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The aim of this study was to assess the feasibility of creating a prototype of a self-sufficient houseboat that is capable of prolonged independence from power grids and freshwater sources. In this design, electricity demand is met by a photovoltaic installation, and the energy is stored in batteries. Fresh water for living needs may be obtained from many sources, depending on the environmental conditions, such as through purifying outboard water, desalinating seawater, and collecting and storing rainwater. No waste production of the vessel can be achieved in two ways: waste can be treated and discharged into a body of water, or processed into fertiliser for later use in agriculture. Four possible locations were analysed: Rome, Lisbon, Gdańsk and Stockholm. The findings reveal that the length of time for which the unit is autonomous and emission-free depends on the geographical location of the facility. In periods when there is overproduction of energy, the system can produce hydrogen, donate energy to the grid, use it for the needs of its own movement, or perform other useful work, e.g. cleaning or aerating the water body on which it is floating. [ABSTRACT FROM AUTHOR]

Hybrid microgrids, integrating local energy resources, present a promising but challenging solution, especially in areas with limited or no access to the national grid. Reliable operation of off-grid energy systems necessitates sustainable energy sources, given the intermittent nature of renewables. While fossil fuel diesel generators mitigate risks, they increase carbon emissions. This study assesses the viability of integrating a very small modular renewable energy reactor into a microgrid for replacing conventional diesel generators, substantially curbing greenhouse gas emissions. A comprehensive analysis, including design and economic evaluation, was conducted for an off-grid community microgrid with an annual generation and load of 8.5 GWh and 7.8 GWh, respectively. The proposed microgrid configurations incorporate very small modular reactors, alongside solar, wind, and battery storage systems. MATLAB modeling and simulation across eight cases, accounting for seasonal variations, demonstrate the technical and economic feasibility of case 7. This configuration, integrating modular reactors, photovoltaics, wind turbines, and battery storage, satisfactorily meets load demands. Notably, it boasts a high internal rate of return up to ~31% and a shorter payback period of around 4 years compared to alternative scenarios. [ABSTRACT FROM AUTHOR]

Off‐grid solar systems provide clean and affordable energy sources. Adoption of off‐grid Solar energy is becoming increasingly popular in Kenya as a source of renewable energy, with an estimated 10 million people using off‐grid solar power systems as of the end of year 2022. However, the rising off‐grid solar systems technology uptake comes with a growing amount of solar e‐waste, which can have harmful environmental and health effects if not managed properly. Current data on the exact amount of solar e‐waste being generated in Kenya is unavailable and this amount will continue to rise with the expiry of many of these off‐grid solar systems lifespans. This study through stakeholder's workshop and document review data collection and analysis approaches, established that Kenya just like many countries in the Global South has a robust general waste policy and regulation management framework. However, it lacks specific policies and regulations on off‐grid‐solar electronic waste management a challenge that many countries in the Global North have made considerate steps in addressing. In addition, there is a lack of awareness of the hazardous nature of off‐grid solar systems' e‐waste components to both consumers and institutions of governance. There is a lack of adequate infrastructure and sufficient systems for off‐grid solar e‐waste management in the country. Enforcement and implementation challenges of the existing general waste regulations due to limited resources and capacity and corruption culture are major impending factors. This calls for the development of effective policies and regulations to ensure sustainable off‐grid solar e‐waste management in Kenya against the backdrop of the rising uptake of off‐grid solar systems. [ABSTRACT FROM AUTHOR]

The study determined optimum roof tilt and building azimuth for rooftop-based distributed photovoltaic (PV) energy generation in Ikeja, Lagos State, Nigeria, as strategic technological input to alternative power generation and new housing development in Metropolitan Lagos. The energy planning & foresight analysis methodology was used. The data were obtained via literature, Global Positioning System (GPS) systems, energy models, and site visits and comprised manual and satellite imagery, dimensions, roof angles, and coordinates of the building structures in the study area (Rows between 0 – 60o, Columns between 0 – 180o ; System sizes: 533 kW, 110 kW, and 0.547 kW). The results showed solar array yield varied from 768,944 kWh per annum for a 500 kVA system to 780 kWh per annum for a 0.5 kVA system. A five-tier rooftop generation template of 245 MWp was consequently developed. The systems ' optimal roof tilt and building azimuth angles were estimated to be 5o and 180o, respectively, though combinations of azimuth and tilt angles not exceeding 30o tilt and 90o azimuth gave acceptable yields. The study concluded that the optimum roof tilt and building azimuth for rooftop-based distributed photovoltaic (PV) energy generation in the study area were strategic policy intelligence inputs for the Federal and Lagos State governments' renewable power generation and new housing development programmes. [ABSTRACT FROM AUTHOR]

