Presently, fossil fuels are the main energy sources and energy carriers in the world. However, the supply of fossil fuels is finite and their use causes environmental impacts. As supplies eventually begin to become scarcer and environmental concerns increase, the world will turn increasingly to alternative energy sources. But all foreseeable future energy sources (falling water, solar radiation, uranium, wind, tides, waves, etc.) cannot act as energy carriers for the provision of end-use services. Moreover, using present technology, these sources are capable of producing, for the most part, one energy carrier: electricity.
alternative energy systems and applications by bk hodge pdf 32
Hydrogen storages have energy storage densities that are less than those for gasoline storages on both mass and volume bases. On a mass basis, the highest hydrogen energy storage density is attained using a liquid hydrogen storage, whose energy storage density is approximately 80 % that of a gasoline storage. On a volume basis, the highest hydrogen energy storage density is attained using a type of metal hydride storage, whose energy density is approximately 35 % that of a gasoline storage. In general, no hydrogen storage option has a high energy storage density on both a mass and volume basis. This is especially an issue in automotive applications of hydrogen as a fuel.
In the transition era, hydrogen will continue to be used as an industrial chemical feedstock and will be increasingly used directly as a chemical fuel, and as an intermediate in the production of alternative and conventional chemical fuels (Lattin and Utgikar 2007). Thus, hydrogen will find uses in the transportation, commercial and residential sectors as well as in the industrial sector. Use of energy technologies fed by various sources that exchange energy through numerous carriers is optimized in a case study by Maroufmashat et al. (2015). Besides the uses listed for hydrogen in the fossil-fuel era, researchers expect hydrogen also to have the following uses:
Some state that hydrogen production through water electrolysis using renewably generated electricity from wind turbines and photovoltaic cells is not efficient as high-quality energy carrier is converted to one of lower quality in these processes, and these energy sources should be used for meeting power demands. They suggest biologically based processes for hydrogen production such as use of gasification, fast pyrolysis and acid hydrolysis of harvested biomass with aqueous phase reforming (Tanksale et al. 2010). Artificial or biomimetic photosynthesis, where artificial photosynthetic systems capture light energy and drive proton reduction, is another biological path to hydrogen production (Magnuson et al. 2009). Some suggest microbial paths to hydrogen production such as dark fermentation, microbial electrolysis, biophotolysis and photofermentation (Hallenbeck 2011). However, all these processes suffer from technical barriers which prevent their practical applications at present.
One of the principal reasons hydrogen complements well electricity as an energy carrier is that hydrogen can be stored over long periods of time. Furthermore, hydrogen production from intermittent renewable energy sources, such as solar energy sources, is only viable with an integration of a hydrogen storage system with production. The reversible storage of hydrogen is a substantial challenge, especially for use of hydrogen as a fuel in automotive applications. Hydrogen has a low energy density on a volume basis compared to the other fuels, requiring a much larger fuel tank for a vehicle operating on hydrogen rather than petrol/diesel. Furthermore, hydrogen is the lightest of all elements and harder to liquefy than methane and propane. Due to its low density and also its small molecular size, it can leak from containment vessels. In addition, for hydrogen to be used in automotive applications, the storage system should have the ability to extract/insert hydrogen at sufficiently rapid rates. To date, only relatively small-scale storages have been developed; however, several large-scale storages are being developed to satisfy future storage requirements, which are expected to be much greater than present ones. New materials with improved performance, or new approaches to the synthesis and/or processing of existing materials, are highly desirable for use of hydrogen as a vehicular fuel. Desirable characteristics for hydrogen storage materials are investigated by Yang et al. (2010) and Winter (2009), accounting for fuel cell vehicle requirements. Hydrogen can be stored in bulk in many forms and using many technologies:
The technologies needed for hydrogen energy systems are currently receiving much research and development effort. There are many commercial processes for producing hydrogen from fossil sources, such as steam-methane reforming and partial oxidation of heavy oils. As well, there are several processes for producing hydrogen from non-fossil sources existing or under development, such as electrolysis and thermochemical water splitting. Technologies for the storage and distribution of hydrogen are also receiving much attention. Hydrogen can be stored and transported as a compressed gas or as a cryogenic liquid, or using methods by which hydrogen is absorbed onto the surface, or permeates into, specially chosen substances. Technologies for utilizing hydrogen in certain industrial processes, such as upgrading of heavy oils and production of methanol and ammonia, are presently in place; technologies for utilizing hydrogen as an energy carrier, mainly in transportation applications, are being developed.
The Handbook of Clean Energy Systems brings together an international team of experts to present a comprehensive overview of the latest research, developments and practical applications throughout all areas of clean energy systems. Consolidating information which is currently scattered across a wide variety of literature sources, the handbook covers a broad range of topics in this interdisciplinary research field including both fossil and renewable energy systems. The development of intelligent energy systems for efficient energy processes and mitigation technologies for the reduction of environmental pollutants is explored in depth, and environmental, social and economic impacts are also addressed.
Editor- in-ChiefProfessor Jinyue Yan- Director of Future Energy Profile, Royal Institute of Technology (KTH) and Malardalen University (MDU), SwedenJinyue Yan is Professor at the Royal Institute of Technology (KTH) and Malardalen University (MDU) in Sweden. An expert in energy engineering, his research focuses on the efficient distribution and consumption of energy, advanced power plants, CO2 capture and storage, biomass and bioenergy, carbon trading and associated policy issues.Since 2007, Professor Yan has been the Editor-in-Chief of the International Journal, Applied Energy (Elsevier). In its 35 year history, Applied Energy has earned a place among leading journals as the preferred vehicle for the sharing and transfer of technical knowledge and innovation in energy research and applications. This successful journal had a 2013 impact factor of 5.261 (7/82 in the ISI Web of Knowledge 'Energy and Fuels' category).Professor Yan has been actively involved in organizing the annual International Conference on Applied Energy since the first meeting in Hong Kong, 2009. The aim of this conference series is to bring together international experts in applied energy technology, from academia and industry, and across a range of disciplines including engineering, chemistry, physics and materials science. There is a strong focus on the Asia-Pacific region and the conference regularly attracts >300 delegates.
Categorical and technological solutions and challenges are generally not specifically available in the literature. This is because most categories are implicit and have differences in the focus of each research. The study of power systems are flexible such as technology that can consume and produce power actively [25, 97]. Meanwhile, research on electricity networks tends to focus on technology for power distribution and transmission only ([99, 100]. Technology solutions that are comprehensively registered are not included in the technology identification as reported in the study [63]. Categorization of technology solutions is determined such as transformation in the energy sector and conclusions with a higher level. Research on top-line classification using two characteristics assigned to technological solutions has been reported by [54]. Transformations in the energy sector that lead to distributed or centralized systems are characteristics as reflected in the literature [19, 22, 26]. Therefore, the difference between distributed and centralized technology solutions can be used at a higher or lower level of system challenge. Technology with one side of generation and transmitted technology that is distributed with the other side can be categorized into the second as reported in several kinds of literature. Technology flexibility can be classified as technological solutions such as technology that contributes to system flexibility producing or consuming active power or better known as grid technology that is also classified as a technological solution. The characteristics of technological solutions can be divided into four groups through two assignments. The group which is categorized as two assignments includes a description, e.g. potential applications and solutions for each technology solution as shown in Table 4. Twenty one technology solutions have been identified; 10 of which are distributed technology solutions, while the remaining 11 technological solutions are centralized. Besides, 21 technological solutions are also distinguished from the flexibility and grid technology systems. Whereas, there are 8 flexibility technologies and 13 grid technologies. 2ff7e9595c
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