewable energy system integrating batteries and supercapacitors

The continuous rise of global electricity demand and significant dependency on fossil fuel-based centralised power plants are the main indicators of increasing greenhouse gas emissions, thus negatively affecting climate change and human health and increasing the earth temperatures. This alarming situation has demanded the transition to 100 % renewable energy to decarbonise energy use. However, the fluctuating weather resources, and high investment cost are the major challenges with renewable energy implementation. In this context, the combined integration of multiple sources with energy storage in a so-called hybrid renewable energy system was developed as a durable remedy for the previous issues. This paper proposes a joint and conceptual approach for techno-economic design and dynamic rule-based power control of an off-grid solar/wind hybrid renewable energy system integrated with a hybrid energy storage system that comprises a lithium-ion battery, lead-acid battery, and a supercapacitor. Such concurrent integration of 100 % renewable energy systems and hybrid energy storage systems is lacking in the existing literature. First, with the aid of HOMER software, the feasibility and optimisation analysis of nine different configurations was performed in 1 min resolution to find the optimal component sizes. Second, MATLAB/Simulink models were assembled for the winning design based on a dynamic rule-based strategy to investigate and analyse the system’s dynamic response, power equilibrium, DC-bus voltage supervision and load voltage/frequency control against instantaneous and dynamic changes in the load or renewable energy resources. The proposed approach was promoted and validated on an actual case study for isolated residential community electrification in Saudi Arabia, in which a multi-tier framework was adopted to accurately simulate the stochastic energy consumption of the community’s households. From the design results, the hybrid renewable energy system, which integrates solar, wind, lead-acid batteries, and converter with optimal capacities of 55 kW, 18 kW, 325 kWh and 42 kW converter, respectively, is the most cost-effective alternative with the minimum net present and energy costs of $232,423.3 and $0.3458/kWh, respectively. The system has the least unmet load with 13.5 kWh/years (0.02 %), thus ensuring maximum reliability and customer satisfaction. Meanwhile, the developed control strategy efficiently improved the dynamic response, the DC-bus voltage stability, and the load voltage/frequency during different climatological and load interruptions. Further, the use of lead-acid batteries and supercapacitors has effectively diminished the maximum overshoot of the DC-bus and load voltages by 50 % during all disturbances. In addition, the integration of supercapacitors proficiently saved 2.3–6 kW during wind speed change and 2–9 kW during simultaneous changes in the radiation and load. Overall, the presented method, together with the reported results, provides an improved understanding and highlights the extent to which the successful integration of hybrid renewable energy system and hybrid energy storage system can be used to develop reliable and sustainable energy access for off-grid areas.

