Energy Options Research Articles

A new approach for environmental analysis of vapor compression refrigeration systems: Environmental impact index

Vapor-compression refrigeration (VCR) cycles are used to transfer heat from a low-temperature environment to a high-temperature environment. To reduce harmful emissions, environmentally friendly refrigerants should be selected. Metrics like global warming potential and life cycle climate performance are used for environmentally friendly refrigerants. These metrics are independent of each other and are analyzed and evaluated separately. In this study, a new metric was proposed for the environmental analysis of VCR systems and named as environmental impact index (EII). EII defined for the first time in this research, includes the use of both energy, exergy, and low-emission renewable energy at the same time. Also, EII analysis of a cooling system using various refrigerants was performed for all cities of Türkiye. In the case of using R134a, R1234yf, and R1234ze refrigerants in the cooling system the cities with the highest and lowest EII values of the cooling system are Ardahan and Şanlıurfa, respectively. The EII of R134a, R1234yf, and R1234ze (E) for Şanlıurfa are 49.79, 51.81, and 49.75, respectively. The EII of R134a, R1234yf, and R1234ze (E) for Ardahan are 73.75, 75.13, and 73.13, respectively. It was concluded that when choosing refrigerants for VCR systems, attention should be paid not only to the GWP ratios of refrigerants, but also to energy and exergy performance, and energy options with lower emissions.

Analysis of portable solar concrete ponds by using coal cinder to trap thermal energy of sustainable building using artificial intelligence

Cinder is a waste product made from the coal residue left over from power plant blast furnaces. Solar energy is a promising renewable energy source, but because of its erratic availability, energy storage technologies must be used. Our research suggests employing coal cinder (CC) to boost the thermal energy stored in transportable solar concrete ponds, combining rock mechanics with renewable energy. The concepts of renewable energy and rock mechanics are combined in this invention. Additionally, because it doesn't release any pollutants into the sky, it is great for low heat applications like building cooling and heating. However, due to its sporadic nature, solar energy requires effective energy storage to be used at night and in cloudy weather. By adding coal cinders to the bottom layer of a solar concrete pond in order to increase its heat energy, this work integrates rock mechanics with sustainable energy. A variety of small-scale research use the standard micro solar concrete ponds. Also offered is a numerical calculation for predicting energy development over a sizable area of a solar pond with a salt gradient. The coal cinders may significantly raise the temperature at the pond's bottom. With a constant temperature differential of 30 °C and 20 °C throughout the gradient layer for two different pond sizes with depths of 1.5 m and 1.0 m, this study provides thermal analysis of a salt gradient solar pond using machine learning as Particle Swarm Optimization (PSO) and extracting heat from the Lower Convective Zone (LCZ). Going through the regression indices (RMSE, R2, r), the energy efficiency (heat) of the first 1.5-meter-deep concrete pond varies between 22.1 and 11.3% throughout the winter. The energy performance of a solar pond decreases dramatically when the non-convective zone thickness and its size are decreased. For the two concrete ponds with depths of 1.5 m and 1.0 m, respectively, the annual average efficiencies are 23% and 16%. Hence, the solar pond demonstrates that it is an effective method for utilizing solar energy and may be a useful option for low-temperature energy needs, such as room heating.

Floating wave energy harvester: a new perspective

Sustainable development principles have brought forth the imperative to harness renewable energy sources to conserve our fragile ecosystems. Among the various renewable energy options, ocean wave energy has garnered significant global interest and is now poised as a leading contender. However, current wave energy collection methods suffer from limitations and technical immaturity, thereby necessitating the need for a more advanced and innovative solution. This paper presents a concept for the development of a floating wave harvester, which aims to convert the energy of ocean waves into usable electrical energy. The focus of this document is to outline the methodology behind the design and construction of the harvester’s buoys, which play a crucial role in determining the overall effectiveness of the system. The buoy shape and material choice are critical to the harvester’s dynamic behavior, energy absorption capacity, and the ability to transform wave kinetic energy into direct and indirect electrical energy. The primary objectives of this ongoing research project are to define the system requirements and specifications and to implement these through practical application. The development of this floating wave harvester holds the potential to significantly contribute to the renewable energy landscape and make significant strides in sustainable development.

