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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Introduces the field of hydrogen technology and explains the basic chemistry underlying promising and innovative new technologies
This new and completely updated edition of Introduction to Hydrogen Technology explains, at an introductory level, the scientific and technical aspects of hydrogen technology. It incorporates information on the latest developments and the current research in the field, including: new techniques for isolating and storing hydrogen, usage as a fuel for automobiles, residential power systems, mobile power systems, and space applications.
Introduction to Hydrogen Technology, Second Edition features classroom-tested exercises and sample problems. It details new economical methods for isolating the pure hydrogen molecule. These less expensive methods help make hydrogen fuel a very viable alternative to petroleum-based energy. The book also adds a new chapter on hydrogen production and batteries. It also provides in-depth coverage of the many technical hurdles in hydrogen storage. The developments in fuel cells since the last edition has been updated.
- Offers new chapters on hydrogen production, storage, and batteries
- Features new sections on advanced hydrogen systems, new membranes, greenhouse gas sensors and updated technologies involving solar and wind energies
- Includes problems at the end of the Chapters, as well as solutions for adopters
This book is an introduction to hydrogen technology for students who have taken at least one course in general chemistry and calculus; it will also be a resource book for scientists and researchers working in hydrogen-based technologies, as well as anyone interested in sustainable energy.
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Veröffentlichungsjahr: 2017
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Table of Contents
Cover
Title Page
Copyright
Preface
About the Companion Website
Chapter 1: Available Energy Resources
1.1 Civilization and the Search for Sustainable Energy
1.2 The Planet's Energy Resources and Energy Consumption
1.3 The Greenhouse Effect and its Influence on Quality of Life and the Ecosphere
1.4 Nonrenewable Energy Resources
1.5 Renewable Energy Sources
1.6 Energy Storage
1.7 Energy Ethics
Problems
Multiple Choice Questions
Bibliography
Chapter 2: Chemistry Background
2.1 Reversible Reactions and Chemical Equilibrium
2.2 Acid–Base Chemistry
2.4 Chemical Kinetics
2.5 Electrochemistry (Oxidation–Reduction Reactions)
2.6 Organic Chemistry
2.7 Polymer Chemistry
2.8 Photochemistry
2.9 Plasma Chemistry
Problems
Multiple Choice Questions
Thermodynamic Questions
Photochemistry Questions
Plasma Chemistry Questions
Chemical Equilibrium
Acid-Base Chemistry
Kinetics
Organic Chemistry
Polymers
Bibliography
Chapter 3: Hydrogen Production
3.1 Electrolysis
3.2 Thermolysis (Thermal Reactions Involving Solar Energy)
3.3 Photovoltaic Electrolysis
3.4 Plasma ARC Decomposition
3.5 Thermochemical Process (Thermal Decompositions by Processes other than Solar Energy)
3.6 Photocatalysis
3.7 Biomass Conversion
3.8 Gasification
3.9 High-Temperature Electrolysis
3.10 Miscellaneous Methods
3.11 Comparative Efficiencies
Problems
References
Chapter 4: Hydrogen Properties
4.1 Occurrence of Hydrogen, Properties, and Use
4.2 Hydrogen as an Energy Carrier
4.3 Hydrogen Storage
Multiple Choice Questions
Bibliography
Chapter 5: Hydrogen Infrastructure and Technology
5.1 Production of Hydrogen
5.2 Hydrogen Transportation, Storage, and Distribution
5.3 Hydrogen Safety
5.4 Hydrogen Technology Assessment
Multiple Choice Questions
Bibliography
Chapter 6: Batteries
6.1 Introduction
6.2 Definitions
6.3 Working Units
6.4 Examples of Selected Batteries
6.5 Conducting Polymer Batteries (Organic Batteries)
6.6 Practical Considerations
6.7 Electric Transportation
Problems
Multiple Choice Questions
Bibliography
Chapter 7: Fuel Cell Essentials
7.1 Introduction
7.2 Definition of Fuel
7.3 What is a Fuel Value?
7.4 Why do we Want to use Hydrogen as Fuel?
7.5 Classification of Fuel Cells
7.6 Open Circuit Voltages of Fuel Cells
7.7 Thermodynamic Estimate of Fuel Cell Voltage
7.8 Efficiency of a Fuel Cell
7.9 Efficiency and Temperature
7.10 Influence of Electrode Material on Current Output
7.11 Pressure Dependence of Fuel Cell Voltage
7.12 Thermodynamic Prediction of Heat Generated in a Fuel Cell
7.13 Fuel Cell Management
7.14 Rate of Consumption of Hydrogen and Oxygen
7.15 Rate of Production of Water
Problem
7.16 Fuel Crossover Problem
7.17 Polymer Membranes for PEMFC
7.18 Parts of PEMFC and Fabrication
7.19 Alkaline Fuel Cells (AFCs)
7.20 Molten Carbonate Fuel Cell (MCFC)
7.21 Solid Oxide Fuel Cell (SOFC)
7.22 Flowchart for Fuel Cell Development
7.23 Relative Merits of Fuel Cells
7.24 Fuel Cell Technology
7.25 Fuel Cells for Special Applications
7.26 Fuel Cell Reformers
7.27 Fuel Cell System Architecture
Appendix 7
Problems
Multiple Choice Questions
Bibliography
Chapter 8: Fuel Cells Applications
8.1 Stationary Power Production
8.2 Fuel Cell Transportation
8.3 Micropower Systems
8.4 Mobile and Residential Power Systems
8.5 Fuel Cells for Space and Military Applications
8.6 Conclusion
Multiple Choice Questions
Bibliography
Index
End User License Agreement
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Guide
Cover
Table of Contents
Preface
Begin Reading
List of Illustrations
Chapter 1: Available Energy Resources
Figure 1.1 Energy pyramid.
Figure 1.2 US energy use by sector.
Figure 1.3 Consumption by type of energy source.
Figure 1.4 Solar radiation.
Figure 1.5 Global atmospheric concentrations of carbon dioxide over time.
Figure 1.6 Oil reserves in the world in 2005.
Figure 1.7 World petroleum production.
Figure 1.8 The world's nuclear power.
Figure 1.9 Electricity cost by different methods.
Figure 1.10 Different methods of generation of electricity (2003).
Figure 1.11 Change in oil price in the United States during 1998–2006.
Figure 1.12 Thermal radiation contour. Outgoing thermal radiation (W/m
2
) at the top of the atmosphere in January 1988 (7:30), calculated without clouds.
Figure 1.13 Thermal radiation contour. Outgoing thermal radiation (W/m
2
) at the top of the atmosphere in January 1988 (7:30), with cloud cover. The cloud cover radically changes this zonal distribution by preventing a part of the thermal radiation, up to 60 W/m
2
.
