Biohydrogen: For Future Engine Fuel Demands

276 Pages·2009·3.08 MB·english

by  Ayhan Demirbas (auth.)

Green Energy and Technology
Ayhan Demirbas
Biohydrogen
For Future Engine Fuel Demands
123
Ayhan Demirbas, Professor of Energy Technology
Sila Science and Energy
Trabzon
Turkey
ISSN 1865-3529
ISBN 978-1-84882-510-9 e-ISBN 978-1-84882-511-6
DOI 10.1007/978-1-84882-511-6
Springer Dordrecht Heidelberg London New York
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Preface
Today’s world faces three critical problems: (1) high fuel prices, (2) climatic
changes, and (3) air pollution. Experts suggest that current oil and gas reserves are
only sufficient to last a few more decades. It is well-known that transport is almost
totally dependent on fossil fuels, particularly petroleum-based fuels such as gaso-
line, diesel fuel, liquefied petroleum gas, and compressed natural gas. Petroleum-
based fuels are well-established products that have served industry and consumers
for more than one hundred years, and for the foreseeable future, automotive fuels
will still be largely based on liquid hydrocarbons. However, time is running out and
petroleum, once considered inexhaustible, is now being depleted at a rapid rate. As
the amount of available petroleum decreases, the need for alternate technologies to
produce liquid fuels that could potentially help prolong the liquid fuels culture and
mitigate the forthcoming effects of the shortage of transportation fuels increases.
There are several reasons for biofuels to be considered as relevant technologies
by both developing and industrialized countries. They include energy security rea-
sons, environmental concerns, foreign exchange savings, and socioeconomic issues
related to the rural sectors of all countries in the world.
This book discusses the production, storage, transportation, usage, economy,
policy, and environmental impacts of biohydrogen. Biohydrogen is a replacement
for fossil and biorenewable liquid fuels. In this book, the modern biomass-based
transportation fuels bioethanol, biomethanol, biodiesel, bio-oil, biogas, and biohy-
drogen are briefly reviewed. Biomass conversion technologies are important for
obtaining biofuels such as bioethanol, biodiesel, bio-oil, and biohydrogen.
A comprehensive definition of biohydrogen is hydrogen produced chemically,
thermochemically, biologically, biochemically, and biophotolytically from all bio-
mass materials. Biohydrogen is a renewable biofuel produced from biorenewable
feedstocks by chemical, thermochemical, biological, biochemical, and biophotolyt-
ical methods. Biohydrogen is an environmentally friendly alternative automotive
fuel that can be used in an internal combustion engine.
Hydrogen can be produced from biorenewable feedstocks via thermochemi-
cal conversion processes such as pyrolysis, gasification, steam gasification, steam
reforming of bio-oils, and supercritical water gasification (SWG) of biomass.
Hydrogen can also be produced by renewable biological systems. For example,
there are three types of microorganisms that generate hydrogen: cyanobacteria,
anaerobic bacteria, and fermentative bacteria.
The hydrogen economy is a vision for a future in which hydrogen replaces fossil
fuels. Economically, the wasteful hydrogen process translates to electricity from
v
vi Preface
hydrogen and fuel cells costing at least four times as much as electricity from the
grid. In fact, electricity would be used much more efficiently if it were sent directly
to the appliances instead. The transition to a hydrogen economy would require a
huge investment in new infrastructure to produce, store and deliver hydrogen to
end-users, to establish hydrogen stationary systems, as well as to develop and man-
ufacture fuel cells. The transition to the hydrogen-powered system could take sev-
eral decades due to the slow turnover of the existing stock of capital. The transition
to a hydrogen economy is likely to begin later in most developing economies than
in industrialized countries.
Hydrogen is a synthetic energy carrier. The synthesis of hydrogen requires
energy. Since production, packaging, storage, transfer and delivery of hydrogen
gas, in essence all key components of an economy, are extremely energy consum-
ing, alternatives should be considered. The production technology would be site-
specific and include steam reforming of methane and electrolysis in hydropower-
rich countries. Conventionally produced hydrogen gas costs about twice that of
natural gas or oil and about three times that of coal. At present only the space indus-
try seems to be willing to pay the high cost of hydrogen energy.
Hydrogen can be transported by two systems: (1) a road delivery system (cryo-