An Evaluation of ASEAN Renewable Energy Path to Carbon Neutrality

Maintaining our standard of living and keeping the economy running smoothly is heavily reliant on a consistent supply of energy. Renewable energy systems create abundant energy by utilizing resources such as the sun, wind, earth, and plants. The demand for renewable energy is increasing, despite power scarcity, pollution, and climate change posing challenges to long-term development in the Association of Southeast Asian Nations (ASEAN), which has seen significant social and economic growth in recent years. To achieve its 23% renewable energy (RE) target, ASEAN can develop solar photovoltaic (PV) electricity. Members of the ASEAN have established regulations and incentives to encourage individuals and businesses to use renewable energy in the future. This paper explores Southeast Asian countries’ comprehensive fossil-free energy options, the region’s renewable energy potential, current capacity, goals, and energy needs. Through the ASEAN Plan of Action for Energy Cooperation (APAEC) 2016–2025 and the ASEAN Declaration on Renewable Energy, ASEAN is committed to reducing its greenhouse gas emissions and promoting sustainable development aligning with the Paris Agreement’s aim to limit global warming to well below 2 degrees Celsius above pre-industrial levels. Results show that decarbonizing the region’s energy system is possible, but current policies and actions must be altered to reach that target level. Further research is necessary to optimize the ASEAN region’s renewable resource technical potential and commercial viability with available technology.

Exploring options for energy recovery from wastewater: Evaluation of hydropower potential in a sustainability framework

Current energy demand for wastewater treatment is very high and expected to increase in the next decade. As climate change poses a challenge too, renewable energy options for this industry are needed. Studies for hydropower assessment addressed to governance stakeholders have shown that some mechanical energy might be recovered from wastewater. However, none of them applied a sustainability approach. Neither the decision-making level was considered. The objective of this work is to present a methodology, developed and applied to a case study, with a novel approach, including all these considerations. After analyzing the context in the region of study, the proposed methodology includes all three dimensions of sustainability: economic, environmental, and social. Firstly, the methodology was applied to a group of 186 plants, selected according to their management model. Based on technical feasibility, 34 potential sites were identified. Secondly, to obtain the sustainability perspective, a survey of suitable criteria was conducted. Then, a multi-criteria method, aligned with existing governance guidelines, was proposed and applied. The results show that, in a sustainability framework, hydropower might be an interesting option to consider for the decarbonization of wastewater systems. Based on this study, stakeholders could directly design decision-making methodologies adapted to their context.

Modeling and simulation of biomass anaerobic digestion for high biogas yield and CO2 mineralization

Bioenergy is one of several renewable energy options derived from biomass that can help satisfy our energy needs. Anaerobic digestion is a viable method for producing bioenergy in the form of biogas from biomass. The anaerobic digestion process is challenged with low biogas recovery, and low-quality effluent or CO2 emission, which contribute to environmental pollution and the carbon footprint in the atmosphere. Computational process modelling and simulation can provide realistic information for dealing with the technological challenges involved with anaerobic digestion. In this study, modeling and simulation of the simplified anaerobic digestion process were done using SuperPro Designer software fed with biomass feedstock containing carbohydrates, proteins, and fats, as well as yeast, at 37 °C mesophilic temperature. The anaerobic digestion process yielded 89.655% of CH4 and 10.345% of CO2 and confirmed that the carbohydrate feedstock produces more CH4 composition in the biogas. Mineralization of CO2 using MgO yielded 0.23% MgCO3, consuming > 99% of the CO2 produced during the anaerobic digestion process. Environmental impact assessment of the effluent discharge yielded 0.142 kg Slds/L volatile solid with 6.01% COD reduction per batch of the anaerobic digestion process in an anaerobic digester with 90% (1.925 kg/batch) feedstock dosage. The data indicate that single-batch effluent cannot be discharged into the environment, hence indicating the possible recycling for multiple anaerobic digestion processing. The results are a significant guide for the realistic scalable production of high-quality biogas for bioenergy application, CO2 mineralization, and environmental remediation.