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Electric car charging stations are in high demand as a result of the development of the e-mobility sector and the adoption of electric vehicles in transportation. This study aims to construct and analyze a stand-alone solar PV-powered electric car charging station to fulfil electric vehicle load demand and make recommendations for optimizing its operation. The goal is to achieve 3D’s i.e., Decarbonization, Digitalization and Decentralization in both the transport and power supply (electricity supply). Advancing towards attaining 3D’s goal, an off-grid solar PV-powered EV charging station was built at the University of Sharjah to meet the load demand. The EV charging station includes PV panels, inverters, energy storage devices and EV charging outlets. A solar PV system of 7.4 kWp with an energy storage capacity of 34.56 kWh is installed. A battery inverter of 4.6 kW is incorporated to meet the load demand of three electrical vehicles simultaneously. The performance of the system is monitored over a year. The EV charging station is in off-grid mode; thus, it is following the load demand for PV energy production. The findings reveal that the total energy production by the PV system is 2971.59 kWh from which the direct consumption is 383.77 kWh (12.91 %), and 2587.83 kWh (87.09 %) is stored in the energy storage devices. The total energy consumption by electric vehicles is 2379.01 kWh of which 1995.24 kWh (83.87 %) is taken from the battery bank. The PV system is working at 24.58 % of its full capacity. By elevating the daily load demand to 33 kWh, the full utilization of the solar resource can be achieved. To evaluate the adverse effect of dust, natural dust is allowed to settle down on the surface of PV panels continuously for 322 days. A linear degradation was recorded in the performance ratio from 77.92 % to 27.30 % in 218 days. Thereafter a plateau was attained and insignificant variation (min. 26.36 % and max. 33.78 %) was observed in the next 104 days. It is concluded that once a thick layer of dust forms on the surface of the PV panels, further dust accumulation becomes minimal.

Universal access to electricity is beneficial for the socio-economic development of a country and the development of smart communities. Unfortunately, the electrification of remote off-grid areas, especially in developing countries, is rather slow due to geographic and economic barriers. In the Philippines, specifically, many electrified off-grid areas are underserved, with access to electricity being limited to only a few hours a day. This is mainly due to the high dependence on diesel power plants (DPPs) for electrifying these areas. To address these problems, hybrid renewable energy systems (HRESs) have been considered good electrification alternatives and have been extensively studied for their techno-economic and financial feasibility for Philippine off-grid islands. In this work, articles published from 2012 to 2023 focusing on off-grid Philippine rural electrification were reviewed and classified based on their topic. The taxonomical analysis of collected studies shows that there is a saturation of works focusing on the technical and economic aspects of off-grid electrification. Meanwhile, studies focusing on environmental and socio-political factors affecting HRES off-grid electrification are lagging. A bibliographic analysis of the reviewed articles also showed that there is still a lack of a holistic approach in studying off-grid electrification in the Philippines. There are only a few works that extend beyond the typical techno-economic study. Research works focusing on environmental and socio-political factors are also mainly isolated and do not cross over with technical papers. The gap between topic clusters should be addressed in future works on off-grid electrification.

Abstract The transition to sustainable power infrastructure necessitates integrating various renewable energy sources efficiently. Our study introduces the deterministic balanced method (DBM) for optimizing hybrid energy systems, with a particular focus on using hydrogen for energy balance. The DBM translates the sizing optimization problem into a deterministic one, significantly reducing the number of iterations compared to state-of-the-art methods. Comparative analysis with HOMER Pro demonstrates a strong alignment of results, with deviations limited to a 5% margin, confirming the precision of our method in sizing determinations. Utilizing solar and wind data, our research includes a case study of Cairo International Airport, applying the DBM to actual energy demands.

Off-grid electrification planning increasingly recognizes the importance of productive use of electricity (PUE) to promote community value creation and (financial) project sustainability. To ensure a sustainable and efficient integration in the community and energy system, PUE assets must be carefully evaluated to match both the community needs and the residential electricity demand patterns. We propose a novel methodology interlinking qualitative interviews, statistical analysis and energy system modeling to optimize decision making for PUE integration in off-grid energy systems in rural Madagascar by aligning relevant PUE effectively with anticipated residential electricity demand patterns based on socio-economic determinants of the community. We find that a possible contribution of the PUE to reducing the electricity costs depends significantly on three factors: (1) The residential electricity consumption patterns, which are influenced by the socio-economic composition of the community; (2) The degree of flexibility of (i) PUE assets and (ii) operational preferences of the PUE user; and (3) The capacity of community members to finance and operate PUE assets. Our study demonstrates that significant cost reductions for PUE-integrated off-grid energy systems can be achieved by applying our proposed methodology. When matching PUE and residential consumption patterns, the integration of PUE assets in residential community energy systems can reduce the financial risk for operators, provided the PUE enterprise operates reliably and sustainably. We highlight that the consideration of local value chains and co-creation approaches are essential to ensure the energy system is addressing the community's needs, creates value for the community, enhances the project's financial sustainability and is achieving the overall objectives of decentralized energy system planning. [ABSTRACT FROM AUTHOR]

A properly designed and manufactured autonomous lighting system has an impact on reducing the amount of conflicts between pedestrians and drivers. For pedestrian crossings located outside of urban areas, one of the utilized solutions is PV installations with an electrochemical energy storage bank. So, the question should be asked: is it possible to maintain proper energy and lighting parameters throughout the year? This depends on the technical parameters of the installation, insolation, operating time, and the number and power of lighting luminaires directly prescribed by formal regulations. The purpose of this article is to present a method for evaluating the performance of a lighting installation at isolated pedestrian crossings based on annual power generation data obtained from a photovoltaic installation. This article presents lighting requirements for pedestrian crossing lighting. Based on the developed five lighting scenarios and energy calculations, year-round operation was simulated. Problems and risks that may affect the availability and performance of the lighting system were introduced. Directions for further research on the application of photovoltaic installations in road infrastructure were identified. [ABSTRACT FROM AUTHOR]