Comments: Oil Demand Optimism

Forecasts for oil demand are looking up, according to OPEC and the International Energy Agency as of mid-July. Will the optimistic views prove to be on target? We have learned how the market can shift or wildly careen, both historically and in the very recent past. Looking at the forecasts, which reflect a consensus of sorts, is encouraging for producers. OPEC’s monthly report of 15 July projected global oil demand to reach nearly 100 million B/D next year, a level similar to pre-pandemic in 2019. The 2021 oil demand growth remains unchanged at 5.95 million B/D, or approximately 6.6%. Led by demand growth in the US, China, and India, a 3.4% increase is expected in 2022 to 99.86 million B/D and would average more than 100 million B/D in the second half of the year. “Solid expectations exist for global economic growth in 2022,” OPEC said. “These include improved containment of COVID-19, particularly in emerging and developing countries, which are forecast to spur oil demand to reach pre-pandemic levels in 2022.” If the actual recovery tracks with these predictions, OPEC can dial back further its record-level supply cuts made in 2020. The IEA points to the growth expected in global electricity demand as spurring fossil-fuel demand, including oil, coal, and natural gas. After falling by around 1% in 2020, electricity demand growth may approach 5% in 2021 and 4% in 2022. The Asia Pacific region will account for the majority of the increases. China, the world’s largest consumer of electricity, leads the tally, accounting for more than 50% of the 2022 growth. India, the third largest, will account for 9% of the global electricity growth. Renewables are expected to be able to serve around half of the projected growth in global demand in 2021 and 2022. IEA wrote, “Renewable electricity generation continues to grow strongly—but cannot keep up with increasing demand. After expanding by 7% in 2020, electricity generation from renewables is forecast to increase by 8% in 2021 and by more than 6% in 2022.” Fossil fuel-based electricity is set to cover 45% of additional demand in 2021 and 40% in 2022. After declining by 4.6% in 2020, coal-fired electricity generation will increase by nearly 5% in 2021, exceeding pre-pandemic levels. In 2022, it will grow another 3% and could reach an all-time high. Natural gas-generated electricity lags coal because it is less commonly used in the Asia Pacific and competes with renewables in the US and Europe. It is expected to increase globally by 1% in 2021 and by nearly 2% in 2022 after declining by 2% in 2020. The US Energy Information Administration published a global financial review last month of 91 oil and gas companies, most headquartered in the US, in the first quarter 2021. It indicated that companies are implementing their plans announced over the past year to reduce capital expenditures to pay down debt. Capital expenditure in 1Q2021 was reported as $48 billion, 28% lower than in 1Q2020 and the second- lowest amount for any quarter since 2016. Cash from operations in Q1 this year totaled $79 billion, 19% higher than in 1Q2020; about 76% of companies had positive free cash flow. Overall, the companies decreased debt by $16 billion in 1Q2021, and the long-term debt-to-equity ratio decreased to 54%.

Comparison of Different Synthesis Methods to Obtain GDC as Nanoparticulated Electrolytic Material for SOFCs Operating at Intermediate Temperature (~500°C)

The necessary global electrical energy demand employs a high amount of fossil fuels and produces emissions of polluting gases due to its combustion, which needs the improving of the electric power generation technologies friendlier with the environment. This technology must guarantee to be sustainable, economic and available for all people. The SOFCs represent a promising alternative in the production of electrical energy directly from chemical energy through a series of electrochemical reactions with the use of fuels as hydrogen, carbon monoxide, methane and several synthesis gases rich in hydrogen or methane.The development of SOFCs has several challenges, related with thermic and electrochemical properties of the materials that constitutes anode, cathode and electrolyte. Several materials has been tested, for instance perovskites, aiming for facilitate the ionic conductivity inside these cells and reduce the operating temperatures, also looking for the increase of performance. To get similar thermal expansion coefficients (TEC) in anode, electrolyte and cathode, researchers have tested different chemical compositions to modify the perovskite structure of materials utilized in these components for SOFCs. Specifically for the electrolyte, these modifications could enhance the creation of oxygen vacancies, contributing to decrease TEC and also reduce the cathodic polarization, which are IT-SOFC operating challenges.Aiming for solve these issues, in this work, the synthesis of a cobaltite of lanthanum type perovskite LSCF, as cathode material, is developed by the co-precipitation method, using nitrate precursors. Also GDC is synthetized by three synthesis methods, which is the main purpose of this work: co-precipitation, sol-gel combustion (SGC) and hydrothermal. The obtained compounds are characterized physical and chemically by FTIR, TGA, TEM, SEM-EDS, and XRD.GDC synthesis was carried out by three different synthesis routes (SGC, Hydrothermal and Co-precipitation). The analysis of the mapping with EDS showed the uniform presence of each of the components Ce, Gd and O in the entire sample, in all the studied cases. In addition, the chemical composition in weight percent (% wt) by zones was evaluated to delimit the compositional homogeneity of the sample, but two different compositions were found that were replicated in all the extent of the powder, (1) Ce0,8Gd0,2O1,9 and (2) Ce0,7Gd0,3O1,85, as possible, which was corroborated with XRD analysis, in addition, the sample is crystalline and organized, the crystallinity decreases as follows SGC> Co-precipitation> Hydrothermal; this is defined as well, since the peaks are more defined and narrow in that order, whereas powders obtained by SGC are considered more crystalline than those obtained by the other two routes. Furthermore, similar stoichiometries of these compounds can be used in this type of fuel cell, since both have been used before.In all the cases studied, FTIR analysis show the characteristic adsorption band of GDC, which is normally at 565 cm-1, and is assigned to vibrations by elongation between metal and oxygen, which in this case would be the Ce bonds, -O and / or Gd-O. On the other hand, with TEM analysis corroborate that all the powders obtained with GDC synthesis have a nanometric size. The particle size obtained in decreasing order was SGC> Co-precipitation> Hydrothermal.The obtained results in this work show that GDC electrolytes are dependent of the synthesis route, but in general have adequate physical and chemical properties to be applied with good performance in IT-SOFCs. Considering this, currently we are building a single IT-SOFC with these materials to test at 500°C.