Figure 1.14 Solar spectrum.
Figure 1.15 Intrinsic semiconductor.
Figure 1.16 Boron doped semiconductor.
Figure 1.17 Phosphorus-doped silicon.
Figure 1.18 p–n diode with forward bias.
Figure 1.19 Electron and hole flow in the forward-bias condition.
Figure 1.20 Current flow under forward- and reverse-bias conditions. For silicon, the current flow starts at about 0.5 V and gives very high currents at 0.7 V.
Figure 1.21 Solar panels used for conversion of sunlight to direct current (DC electricity).
Figure 1.23 Second-generation solar cell materials with solar cell size marked on the bar chart.
Figure 1.22 First-generation solar cell.
Figure 1.24 Chemical routes for solar energy.
Figure 1.25 Space charge regions when n- or p-type semiconductors are in contact with an electrolyte.
E
v
and
E
c
are the valence and conduction bands energy levels.
Figure 1.26 Photosynthetic energy cycles.
Figure 1.27 Geothermal energy hot springs in Bridgeport, CA.
Figure 1.28 Geothermal energy.
Figure 1.29 Corn field for ethanol production.
Figure 1.30 Hydroelectric power generators at Nagarjuna dam and hydroelectric plant, India.
Chapter 2: Chemistry Background
Figure 2.1 Conversion of a reactant and yield of a product with time. At equilibrium, the concentration of reactant and product remain constant.
Figure 2.2 The rates of the forward and reverse reactions with time. At equilibrium, the rates of the forward and reverse reactions become the same.
Figure 2.3 Equilibrium conditions of dissolving of silver sulfate in water.
Figure 2.4 The Haber process for ammonia synthesis.
Figure 2.5 A hydrogen atom and a positive hydrogen ion (a proton).
Figure 2.6 H
+
concentrations and pH values of some common substances at 25°C.
Figure 2.7 (a) When the stoppers are pulled out, the mass in the surroundings compresses the system and does a positive amount of work on the system. (b) When the stoppers are pulled out, the system lifts a mass in the surroundings and the system does work on the surroundings.
Figure 2.8 Concentration versus time for the decomposition of hydrogen iodide into the elements.
Figure 2.9 Three different average rates for the decomposition of hydrogen iodide described in the example on average rates.
Figure 2.10 Different types of rates based on the decrease of the concentration of a reactant with time.
R
Init.
: initial rate;
R
Inst.
: instantaneous rate.
Figure 2.11 General pattern for radioactive decay and first-order reactions. In the case of radioactive decay, the reactant is a radioactive isotope emitting subatomic particles, for example, α, β, and/or γ-rays.
Figure 2.12 Decomposition of hydrogen peroxide as an example of a reaction based on a first-order rate law. The first “snapshot” is taken at the beginning (
t
= 0) and the second after one half-life (
t
1/2
= 10 h), representing the reaction mixture at elevated temperatures when all three substances are in the gaseous state.
Figure 2.13 Concentration versus time dependence for the zero-, first-, and second-order reactions with straight-line plots.
Figure 2.14 Different scenarios for the collision of reactant molecules.
Figure 2.15 Energy/reaction coordinate diagram for the example of an exothermic reaction (uncatalyzed). The reaction kinetics is related to how the reactants are converted to the products, that is, the reaction pathway. Instead of activated complex, the term transition state is also frequently used.
Figure 2.16 Distribution of kinetic energies of molecules at two different temperatures
T
1
<
T
2
. The colored areas below curves correspond to number of molecules that react.
Figure 2.17 The effect of a catalyst on a given reaction: it lowers the activation energy of that reaction.
Figure 2.18 In this scheme, it is shown how the shape of the enzyme (here sucrase) fits with that of a substrate (here, sucrose) to catalyze the reaction, splitting of the substrate into smaller compounds as products (here glucose and fructose).
Figure 2.19 Heterogeneous formation of ammonia from hydrogen and nitrogen.
Figure 2.20 The Wilkinson catalyst—an example of a homogeneous catalyst.
Figure 2.21 Daniel cell.
Figure 2.22 Carbon atoms can form straight and branched chains and rings.
Figure 2.23 Classification of organic compounds. Hydrocarbons are discussed in more detail in Sections 2.6.2–2.6.6 and organic compounds with functional groups in Sections 2.6.7.1–2.6.7.7.
Figure 2.24 Three representations of pentane.
Figure 2.25 Alkanes obtained from the fractionation of crude oil.
Figure 2.26 Reactions of ethylene as an example of an alkene and the products that can be formed.
Figure 2.27 Catalytic hydrogenation of an alkene.
Figure 2.28 Two natural polymers of glucose: cellulose and starch (F13-020 from Olmsted).
Figure 2.29 Four representations of polyethylene.
Figure 2.30 Polymers can form three types of overall structures: (a) linear, (b) branched, and (c) cross-linked.
Figure 2.31 Stress/strain diagram for polymers.
Figure 2.32 The exfoliated (left) and intercalated (right) forms of clay/polymer composites. The gray sheets represent the clay, while the chains represent the polymer.
Figure 2.33 Mechanism of chain-addition polymerization.
Figure 2.34 Mechanism of step-growth polymerizations for bifunctional and difunctional monomers.
Figure 2.35 The molecular weight distribution (MWD) of three polymer samples.
Figure 2.36 Fringed micelle model representing ordered, crystalline and unordered, amorphous regions in a polymer.
Figure 2.37 Illustration of microscopic behavior of polymer chains at the glass transition and melting temperature of the polymer.
Figure 2.38 Hydrogen bonding (dotted) between two polymer chains in a polyamide, that is, nylon.
Figure 2.39 The three types of tacticities, which can occur in polymers of monosubstituted ethylene, such as propylene shown here.
Figure 2.40 Universal resin identification code.
Figure 2.41 Examples of electroconductive polymers.
Figure 2.42 The photoabsorption spectrum of water vapor.
Figure 2.43 Solar flux outside the atmosphere and at sea level, respectively. The emission of a blackbody at 6000 K is also shown for comparison. The species responsible for light absorption in the various regions (O
3
, H
2
O, etc.) are also shown.
Figure 2.44 Atmospheric regions of maximum light absorption of solar radiation in the atmosphere by various atomic and molecular species as a function of altitude and wavelength with the sun overhead.
Figure 2.45 Minimal scheme for photochemical splitting of water with a photochemical sensitizer S.
Figure 2.46 Energy band scheme for intrinsic conductivity in a semiconductor.
Figure 2.47 The absorption spectrum of liquid water.
Figure 2.48 Direct biophotolysis.
Figure 2.49 Indirect biophotolysis.
Figure 2.50 Photofermentation.
Figure 2.51 Typical plasmas characterized by their number density, electron energy, and Debye length.
