Browsing by Author "Nabavi, Sayed Ali"
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Item Open Access Country-level assessment of the deployment potential of greenhouse gas removal technologies.(Cranfield University, 2023-07) Asibor, Jude Odianosen; Clough, Peter T.; Nabavi, Sayed Ali; Manovic, VasilijeThe deployment of greenhouse gas removal (GGR) technologies has been identified as an indispensable option in meeting the warming target of 1.5 °C by the end of the century. Despite the importance of this pathway, the Nationally Determined Contributions (NDCs) of countries indicates a low intent to deploy these technologies. Among the major factors responsible for this low level of inclusion is the lack of robust country-level bio-geophysical and techno-economic feasibility assessments to ascertain national GGR deployment potential. Herein lies the challenge that this thesis aimed to address. This study investigated the potential of 182 countries to deploy five of the most promising GGR technologies, including forestation, enhanced weathering, direct air carbon capture and storage, bioenergy with carbon capture and storage, and biochar. A comparative literature-based assessment was carried out to identify and rank the major factors required for optimum performance of these GGR methods. Based on the bio-geophysical and techno-economic characteristics, Machine Learning (ML) was applied to identify the range of GGR technologies that respective countries can suitably and effectively deploy. ML models were also developed for predictive locational resource mapping of these technologies. Furthermore, the extent of carbon dioxide removable by 2100 via these technologies for each country (national potential) was evaluated using a Multi Criteria Decision Analysis approach. An assessment of domestic and regional sufficiency was also carried out to provide an evidence base for international collaboration. Priority regions for the deployment of these GGR technologies were identified, with Latin America and Sub-Saharan Africa regions found to have surplus potentials, and thus, expected to serve as a major hub to support other regions of the world. While the obtained results indicate the need for regional cooperation among countries, it also provides useful evidence on the need for countries to include and prioritise GGR technologies in their revised NDCs.Item Open Access Numerical modelling of bipolar plate in pem fuel cells to analyse the pressure drop in various channels and development of a novel geometry of the bipolar plate.(Cranfield University, 2022-09) Jayabal, Jayvassanth; Verdin, Patrick G.; Nabavi, Sayed AliThis work centres on comprehending and elevating the performance of Proton Exchange Membrane (PEM) hydrogen fuel cells, with a specific emphasis on minimizing pressure drop in the bipolar plate. Fuel cell efficiency hinges upon core factors, including electrochemical reaction, temperature, and pressure management. Notably, pressure drop within the fuel cell plays a pivotal role in determining overall efficiency and power output. The study aims to tackle the pressing issue of pressure drop, primarily manifested in the bipolar plate, profoundly affecting the fuel cell's output power. Researchers have pursued ground-breaking designs to curtail pressure drop and augment power output. However, certain advanced designs pose challenges in fabrication, leading to a research gap impeding the development of efficient models. To bridge this gap, the study proposes a novel and straightforward bipolar plate design, demanding minimal external power and eliminating the need for intricate geometries. Furthermore, apart from pressure drop, fuel cell inefficiencies are compounded by obstacles like inadequate meshing and porosity integrity of the end plates. Consequently, costly platinum and gold-plated end plates are often deployed to achieve superior output performance. The research reveals that velocity variations influence pressure within existing models, furnishing valuable insights for attaining improved efficiencies in fuel cells. The work presents a comprehensive analysis of PEM fuel cells, with particular attention to the bipolar plate's design and its ramifications on pressure drop. The proposed novel geometry aims to enhance fuel cell performance while addressing challenges linked to complex designs. The research findings offer valuable recommendations for optimizing fuel cell efficiencies, thereby contributing to the advancement of clean energy technologies.