genic liquid trucks, compressed tube trailers), and (2) a pipeline delivery system.
Placing the pipelines in sewers, securing utility status, or converting existing natu-
ral gas pipelines to carry a mixture of hydrogen and natural gas could reduce hydro-
gen pipeline costs.
Hydrogen could be a peaceful energy carrier for all countries. Hydrogen might
be the next great fuel, as it is available worldwide and water is its only byprod-
uct. Hydrogen has received increased attention as a renewable and environmentally
friendly option to help meet today’s energy needs.
Policy makers will need to pay more attention to the implications for the transi-
tion to a hydrogen economy. A major dilemma now faced by developing coun-
tries is how to invest in hydrogen research and development for the transition to a
hydrogen economy. Hydrogen’s share in the energy market is increasing with the
implementation of fuel cell systems for sustainable energy supply. The concept of
sustainable development embodies the idea of the interlinking and balance between
economic, social and environmental concerns.
Hydrogen is currently more expensive than conventional energy sources. There
are different technologies presently being practiced to produce hydrogen economi-
cally from biomass. Biohydrogen technology will play a major role in the future
since it is able to utilize renewable sources of energy.
The use of biohydrogen for transport in order to reduce greenhouse gas emis-
sions and the environmental impact of transport has a strategic importance. Since
hydrogen can be burned in such a way that it produces no harmful emissions, this
makes it an attractive alternative to fossil fuels. But hydrogen is only as clean as the
technologies used to produce and use it. If hydrogen is produced without emitting
any carbon dioxide or other climate-destabilizing greenhouse gases, it could form
the basis of a truly sustainable energy system.
Vehicles and stationary power generation fueled by hydrogen are zero-emission
devices at the point of use, which benefits local air quality. Hydrogen-powered fuel
Preface vii
cells could contribute to reducing or eliminating emissions of carbon dioxide and
other greenhouse gases from road transportation vehicles. The production of hydro-
gen electrolytically, using clean solar power or other forms of renewable energy
is essentially pollution-free. The feedstock, water, is composed of hydrogen and
oxygen. Hydrogen production or distribution would produce no CO2. An internal
combustion engine fueled by hydrogen can be adjusted so that the emission of NOx
is 200 times less than in present vehicles. Emissions of NOx increase with the com-
bustion temperature, the length of the high-temperature combustion period, and the
availability of hydrogen, up to a point.
This book on biohydrogen attempts to address the needs of energy researchers,
chemical engineers, energy specialists, engineers, agriculturists, crop cultivators,
fuel processors, policy makers, environmentalists, environmental engineers, auto-
mobile engineers, college students, research faculty and others interested in a prac-
tical tool for pursuing their interests in relation to bioenergy. Each chapter in the
book begins with fundamental explanations for general readers and ends with in-
depth scientific details suitable for expert readers. The book may even be adopted
as a textbook for college courses that deal with biohydrogen.
Trabzon, Turkey, November 2008 Ayhan Demirbas
Contents
Chapter 1 Introduction ................................................. 1
1.1 Introduction ............................................. 1
1.1.1 Global Energy Sources and the Present Energy Situation ... 2
1.2 Conventional Fossil Fuel Sources ........................... 5
1.2.1 Petroleum and Heavy Oil Refining .................... 6
1.2.2 Petroleum Products and Fuels ........................ 9
1.2.3 Coal ............................................ 10
1.3 Unconventional Fossil Fuel Sources ......................... 14
1.3.1 Natural Gas ...................................... 14
1.3.2 Oil Shale (Shale Oil) ............................... 17
1.3.3 Tar Sand Bitumen ................................. 18
1.4 Renewable Energy Sources ................................. 18
1.4.1 Biomass ......................................... 21
1.4.2 Hydropower ...................................... 25
1.4.3 Geothermal ...................................... 27
1.4.4 Wind ........................................... 28
1.4.5 Solar ............................................ 30
1.4.6 Other Renewable Energy Sources ..................... 33
1.5 Nuclear Fuel Sources ...................................... 36
Summary .................................................... 39