Figure 2.52 Voltage–current characteristics of a DC electric discharge
E
.
Figure 2.53 Temperature and pressure domain for equilibrium and nonequilibrium plasmas for DC discharges E.
Figure 2.54 Reactions taking place in a plasma processing reactor.
Figure 2.55 Some methods for exciting high-frequency discharges.
Chapter 3: Hydrogen Production
Figure 3.1 Single electrolyzer.
Figure 3.2 Solar method of decomposition of water splitting. (a) Central receiver/reactor tower with heliostats. (b) Modular dish-mounted receiver/reactor.
Figure 3.3 Thermochemical method of producing hydrogen using chemical catalysts.
Figure 3.4 Photovoltaic splitting of water to hydrogen.
Figure 3.5 Photocatalysis of water decomposition.
Figure 3.6 Photocatalytic hydrogen generation.
Figure 3.7 Hydrogen generation under different photocatalysts. TS
2
= TiO
2
–SnO
2
(Ti:Sn = 98:2), TS
5
= TiO
2
–SnO
2
(Ti:Sn = 95:5), and TS
10
= TiO
2
–SnO
2
(Ti:Sn = 90:10). Ratios are by atomic weight. Pd–TS
2
, Pd–TS
5
, and Pd–TS
10
refer to palladium-coated photocatalysts.
Figure 3.8 Hydrogen production using a photocatalyst, Ru/Cu
0.25
Ag
0.25
In
0.5
ZnS
2
. The aqueous solution is a mixture K
2
SO
3
and Na
2
S. Notice the bubbles produced using a solar simulator (AM-1.5).
Figure 3.9 Single-walled carbon-nanotube-coated TiO
2
photocatalyst for hydrogen evolution. Pt/TiO
2
, platinum-coated titanium dioxide; SWNT/TiO
2
, single-walled carbon-nanotube-coated TiO
2
; and GS/TiO
2
, graphite-silica-coated TiO
2
.
Figure 3.10 Pyrolytic plant for biomass conversion.
Figure 3.11 Four gasification methods.
Figure 3.12 High-temperature electrolysis using porous electrodes. Electrolyte Yittria stabilized Zirconia.
Figure 3.13 MOXIE for converting carbon dioxide to oxygen by high-temperature fuel cell.
Figure 3.14 MOXIE and its functions.
Figure 3.15 Hydrogen gas production efficiencies.
Figure 3.16 Correlation between hydrogen content of the fuel and environmental pollution factor.
Chapter 4: Hydrogen Properties
Figure 4.1 Atomic structure of protium.
Figure 4.2 Hydrogen bonding (indicated by dashed lines) in water, (H
2
O); and ammonia (NH
3
).
Figure 4.3 The largest consumers of hydrogen today.
Figure 4.4 Hydrogen/gasoline properties.
Figure 4.5 Hydrogen light-weight polymer tanks.
Figure 4.6 Typical high-pressure hydrogen storage system.
Figure 4.7 Comparison data for LH
2
and gasoline storage.
Figure 4.8 Liquid hydrogen storage system.
Figure 4.9 Metal hydride–hydrogen storage.
Figure 4.10 Decomposition–formation cycle of NaAlH
4
.
Figure 4.11 Multiwalled nanotubes structure.
Figure 4.12 Single-wall nanotubes structure.
Figure 4.13 SWNT and MWNT are allotropes of carbon.
Chapter 5: Hydrogen Infrastructure and Technology
Figure 5.1 Hydrogen infrastructure.
Figure 5.2 Hydrogen collection by displacement of air.
Figure 5.3 Renewable energy sources.
Figure 5.4 Wind power conversion into commercial-grade hydrogen and oxygen.
Figure 5.5 Types of biomass for conversion to fuel.
Figure 5.6 Typical landfill gas power generation family.
Figure 5.7 Typical landfill view.
Figure 5.8 Typical landfill gas production.
Figure 5.9 LFG cogeneration plant integrated with hydrogen production.
Figure 5.10 Hydrogen refueling station.
Figure 5.11 The Hubbert curve.
Chapter 6: Batteries
Figure 6.1 Battery made with Zn and Cu metal with electrolytes.
Figure 6.2 Specific energy available with different secondary batteries. NiCd = Nickel–Cadmium, NiMH = Nickel–metal hydride, LTO = Lithium titanate, LFP = Lithium iron phosphate, LMO = Lithium manganese dioxide, NMC = Lithium Nickel manganese cobalt oxide, LCO = Lithium cobalt oxide, and NCA = Lithium nickel cobalt aluminum oxide.
Figure 6.3 Conducting polymer batteries. (a) M is anode metal (typically Li or Zn), M
+
A
−
is the electrolyte filling the anode and cathode, P
+
A
−
is conducting polymer is in the oxidized state, and P is conducting polymer in the reduced state. (b) P
1
−
M
+
is the reduced state of conducting polymer and P
2
+
A
−
is the oxidized state of a conducting polymer. P
1
is oxidized state of the polymer and P
2
is the reduced state of the polymer.
Figure 6.4 Organic battery while charging and discharging, the electron and ion movement paths are shown. The anode compartment and cathode compartment are separated by the center plate (membrane).
Figure 6.5 Applications of batteries.
Figure 6.6 Portable 12 V 50 A/10-h deep cycle sealed lead-acid battery.
Figure 6.7 Lithium-ion battery.
Figure 6.8 2012 Chevrolet Volt T-shaped lithium-ion battery nickel–metal hydride.
Figure 6.9 General motors EV1.
Figure 6.10 The first electric vehicle built in 1897.
Figure 6.11 Simplified block diagram for electric vehicle.
Figure 6.12 Ford focus electric car.
Figure 6.13 Propulsion options.
Figure 6.14 Electric-drive options.
Figure 6.15 Tesla EV electric motors location.
Chapter 7: Fuel Cell Essentials
Figure 7.1 Simplified illustrative picture of a fuel cell.
Figure 7.2 Basic sandwich configuration of compact fuel cell.
Figure 7.3 A sketch of Grove's gas battery (1839), which produced a voltage of about 1 V.
Figure 7.4 Fuel cell reactions in systems where hydrogen is the fuel.
Figure 7.5 Carbon fuel cell. A solid fuel is converted to electrical power.
Figure 7.6 CFC with (a) molten hydroxide electrolyte and (b) molten carbonate electrolyte.
Figure 7.7 Voltage losses in the operation of a fuel cell.
Figure 7.8 Tafel curve.
Figure 7.9 Expected open circuit voltage of fuel cells at different temperatures.
Figure 7.10 Nafion® structure.
Figure 7.11 Disulfonated polymers. (1) sulfonated poly(arylene ether sulfone); (2) sulfophenylated polysulfone; (3) sulfonated styrene–ethylene–butylene–styrene (SEBS) block copolymer; (4) sulfonated styrene–ethylene interpolymer.