The transition to sustainable power infrastructure necessitates integrating various renewable energy sources efficiently. Our study introduces the deterministic balanced method (DBM) for optimizing hybrid energy systems, with a particular focus on using hydrogen for energy balance. The DBM translates the sizing optimization problem into a deterministic one, significantly reducing the number of iterations compared to state-of-the-art methods. Comparative analysis with HOMER Pro demonstrates a strong alignment of results, with deviations limited to a 5% margin, confirming the precision of our method in sizing determinations. Utilizing solar and wind data, our research includes a case study of Cairo International Airport, applying the DBM to actual energy demands. [ABSTRACT FROM AUTHOR]

Hybrid renewable energy sources (HRES) are increasingly being utilized to meet global energy demands, particularly in rural areas that rely on diesel generators and are disconnected from the utility grid, due to their environmental and human health benefits. This study investigates the performance of an off-grid, hybrid PV/diesel generator/battery system for a decentralized power plant in Kuakata, Bangladesh, meeting a load demand of 3000 kWh/day with a 501.61 kW peak load demand. HOMER Pro (hybrid optimization model for electric renewable) software (version 3.11) was used to simulate and optimize system operations utilizing real-time solar radiation and load profile data from that location. This study also includes a sensitivity analysis of the off-grid HRES system under different electrical load demands, project longevity, and derating variables. The results reveal that CO2 emissions have potentially decreased by more than 30% and over 10 tons per year, respectively, when compared to traditional power plants. The optimized system's net present cost (NPC) was determined to be around USD 5.19 million, with a cost of energy (COE) of USD 0.367 per kWh per unit with a 100% renewable component. Furthermore, the current study's findings are compared to previous research that has resulted in an economical hybrid renewable energy system with an affordable COE. The hybrid energy system under consideration might also be applicable to other parts of the world with comparable climate conditions. [ABSTRACT FROM AUTHOR]

Using pumps operating as turbines (PATs) offers the possibility of increasing the sustainability of water and energy systems by recovering the excess energy that would be otherwise lost in pressure-reducing valves or head loss chambers. Regarding on-grid applications, there have been many research works, and PATs have been implemented in several ways. However, more research still needs to be done on optimizing the efficiency and stability of PATs operating in off-grid systems. This work contributes to the development of stable direct current (DC) off-grid electric systems based on PATs using a self-excited induction generator (SEIG). In this context, a methodology is proposed, based on the hydraulic, mechanical, and electric subsystems, to define the PAT-SEIG operational area to maximize energy conversion and system efficiency. These limits depend highly on the capacitor value, rotational speed, and electric load. In addition, an analytical model is proposed to estimate the PAT-SEIG operation under specific conditions. With this, water managers can design and optimize an off-grid PAT-SEIG system and define the best hydraulic machines, electronic equipment, and control elements to maximize energy conversion within the target of operational limits. Two micro PAT-SEIG setups were implemented in the hydraulic laboratory of IST/CERIS under typical operating conditions to validate the proposed methodology. The system's maximum efficiency and operational limits can be adapted using different capacitor values for the excitation of the SEIG. Considering the nominal efficiencies of the system's components, the maximum p.u. efficiency obtained for each PAT-SEIG system was between 0.7 and 0.8 p.u. [ABSTRACT FROM AUTHOR]

This study assesses the viability of employing a hybrid system that combines wind and tidal turbines, connected to a microgrid, to provide electricity to coastal communities that are geographically isolated from the primary power grid. The specific focus of this research is the case study of Stewart Island, where the cost of electricity from a centralized diesel power station is comparatively higher than that of the main grid in New Zealand. While lithium‐ion batteries are generally regarded as more reliable and efficient than lead‐acid batteries, the analysis conducted indicates that, for the off‐grid storage system in Oban, lead‐acid batteries are the preferable choice. Multiple off‐grid configurations are simulated utilizing the HOMER Pro software. While lithium‐ion batteries demonstrate higher charge power and renewable fraction, it is found that lead‐acid batteries, with their longer battery life, offer advantages such as reduced fuel consumption, lower cost of electricity, discounted payback, and increased power production. The annual fuel consumption for lead‐acid battery is 867 L less compared to the lithium‐ion battery. Power generated in this case is 6780 kWh more and COE with lead‐acid battery is $0.213 in compared with lithium‐ion of $0.217. These findings suggest that for the specific context of the Oban off‐grid system, lead‐acid batteries outperform lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Abstract Off‐grid solar systems provide clean and affordable energy sources. Adoption of off‐grid Solar energy is becoming increasingly popular in Kenya as a source of renewable energy, with an estimated 10 million people using off‐grid solar power systems as of the end of year 2022. However, the rising off‐grid solar systems technology uptake comes with a growing amount of solar e‐waste, which can have harmful environmental and health effects if not managed properly. Current data on the exact amount of solar e‐waste being generated in Kenya is unavailable and this amount will continue to rise with the expiry of many of these off‐grid solar systems lifespans. This study through stakeholder's workshop and document review data collection and analysis approaches, established that Kenya just like many countries in the Global South has a robust general waste policy and regulation management framework. However, it lacks specific policies and regulations on off‐grid‐solar electronic waste management a challenge that many countries in the Global North have made considerate steps in addressing. In addition, there is a lack of awareness of the hazardous nature of off‐grid solar systems' e‐waste components to both consumers and institutions of governance. There is a lack of adequate infrastructure and sufficient systems for off‐grid solar e‐waste management in the country. Enforcement and implementation challenges of the existing general waste regulations due to limited resources and capacity and corruption culture are major impending factors. This calls for the development of effective policies and regulations to ensure sustainable off‐grid solar e‐waste management in Kenya against the backdrop of the rising uptake of off‐grid solar systems.