Assessing the Impacts of Hydropeaking on River Benthic Macroinvertebrates: A State-of-the-Art Methodological Overview

As the global demand for renewable electricity grows, hydropower development of river basins increases across the world. Hydropeaking, i.e., streamflow alteration consisting of daily or subdaily rapid and marked discharge fluctuations, can affect river reaches below hydropower units. Environmental effects of hydropeaking include geomorphological alterations and possible modifications of the freshwater biota. Among affected instream communities, benthic macroinvertebrates are receiving increasing attention and the related scientific research has experienced significant progress in the last decade. In this context, this paper aims to summarize state-of-the-art methods for the assessment of hydropeaking impacts on benthic macroinvertebrate communities. The present review could support the proper design of monitoring plans aimed at assessing the ecological impacts of hydropeaking and the effects of possible mitigation strategies.

Harmonic Effects Due to the High Penetration of Photovoltaic Generation into a Distribution System

The growth in global electricity demand has expanded the search for new energy resources. Renewable sources such as photovoltaic (PV) systems have proven to be major alternatives. PV generators connected to distribution grids have exhibited significant growth in the last decade, so it is essential to analyse the impacts resulting from this increase. This work investigated the influence of high PV system penetration in distribution grids in terms of harmonic levels. In particular, this study addressed the distortions in voltage and current waveforms in the presence and absence of PV generators connected to a distribution grid. Additionally, the total harmonic content and the individual harmonic frequencies of voltage and current were analysed. This study was performed with an IEEE 37 bus distribution system and the Open Distribution System Simulator software (OpenDSS). The results show that the voltage limits of some phases far away from a substation can exceed the limits. Furthermore, the total harmonic distortion (THD) and individual harmonic distortion (IHD) levels for voltage and current were significantly high for harmonics of the 3rd, 5th, and 7th orders, where current levels violate the standard levels.

Techniques for Ensuring Fault Ride-Through Capability of Grid Connected DFIG-Based Wind Turbine Systems: A Review

Renewable energy sources (RES) are being integrated to electrical grid to complement the conventional sources to meet up with global electrical energy demand. Among other RES, Wind Energy Conversion Systems (WECS) with Doubly Fed Induction Generator (DFIG) have gained global electricity market competitiveness because of the flexible regulation of active and reactive power, higher power quality, variable speed operation, four quadrant converter operation and better dynamic performance. Grid connected DFIG-based WECS are prone to disturbances in the network because of direct connection of stator windings to grid. The ability of the Wind Turbine (WT) to remain connected during grid faults is termed the Fault Ride-Through (FRT) capability. The grid code requirement for integrating the DFIG-based WTs to power networks specified that they must remain connected and support the grid stability during grid disturbances of up to 1500 ms. The use of compensation devices offers the best FRT compliance thereby protecting the DFIG and the converters from voltage fluctuations and over currents during the grid fault. The paper presents a review of techniques employed in ensuring FRT compliance. The article also proposes the state-of-the-art techniques for compensating voltage sag/swell and limiting the fault short-circuit current.
 Keywords: Renewable energy sources, DFIG, wind turbine system, fault ride-through, grid codes, dual-functional DVR