Figure 7.12 Conductivity of disulfonated monomer.
Figure 7.13 Water uptake by BPSH at 30°C.
Figure 7.14 Process for the preparation of PEMs by radiation.
Figure 7.15 Hydrogen and hydroxyl ion movement in the membrane. Although Nafion membrane has been successfully used in PEMFC, there are several new membranes that can stand high temperatures have been developed. Phosphoric acid-doped polybenzimidazole (PBI) can be used up to temperatures of 200°C. A membrane that requires new humidification has been developed by Celtec using PBI and phosphoric acid. It has higher tolerance against carbon monoxide gas. Gyner Electrochemical Systems developed perflurosulfonic acid that has higher conductivity than Nafion. Thus, the activity in membranes has been focused on high temperature operations with lower relative humidity, preferably at less than 10%.
Figure 7.16 A view of a single PEMFC.
Figure 7.17 Bipolar plate.
Figure 7.18 Stacked PEMFC.
Figure 7.19 Current–voltage curves for PEMFC with different amounts of RuO
2
.
Figure 7.20 Flow fields design.
Figure 7.21 Alkaline fuel cell.
Figure 7.22 Alkaline fuel cell used in space missions.
Figure 7.23 Molten carbonate fuel cell.
Figure 7.24 Fuel cell voltage and current of PEMFC in the presence of CO.
Figure 7.25 Solid oxide fuel cell.
Figure 7.26 Tubular SOFC.
Figure 7.27 SOFC stacking arrangement.
Figure 7.28 Current–voltage curve for SOFC fuel cell.
Figure 7.29 Power density curve for SOFC fuel cell.
Figure 7.30 Flowchart for developing and designing a fuel cell.
Figure 7.31 Fifty-nine-megawatt Gyeonggi Green Energy fuel cell park in Hwasung City.
Figure 7.32 Fuel cell energy completes 14.9 MW fuel cell park in Connecticut (USA).
Figure 7.33 Market share of carbon dioxide generating vehicles. ICE (internal combustion engine), BEV (battery-operated vehicle), FCEV (fuel cell electric vehicle), HEV (hybrid electric vehicles) and REEV (range extender electric vehicle).
Figure 7.34 Micropower system configuration.
Figure 7.35 Fuel cell power system principal configuration.
Figure 7.36 Fuel processor temperature requirements.
Figure 7.37 Fuel cell power system for transportation.
Figure 7.38 Fuel cell power system functions and features.
Figure 7.39 Methanol fuel processor subsystem.
Figure 7.40 Gasoline fuel cell vehicle architecture.
Chapter 8: Fuel Cells Applications
Figure 8.1 Energy conversion for transportation.
Figure 8.2 Fuel-cell vehicle design option.
Figure 8.3 Well-to-wheel diagram.
Figure 8.4 Fuel cell fork lift.
Figure 8.5 The fuel cell/battery hybrid railway vehicle. http://w3.gorge.net/eclipse/projects/proj_wtw.html.
Figure 8.6 The chemical reaction in micropower PEMFC.
Figure 8.7 Low content direct methanol fuel cell (DMFC) active system.
List of Tables
Chapter 1: Available Energy Resources
Table 1.1 Pathways for the dissipation of solar radiation
Table 1.2 Polluted air: causes and remedies
Table 1.3 Oil reserves by country in billions of barrels
Table 1.4 World natural gas reserves: world proven natural gas reserves by country, 2005 and 2006
Table 1.5 Proved recoverable coal reserves at end-2006 (million tons)
Table 1.6 Known recoverable resources of uranium
Chapter 2: Chemistry Background
Table 2.1 Acid dissociation constants,
K
a
, for some acids (25°C)
Table 2.2 Chemical thermodynamic properties at 298.15 K and 1 bar
Table 2.3 Molar heat capacities at constant pressure as a function of temperature from 300 to 1800 K:
Table 2.4 Table of redox reactions at 25°C
Table 2.5 Names, structures, and formulas for representative hydrocarbons
Table 2.6 Alkanes with up to 10 C-atoms and some of their branched isomers
Table 2.7 Names and structures of alkyl and aryl groups
Table 2.8 Overview of organic compounds with functional groups
Table 2.9 The formulas and names of some simple polymers
Table 2.10 Overview of major chain-addition polymers
Table 2.11 Some preferred monomer/initiator combinations for chain-addition polymerizations
Table 2.12 Important step-growth polymers
Table 2.13 The glass transition and melting temperatures of several of the above-discussed polymers [55]
Table 2.14 Energies of electromagnetic radiation
Table 2.15 Photoabsorption cross sections for water vapor
Table 2.16 Estimates of integrated solar flux values at the earth's surface as a function of wavelength interval and solar zenith angle within specific wavelength intervals
a
Table 2.17 Semiconductor energy gaps between the valence and conduction bands
Table 2.18 Physical and chemical processes involving excited hydrogen atoms (H*)
Chapter 3: Hydrogen Production
Table 3.1 Hydrogen production by thermochemical process
Table 3.2 Photocatalytic production of hydrogen
Table 3.3 Photocatalytic evolution of hydrogen from H
2
S
Table 3.4 Hydrogen production—important benefits and challenges
Chapter 4: Hydrogen Properties
Table 4.1 Atomic properties of hydrogen
Table 4.2 Physical properties of hydrogen
Table 4.3 Energy content for 1 kg of hydrogen in the reaction with oxygen to form water
Table 4.4 Comparative fuels properties
Table 4.5 Specific energy value of compressed gases and gasoline
Table 4.6 Hydrogen storage material
Table 4.7 Key properties of metal hydrides suiTable for gas-phase applications
Chapter 5: Hydrogen Infrastructure and Technology
Table 5.1 Fire hazard characteristics
Chapter 6: Batteries
Table 6.1 Standard potentials of redox reactions
Table 6.2 Batteries and their parameters
Table 6.4 Secondary batteries
Table 6.5 List of conducting polymers for battery applications
Table 6.6 Battery characteristics: primary batteries and their characteristics
Table 6.7 Battery characteristics: secondary (rechargeable or traction) batteries and their characteristics
Table 6.8 Nissan Leaflet
Chapter 7: Fuel Cell Essentials
Table 7.1 Fuel values of different chemicals
Table 7.2 Fuel values of series of alcohols
Table 7.3 Fuel values of biodiesels
Table 7.4 Fuel value of diesels
Table 7.5 Standard electrode potentials at 25°C
a
Table 7.6 Standard free energy of formation of selected fuel cell substances at 25°C
Table 7.7 Free energies and enthalpies of fuel cell reaction at different temperatures
Table 7.8 Exchange current densities for hydrogen in acid electrolyte
Table 7.10 Exchange current densities at silicon membranes
Table 7.11 High-pressure cylinder technical specifications
Table 7.12 Estimated consumption of hydrogen in the fuel cell for selected currents and durations
Table 7.13 Power output and hydrogen consumption in PEMFC
Table 7.14 Modifications of polymer membranes
Table 7.15 Commercially available PEMs and their properties
Table 7.16 PEMFC performance with modified membranes
Table 7.17 AFC conditions of operation
Table 7.18 Methods of making SOFC components
Table 7.19 Parameters used in simulation of SOFC load curves
Table 7.20 Performance characteristics and applications of fuel cells
Table 7.21 Fuel cell market
Table 7.22 Fuel cells with halogens
Chapter 8: Fuel Cells Applications
Table 8.1 FCV produced in Asia
Introduction to Hydrogen Technology
Second Edition
K.S.V. Santhanam
School of Chemistry and Materials Science, Rochester Institute of Technology, USA
Roman J. Press
School of Chemistry and Materials Science, Rochester Institute of Technology, USA
Massoud J. Miri
School of Chemistry and Materials Science, Rochester Institute of Technology, USA
Alla V. Bailey
School of Chemistry and Materials Science, Rochester Institute of Technology, USA
Gerald A. Takacs
School of Chemistry and Materials Science, Rochester Institute of Technology, USA
This edition first published 2018
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Library of Congress Cataloging-in-Publication Data
Names: Santhanam, K. S. V. (Kalathur S. V.), author. | Press, Roman J., author. | Miri, Massoud J., 1954- author. | Bailey, Alla V., 1949- author. | Takacs, Gerald A., 1943- author.