Hybrid microgrids, integrating local energy resources, present a promising but challenging solution, especially in areas with limited or no access to the national grid. Reliable operation of off-grid energy systems necessitates sustainable energy sources, given the intermittent nature of renewables. While fossil fuel diesel generators mitigate risks, they increase carbon emissions. This study assesses the viability of integrating a very small modular renewable energy reactor into a microgrid for replacing conventional diesel generators, substantially curbing greenhouse gas emissions. A comprehensive analysis, including design and economic evaluation, was conducted for an off-grid community microgrid with an annual generation and load of 8.5 GWh and 7.8 GWh, respectively. The proposed microgrid configurations incorporate very small modular reactors, alongside solar, wind, and battery storage systems. MATLAB modeling and simulation across eight cases, accounting for seasonal variations, demonstrate the technical and economic feasibility of case 7. This configuration, integrating modular reactors, photovoltaics, wind turbines, and battery storage, satisfactorily meets load demands. Notably, it boasts a high internal rate of return up to ∼31% and a shorter payback period of around 4 years compared to alternative scenarios.

The electricity production from Renewable Energy (RE) in isolated locations requires long-term energy storage systems. To that end, Hybrid Energy Storage Systems (HESS), through a combination of hydrogen and batteries, can benefit from the different advantages of both technologies. This paper presents a hybrid Power-to-Power (PtP) Optimal Power Dispatch (OPD) model for isolated systems with no electric grid access. Currently, the electricity supply in such cases is usually based on a mix of RE as the primary energy source sustained by a diesel genset acting as a backup generator. In this context, the model delivers the hourly energy flows between renewable production sources, energy storage devices and the electrical load, which minimises costs and Green House Gases (GHG) emissions. For validation purposes, the model was tested through its application to a case study in an isolated area in the Canary Islands, Spain. The results show that the algorithm calculates the hourly OPD successfully for a given plant sizing, considering the defined operational states of the different assets. These operational constraints showed a decrease in the PtP round-trip efficiency of 5.4% and a reduction of the hydrogen production of 9.7%. Finally, the techno-economic analysis of the results proves that the combination of hydrogen and batteries with RE production is a feasible alternative to phasing out fossil fuels for the selected case study – reducing the diesel generator usage down to 1.2% of the yearly energy supply. • Novel multi-state optimal power dispatch model for power-to-power energy systems. • Multi-year techno-economic evaluation of an off-grid case study. • Phasing out fossil fuels with renewable energy-based hybrid energy storage systems. • Hydrogen technology contributes to a lower levelized cost of energy. • High initial investment cost was a significant entry barrier to deploying hydrogen. [ABSTRACT FROM AUTHOR]

Growing concerns about the climate change accompanied with energy crisis due to the unrest in the world have pushed the energy market to utilize sustainable and secure alternatives such as solar photovoltaics (PV). However, for residential consumers, the primary concerns are the reliability of the supply and the cost of PV-generated electricity. This study reports on the economic feasibility and technical analysis of PV systems in megacities worldwide. Nine mega cities, Beijing, Berlin, Istanbul, London, New Delhi, New York, Paris, Seoul, and Tokyo, have been selected based on their significant population sizes and the pronounced demand for electricity independence among residents. The annual production, load matching, and PV-electricity and battery dispatch are discussed, with Lazard's levelized cost of electricity (LCOE) and net present value (NPV) employed as economic indicators. While calculated LCOEs ranged from $0.084/kWh to $0.27/kWh across different cities, the NPVs were predominantly negative, varying approximately between –$2,000 and –$20,000, with Berlin as an exception. Finally, a sensitivity analysis was conducted, revealing that the LCOE is more sensitive to financial parameters than to module efficiency and irradiation. [ABSTRACT FROM AUTHOR]

Smart urbanism is an established research area in geography and the social sciences. We draw on 'worlding-provincialising' strategies identified in an Urban Studies Special Issue from February 2021 to explore how smart infrastructures, a form of smart urbanism, disrupt representations of informality and urban development in new and productive ways. Focussing on the disruptive or troublesome implications of smart infrastructures reveals site-level considerations for developing policy and practice, where acknowledging the nuanced context for its use can present opportunities for not only understanding energy transitions in the Global South, but also creates opportunities for cross-learning. Drawing on our collective insights on a solar mini-grid project in Qandu-Qandu, Cape Town, we sketch out three ways the disruptive aspects of solar energy can be helpful for re-building knowledge on the informal city by: (i) re-positioning notions of 'formal' and 'informal' infrastructure(s) in urban planning and policymaking; (ii) highlighting new avenues for citizen autonomy; and (iii) recasting the informal city as a site for continuous innovation and learning. [ABSTRACT FROM AUTHOR]

