South Africa

This paper performs a technoeconomic comparison of two hybrid renewable energy supplies (HRES) for a specific location in Ghana and suggests the optimal solution in terms of cost energy generation capacity and emissions. (e two HRES considered in this paper were wind/hydrogen/fuel-cell and wind/battery storage respectively. (e necessity of this study was derived from the rise and expansion of hybrid renewable energy supply in a decentralised network. (e readiness to embrace these new technologies is apparently high but the best combination for a selected location that brings optimum benefits is not obvious and demands serious technical knowledge of their technical and economic models. In the methodology an analytical model of energy generation by the various RE sources was first established and data were collected about a rural-urban community in Doderkope Ghana to test the models. HOMER software was used to design the two hybrid systems based on the same load profiles and results were compared. It turns out that the HRES 1 (wind/hydrogen/fuel-cell) had the lowest net present cost (NPC) and levelized cost of electricity (COE) over the project life span of 25 years. (e energy reserve with the HRES 2 (wind/battery storage) was huge compared to that with the HRES 1 about 270% bigger. Furthermore with respect to the emissions the HRES 2 was environmentally friendlier than the HRES 1. Even though the battery storage seems to be more cost-effective than the hydrogen fuel cell technology the latter presents some merits regarding system capacity and emission that deserve greater attention as the world looks into more sustainable energy storage systems.

Efficiently predicting and understanding refuelling patterns in the context of HFVs is paramount for optimising fuelling processes infrastructure planning and facilitating vehicle operation. This study evaluates several supervised machine learning methodologies for predicting the refuelling behaviour of HFVs. The LightGBM model emerged as the most effective predictive model due to its ability to handle time series and seasonal data. The selected model integrates various input variables encompassing refuelling metrics day of the week and weather conditions (e.g. temperature precipitation) to capture intricate patterns and relationships within the data set. Empirical testing and validation against real-world refuelling data underscore the efficacy of the LightGBM model demonstrating a minimal deviation from actual data given limited data and thereby showcasing its potential to offer valuable insights to fuelling station operators vehicle manufacturers and policymakers. Overall this study highlights the potential of sustainable predictive modelling for optimising fuelling processes infrastructure planning and facilitating vehicle operation in the context of HFVs.

The depletion and overuse of fossil fuels present formidable challenge to energy supply system and environment. The human society is in great need of clean renewable and sustainable energy which can guarantee the long-term utilization without leading to escalation of greenhouse effect. Hydrogen as an extraordinary secondary energy is capable of realizing the target of environmental protection and transferring the intermittent primary energy to the application terminal while its nature of low volumetric energy density and volatility need suitable storage method and proper carrier. In this context liquid organic hydrogen carrier (LOHC) among a series of storage methods such as compressed and liquefied hydrogen provokes a considerable amount of research interest since it is proven to be a suitable carrier for hydrogen with safety and stability. However the dehydrogenation of hydrogen-rich LOHC materials is an endothermic process and needs large energy consumption which hampers the scale up of the LOHC system. The heat issue is thus essential to be addressed for fulfilling the potential of LOHC. In this work several strategies of heat intensification and management for LOHC system including the microwave irradiation circulation of exhaust heat and direct LOHC fuel cell are summarized and analyzed to provide suggestions and directions for future research.

The majority of rail vehicles worldwide use diesel as a primary fuel source. Diesel engine carbon emissions harm the environment and human health. Although railway electrification can reduce emissions it is not always the most economical option especially on routes with low vehicle demand. As a result interest in hydrogen-powered trains as a way to reduce greenhouse gas (GHG) emissions has steadily grown in recent years. In this paper we discuss advancements made in hydrogen-powered freight and commuter trains as well as the technology used in some aspects of hydrogen-powered vehicles. It was observed that hydrogen-powered trains are already in use in Europe and Asia unlike most developing countries in Africa. Commuter trains have received most of the research and development (R&D) attention but interest in hydrogen-powered freight trains has recently picked up momentum. Despite the availability and use of gray and blue hydrogen green hydrogen is still the preferred fuel for decarbonizing the rail transport sector.

