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This paper provides a comprehensive review on the status of renewable energy developments and hydrogen economy in the Middle East and North Africa region. This region is heavily reliant on fossil fuels for its domestic energy supply and is also considered a global energy exporter. In this regard, an overview of the current state of energy sector in the region is provided. Moreover, the region possesses great potential for renewable energy exploitation due to its climatic advantages. Therefore, the current status of renewable energy utilization within the region's various countries is reviewed by presenting several operational renewable energy-based plants and future projects for deployment of renewable power in the region. Green hydrogen is an important sustainable clean fuel, and its utilization is essential for both environmental preservation and energy security. Thus, the status of hydrogen production and utilization in the region is discussed considering the various operational systems and future hydrogen generation projects. The concept of source, system and service is also incorporated which considers the utilization of clean energy sources for sustainable hydrogen production through environmentally benign pathways. The potential deployment opportunities for the renewable hydrogen production are also discussed based on available renewable sources in the region. Moreover, this paper discusses the challenges of increasing renewable energy utilization in the region. Furthermore, this paper provides a road map for achieving renewable hydrogen economy including a reduction in domestic utilization of oil and gas sources, subsidization of renewable production sector, and financial support to hydrogen production and transportation infrastructure. • Providing an overview of the status of energy sector in the region. • Providing an overview of the status of renewable energy utilization in the region. • Discussing the challenges and opportunities of renewable and hydrogen energy development in the region. • Providing a road map for renewable hydrogen development in the region. [ABSTRACT FROM AUTHOR]

Rapidly increasing catastrophic environmental incidents and changes in global climate have compelled researchers to take proactive measures for climate change mitigation. Consequently, reducing greenhouse gas emissions has become one of the most significant global targets. The transportation sector has a massive carbon footprint accounting for 22% of the total carbon dioxide emissions. In this regard, road transport contributes the largest fraction of the total emissions within the transportation sector. Conversely, the railway which is the cleanest form of transportation contributes slightly more than 1% of the total emissions. Moreover, since most of the rail systems are operated by government or private companies, it is relatively convenient to implement policies and replace conventional technology with environmentally friendly ones. This could be achieved by taking certain measures from technical and operational viewpoints for conserving energy to lower the carbon intensity of all transport modalities. Hence, this review paper focuses on investigating the railway sector to encourage a modal shift to the least carbon-intensive option. This study provides a critical review of the past and present rail technologies in terms of the environmental, economic, social, and technical perspectives. Moreover, a comparative assessment of the various locomotive types has been performed. The results reveal that battery-hydrogen hybrid locomotives are the best choice to be considered as a future locomotive technology. Hydrogen locomotives have the potential to be a promising alternative to diesel railway locomotives. However, certain technical barriers need to be overcome to enhance the overall system's performance and reliability to further improve the viability of its deployment in the railway sector. [Display omitted] • A critical review of the various rail technologies is provided through different viewpoints. • The assessment constitutes environmental, economic, social, and technical perspectives. • A decision-support tool for comparison of four rail technologies is also developed. • Battery-hydrogen hybrid locomotive results in the highest score of 1.47. • Standalone hydrogen locomotive results in the second highest score of 1.38. [ABSTRACT FROM AUTHOR]

Energy retrofitting for buildings has gained great attention in recent years due to the significant benefits of reducing environmental impacts and costs. Generally, retrofit planning involves considering criteria such as energy savings, emissions savings, and cost savings. However, the rapid transition of climate and extreme climate forces integrate climate adaptation into retrofit practices. This study examines strategies and modifications necessary to transform the current climate mitigation-based retrofit processes into frameworks that simultaneously improve climate mitigation and adaptation. A comprehensive literature review is conducted on building energy retrofit studies based on climate adaptation. It was found that future climate events are anticipated to be more related to overheating than under-cooling in many regions. Passive retrofit strategies can reduce overheating risks substantially, while the dependency on active cooling is unavoidable in warm climatic regions in future climates. Retrofit strategies designed based on traditional approaches may not be effective and may even worsen the risks of overheating in the future climate due to drastic climate change. Climate resiliency criteria must be adapted to the building retrofit field. Climate modelling and energy simulation have a substantial role in designing retrofits, and yet significant research and development is required to penetrate the current retrofit practices. The synthesis of the findings guides the systematic and careful designing and implementation of building energy retrofits. These findings offer valuable insights to policymakers, urban planners, and researchers seeking to improve buildings' energy performance and resiliency and act as a guideline to implement climate change adaptation strategies. • Reviewed climate adaptation-based retrofit designing and planning studies. • Revealed a significant gap in existing retrofit frameworks that consider both climate mitigation and adaptation. • Highlighted careful design and implementation of retrofits is necessary to overcome future climate risks. • Presented a comprehensive guideline to integrate climate adaptation aspects into current retrofit practices. • Suggested future research directions, including the development of climate resilience benchmarks. [ABSTRACT FROM AUTHOR]