THE BENEFITS OF RENEWABLES FOR ENERGY

Renewables come with an array of benefits, but why might they be the better option for energy? Over the past few years, solar panels and wind turbines have become more and more common. Why? Because people are quickly waking up to the fact that renewable energy comes with a host of benefits, not just for the planet but for people too. Renewable energy is an umbrella term that covers an array of energy sources such as solar, wind, geothermal, hydroelectric and biomass. This paper will explore why renewables are a great option for sourcing energy and the vast array of benefits they bring.

Specifics of Public Administration in Countries With a Developed Energy Sector: The Case Study

Countries with a large energy sector are faced with the issues of forming and developing a state energy policy that takes into account not only sectoral and intersectoral aspects, but also the components of managing significant amounts of rental income. In this regard, any of these economic systems, on the one hand, has great opportunities associated with the management of energy resources as a factor of development, on the other hand, it is constantly at risk of destabilization of the economic system as a whole. To date, the economic history allows us to speak about the accumulation of a sufficient number of observations for conducting a comprehensive study of the features of the development of public energy policies. The study is based on the formalization of historical descriptions of the experience of 24 countries (30 cases). The article describes in detail the experience of 13 of the most striking cases. This made it possible to identify 14 variables for evaluating the state energy policy, while outlining three areas (areas of attention) of public administration. The choice of variables used in the model was made on the basis of the relative frequencies of the mechanism application for the observed population, MNRW-TF recommendations within the improving extractive industry, the formation of the contribution of resource industries to the socio-economic development of the country and etc. Further cluster analysis led to the identification of both a pronounced polarity in the development of the state energy policy and options for combining its areas.JEL Classifications: C82, Q43, Q48, P51, O57, O11.

Projecting China’s future water footprints and water scarcity under socioeconomic and climate change pathways using an integrated simulation approach

Future changes in climate and socioeconomic systems will exacerbate water scarcity. Previous studies on China’s water footprint and scarcity often consider only climate change or socioeconomic factors in isolation. Here, we address these issues by coupling an integrated assessment model, the Global Change Analysis Model, with a global hydrological model to project China’s future water footprints and water scarcity, considering both climate change and socioeconomic factors. We simulated China’s water footprints under 52 scenarios, which include four global climate models (GCMs) and 13 combinations of Shared Socioeconomic Pathway (SSP)–Representative Concentration Pathway (RCPs) scenarios. We then projected the intensity of water stress (WSI), defined as a ratio of water footprint to renewable water volume, based on the simulations of the SSP2-RCP6.0 scenario. Our results align well with statistical data on water footprint variations between 2005 and 2020. China’s water footprints are likely to peak around 2030 and then decrease. We find through a scenario matrix analysis that emission-mitigation measures will significantly impact the water footprint, particularly in the electricity sector, which will become the largest water use sector in the future. This means that the low carbon energy option on China’s path to carbon neutrality may aggravate water scarcity. Water stress in China is projected to be greatest in 2025–2035, and all northern basins will experience water scarcity. Projections based on all GCMs consistently show a decline in WSI in China after 2050.