Hydrogen-based Fuel Cells (FCs) hold significant potential as energy conversion technologies. In a previous study, we presented a pump-based hydrogen generator (PHG) that utilizes a catalytic reaction between sodium borohydride (NaBH4) powder and water. The pump circulates the water solution through the powder chamber in a closed-loop reaction. The PHG demonstrated clear advantages over alternative hydrogen sources in terms of both safety and energy density. However, as operating time increases, the solution in the closed-loop PHG becomes saturated, causing the reaction rate to decline. This limitation can be overcome in cases where an external water source is available, such as marine vehicles, drones equipped with water recovery systems from their fuel cells, or systems located near pipelines. In such scenarios, introducing freshwater feeding and product emission offers intriguing possibilities for significantly enhancing the fuel's energy density and extending its effective operation time.Our current research introduces an innovative concept: a dual-cycle generator (DCG) that effectively overcomes the issue of solution saturation over time. It achieves this by combining solution circulation with freshwater feeding and product emission. Our study employed a DCG prototype to examine various operating modes and to demonstrate the effectiveness of this approach. The DCG achieved a calculated energy density for the fuel of 3868 Wh/kg, with 93% H2 extraction yield from the powder. Our findings reveal substantial improvements in terms of extended operation duration (81%), increased hydrogen flow rate (36%), enhanced energy density (33%), and improved H2 yield extraction from the powder (39%). This methodology holds promise for mobile applications or off-grid systems situated in proximity to a water source.

Liberia, a developing nation, faces significant challenges in its energy sector, with limited access to electricity and heavy reliance on traditional biomass and imported fossil fuels. This review explores Liberia's energy landscape, policies, challenges, and opportunities, aiming to identify ways to improve energy access and foster sustainable development. Our methodology employed a systematic search strategy, examining relevant literature from various sources, encompassing research articles, reports, and studies related to Liberia's energy landscape from 2010 onward. Our findings indicate that Liberia's energy mix is historically dominated by traditional biomass fuels such as firewood and charcoal, accounting for more than 80 % of the country's total energy consumption. Petroleum products, including gasoline and diesel, contribute to about 10 % of energy consumption, while hydroelectric power makes up just over 6 %. The remaining energy comes from various sources, including solar energy. This heavy reliance on traditional biomass and limited access to affordable energy has significant social and economic implications. Efforts have been made in recent years to improve Liberia's energy situation. Yet, significant challenges, including financial constraints, inadequate infrastructure, affordability issues, and an outdated energy policy, continue to hinder progress. However, the review identifies opportunities for improving energy access, including abundant renewable energy resources, international support, public-private partnerships, off-grid solutions, and energy efficiency measures. Additionally, regular reviews and updates of policies, informed by accurate data and forward-looking strategies, are also essential to ensure that the energy sector remains aligned with changing circumstances and technological advancements.

A properly designed and manufactured autonomous lighting system has an impact on reducing the amount of conflicts between pedestrians and drivers. For pedestrian crossings located outside of urban areas, one of the utilized solutions is PV installations with an electrochemical energy storage bank. So, the question should be asked: is it possible to maintain proper energy and lighting parameters throughout the year? This depends on the technical parameters of the installation, insolation, operating time, and the number and power of lighting luminaires directly prescribed by formal regulations. The purpose of this article is to present a method for evaluating the performance of a lighting installation at isolated pedestrian crossings based on annual power generation data obtained from a photovoltaic installation. This article presents lighting requirements for pedestrian crossing lighting. Based on the developed five lighting scenarios and energy calculations, year-round operation was simulated. Problems and risks that may affect the availability and performance of the lighting system were introduced. Directions for further research on the application of photovoltaic installations in road infrastructure were identified.

Using pumps operating as turbines (PATs) offers the possibility of increasing the sustainability of water and energy systems by recovering the excess energy that would be otherwise lost in pressure-reducing valves or head loss chambers. Regarding on-grid applications, there have been many research works, and PATs have been implemented in several ways. However, more research still needs to be done on optimizing the efficiency and stability of PATs operating in off-grid systems. This work contributes to the development of stable direct current (DC) off-grid electric systems based on PATs using a self-excited induction generator (SEIG). In this context, a methodology is proposed, based on the hydraulic, mechanical, and electric subsystems, to define the PAT-SEIG operational area to maximize energy conversion and system efficiency. These limits depend highly on the capacitor value, rotational speed, and electric load. In addition, an analytical model is proposed to estimate the PAT-SEIG operation under specific conditions. With this, water managers can design and optimize an off-grid PAT-SEIG system and define the best hydraulic machines, electronic equipment, and control elements to maximize energy conversion within the target of operational limits. Two micro PAT-SEIG setups were implemented in the hydraulic laboratory of IST/CERIS under typical operating conditions to validate the proposed methodology. The system’s maximum efficiency and operational limits can be adapted using different capacitor values for the excitation of the SEIG. Considering the nominal efficiencies of the system’s components, the maximum p.u. efficiency obtained for each PAT-SEIG system was between 0.7 and 0.8 p.u.