Title: Introduction to hydrogen technology / K.S.V. Santhanam, Roman J. Press, Massoud J. Miri, Alla V. Bailey, Gerald A. Takacs.
Description: Second edition. | Hoboken, NJ : John Wiley & Sons, 2018. | Includes bibliographical references and index. |
Identifiers: LCCN 2017022078 (print) | LCCN 2017036357 (ebook) | ISBN 9781119265580 (pdf) | ISBN 9781119265573 (epub) | ISBN 9781119265542 (cloth)
Subjects: LCSH: Hydrogen. | Renewable energy sources. | Hydrogen as fuel.
Classification: LCC TP245.H9 (ebook) | LCC TP245.H9 S27 2017 (print) | DDC 665.8/1-dc23
LC record available at https://lccn.loc.gov/2017022078
Cover Design: Wiley
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(Image) © Artwork studio BKK/Shutterstock
Preface
Hydrogen gas continues to occupy a unique place in the world as it possesses properties that other elements do not. Consequently, scientists and engineers have been working on using it for improving the existing technology. The scientific literature on hydrogen technology is astronomically growing with the result that a large number of hydrogen-powered devices have entered the market and are being used in mobile phones, laptops, automobiles, utility vehicles, and so on. In addition, fuel cells have been developed to produce stationary power in a number of countries; it is predicted that the utilization will grow to 1.25 million fuel cells in the next 5 years.
The second edition of this book is to keep pace with the above developments and contains updated information on renewable energies, world petroleum production, and greenhouse gases. The new generation of solar cells is included in this book. Each chapter of the first edition is updated by including new developments. Of particular importance is fuel value of biodiesels, solid carbon fuel cells that is being considered for new developments, new Nafion membranes produced by grafting for polymer electrolyte membrane fuel cell, improved electrode materials for molten carbonate, and solid oxide fuel cells. The chapter on hydrogen technology is modified to address infrastructure technology.
Two new chapters—Hydrogen Production and Batteries—are added in this edition. The Hydrogen Production chapter reviews the various developments in improving the water decomposition efficiency and the resulting environmental impact factor. In this chapter, nine different methods of hydrogen production are considered, which, hopefully, will lower the cost of hydrogen. The Batteries chapter is included to provide a deeper examination of how hydrogen is used as a fuel in a fuel cell to generate electricity. With battery, electricity is generated from the stored energy. In essence, both are generating electricity for practical applications. Hence, for comparison of the chemistries involved in the two ways of generating electricity, this chapter hopefully will stimulate the reader for appreciating the suitability of the two methods toward fulfilling the greenhouse gas effect in the atmosphere.
In the first edition, it was mentioned that UN's Intergovernmental Panel on Climate Change had been enforcing the need to reduce the greenhouse gases in the atmosphere. The second phase (2013–2020) of Kyoto agreement has begun, and the United Nations Framework Convention on Climatic Change (UNFCC) passed a resolution in Paris in 2015 (http://unfccc.int/paris_agreement/items/9485.php) to stabilize the concentrations of greenhouse gases in the atmosphere such that there would be minimum interference with the climatic system. The hydrogen technology can go a long way to fulfilling this goal.
Finally, this book, if it is used as a textbook for a course, contains problems at the end of each chapter.
The authors thank Profs. Paul Craig and Sophia Maggelakis for their support in bringing out this edition.
K.S.V. Santhanam, Roman J. Press, Massoud J. Miri, Alla V. Bailey, and Jerry A. Takacs June 3, 2017, Rochester, NY
About the Companion Website
This book is accompanied by Instructor website:
www.wiley.com/go/santhanam/hydrogentech_2e
On this website you will find
Multiple choice questions as a preparation for class room examinations.
Problems and their solutions.
Appendix
Chapter 1Available Energy Resources
1.1 Civilization and the Search for Sustainable Energy
Many thousands of years ago, our ancestors knew how to produce fire and they used it for several different purposes, including warming themselves and preparing food. They discovered that energy could be liberated from burning wood. The energy-liberating material was defined as fuel, and this led to the recognition that wood is a fuel. Early civilizations depended on this fuel for a long time. To improve their living conditions, humans searched for new forms of sustainable energy. This exploration resulted in the invention of wind-driven wheels that could be used to pump water from wells. Before this discovery, water was pulled from wells by human energy. This led to a correlation that wind is a source of energy. The wheel was also found useful for transportation forming a part of a chariot that could be rotated when drawn by horses.
During the 18th century, the most commonly used forms of energy were derived from wood, water, horses, and mills. The composition and structure of these materials were mysteries, and more so how the energy was liberated from them. These mysteries led to detailed investigations into the structure of matter by numerous scientists, including J.J. Thompson, J. Dalton, M. Faraday, M. Curie, N. Bohr, A. Einstein, and J. Gibbs. This search for understanding the composition and structure of matter resulted in astounding discoveries in science, including the discovery and understanding of molecules and atoms.
The energy liberates upon combustion and products of combustion were established during this period. During the 18th century, as mentioned in the beginning of the paragraph, it was demonstrated that alcohol could be produced by the destructive distillation of wood, and that alcohol could be used as a source of energy. A realization that wood could be replaced by alcohol and that it could do the job much more effectively resulted in the use of alcohol as a source of energy. Coal was used as a source of energy for running steam engines.