An Assessment of Biodiesel Production from Three Species of Micro Algae (Chlamydomonas reinhardtii, Chroococcus species and Ankistrodesmus falcatus)

Aim: Over dependence on fossil fuels has triggered environmental and economic concerns, creating an ultimate need to redirect towards renewable energy options. Hence, the study on biodiesel production from algal biomass.
 Study Design: Modified open pond culture system was applied in the biomass culture and growth was monitored via pH and turbidity.
 Place and Duration of Study: Study was done in the laboratory of the Department of Environmental Management and Toxicology, Federal University of Petroleum Resources, Effurun between June 2020 and July 2021.
 Methodology: Soxhlet extraction was applied in algal oil extraction. Alkali-mediated transesterification of algal oil blends into biodiesel was conducted. Biodiesel blends were characterized physically and spectroscopically for fuel properties and chemical position. The synthesis and fuel properties of biodiesels from three micro algal species: Chroococcus sp, Ankistrodesmus falcatus, and Chlamydomonas reinhardtii were conducted. Due to low algal oil yield, characterization of four types of hybrid oils were prepared: 100 percen(%)t lavender oil (100LO), 10% Ankistrodesmus falcatus oil plus 90% LO (10AN90LO), 10% Chlamydomonas reinhardtii oil plus 90% LO (10CHL90LO), and 10% Chroococcus sp oil plus 90% LO (10CHR90LO).
 Results: The synthesis and fuel properties of biodiesels from the micro algal species: Chroococcus sp, Ankistrodesmus falcatus, and Chlamydomonas reinhardtii gave a percentage yield of algal oil of 29.6%, 23.4% and 15.5%, respectively. The percentage yield of biodiesel from 10AN90LO, 10CHL90LO, 10CHL90LO was 66.7%, 61.7% and 50.0%, respectively. Gas Chromatography-Mass Spectrometry(GC-MS) analysis revealed presence of four fatty acid methyl and vinyl esters namely; hexadecanoic acid methyl ester, octadecadienoic acid methyl ester, methyl stearate, carbonic acid eicosyl vinyl ester and carbonic acid, tetradecyl vinyl ester. Fourier transform infrared spectroscopy(FTIS) confirms that chemicals produced are esters.
 Conclusion: Fuel properties of biodiesel from these selected algal strains appear appreciable when compared to standard limits. Blends with petroleum diesel showed great potential for use in diesel engines.

New paradigms in sustainable energy systems with hydrogen

Climate change, disturbance of the energy security resulting from increasing fuel prices due to conflicts, and disruptions to production and supply chains caused by COVID-19 have highlighted the need for the world to be prepared for future challenges. The environmental and climate change impacts of heavy use of fossil fuels for energy production have yielded numerous crucial challenges and will even cause increasingly more severe effects in the years to come. This is particularly important, as the utilization of fossil fuels is the largest contributor to the increasing emissions of greenhouse gases in the atmosphere, which is leading to climate change and other problems. As a result, there is an emerging need to transition towards low or zero-emission energy systems where renewables and nuclear energy can play a critical role in the new energy equation and help establish the source ecosystem for hydrogen. Hydrogen, being the most abundant, clean, and energy-intensive element in nature, is an attractive alternative to fossil fuels. Furthermore, when produced using renewable energy sources, it is easier to reduce and control upstream emissions to produce or store hydrogen than fossil fuels. This study presents a framework for developing hydrogen technologies, building the necessary infrastructure, and selecting appropriate energy sources to help transition to a more sustainable and resilient energy system. There are also life cycle assessment studies conducted for various energy production technologies, including hydrogen, and their results are comparatively evaluated to confirm renewables and nuclear energy options would be the most suitable sources for hydrogen production. The global warming potential values of electricity production using nuclear and renewable energy are found to be 0.027 and 0.043 kg CO2 eq./kWh. Comparatively, the global warming potential for natural gas, oil and coal are found to be 0.2, 0.3 and 0.36 kg CO2 eq./kWh, respectively.

Role of International Oil Companies in the Net-Zero Emission Energy Transition.

Scientific and engineering capabilities in hydrocarbon supply chains developed over decades in international oil and gas companies (IOCs) uniquely position these companies to drive rapid scale-up and transition to a net-zero emission economy. Flexible large-scale production of energy carriers such as hydrogen, ammonia, methanol, and other synthetic fuels produced with low- or zero-emission renewable power, nuclear energy, or hydrogen derived from natural gas with carbon capture and storage will enable long-distance transport and permanent storage options for clean energy. Use of energy carriers can overcome the inherent constraints of a fully electrified energy system by providing the energy and power densities, as well as transport and storage capacity, required to achieve energy supply and security in a net-zero emission economy, and over time allow optimization to the lowest cost for a consumer anywhere on the globe.