Hydroxy functionalized triptycene based covalent organic polymers for ultra-high radioactive iodine uptake

Nuclear energy is considered as the best alternative to fossil fuel to meet the ever-increasing global electricity demand. Nuclear electricity generation is not associated with direct emission of greenhouse gases unlike thermal power plants. On the flipside, tackling nuclear waste and spent fuel is a major issue, which becomes even more challenging due to the presence of volatile radionuclides such as 131I and 129I. In unfortunate events of accidental release of fission products in the environment, 131I and 129I are considered as the most dreaded air pollutants. Therefore, development of materials for efficient and rapid uptake/storage of 129I or 131I, is a research topic of utmost importance in this context. Herein, we report unique triptycene based covalent organic polymers (T_COPs) derived from benzene-1,3,5-tricarbaldehyde derivatives possessing varying number of hydroxy groups. The microporous T_COPs feature presence of abundant imine groups and π-rich environment. Interestingly, we observed that varying the number of hydroxy groups in T_COPs alter their surface area as well as their iodine uptake capacity. T_COPs exhibited ultra-high iodine uptake up to 4860 mg/g, which is superior compared to previously reported COPs. For practical applications, the T_COPs can be reused up to five cycles with smaller loss in the uptake performance - a desirable feature expected in a superior adsorbent. Our results reflect immense potential of these triptycene based COPs for environmental remediation.

Techno-economic comparison between photovoltaic systems with solar trackers and fixed structure in “El Valle de Sula”, Honduras

Solar energy has the greatest energy potential among all types of renewable energies. In 2018, the annual demand for electricity worldwide was 22,964 TWh. Daily, earth receives about 174 PW in the form of solar irradiance. This means that, if all this radiation could be harnessed, in approximately 8 minutes the electricity needed to meet the global annual electricity demand could be generated. Therefore, the need arises to implement photovoltaic systems that take better advantage of the solar resource, but in turn provide greater economic profitability. This article aims to evaluate the technical and economic feasibility of photovoltaic systems with solar trackers and compare them with fixed structure systems in “El Valle de Sula”, Honduras, Central America. The research was able to determine the levelized cost of electricity (LCOE) of each type of photovoltaic system from the generation of electricity in municipalities comprising the study area and the costs associated with initial investment, and operation and maintenance of each photovoltaic system. This research was carried out by implementing a methodology with a quantitative approach, using data collection to test hypotheses, based on numerical measurement and statistical analysis. Considering the value of the land, the photovoltaic system with a horizontal axis tracker has the lowest LCOE in 14 of the 18 municipalities of “El Valle de Sula”. Without taking into account the value of the land, the system with the lowest LCOE in all municipalities of this region is the system with a horizontal axis tracker, then the system with a dual-axis tracker and finally the system with fixed structure.

Stationary, Second Use Battery Energy Storage Systems and Their Applications: A Research Review

The global demand for electricity is rising due to the increased electrification of multiple sectors of economic activity and an increased focus on sustainable consumption. Simultaneously, the share of cleaner electricity generated by transient, renewable sources such as wind and solar energy is increasing. This has made additional buffer capacities for electrical grids necessary. Battery energy storage systems have been investigated as storage solutions due to their responsiveness, efficiency, and scalability. Storage systems based on the second use of discarded electric vehicle batteries have been identified as cost-efficient and sustainable alternatives to first use battery storage systems. Large quantities of such batteries with a variety of capacities and chemistries are expected to be available in the future, as electric vehicles are more widely adopted. These batteries usually still possess about 80% of their initial capacity and can be used in storage solutions for high-energy as well as high-power applications, and even hybrid solutions encompassing both. There is, however, no holistic review of current research on this topic. This paper first identifies the potential applications for second use battery energy storage systems making use of decommissioned electric vehicle batteries and the resulting sustainability gains. Subsequently, it reviews ongoing research on second use battery energy storage systems within Europe and compares it to similar activities outside Europe. This review indicates that research in Europe focuses mostly on “behind-the-meter” applications such as minimising the export of self-generated electricity. Asian countries, especially China, use spent batteries for stationary as well as for mobile applications. In developing countries, off-grid applications dominate. Furthermore, the paper identifies economic, environmental, technological, and regulatory obstacles to the incorporation of repurposed batteries in second use battery energy storage systems and lists the developments needed to allow their future uptake. This review thus outlines the technological state-of-the-art and identifies areas of future research on second use battery energy storage systems.

