Yusuf Bicer

Impact Assessment and Environmental Evaluation of Various Ammonia Production Processes

In the current study, conventional resources-based ammonia generation routes are comparatively studied through a comprehensive life cycle assessment. The selected ammonia generation options range from mostly used steam methane reforming to partial oxidation of heavy oil. The chosen ammonia synthesis process is the most common commercially available Haber-Bosch process. The essential energy input for the methods are used from various conventional resources such as coal, nuclear, natural gas and heavy oil. Using the life cycle assessment methodology, the environmental impacts of selected methods are identified and quantified from cradle to gate. The life cycle assessment outcomes of the conventional resources based ammonia production routes show that nuclear electrolysis-based ammonia generation method yields the lowest global warming and climate change impacts while the coal-based electrolysis options bring higher environmental problems. The calculated greenhouse gas emission from nuclear-based electrolysis is 0.48 kg CO2 equivalent while it is 13.6 kg CO2 per kg of ammonia for coal-based electrolysis method.Graphical Abstract

A comparative life cycle assessment of alternative aviation fuels

In this study, a comparative life cycle assessment of various alternative aviation fuels is conducted with a well-to-wake approach in order to determine the overall life cycle of a passenger aircraft running on these conventional and alternative fuels. The investigated fuels include: hydrogen, ammonia, methanol and ethanol, as well as bio fuels and jet fuels. Although there are modifications required to fulfil the aviation fuel specifications for such alternative fuels, the long term viability and environmental sustainability make them attractive solutions for the future of aviation industry. The present study uses a life cycle assessment of a passenger aircraft using various alternative aviation fuels to determine the relative environmental impact of each life cycle phase. The overall life cycle emissions of an aircraft running on various aviation fuels are calculated from well-to-wake. The processes considered in the analyses include: 1) production, operation and maintenance of the aircraft, 2) construction, maintenance and disposal of the airport, 3) production, transportation and utilisation of the aviation fuel in the aircraft. The results show that hydrogen and liquefied natural gas represent more environmentally benign alternatives although fuel costs are higher compared to ammonia, jet fuel and methanol.

Evaluation of Renewable and Conventional Ammonia as a Potential Solution

Ammonia is projected to be a potential hydrogen carrier with high hydrogen content in the near future. In recent years, expectations are rising for hydrogen and hydrogen carriers as a medium for storage and transportation of energy in the mass introduction and use of renewable energy. Both storage and transport of hydrogen are considered an important issue since hydrogen is a gas under normal temperature and pressure. Hydrogen carriers are mediums that convert hydrogen into chemical substances containing large amounts of hydrogen, to simplify storage and transport processes. Hydrogen carriers include ammonia synthesized from nitrogen and hydrogen that can be used for direct combustion. Ammonia becomes an important hydrogen carrier that does not contain any carbon atoms and has a high hydrogen ratio. Therefore, it is evaluated as a power-generating fuel. Since ammonia produces mainly water and nitrogen on combustion, replacing a part of conventional fuel with ammonia will have a large effect in reducing carbon dioxide emissions.

3.17 Photonic Energy Production

In this contribution, photonic energy production systems and applications are introduced and discussed comparatively. A focus is placed on the photosensitive materials and photocatalysts. The theory behind the photonic energy production process is provided in detail. The types of photoresponsive materials ranging from crystalline to polymer-based materials are also presented and compared for various applications. Furthermore, thermodynamic analyses and performance assessments through energy and exergy approaches are presented. Moreover, a case study is performed for photo-thermo-electrical processes inside the photovoltaic cell from energy and exergy analyses perspective.

4.21 Photoelectrochemical Energy Conversion

In this contribution, photoelectrochemical (PEC) energy conversion processes, systems, and applications are introduced with details ranging from basics to advanced applications. PEC water splitting and PEC measurements are specifically described with some fundamental background information. The theory behind the PEC measurements is extensively presented for evaluation and comparison purposes. The types of materials used in PEC hydrogen production reactors, such as membranes and photoelectrodes, are described and classified based on various criteria. Furthermore, a case study is included to conduct the analysis and performance assessment for electrochemical impedance spectroscopy of a PEC hydrogen production cell.

4.19 PV-Based Energy Conversion Systems

In this contribution, a comprehensive introduction and discussion on various technical and operational aspects of solar energy systems, primarily focusing on photovoltaic-based energy conversion systems, namely, sole photovoltaic (PV), photovoltaic and thermal (PV/T) and concentrated photovoltaic (CPV) systems is presented. The theory behind the working principle of each PV-based energy conversion system is extensively discussed. A critical evaluation of the current PV, PV/T, and CPV technologies and their marketing dimensions is performed for various applications. The solar-to-product conversion efficiencies are also described including the thermodynamic conversion limits. Thermodynamic analyses of these PV-based energy conversion systems are undertaken through energy and exergy approaches, and some examples are presented to illustrate how their efficiencies are affected by varying operating and environmental conditions.

4.22 Electrochemical Energy Conversion

In this contribution, a comprehensive discussion of electrochemical energy conversion systems, particularly about batteries, fuel cells, and capacitors, is presented, by focusing on fundamental theory, background information, classification, analysis, and performance assessment. The types of fuel cells, batteries, and supercapacitors are described for various applications. Thermodynamic analyses of fuel cell systems are also presented, including a case study and illustrative example. Furthermore, the electrochemical measurement techniques are evaluated for practical applications.

2.1 Ammonia

In this contribution, a chemical substance, named ammonia with a chemical formula (NH 3 ) is comprehensively presented as a non-carbon fuel, refrigerant, and working fluid. Ammonia is a significant energy carrier and offers various advantages over other alternative fuels. The contribution explains the production, storage, and transportation processes of ammonia. Furthermore, the analyses for the utilization of ammonia in fuel cells are presented including a case study. The utilization of ammonia in different types of transportation sectors is presented in environmental impact point of view to emphasize the importance of clean fuel switching options.

4.23 Solar Thermochemical Energy Conversion

In this chapter, an overview of solar energy systems utilized for thermochemical energy conversing processes are presented, covering the information from fundamentals to advanced cycles and from applications to case studies. In addition, numerous thermochemical cycles are included for discussion and evaluation, and among these cycles, sulfur iodine, copper chlorine, and magnesium chlorine thermochemical cycles are selected for further analyses and assessments. The discussion proceeds from single-step thermochemical water-splitting processes, to two-step and multistep processes, followed by introduction of hybrid cycles. Furthermore, multiple processes for solar-to-useful commodities conversion are defined, illustrated, and discussed in this chapter. Moreover, two case studies using solar thermochemical cycles are presented for multigeneration purposes.

1.27 Life Cycle Assessment of Energy

Abstract In this chapter, the methods of life cycle assessment (LCA), which are commonly used to analyze the life cycle of a system or service from cradle to grave, are presented, discussed from various perspectives and applied to various energy systems and applications to really reflect the importance and potential use in comprehensive analysis and assessment studies. Such methods are crucial for the development of sustainable energy systems which implies comprehensive analyses that go beyond thermodynamics, such as conducting LCA studies. In this regard, the importance of such LCA studies for energy systems and applications becomes critical for a complete understanding, assessment, evaluation, and comparison. In this contribution, there are various methodologies and approaches and applications presented comprehensively along with impact categories. Various case studies ranging from conventional to renewable resources for energy production and utilization are performed for comparison and assessment purposes.