Hybrid renewable energy sources (HRES) are increasingly being utilized to meet global energy demands, particularly in rural areas that rely on diesel generators and are disconnected from the utility grid, due to their environmental and human health benefits. This study investigates the performance of an off-grid, hybrid PV/diesel generator/battery system for a decentralized power plant in Kuakata, Bangladesh, meeting a load demand of 3000 kWh/day with a 501.61 kW peak load demand. HOMER Pro (hybrid optimization model for electric renewable) software (version 3.11) was used to simulate and optimize system operations utilizing real-time solar radiation and load profile data from that location. This study also includes a sensitivity analysis of the off-grid HRES system under different electrical load demands, project longevity, and derating variables. The results reveal that CO2 emissions have potentially decreased by more than 30% and over 10 tons per year, respectively, when compared to traditional power plants. The optimized system’s net present cost (NPC) was determined to be around USD 5.19 million, with a cost of energy (COE) of USD 0.367 per kWh per unit with a 100% renewable component. Furthermore, the current study’s findings are compared to previous research that has resulted in an economical hybrid renewable energy system with an affordable COE. The hybrid energy system under consideration might also be applicable to other parts of the world with comparable climate conditions.

This document is an erratum for an article titled "Integration of very small modular reactors and renewable energy resources in the microgrid." The erratum acknowledges a production error in Figure 1 of the original article, where Figure 1A was mistakenly removed. The corrected Figure 1 is provided in the erratum. The publisher apologizes for the mistake and has updated the original article. [Extracted from the article]

[Display omitted] • A new multi-criteria decision-making approach is proposed. • Fixed panel-based off-grid hybrid energy systems is the right choice. • The optimal hybrid system is sustainable during flood event without any damage. • The optimal hybrid system is cost-effective and beneficial for future load demand. • Sensitivity analysis proved the effectiveness of the proposed approach. The unique geographical features of wetlands pose challenges to the conventional energy infrastructure. To address these challenges, this study proposes the establishment of off-grid hybrid energy systems (HES) that integrate photovoltaic (PV), wind turbine (WT), diesel generator (DG), and hydrokinetic turbine (HKT) units, along with batteries for energy storage. Initially, a list of criteria was determined for analysis. The Hybrid Optimization of Multiple Energy Resources (HOMER) tool was utilized for techno-economic optimization and to identify optimal off-grid HES designs for powering three villages in the wetland (Haor) region of Bangladesh. Subsequently, the Linear Bounded Weighted Average (LBWA) method was used to calculate the weights of the criteria. Then, a wins in league (WIL) theory-based Multi-Criteria Decision Making (MCDM) method, known as the Combined Compromise Solution (CoCoSo), was introduced to rank the identified optimal off-grid HES alternatives. The results favor an integrated system comprising 388 kW PV, 39 kW WT, 150 kW DG, 160 kW HKT, and 893 kWh Li-Ion BT for optimal load demand fulfillment, providing benefits to nearby communities. This study underscores that a fixed panel-based optimal hybrid system consumes 5 %, 8 %, and 9 % less fuel, emits minimal CO 2 , requires fewer water resources, and creates more job opportunities than other tracking technologies. Compared with a DG-only system, the optimal off-grid HES proved to be 59 % more cost-effective and reduced CO 2 emissions by 96 %. In contrast, compared with a stand-alone PV system, the optimal off-grid HES is 35.5 % more cost-effective and reduces excess energy by 62 %. The proposed off-grid HES is highlighted as cost-effective, and environmentally sustainable, without any damage to the PV system during flood. Furthermore, the optimal hybrid system can reduce energy costs and excess energy by 2 % and 9 %, respectively, in future load demand scenarios while also generating 6 % more employment. The effectiveness of the analysis and the proposed approach was demonstrated through sensitivity analyses. The proposed WIL-CoCoSo approach effectively addresses the problem of rank reversal in decision making. The findings of this study also provide a foundational model for designing flood-resilient and sustainable off-grid HES in wetland areas of developing countries. [ABSTRACT FROM AUTHOR]

Increasing energy autonomy is one of the main reasons for municipalities to invest in renewable energy technologies. In this study, the potential of weather-robust autonomous energy systems is evaluated for 11 003 German municipalities in over one million parallelized techno-economic optimizations utilizing high-performance computing clusters. For this purpose, a holistic municipal-level energy system model (ETHOS.FineRegions) was developed that minimizes annualized system costs in 2045. The completely energy autonomous supply can be established in around 90% of German municipalities corresponding to 50% of the country's population. Especially highly populated municipalities often do not have the capacity to meet their own energy demands due to low wind and open-field PV potentials. Large rooftop PV capacities account for 40% of installed capacity in the autonomous municipalities. Seasonal storage needs are met by large underground thermal storage tanks and batteries provide intraday storage. Furthermore, huge capacity increases are often required for the final 20% of energy demand to be met in order to achieve a degree of autonomy of 100%. The large storage and rooftop PV capacities lead to high specific system costs in the autonomous municipalities with between 144 €/MWh and 174 €/MWh on average, depending on legislation and opposition towards onshore wind installations. By paying a premium of up to 50% compared to the grid-dependent system, 3945 municipalities with 17.2 million inhabitants could become completely autonomous by 2045. For regions that could achieve an autonomous energy supply at moderate costs, however, lost revenues through energy exports could be a decisive argument against autonomy efforts. • Single energy system optimizations for 11003 German municipalities. • Assessment of various scenarios in more than one million techno-economic optimizations. • Utilization of high-performance computing clusters for parallelized optimizations. • Complete energy autonomy technically feasible in 90% of German municipalities. • Extended economic potential for autonomy in 36% of German municipalities. [ABSTRACT FROM AUTHOR]