Streamlined Social Footprint Analysis of the Nascent Bio-Pellet Sub-Sector in Zambia

Climate change concerns have goaded countries toward seeking renewable energy options (bio-energy being one of them) to replace/supplant the conventional fossil-fuel alternatives (coal, oil and natural gas) commonly used now. Fuel pellets—at the confluence of the forestry, agriculture, waste management and bio-energy sectors—when produced from biomass residues, serve the dual purpose of ensuring energy security and environmental sustainability. By valorizing more and more organic wastes to bio-energy products, one could, to use the old adage, ‘kill two birds with one stone’. Social LCA is a method used to analyze a very wide range of social issues associated with the stakeholders in a value chain—workers, local community dwellers, society, global consumers, banks, investors, governments, researchers, international organizations and NGOs. In this analysis, the authors commence with a highly focused, niche literature review on the social dimension of sustainability in the African energy/bio-energy sector. The streamlined social footprint analysis inspired by the relatively lesser number of such studies for this sector in Africa is not a novel addition per se to the S-LCA knowledge base. The purpose of the application is to shed light on something in Zambia that must be understood better so as to bring about much-needed alterations in the direction of sustainable development. While the questions addressed to four different groups of stakeholders encompass a clutch of sustainable development goals, gender equality (SDG 5) and the need for greater interest on the part of governments and investors (SDG 9) to look at sustainable alternatives to the status quo stand out as concerns that need to be tided over. This paper and the streamlined social footprint analysis carried out are all the more relevant and timely when one considers some key changes that have happened in Zambia over the last five years—the implementation of the National Energy Policy in 2019 and the creation of the Ministry of Green Economy in 2021. These are verily harbingers of positive change auguring well for future developments in the bio-energy (and bio-pellets) sector, not just in Zambia but, by way of emulating and learning, in other countries on the continent.

Domestic Wind Energy Planning for Deprived Communities in the Tropics: A Case Study of Nigeria

Despite the notable inventions in solar energy, it is still too high for standalone users from developing countries. For example, it cost $2200 to provide power for a two-bedroom apartment while the average citizen lives below the country’s poverty line of $381.75 per year. The use of fossil fuel generators remains cheaper, except there is an affordable energy option for the average populace. The objective of this study is to investigate the wind energy potential for domestic or standalone use in Nigeria. It is proposed that the domestic wind turbine will be relatively cheap for adoption. Hence, there is the need to wholistic examine the prospects of wind energy generation in Nigeria. Though previous studies had been carried out, none has been wholistic as presented in this research work. Forty years wind speed and wind direction dataset, i.e., 1980-2020, was obtained from the Modern-Era Retrospective analysis for Research and Applications (MERRA). The analysis of the wind energy potential across the research locations was considered using five sampling techniques, i.e., considering the general statistics of the forty years dataset; considering ten years in an evenly distributed pattern and accruable wind energy across the nation. It was observed that the early wet season (MAM) is the most unstable among the seasons. Also, sudden multi-directionality of the wind vectorization within forty years was observed. This event is ascribed to evidence of climate change to wind energy generation. Wind energy generation prospect was seen to be generally sustainable and reliable with SON, MAM, DJF and JJA having energy distribution of 325-950 kWh, 539-1700 kWh, 161-650 kWh and 761-3650 kWh respectively. Despite the variation of energy generation over the years within all seasons over Nigeria, it was found that it is predictable and can be optimized using various technological solutions.

Integration of geothermal-driven organic Rankine cycle with a proton exchange membrane electrolyzer for the production of green hydrogen and electricity.