Importing substantial amount of green hydrogen from countries like South Africa which have abundant solar and wind potentials to replace fossil fuels has attracted interest in developed regions. This study analyses South African strategies for improving and decarbonizing the power sector while also producing hydrogen for export. These strategies include the Integrated Resource Plan the Transmission Development Plan Just Energy Transition and Hydrogen Society Roadmap for grid connected hydrogen production in 2030. Results based on an hourly resolution optimisation in Plexos indicate that annual grid-connected hydrogen production of 500 kt can lead to a 20–25% increase in the cost of electricity in scenarios with lower renewable energy penetration due to South African emission constraints by 2030. While the price of electricity is still in acceptable range and the price of hydrogen can be competitive on the international market (2–3 USD/kgH2 for production) the emission factor of this hydrogen is higher than the one of grey hydrogen ranging from 13 to 24 kgCO2/kgh2. When attempting to reach emission factors based on EU directives the three policy roadmaps become unfeasible and free capacity expansion results in significant sixteen-fold increase of wind and seven-fold increase in solar installations compared to 2023 levels by 2030 in South Africa.

One such technology is hydrogen-based which utilizes hydrogen to generate energy without emission of greenhouse gases. The advantage of such technology is the fact that the only by-product is water. Efficient storage is crucial for the practical application of hydrogen. There are several techniques to store hydrogen each with certain advantages and disadvantages. In gaseous hydrogen storage hydrogen gas is compressed and stored at high pressures requiring robust and expensive pressure vessels. In liquid hydrogen storage hydrogen is cooled to extremely low temperatures and stored as a liquid which is energy-intensive. Researchers are exploring advanced materials for hydrogen storage including metal hydrides carbonbased materials metal–organic frameworks (MOFs) and nanomaterials. These materials aim to enhance storage capacity kinetics and safety. The hydrogen economy envisions hydrogen as a clean energy carrier utilized in various sectors like transportation industry and power generation. It can contribute to decarbonizing sectors that are challenging to electrify directly. Hydrogen can play a role in a circular economy by facilitating energy storage supporting intermittent renewable sources and enabling the production of synthetic fuels and chemicals. The circular economy concept promotes the recycling and reuse of materials aligning with sustainable development goals. Hydrogen availability depends on the method of production. While it is abundant in nature obtaining it in a clean and sustainable manner is crucial. The efficiency of hydrogen production and utilization varies among methods with electrolysis being a cleaner but less efficient process compared to other conventional methods. Chemisorption and physisorption methods aim to enhance storage capacity and control the release of hydrogen. There are various viable options that are being explored to solve these challenges with one option being the use of a multilayer film of advanced metals. This work provides an overview of hydrogen economy as a green and sustainable energy system for the foreseeable future hydrogen production methods hydrogen storage systems and mechanisms including their advantages and disadvantages and the promising storage system for the future. In summary hydrogen holds great promise as a clean energy carrier and ongoing research and technological advancements are addressing challenges related to production storage and utilization bringing us closer to a sustainable hydrogen economy.

Hydrogen and electricity derived from renewable sources present feasible alternative energy options for the decarbonisation of the transportation and power sectors. This study presents the utilisation of hydrogen generated from solar and wind energy resources as a clean fuel for mobility and backup storage for stationary applications under economic and environmental uncertainties. This is achieved by developing a detailed technoeconomic model of an integrated system consisting of a hydrogen refuelling station and an electric power generation system using Mixed Integer Quadratic Constrained Programming (MIQCP) which is further relaxed to Mixed Integer Linear Programming (MILP). The model is implemented in the Advanced Interactive Multidi mensional Modelling Software (AIMMS) and considering the inherent uncertainties in the wind resource solar resource costs and discount rate the total cost of the three configurations (Hybrid PV-Wind Standalone PV and Standalone wind energy system) was minimised using robust optimisation technique and the corresponding optimal sizes of the components levelised cost of energy (LCOE) excess energy greenhouse emission avoided and carbon tax were evaluated. The levelised cost of the deterministic optimisation solution for all the config uration ranges between 0.0702 $/kWh to 0.0786 $/kWh while the levelised cost of the robust optimisation solution ranges between 0.07188 $/kWh to 0.1125 $/kWh. The proposed integration has the advantages of affordable hydrogen and electricity prices minimisation of carbon emissions and grid export of excess energy.