Review of Multilevel Inverters for PV Energy System Applications

Over the last decade, energy demand from the power grid has increased significantly due to the increasing number of users and the emergence of high-power industries. This has led to a significant increase in global emissions with conventional energy generation. Therefore, the penetration of renewable energy resources into the power grid has increased significantly. Photovoltaic systems have become the most popular resources as their protentional is enormous, thus, the worldwide installed PV capacity has increased to more than 635 gigawatts (GW), covering approximately 2% of the global electricity demand. Power electronics are an essential part of photovoltaic generation; the drive for efficient power electronic converters is gaining more and more momentum. Presently, multilevel inverters (MLI) have become more attractive to researchers compared to two-level inverters due to their abilities to provide lower electromagnetic interference, higher efficiency, and larger DC link voltages. This paper reviews multilevel inverters based on their classifications, development, and challenges with practical recommendations in utilizing them in renewable energy systems. Moreover, PV systems with various maximum power point tracking (MPPT) methods have been extensively considered in this paper as well. The importance and the development of a modified multilevel inverter are also highlighted in this review. In general, this paper focuses on utilizing multilevel inverters for PV systems to motivate and guide society to focus on inventing an efficient and economical multilevel inverter that has the combined capabilities of these converters reported in the literature.

Comparative analysis of machine learning algorithms for prediction of smart grid stability †

The global demand for electricity has visualized high growth with the rapid growth in population and economy. It thus becomes necessary to efficiently distribute electricity to households and industries in order to reduce power loss. Smart Grids (SG) have the potential to reduce such power losses during power distribution. Machine learning and artificial intelligence techniques have been successfully implemented on SGs to achieve enhanced accuracy in customer demand prediction. There exists a dire need to analyze and evaluate the various machine learning algorithms, thereby identify the most suitable one to be applied to SGs. In the present work, several state-of-the-art machine learning algorithms, namely Support Vector Machines (SVM), K-Nearest Neighbor (KNN), Logistic Regression, Naive Bayes, Neural Networks, and Decision Tree classifier, have been deployed for predicting the stability of the SG. The SG dataset used in the study is publicly available collected from UC Irvine (UCI) machine learning repository. The experimentation results highlighted the superiority of the Decision Tree classification algorithm, which outperformed the other state of the art algorithms yielding 100% precision, 99.9% recall, 100% F1 score, and 99.96% accuracy.