Engineers and scientists are increasingly interested in clean energy options to replace fossil fuels in response to rising environmental concerns and dwindling fossil fuel resources. There has been an increase in the installation of renewable energy resources, and at the same time, conventional energy conversion systems have improved in efficiency. In this paper, several multi-generation systems based on geothermal energy are modeled, assessed, and optimized which employ an organic Rankine cycle and a proton-exchange membrane electrolyzer subsystem in five different configurations. Based on the results, the evaporator mass flow rate and inlet temperature, turbine efficiency, and inlet temperature are the most influential parameters on system outputs, namely, net output work, hydrogen production, energy efficiency, and cost rate. In this study, the city of Zanjan (Iran) is selected for a case study, and the results of system energy efficiency for changes in ambient temperature are examined during the four seasons of the year. To determine the optimal values of the objective functions, energy efficiency, and cost rate, NSGA-II multi-objective genetic algorithm is employed, and a Pareto chart is derived. The system's irreversibility and performance are gauged by energy and exergy analyses. At the optimum state, the best configuration yields an energy efficiency and cost rate of 0.65% and 17.40 $/h, respectively.

Evaluating the Potential of Renewable Energy Sources in a Full-Scale Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Wastewater in Ghana

Wastewater management remains a major challenge in developing countries due to the lack of adequate infrastructure, making the need for economically viable and efficient technologies that can be sustained by emerging economies imperative. The upflow anaerobic sludge blanket (UASB) reactor represents an efficient and low-cost technology that produces by-products from which valuable resources can be recovered. This study assessed the energy recovery potential in the form of electricity from biogas and sludge by-products produced by a full-scale UASB reactor. Biogas production rate and composition were monitored to determine the biogas energy recovery potential. Dehydrated sludge from sludge drying beds was likewise quantified and characterised for its elemental composition, immediate composition, gross calorific value and net calorific value to estimate sludge energy recovery potential. The average daily biogas production was found to be 611 ± 275 Nm3/d, with 65% methane in the biogas output. Average sludge dry matter production was determined to be 358.24 TS kg/d. The net energy recovery potential was estimated to be 534.1 MWh/yr, 36% more than the yearly energy demand (392.7 MWh/yr) of the entire plant. Conservative energy recovery at a UASB-based municipal wastewater treatment facility could serve as a self-supply energy option to support its operations.

Valorization of Food Waste Slurry as Potential Candidate for Lipid Accumulation: A Concept of Oleaginous Bio-Refinery

In the current state of huge waste production and energy crisis, there is a need to find additional alternate energy resources and options for waste management. The present study was designed to measure the potential of different fruit wastes to serve as substrate for lipid accumulation in oleaginous bacteria. For this purpose, three novel bacterial strains (AF3, KM1 and KM10) isolated from the crude oil samples were systematically compared for their lipid accumulation potential using three types of waste including orange waste (OW), mango waste (MW) and apple waste (AW). Using waste as sole substrate, it was observed that maximum lipid accumulation by each strain was above 20%, which confirms that the bacteria belong to the oleaginous group. However, each bacterial isolate represented differential accumulative capacity with varying organic matter removal efficiency. Maximum lipid accumulation was achieved by KM10 (>25%) with AW as substrate, and KM1 (>24%) with MW as substrate; however, AF3 represented only 21% lipid accumulation using AW as substrate. Similarly, the maximum removal efficiency was recorded for KM10 in AW, followed by OW, where >60% and >50% of volatile solids (VS) removal, respectively, were achieved over the period of 7 days of incubation. This showed that the oleaginous strains also exhibit excellent waste treatment efficiency. The 16s RNA gene sequencing results showed that these KM1 and KM10 strains were Serratia surfactantfaciens and Serratia liquefaciens. In the end, a circular economy model was presented to highlight the significance of the mechanisms, which offers dual benefits over the linear economy model. Overall, the findings of the present study revealed that the novel oleaginous strains not only provide considerable lipid accumulation, but are simultaneously capable of low-cost waste treatment.