• Net-zero energy planning and multi-objective optimizations on an outdoor laboratory. • The optimization algorithm strikes a trade-off between renewable factor and LCC. • The annual carbon mitigation in the net-zero energy solution exceeds 828 kg. • Annual hydrogen production in optimal scenarios can increase up to 60%. • The LCOE for different optimization objectives varies between 0.389 and 0.537 $/kWh. Hydrogen production and storage in hybrid systems is a promising solution for sustainable energy transition, decoupling energy generation from demand and boosting the deployment of renewable energy. Nonetheless, the optimal and cost-effective design of hybrid hydrogen-based systems is crucial to tackle existing limitations in the diffusion of these systems. The present study explores net-zero energy management via a multi-objective optimization algorithm for an outdoor test facility equipped with a hydrogen-based hybrid energy production system. Aimed at enabling efficient integration of hydrogen fuel cell system, the proposed solution attempts to maximize the renewable factor (RF) and carbon mitigation in the hybrid system as well as to minimize the grid dependency and the life cycle cost (LCC) of the system. In this context, the techno-enviro-economic optimization of the hybrid system is conducted by employing a statistical approach to identify optimal design variables and conflictive objective functions. To examine interactions in components of the hybrid system, a series of dynamic simulations are carried out by developing a TRNSYS code coupled with the OpenStudio/EnergyPlus plugin. The obtained results indicate a striking disparity in the monthly RF values as well as the hydrogen production rate, and, therefore, in the level of grid dependency. It is shown that the difference in LCC between optimization scenarios suggested by the design of experiments could reach $15,780, corresponding to 57 % of the mean initial cost. The LCOE value yielded for optimum scenarios varies between 0.389 and 0.537 $/kWh. The scenario with net-zero target demonstrates the lowest LCOE value and the highest carbon mitigation, i.e., 828 kg CO 2 /yr, with respect to the grid supply case. However, the LCC in this scenario exceeds $57,370, which is the highest among all optimum scenarios. Furthermore, it was revealed that the lowest RF in optimal scenarios is equal to 66.2 % and belongs to the most economical solution. [ABSTRACT FROM AUTHOR]

Aiming to amplify the renewable energy consumption capacity, this study delineates the development of an off-grid Renewable Energy Large-Scale Hydrogen Production System (H2-RES). The system was optimized for economic efficiency and safety, promising a reduction in both the investment cost for grid connection and the overall cost of hydrogen production from electrolytic water. We presented a comprehensive mathematical model for each H2-RES unit and designed a control strategy to enhance energy optimization and management. An intelligent energy scheduling policy empowered by the DDPG algorithm is introduced for optimal decision-making in continuous state and action spaces. Comparative analysis with traditional control policies, PSO, and DQN algorithms underscores the superior economic efficiency, enhanced renewable energy consumption, and safe operation facilitated by DDPG. These findings underscore the academic and engineering potential of DDPG in the energy dispatch of H2-RES. [ABSTRACT FROM AUTHOR]

Solar water heaters (SWHs) are thermal storage devices that effectively use sunlight as an energy source to heat water and supply hot water. In Japan, single-person households and younger generations living in apartment buildings in urban areas have few opportunities to use SWHs. Thus, we developed a simple portable and size-adjustable SWH using a commercial portable black container as the heat absorber and greenhouse materials for heat insulation to promote the use of SWHs. Moreover, we tested its practical performance using it at home for more than one year. The developed SWH can heat approximately 150 L water by >20 °C throughout the year with the energy conversion efficiency of 25 %–50 %, except during the rainy season. In addition, the annual gas consumption was reduced by approximately 25 % using the heated water for bathing at home. The initial cost for this SWH was 1/10 of those for conventional roof-mounted SWHs, resulting in an estimated payback period of less than two years, which is considerably shorter than those of conventional ones. Furthermore, this SWH can be prepared and used without any installation and maintenance works that require specialized skills or power sources and can be easily and inexpensively used by anyone anywhere at any time, even during a disaster. Such SWHs are expected to contribute to the realization of a resilient decarbonized society. • This portable off-grid solar water heater (SWH) consists of plastic containers. • The SWH heats 150 L water by ~20 °C with 25–50 % conversion efficiency in sunny days. • The SWH reduces the CO 2 emission for bath water supply by 25 % a year. • The SWH's payback period is less than two years due to its low initial cost. • The SWH is useful for apartment residents' daily use, even in a disaster. [ABSTRACT FROM AUTHOR]

