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Über dieses Buch

This book provides a comprehensive analysis of various solar based hydrogen production systems. The book covers first-law (energy based) and second-law (exergy based) efficiencies and provides a comprehensive understanding of their implications. It will help minimize the widespread misuse of efficiencies among students and researchers in energy field by using an intuitive and unified approach for defining efficiencies. The book gives a clear understanding of the sustainability and environmental impact analysis of the above systems. The book will be particularly useful for a clear understanding of second law (exergy) efficiencies for various systems. It may serve as a reference book to the researchers in energy field. The definitions and concepts developed in the book will be explained through illustrative examples.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Hydrogen

Abstract
Hydrogen, which is the first element in the periodic table of elements, having the atomic number 1, is a non-metal, colorless, odorless, highly reactive, self-burning characteristic gas that has all the qualities to be a fuel for our automobiles and a future energy source. In contrast to conventional energy sources (coal, oil, natural gas), it is carbon free and hence environmentally friendly. The countdown for conventional sources of energy has already begun as they are depleting fast. Therefore, hydrogen is a perfect candidate to fulfill the energy needs of humans for the future. In addition to the aforementioned qualities, hydrogen is quite challenging as an energy source or fuel because of its availability. Although hydrogen is naturally present on the Earth in the combined state in both organic and inorganic compounds, for example, as water and hydrocarbons, it is scarcely present in the free and molecular state. Therefore, elemental hydrogen is artificially produced, and hence its safe and environmentally benign production is most important. When considering environmentally friendly hydrogen production, the obvious choice for the input energy is renewable energy, mainly solar energy.
Ibrahim Dincer, Anand S. Joshi

Chapter 2. Hydrogen Production Methods

Abstract
As hydrogen appears to be a potential solution for a carbon-free society, its production plays a critical role in showing how well it fulfills the criteria of being environmentally benign and sustainable. Of course, hydrogen can be produced from a number of sources, such as water, hydrocarbon fuels, biomass, hydrogen sulfide, boron hydrides, and chemical elements with hydrogen. Because hydrogen is not available anywhere as a separate element, it needs to be separated from the aforementioned sources, for which energy is necessary to do this disassociation. The forms of energy that can drive a hydrogen production process can be classified in four categories: thermal, electrical, photonic, and biochemical energy. These kinds of energy can be obtained from primary energy (fossil, nuclear, and renewable) or from recovered energy through various paths. The literature is quite large and covers many options.
Ibrahim Dincer, Anand S. Joshi

Chapter 3. Solar Energy Aspects

Abstract
To utilize solar energy, the solar irradiance of the place where it is being used should be known, including the type of day and the number of sunshine hours or daylength. The days of a year can be divided into four types, namely, clear day (blue sky), hazy day, partially hazy and cloudy day, and completely cloudy day, based on the ratio of daily diffuse to daily global radiation and the number of sunshine hours (Singh and Tiwari [32]). Their criteria are given in Table 3.1.
Ibrahim Dincer, Anand S. Joshi

Chapter 4. Solar Hydrogen Production

Abstract
The common methods of hydrogen production impose many concerns regarding the decline in fossil fuel resources, CO2 emission, and ecological impacts. Subsequently, all the downstream industries that consume hydrogen involve the aforementioned drawbacks and risks. Therefore, H2 production technologies with almost zero greenhouse gas emissions are the ideal candidates to address the hydrogen supply issue. In one approach, biomass gasification can be utilized to release hydrogen and carbon monoxide. Considering the CO2 adsorption characteristics during the photosynthesis process, this method is basically carbon neutral. Alternatively, water electrolysis using renewable power sources such as geothermal, wind, and solar cells can be utilized.
Ibrahim Dincer, Anand S. Joshi

Chapter 5. Thermodynamic Analysis

Abstract
In this chapter, photovoltaic and solar thermal hydrogen production systems are analyzed. The two different routes are shown in Fig. 5.1. In the photovoltaic (PV) route, DC electricity is generated first by PV panes and then stored in a battery bank. The DC electricity can be converted to AC electricity by using an inverter, and then this electricity is further used to run an electrolyzer. In the solar thermal route, the thermal energy of solar radiation is first collected and concentrated using a concentrating solar collector. A thermal storage system may also be used to ensure the continuous supply of thermal energy. Then, by using a heat engine the thermal energy is converted into mechanical shaft work, and by coupling a generator to the heat engine, the shaft work is converted into electricity. This electricity is used by an electrolyzer for water electrolysis.
Ibrahim Dincer, Anand S. Joshi

Chapter 6. Environmental Impact and Sustainability Assessment

Abstract
The world’s energy demand is ever increasing, and to fulfill that demand we often look for engineering solutions, that is, conversion of energy from one form to another. We convert one form of energy to another convenient form to use the energy better. This statement can better be understood by the following example: we convert chemical energy of fossil fuels to heat (thermal energy) first, and then the thermal energy is converted to electrical energy for our convenience to use it in our homes, offices, industries, hospitals, schools, etc. Such energy conversion activities come under engineering activities. Engineering activities are often associated with some environmental problems/issues, mainly the injection of greenhouse gas into the environment. Environmental damage caused by the greenhouse effect further causes global warming, which is responsible for climate change. Therefore, it is important to know how adversely engineering activities are affecting our environment. Environmental impact assessment is simply an indicator of these concerns.
Ibrahim Dincer, Anand S. Joshi

Chapter 7. Case Studies

Abstract
In this section, some case studies are presented to analyze the performance of some solar hydrogen production systems on the basis of their exergy and energy efficiencies, sustainability, and environmental impact. The section is subdivided into three parts: first, exergy and energy analysis; second, the sustainability of different systems; and third, the environmental impact of a natural gas-based hydrogen production system.
Ibrahim Dincer, Anand S. Joshi

Chapter 8. Concluding Remarks

Abstract
The present book on solar hydrogen production covers almost all the available solar hydrogen production techniques in terms of basic understanding of their concepts, different systems and system components, various chemical reactions and methods, thermodynamic analysis based on energy and exergy efficiencies, sustainability, and environmental impact. A new concept based on solar hydrogen production via artificial photosynthesis is also discussed. Some case studies are also presented to implement the analysis part with some actual data. Some appropriate concluding remarks are as follows.
Ibrahim Dincer, Anand S. Joshi

Backmatter

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