In the 19th century, organic chemists synthesized hydrocarbons and determined the energies available from them. The 20th century led to the search for naturally available sources of hydrocarbons, and the discovery, that oil and natural gas contain them, paved the way for their utilization as energy sources in transportation. The rapid utilization and resulting depletion of these naturally occurring sources by mankind is leading to the search for viable alternatives. In addition, hydrocarbon-based energy sources are responsible for pollution of the atmosphere. These energy sources release carbon dioxide and carbon monoxide gases. Such gases are causing global warming (Section 1.3).
The 21st century is facing challenging problems, with faster depletion of fossil fuels and pollution arising from their use. Energy sources that are sustainable and producing negligible pollution are needed. In this context, hydrogen and fuel cells are being considered, but their exploration and use require policy decisions. Historically, the United States depends heavily on imported oils, and the infrastructure has been built on the imported oils and natural gases. In order to switch over to other fuels free from the restrictions discussed earlier, a smooth transitional infrastructure needs to be evolved.
A symbol of early human ingenuity is the first step pyramid, built for King Zoser in 2750 BC in Saqqará/Egypt. Similarly, the “energy pyramid” represents another advancement in human ingenuity. As the “food pyramid” represents a balanced approach to a healthy lifestyle, the energy pyramid (Figure 1.1) represents a balanced approach to consuming renewable and nonrenewable energy sources. With the gradual depletion of most nonrenewable sources of hydrocarbon-based fuels, the energy pyramid contains a diverse proportion of renewable fuels—hydro, solar, and wind power, along with various biomass-produced fuels.
Figure 1.1 Energy pyramid.
During the 19th century, hydrogen was experimented as an energy source, and Sir William Grove demonstrated in 1839 that hydrogen and oxygen would combine to produce electricity. The product of the reaction was water. He called the device a fuel cell. In this method of producing electricity, there is no pollution generated and it is environmentally friendly for transportation. These two factors are very important in the 21st century. President George W. Bush spoke of the potential of hydrogen as a future energy source in his address to the National Building Museum on February 6, 2003. He stated, “Hydrogen fuel cells represent one of the most encouraging, innovative technologies of our era,” and predicted that any obstacles in building hydrogen-based technology could be overcome by thoughtful research by scientists and engineers. This trend is continued by President Obama's administration by speeding up the hydrogen-powered transportation and energy production.
The United States is in a unique situation in its energy consumption. Growth was exponential in the second half of the 20th century. The United States consumes 25% of the world's energy supplies, which are distributed over the following four sectors: industrial commercial, transportation, and residential use (Figure 1.2). A deeper analysis shows that these four sectors showed a 300% increase in the annual usage since 1950. This trend has resulted in faster depletion of fossil fuels and greater environmental effects. Petroleum and gas reserves (fuels) are being rapidly depleted at a rate of a thousand times faster than the fuels are formed and stored. With the economic viability of the United States closely linked to fuel supplies from unstable regions around the globe, additional problems are likely to arise in the future. If domestic supplies of fuels decline, the need for importing fuels will increase. With current evidence for the imported fuel prices increasing year by year, the fuel needs and cost are likely to severely escalate in the near future.
Figure 1.2 US energy use by sector.
Increased use of fossil fuels has had negative environmental effects: oil spills endanger aquatic and plant life, contaminate beaches and soil, and cause erosion of large masses of land. It also results in global warming effects. If we wish to solve all these problems, then we have to find alternative sources of energy. Hydrogen is one of the alternative energy sources that the world could rely on safely.
Industrialized society is built on the existing infrastructure and is primarily fueled by petroleum. If fuel prices are stable, then the infrastructure requires very little change and the status quo can be maintained. Unfortunately, the status quo does not address the problems of the future. Future needs can be met only by recognizing the problems generated by petroleum-based technology and making efforts to find energy sources free from these problems. Hydrogen-based technology appears to be an ideal solution in this context.
Hydrogen-based technology offers attractive options for use in an economically and socially viable world with negligible environmental effects. Hydrogen is everywhere on earth in the form of water and hydrocarbons. In other words, hydrogen as fuel produces water as the by-product, and water is the source for hydrogen. It is an ideal energy carrier and hence could play a major role in a new decentralized infrastructure that would provide power to vehicles, homes, and industries. Hydrogen is nontoxic, renewable, clean, and provides more energy per dollar. Hydrogen is also the fuel for energy-efficient fuel cells.
Fossil fuels such as oil and gas are being currently used to harvest hydrogen. This is not ideal as it does not solve environmental issues that arise with the usage of fossil fuels. In the future, it will be necessary to use renewable energy sources such as wind, hydro, solar, biomass, and geothermal instead.
The stationary power generation based on fuel cell technology is a viable energy source and has been implemented in several places in the world. This technology provides a drastic reduction in carbon dioxide output in comparison to the existing technology.
Leading automotive companies, such as GM, Ford, Opel, Daimler-Chrysler, and Toyota, have even made significant progress in developing advanced fuel cell propulsion systems using hydrogen. Hydrogen-powered fuel cells are approximately two times more efficient than gasoline engines. With 650 million vehicles worldwide fueled by gasoline, the market potential is immense. Fuel cells power modules, using either proton exchange membranes or solid oxide, can potentially be the source of distributed electric power generation for business and home use.
The purpose of this book is to introduce the reader to the fundamental, chemistry-based aspects of hydrogen technology. It also provides information on renewable energy, hydrogen production, and fuel cells. The latest developments and current research on alternative fuels are discussed. The core topics include acid–base chemistry, reaction topics, chemical equilibrium, thermodynamics, electrochemistry, organic chemistry, polymers, photochemistry, and environmental chemistry. The topics covered in this text are highly relevant to current international and national concerns about overconsumption of our planet's natural resources and the political implications of the United States' dependence on foreign oil to meet the majority of its energy needs. There are many reasons to search for renewable sources of energy—including, but not limited to, energy conservation, pollution avoidance, and prevention. Hydrogen, being one of the cleanest and most abundant alternative energy, will most likely play a critical role in a new energy infrastructure by providing a cleaner source of power to vehicles, homes, and industries.
The authors are members of the Rochester Institute of Technology Renewable Energy Enterprise (RITree). They sincerely hope that this book will give a very good background on chemical aspects of hydrogen technology, including its potential in fuel cells and impact on environment. It is also the hope of the authors that this publication will contribute to the preparation of a workforce ready for future challenges in the areas of energy consumption, generation, and the rapid commercialization of both hydrogen-powered transportation and nonautomotive applications.
