Physics of Energy Conversion

Description

A profound understanding of the physical laws underlying energy converters is a prerequisite for a sustainable use of our energy resources.   The aim of this textbook is to provide a unified view on the different energy conversion processes ranging from power plants to solar cells. It offers an interdisciplinary introduction to energy sciences for senior undergraduate and graduate students from natural sciences and engineering. The central theme is the treatment of energy converters as open thermodynamical systems and the performance of efficiency analyses, based on the concept of exergy. Presents the physics behind the most important energy converters in a unified framework. Evaluates the performance of ideal and realistic energy converters in terms of energy and exergy efficiencies Provides basic concepts needed for a discussion of energy converters, such as chemical and applied thermodynamics, electrochemistry and solid state physics. About the Authors Katharina Krischer is a professor of physics at the Technische Universität München, Germany. She has taught lectures on energy sciences for undergraduate and graduate students for more than 10 years. Her research topics include the photo-electrochemical production of solar fuels. Konrad Schönleber is a researcher in the group of Prof. Krischer which he joined after graduating in physics from the Technische Universität München.  His research interest focuses on light-driven semiconductor electrochemistry and its application for renewable energies. Provides coherent presentation of the basic physics behind the processes. Basic thermodynamics and solid states physics are given in two separate chapters, providing an organizing framework Preface Contents 1 Introduction 1.1 Terms and definitions 1.1.1 Units 1.1.2 Example: Energy consumption and production 1.2 Energy conversion processes 1.2.1 Exergy 1.2.2 Conversion efficiency 1.2.3 Example: heating of a room 2 Exergy in closed systems 2.1 Thermodynamic basics 2.1.1 The first law of thermodynamics 2.1.2 The second law of thermodynamics 2.2 Exergy in closed systems 2.3 Exergy transfers 2.3.1 Exergy transfer via work transfer 2.3.2 Exergy transfer via heat transfer at T = Th 2.3.3 Exergy and anergy contents of transferred energy 2.3.4 The laws of thermodynamics in terms of exergy 2.4 Exergy sources 2.5 Heat pumps 2.5.1 Working principle 3 Exergy in open systems 3.1 Thermodynamics of open systems 3.1.1 The first law of thermodynamics for open systems 3.1.2 Steady flow conditions 3.1.3 Technical work 3.2 Exergy of open systems 3.3 Important example components 3.3.1 Heat exchangers 3.3.2 Water turbines 3.3.3 Wind turbines 4 Thermal power plants 4.1 Steam power plants 4.1.1 Rankine cycle 4.1.2 Efficiency of a steam power plant 4.1.3 Example calculation 4.1.4 Modifications in a real steam power plant 4.2 Gas turbine power plants 4.2.1 Joule–Brayton cycle 4.2.2 Optimization criteria 4.2.3 Efficiency of a gas turbine power plant 4.2.4 Example calculation 4.2.5 Intercooling 4.2.6 Combined cycle power plants (CCPP) 5 Electrical exergy 5.1 The electrochemical potential 5.1.1 Interfaces 5.1.2 Electrical currents 5.2 Voltage sources 5.3 Generators 5.3.1 Electrical power output 5.3.2 Mechanical power input 5.4 Thermoelectrics 5.4.1 Seebeck coefficients 5.4.2 Thermoelectric energy conversion 6 Chemical exergy 6.1 Basic concepts 6.1.1 Example calculation 6.2 The driving force of a chemical reaction 6.2.1 Chemical activity 6.2.2 The driving force of a chemical reaction at a given state 6.3 The exergy of fuels 6.4 Efficiency of the combustion process 7 Electrochemical energy conversion 7.1 Electrochemistry 7.1.1 The standard hydrogen scale 7.1.2 Origin of the electrode potential 7.1.3 Electrode potential and cell voltage 7.1.4 The Nernst equation 7.1.5 Electrochemical voltage sources 7.2 Electrochemical energy conversion 7.2.1 Maximal efficiency 7.2.2 Efficiency of a realistic galvanic cell 7.2.3 Reaction kinetics 7.2.4 Fuel cells 7.2.5 Nonrechargeable batteries 8 Solar energy 8.1 Properties of solar irradiation 8.1.1 Stefan–Boltzmann law 8.1.2 Exergy of the solar irradiation 8.2 Influence of the atmosphere 8.2.1 The greenhouse effect 8.3 Photosynthesis 8.3.1 Conversion efficiency 9 Solarthermal energy conversion 9.1 Heat radiation of the absorber 9.1.1 Selective absorption 9.2 Concentrating devices 9.2.1 Imaging optics 9.2.2 Technical realization 9.2.3 Efficiency of concentrating solarthermal energy converters 9.2.4 Solarthermal power plants 10 Photovoltaic energy conversion 10.1 Conversion of solar into chemical energy 10.1.1 Chemical energy and exergy at a given ne and nh 10.1.2 Radiative recombination 10.1.3 Maximal efficiency of a solar cell 10.2 Selective contacts 10.3 Conversion of chemical into electrical energy 10.3.1 Current voltage characteristic 10.3.2 Electrical power output 10.3.3 Losses 10.4 Solar cell design 10.4.1 c-Si solar cell 10.4.2 Other types of solar cells 11 Exergy storage 11.1 Mechanical exergy storage 11.1.1 Pumped storage hydro power plant 11.1.2 Compressed air energy storage 11.2 Thermal exergy storage 11.2.1 High temperature storage 11.2.2 Low-temperature storage 11.3 (Electro-)Chemical exergy storage 11.3.1 Rechargeable batteries (Li-ion batteries) 11.3.2 Water splitting 11.3.3 Power to gas A Basics: Thermodynamics A.1 Thermodynamic potentials A.2 Ideal gases A.2.1 Heat capacity A.2.2 State changes in ideal gases A.3 The Carnot cycle A.4 Phase transitions B Basics: Solid state physics B.1 Particle ensembles B.1.1 Density of states B.1.2 Distribution functions and the electrochemical potential B.1.3 Selected properties B.1.4 The Sommerfeld expansion B.2 Semiconductors B.2.1 Intrinsic semiconductors B.2.2 Doping B.2.3 Optical properties C Further Reading Index