„Climate Impacts“ of Fossil Fuels in Today’s Energy Systems

The main fossil fuels oil, coal, and gas provide ~80% of global energy. In the next few years, “renewables” may meet only half the additional growth in global electricity demand or only about 20% of primary energy demand growth. The remaining increased energy demand will need to be matched by increased conventional energy generation. Coal and gas together account for 50% of primary energy and 60% of electricity. Therefore, the authors examine the global warming potential for both fuels. The surprising conclusion is that surfaced-mined coal appears “better for the climate” than the average natural gas and all coal appears beneficial over LNG. Therefore, current CO2-only reduction policies and CO2 taxes are leading to misguided consequences and the switch from coal to gas, especially LNG, will not have the desired impact of reducing predicted future global warming, quite the contrary. With IPCC’s global warming potential of CH4 over 20 years, a ~2% higher loss of methane across the value chain prior to combustion of gas vs. coal will lead to “climate parity” of coal with gas. Analyzing IEA information, natural gas value chains have high methane and undocumented CO2 losses. On global average, natural gas emits ~20% more CO2eq than surface-mined coal. This difference increases as the use of shale gas and LNG expands. Global GHG policies need to include documented changes in measured airborne CO2eq to avoid spending large amounts of public funds on ineffective or sub-optimal policies. I.e., most global funds, international banks, conglomerates, and insurances have publicly announced that, mostly for climate protection reasons, they will abandon coal but will continue to support LNG and pipeline natural gas projects which are all required to power human life. This is likely to have unexpected consequences. The potential effects of a warming climate system should not be discounted or played down. However, the undisputed benefits of increased CO2 concentrations in the atmosphere because of its photosynthetic and growth effects (fertilization) on plants need to be considered in energy policy decisions as well. The authors suggest sponsoring ultra-super-critical power plants, whether fossil fuel fired, nuclear, or renewable, at no cost to developing nations to reduce their emissions while also providing essential and reliable energy to encourage industrial growth. Such “technological” gifts could replace less efficient existing plants or even provide new power plants that have far higher emission reduction factors thereby supporting economic and environmental activities in both developing and developed nations. NOTE: This is a draft paper, currently for review

Group Teaching Optimization Algorithm Based MPPT Control of PV Systems under Partial Shading and Complex Partial Shading

The most cost-effective electrical energy is produced by photovoltaic (PV) systems, and with the smallest carbon footprint, making it a sustainable renewable energy. They provide an excellent alternative to the existing fossil fuel-based energy systems, while providing 4% of global electricity demand. PV system efficiency is significantly reduced by the intrinsic non-linear model, maximum power point (MPP), and partial shading (PS) effects. These two problems cause major power loss. To devise the maximum power point tracking (MPPT) control of the PV system, a novel group teaching optimization algorithm (GTOA) based controller is presented, which effectively deals with the PS and complex partial shading (CPS) conditions. Four case studies were employed that included fast-changing irradiance, PS, and CPS to test the robustness of the proposed MPPT technique. The performance of the GTOA was compared with the latest bio-inspired techniques, i.e., dragon fly optimization (DFO), cuckoo search (CS), particle swarm optimization (PSO), particle swarm optimization gravitational search (PSOGS), and conventional perturb and observe (P&O). The GTOA tracked global MPP with the highest 99.9% efficiency, while maintaining the magnitude of the oscillation <0.5 W at global maxima (GM). Moreover, 13–35% faster tracking times, and 54% settling times were achieved, compared to existing techniques. Statistical analysis was carried out to validate the robustness and effectiveness of the GTOA. Comprehensive analytical and statistical analysis solidified the superior performance of the proposed GTOA based MPPT technique.

The role of residential rooftop photovoltaic in long-term energy and climate scenarios

The use of solar photovoltaic has strongly increased in the last decade. A significant part of this growth comes from home owners installing rooftop photovoltaic. Despite this key role, most long-term model-based scenarios do not consider decentralized supply of rooftop photovoltaic but concentrate on utility-scale photovoltaic instead. In this paper, we implement rooftop photovoltaic in the Integrated Assessment Model IMAGE to study its possible role in energy and climate scenarios. We first calculated the global technical and economic potential to derive regional cost-supply curves for rooftop photovoltaic. Next, we have added a new decision in the IMAGE model allowing household investment in rooftop photovoltaic based on the comparison of the whole-sale electricity price with the price of rooftop photovoltaic. The global suitable roof surface area was assessed at 36 billion m2, or 4.7 m2 capita−1, leading to a potential for rooftop photovoltaic of 8.3 PWh y−1, roughly 1.5 times the 2015 global residential electricity demand. In the baseline scenario, adding rooftop photovoltaic could lead to a 80–280% increased share of photovoltaic electricity production in 2050 (i.e. from 6% to 17% in total power production). This increase depends on regional characteristics that are essential to the deployment of rooftop photovoltaic: differences in social-economic and policy factors (capital costs, household income, and electricity prices) are considerably more important than physical factors, such as solar irradiance.