Hydrogen-based Fuel Cells (FCs) hold significant potential as energy conversion technologies. In a previous study, we presented a pump-based hydrogen generator (PHG) that utilizes a catalytic reaction between sodium borohydride (NaBH 4 ) powder and water. The pump circulates the water solution through the powder chamber in a closed-loop reaction. The PHG demonstrated clear advantages over alternative hydrogen sources in terms of both safety and energy density. However, as operating time increases, the solution in the closed-loop PHG becomes saturated, causing the reaction rate to decline. This limitation can be overcome in cases where an external water source is available, such as marine vehicles, drones equipped with water recovery systems from their fuel cells, or systems located near pipelines. In such scenarios, introducing freshwater feeding and product emission offers intriguing possibilities for significantly enhancing the fuel's energy density and extending its effective operation time. Our current research introduces an innovative concept: a dual-cycle generator (DCG) that effectively overcomes the issue of solution saturation over time. It achieves this by combining solution circulation with freshwater feeding and product emission. Our study employed a DCG prototype to examine various operating modes and to demonstrate the effectiveness of this approach. The DCG achieved a calculated energy density for the fuel of 3868 Wh/kg, with 93% H 2 extraction yield from the powder. Our findings reveal substantial improvements in terms of extended operation duration (81%), increased hydrogen flow rate (36%), enhanced energy density (33%), and improved H 2 yield extraction from the powder (39%). This methodology holds promise for mobile applications or off-grid systems situated in proximity to a water source., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Idit Avrahami and Alex Schechter report financial support was provided by Israel Ministry of Energy. Idit Avrahami and Alex Schechter report a relationship with NugenX clean energy LTD. that includes: board membership and equity or stocks. Idit Avrahami and Alex Schechter have patent #U.S. patent No. 20210371276: Alex Schechter and Idit Avrahami, “System, device and method for hydrogen production “. Eyal Hayouk declare that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

The supply of freshwater based on wind-powered desalination is technically feasible, but energetic losses associated with conventional systems necessitate new approaches. This study explores a direct wind-powered desalination (D-WPD) system using a small-scale vertical axis wind turbine (VAWT) for reverse osmosis via a high-pressure pump without electricity generation or a system controller. A comprehensive parametric study examined the effects of feed water salinity, loading, and wind speed on the system's performance, demonstrating high efficiency under various operating conditions. A stand-alone system demonstrated operation at effectively constant system efficiency, approximately 13.5 %, and low specific energy consumption for a wide range of wind speeds and salinities. Despite the turbine's small projected area of 0.8 m2, the D-WPD system yielded a daily permeate production of up to 0.6 m3/day at an average wind speed of 6 m/s. The D-WPD system surpassed previous wind-powered desalination studies in terms of specific energy consumption, relative efficiency, and relative desalination capacity. Leveraging the environmental benefits of the slow-spinning VAWT, this D-WPD offers a cost-effective off-grid solution for small-scale desalination. [Display omitted] • Direct coupling between VAWT and brackish-water RO desalination was explored. • The system operated at efficiencies of 10 %–15 % at various wind speeds and TDS. • Effective SEC of 0.7–1.7 kWh/m3 was obtained for TDS < 5000 ppm. • A sub-component model showed excellent correspondence with data. • A laboratory scale, 0.8 m2, produced 0.6m3/day at 6 m/s wind speeds. [ABSTRACT FROM AUTHOR]

Liberia, a developing nation, faces significant challenges in its energy sector, with limited access to electricity and heavy reliance on traditional biomass and imported fossil fuels. This review explores Liberia's energy landscape, policies, challenges, and opportunities, aiming to identify ways to improve energy access and foster sustainable development. Our methodology employed a systematic search strategy, examining relevant literature from various sources, encompassing research articles, reports, and studies related to Liberia's energy landscape from 2010 onward. Our findings indicate that Liberia's energy mix is historically dominated by traditional biomass fuels such as firewood and charcoal, accounting for more than 80 % of the country's total energy consumption. Petroleum products, including gasoline and diesel, contribute to about 10 % of energy consumption, while hydroelectric power makes up just over 6 %. The remaining energy comes from various sources, including solar energy. This heavy reliance on traditional biomass and limited access to affordable energy has significant social and economic implications. Efforts have been made in recent years to improve Liberia's energy situation. Yet, significant challenges, including financial constraints, inadequate infrastructure, affordability issues, and an outdated energy policy, continue to hinder progress. However, the review identifies opportunities for improving energy access, including abundant renewable energy resources, international support, public-private partnerships, off-grid solutions, and energy efficiency measures. Additionally, regular reviews and updates of policies, informed by accurate data and forward-looking strategies, are also essential to ensure that the energy sector remains aligned with changing circumstances and technological advancements. • Only 3 % of Liberians had grid electricity access in 2019, among the lowest globally. • Traditional biomass use poses indoor air pollution risks, especially for women and children. • Outdated infrastructure, fuel dependence, and funding constraints hinder progress. • Abundant renewables, international support, and off-grid options offer solutions. • Regular policy updates vital for adapting to change and progress. [ABSTRACT FROM AUTHOR]