1.2 The Planet's Energy Resources and Energy Consumption
On this planet, sources of energy are fossil fuels, the sun, the wind, water, and the earth (the latter includes geothermal and nuclear energy). Fossil fuels-oil, natural gas, and coal- and nuclear energy are abundantly used at present. Since these energy sources are expected to be depleted within a couple of centuries, they have been called “nonrenewable” energy sources. Only about 20% of our energy needs come from renewable sources. Examples in this category are solar energy, wind energy, hydro energy, biomass, geothermal energy, tidal energy, and hydrogen. These sources are not very efficient and research needs to be done to improve their efficiencies.
1.2.1 Energy Consumption
The total world consumption of energy amounted to 400 Quad (=quadrillion) Btu in 2000.1 A human being consumes about 0.9 GJ/day of energy, equivalent to burning 32 kg of coal per day, or as average energy supply, 10.4 kW. Any human being needs as nutrition only 0.14 kW or about 1% of the energy consumed per capita. Essentially, all human activities involve consumption of energy, for example, construction of buildings, production of consumer goods, medicine, food, packaging of products, transportation, heating and cooling, administrative work, and even activities in our leisure time. Between 1850 and 1970, the world population tripled with the result that energy consumption increased by a factor of 12.
CRITICAL THINKING QUESTIONS
A What are the sources of energy considered in the global energy consumption?
B Which continent is consuming the highest Quadrillion Btu?
Answer: A
(a) Crude oil (b) oil-derived sources (c) natural gas (d) coal and lignite (e) power production and (f) renewables.
Answer: B
Based on US Energy Information Administration (EIA),
North America: 116.191 Quadrillion BtuCentral and South America: 28.674 Quadrillion BtuEurope: 81.45 Quadrillion BtuEurasia: 46.09 Quadrillion BtuMiddle East: 32.213 Quadrillion BtuAfrica: 17.335 Quadrillion BtuAsia and Oceania: 202.19 Quadrillion BtuWorld: 524.076 Quadrillion BtuBased on the 2012 data provided by EIA, Asia and Oceania consume the highest, and Africa is the lowest ranked in total primary energy consumption.1.2.2 Regional Differences
Energy consumption is not evenly distributed over the countries of the world. The developed rich countries, for example, the United States, Europe, and Japan, consume about 80% of the worldwide energy and represent 20% of the world's population. Consumer habits differ from region to region. In the United States, people drive larger, lesser-fuel-efficient automobiles and buy larger homes than in many other countries, such as China or India. Currently, an American on the average uses 10 times more energy than the average Chinese and 20 times more than the average Indian. However, energy consumption is rising faster in the developing countries.
1.2.3 Distribution by Economic Sector
Transportation accounts for 30% of the world's energy consumption, mainly due to the use of passenger cars. About one billion cars are used worldwide and about a quarter of all of the world's automobiles are driven in the United States. In Europe and Japan, more mass transportation is used, often encouraged by government policies such as high taxes for car registration and subsidies for mass transport. Since most automobiles run on petroleum-based gasoline, the higher use of mass transportation significantly reduces production of greenhouse gases and global warming (see Section 1.3) and causes less pollution. Approximately a third of the world's energy is used in residential and commercial buildings, for heating, cooling, cooking, and other appliances. Americans use about 2.4 times the energy of Europeans, due to larger homes and more appliances. The average size of the living space for a citizen in the United States is about 25 times that of a person on the African continent. Another third of the world's energy is used in industry for the production of various goods, such as consumer products, cars, buildings, and food.
1.2.4 Differentiation by Type of Energy Resource
Figure 1.3 shows the consumption by energy source for the last three decades along with projections up to 2020. In 2000, close to 150 Quad Btu of the energy we used was from petroleum, followed by another 70 Quad Btu from natural gas, about 70 Quad Btu from coal, and 15 Quad Btu nuclear fuel. The remainder was from renewable energy resources.
Figure 1.3 Consumption by type of energy source.
[Source: EIA (Energy Information Administration), International Energy Outlook 2000, PPT by J. E. Hakes; http://tonto.eia.doe.gov/FTPROOT/presentations/ieo2000/sld002.htm.]
1.2.5 Meeting the Energy Demands of the Future
Improved technology has helped to increase energy efficiency, particularly of the renewable energy resources. However, since the world's economy is also steadily increasing, the consumption of energy grows by about 2% every year, and the demand for energy will only increase.
1.3 The Greenhouse Effect and its Influence on Quality of Life and the Ecosphere
We live on a planet that derives energy for all our activities from the sun. We wash our clothes in water and dry them in the sun. We get hydroelectric power from the evaporation of water by the heat of the sun. The green plants (trees, algae, etc.) on our planet perform photosynthesis using solar energy. There are many other applications of solar energy, such as in solar heaters, photovoltaic cells producing electricity, photogalvanic, and photobiological processes.
CRITICAL THINKING QUESTIONS
1 What is global warming?
1 It is a term used to describe the rapid change of the earth's climate.
2 Explain the different factors associated with the global warming.
a. Increased global air temperaturesb. Increased annual precipitationc. Shorter wintersd. Shrinking ice coverse. Presence of mosquito-borne diseases at higher altitudesf. Rising sea levelsThe sun produces solar radiation by a nuclear process, and the solar spectrum spans a wavelength of about 0.03–14,000 nm. Of these different wavelengths of radiation emitted by the sun, the highly energetic ones (γ-rays, X-rays, and ultraviolet rays) spanning a wavelength region of 0.03–300 nm, are filtered by the atmosphere above our planet. The other wavelengths enter our atmosphere. The radiation that reaches the earth's surface is now subjected to reflection by the atmosphere, the clouds, and the earth's surface. The total solar radiation that is reflected amounts to about 30%. The balance of 70% of incoming solar radiation is absorbed by the atmosphere, clouds, land, and oceans. Table 1.1 gives the estimated contributions by the different entities toward reflection and absorption. However, solar energy powers the life on the earth solely by absorption. Almost all of the short wavelength radiation coming from the sun (ultraviolet light) is absorbed by the ozone layer in the stratosphere. This absorption is very important as it protects life on the earth.
Table 1.1 Pathways for the dissipation of solar radiation
Reflection (%)
Atmosphere
6
Clouds
20
Surface
4
Absorption (%)
Atmosphere
16
Clouds
3
Land and oceans
51
Source: http://en.wikipedia.org/wiki/Greenhouse_effect.
Figure 1.4 shows the path for the greenhouse effect and the solar radiation that is emitted and the radiation reaching the earth. Note that only part of the solar radiation reaches the earth.
Figure 1.4 Solar radiation.
1.3.1 What Is the Effect of Solar Radiation Reaching the Earth?
The solar radiation reaching the earth heats the surface. This heating effect can be calculated from the radius of the earth (R) [0.635 × 107 m], solar constant (S) that describes the average amount of radiation that earth receives from the sun [1.37 kW/m2], and Albedo (A) [the fraction of the radiation reflected by the planet] of the earth as given by equation (1.1).