Decarbonization of the European natural gas grid using hydrogen and methane biologically produced from organic waste: A critical overview

The global CO2 emissions are above 35 GtCO2/year. Recently, the European Commission approved the Green Deal with the aim to reduce the greenhouse gases emissions. Hydrogen, because of its capacity to burn without CO2 formation, is considered one of principal energy option for the future to obtain decarbonization. In 2020, total hydrogen demand was estimated at 8.6 Mt but over 90% of all hydrogen production plants use fossil fuels as feedstock. In perspective, a relatively small part of this hydrogen can be of biological origin. Anaerobic digestion, in particular two stages processes, can assure biological hydrogen and methane productions using organic waste and waste effluents as feedstock. Carbon dioxide in biogas can be removed to obtain a gas blend of methane and hydrogen with typical concentrations of 90:10–70:30% v/v. This review aims to provide an overview on biohythane production in Europe at Technology Readiness Level greater or equal to 5 (technology validated in relevant environment). At the moment, there are few examples of biohythane plants at pilot or higher scales, mainly located in Italy, France and United Kingdom. Here reactors with volumes in the range 20–350 L and 300-1000 L were able to assure a stable hydrogen and methane, respectively, production. The highest volumes of 700 and 3800 L for acidogenic and methanogenic phases, respectively, were successfully tested close Milan (Italy).

A State-of-The-Art Review on the Latest trends in Hydrogen production, storage, and transportation techniques

The transportation sector is one of the major consumers of fuel i.e., mostly relying on fossil-based fuels. With the rising energy demand and consumption of fossil fuels, the concentration of pollutants and greenhouse gases (GHGs) are increasing in the atmosphere. Hydrogen (H2) is a well-known source of clean energy options and a better alternative to fossil fuels. It has the potential to become a promising fuel for renewable transportation by providing safe, efficient, stable, accessible, and customer-friendly energy. This is due to its many characteristics, such as energy density, high calorific value, affordability, and a wide variety of production methods. H2 has the potential to completely replace the use of fossil fuel in internal combustion engines. The review highlights the recent advances in H2 production, storage, and transportation. Apart from the conventional steam reforming technique i.e., producing around 85% of the world’s grey H2, several clean techniques such as partial oxidation, plasma reforming, water electrolysis, pyrolysis, and photoelectrolysis are comprehensively discussed. Despite its many advantages, H2 storage is a significant issue. Hence, the recent advances and challenges in H2 storage i.e., physical, and material-based techniques have been deliberated. Further, the risks involved during the production, handling, and transportation of H2 fuel is highlighted, and the latest trends in its safety recommendations have been suggested. Finally, the techno-economic feasibility challenges and its outlook has been discussed.

Long-term solar PV planning: An economic-driven robust optimization approach

Renewable energy represents an excellent opportunity for improving the living standard of communities. This is even more important in high-density urban systems, where space becomes a key resource and a growing population drives the demand to levels that traditional electricity sources can hardly manage. In this context, the presence of multiple stakeholders with competing objectives needs to be taken into account for long-term planning. Moreover, as the decisions of adopting renewable energy options may be driven by economic considerations and risk-aversion of consumers when facing uncertain future scenarios, the behavior of stakeholders should be considered. To address these challenges, we propose an efficient robust-optimization-based approach for long-term solar PV planning, where the objective is the maximization of the total economic surplus between producers and consumers of solar PV systems. The uncertainty affects the price that risk-averse consumers (i.e., residential, commercial, and industrial) are willing to pay for solar-PV systems. Land-space constraints are included to describe the relationship between installed capacity and available space, which is a scarce resource. Singapore is employed as a case study because of its high solar-energy production potential, limited space profile, ambitious solar PV capacity installation targets, and past data availability that made it possible to calibrate the model. Results show that the projections of our model are compatible with existing assumptions. The analysis of the solution allows quantifying the incentives required for achieving national capacity installation targets in 2025 and 2030, which may otherwise be underestimated by 20–30%.