This radiation heats up the earth to an effective temperature, Te. The photons of the wavelengths shown by arrows pointing to earth in Figure 1.4 reach the entire surface and are not localized. If the earth emits radiation as a blackbody, the infrared radiation emitted will follow Stefan–Boltzmann law, according to which
where k = Stefan–Boltzmann constant.
Equating (1.1) with (1.2)
By substituting the constants in equation (1.3), it is possible to estimate the effective temperature Te. The earth's temperature based on this equilibrium model would be about Te = 253 K(−20°C). This is not a suitable condition for life as it would be a frozen world. However, this situation does not exist because of the greenhouse effect and we have an average temperature on the earth of about 288 K (15°C).
1.3.2 How the Temperature Is Kept Higher Than the Equilibrium Model
We have considered in the earlier discussions that the sun's radiation is a blackbody radiation that reaches the earth. The temperature of the sun is much higher than the earth (5880 K vs 288 K), and also the earth's surface (earth diameter = 1.27 × 107 m and surface area 0.51 × 1015 m2) is much smaller than the sun (diameter = 1.39 × 109 m and surface area = 0.609 × 1019 m2). Due to these factors, Wien's displacement law proposes that the wavelength of radiation emitted by the earth should be longer than the one coming from the sun. It is typically in the infrared region of 1000 nm. The sun's radiation that reaches the earth is a visible wavelength of about 500 nm. As the earth radiates infrared radiation, it is absorbed by molecules in the atmosphere, typically molecules such as carbon dioxide, water vapor, nitrous oxide, ozone, and methane. These molecules have the capability to absorb the infrared radiation and reemit it to keep the earth's temperature higher than predicted by the equilibrium model. The molecules absorbing the earth's radiation are called greenhouse gases and the process is known as the greenhouse effect. In other words, the greenhouse effect is a process of absorption of infrared radiation emitted from the earth by the greenhouse gases. Thus, most of the thermal radiation of the earth does not escape and is contained in the atmosphere. Only about 6% of the total radiation from the earth escapes into space. For infrared radiation to be absorbed, the molecule should have a permanent dipole moment or asymmetric stretching or bending that can cause a temporary dipole moment. In the atmosphere, nitrogen and oxygen molecules are available in high concentrations and do not contribute to infrared absorption; this is due to the fact that these molecules do not have permanent dipole moment. The molecules such as water vapor, nitrous oxide, ozone, and methane have permanent dipole moment with the exception of carbon dioxide that possesses temporary dipole moment.
1.3.3 Quality of Life
The quality of our living depends on the environment we have around us. The effective temperature, Te, is one of the deciding factors. If the atmosphere around us has a higher carbon dioxide level, then it will absorb more of the radiation emitted by the earth and reradiate it to the earth. This results in higher Te on the earth and consequently in global warming. If global warming continues to take place, then a stage might be reached when our existence is threatened. Here we could compare the greenhouse effect of other planets. Venus is rich in carbon dioxide and hence it causes the greenhouse effect on its surface, where the temperature is such that a metal like lead can melt. On the other hand, Mars has very small amounts of greenhouse gases and hence produces a minimum greenhouse effect.
The carbon dioxide level in the earth's atmosphere has increased due to heavy industrialization from the original value of 313 ppm in 1960 to the present value of 375 ppm. The average temperature of the earth has increased by 0.5°C. This has been discussed as global warming in several scientific meetings. If this trend were to continue, then after a very long time, the effective temperature may not be tolerable for our living. At this stage, increased water evaporation will take place that will affect the quality and quantity of drinking water. It may cause higher rainfalls that may result in flooding. Another possible concern is in a rising sea level that can also cause flooding of the land. Increased temperature may cause spread of infectious diseases, forest fires, and demand for more air conditioning for our living (Table 1.2).
Table 1.2 Polluted air: causes and remedies
Type of pollution
Gases involved
Sources
Remedies
Universal problemGreenhouse gas effect
CO
2
, CFC, CH
4
, N
2
O, and O
3
Fuel combustionForest firesVolcano eruption Chlorofluorocarbons (CFC)Volatile organic compoundsPeroxy acetyl nitrate
Lesser usage of fossil fuelsUsing nonpolluting fuelsForest conservationStopping volcanoes (???)
Acid rain
Sulfur and nitrogen oxides, ammonia and hydrochloric acid vapors
Caused by combustion of fuels and industrial gasesChemical pulping used in paper industries
Using gas absorbers for desulfuration and denitrationEfficient combustion
Ozone layer
Fluorocarbons, CH
3
CCl
3
, CCl
4
, O
3
Decomposition of O
3
with Cl in UV light
Substitution and collection of CFO
Local problem-smog
SO
2
, HCl, CO, sulfuric acid mist
Industrial waste gasCombustion of coal
Smoke treatment
Photochemical smog
NO
x
, SO
x
, nonmethane HC
Combustion of fuel
Same as acid rain
CFC, chlorofluorocarbons; CFO, chlorofluoro oxides; ???, questionable.
References: Energy and air pollution, World energy outlook special report, International Energy Agency, OECD/IEA, 2016; S. Cole, G. Ellen (14 December 2015). “New NASA Satellite Maps Show Human Fingerprint on Global Air Quality.” NASA. Retrieved 14 December 2015.
Figure 1.5 gives the carbon dioxide level before Christ (BC) and expected level in 2015.
Figure 1.5 Global atmospheric concentrations of carbon dioxide over time.
[www.epa.gov/climatechange/indicators.]
1.3.4 The Ecosphere
Based on our current understanding of the greenhouse effect, it is desirable to examine the ecosphere, which is not only made up of the environment but also includes all the living things. It extends from the stratosphere to the deep abyss of ocean, with several interacting entities. We may divide the ecosphere into local ecosystems. Among these ecosystems within ecosystems, there may be interactions that will affect the atmosphere. With increasing industrialization (producing more carbon dioxide that is let into the atmosphere) and deforestation (absence of photosynthesis resulting in more carbon dioxide in the atmosphere) in the ecosphere, more of the greenhouse gases will surround us that would result in increasing the temperature on the earth. Another problem that we face is the destruction of the ozone layer (this layer filters ultraviolet rays from reaching the earth) by the fluorocarbons that will allow shorter wavelength radiation from the sun to penetrate through the layer and will have significant interaction with our ecosystem. This may bring about destruction of plants, animals, and humans living on our planet. Although the physical and chemical processes involved in greenhouse effect suggests caution in our industrialization and deforestation, it may be several millions of years before the effective temperature can reach the limit of destruction of life on our planet due to the above-mentioned causes.