References ................................................... 39

Chapter 2 Fuels from Biomass ........................................... 43
2.1 Introduction ............................................. 43
2.2 Biomass Feedstocks ....................................... 45
2.3 The Chemistry of Biomass ................................. 49
2.4 Production of Fuels from Wood Sources ...................... 52
2.5 Production of Fuels from Crops ............................. 52
2.5.1 Fuels from Cereal Crops ............................ 53
2.5.2 Fuels from Non-Cereal Crops ........................ 54
2.5.3 Fuels from Energy Crops ........................... 57
Summary .................................................... 58

References ................................................... 58

ix
x Contents
Chapter 3 Biofuels .................................................... 61
3.1 Introduction ............................................ 61
3.2 Bioethanol ............................................. 64
3.3 Other Bioalcohols ....................................... 65
3.4 Biorefinery ............................................. 67
3.5 Biodiesel .............................................. 71
3.6 Biogas ................................................ 74
3.7 Landfill Gas ............................................ 78
3.8 Fischer–Tropsch Liquids from Biorenewable Feedstocks ........ 79
Summary ................................................... 82

References .................................................. 83

Chapter 4 Transportation Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.1 Introduction ............................................ 85
4.2 Liquefied Petroleum Gas .................................. 89
4.3 Compressed Natural Gas .................................. 91
4.4 Hydrogen .............................................. 93
4.5 Electricity ............................................. 94
4.6 Solar .................................................. 94
4.7 Biorenewable Liquid Fuels ................................ 94
Summary ................................................... 103

References .................................................. 104

Chapter 5 Hydrogen .................................................. 105
5.1 Introduction ............................................ 105
5.2 History ................................................ 106
5.3 Properties of Hydrogen ................................... 107
5.4 Fuel Properties of Hydrogen ............................... 108
5.5 Hydrogen Production Processes ............................ 110
5.5.1 Hydrogen from Natural Gas by Steam Reforming ....... 111
5.5.2 Hydrogen Production from Hydrocarbons ............. 111
5.5.3 Hydrogen from Coal .............................. 113
5.5.4 Hydrogen from Water ............................. 115
5.5.5 Photocatalytic Hydrogen Production .................. 119
5.5.6 Solar-Powered Hydrogen Generation ................. 129
5.5.7 Hydrogen from Hydrogen Sulfide .................... 130
5.6 Storage of Hydrogen ..................................... 134
5.6.1 Hydrogen Storage with Metal Hydrides ............... 136
5.6.2 Hydrogen Absorption/Desorption
with Oxygen-Contaminated Boron Film ............... 139
5.6.3 Hydrogen Storage with Carbon Structures ............. 140
5.7 Hydrogen Storage Materials ............................... 141
5.7.1 Boron Hydrides as Metal Hydrides ................... 142
5.7.2 Hydrogen in Mechanically Milled Amorphous Boron .... 143
5.7.3 Boron Complex Hydrides .......................... 143
Contents xi
5.8 Hydrogen Fuel for Internal Combustion Engine ................ 145
5.8.1 Advantages of Hydrogen as an Engine Fuel ............ 146
5.8.2 Disadvantages of Hydrogen as an Engine Fuel .......... 147
5.9 Liquefaction and Compression of Hydrogen .................. 148
5.9.1 Nanocatalytic Liquefaction of Hydrogen .............. 149
Summary ................................................... 152

References .................................................. 153

Chapter 6 Biohydrogen ................................................ 163
6.1 Introduction ............................................ 163
6.2 Definition .............................................. 164
6.3 History ................................................ 164
6.4 Hydrogen from Biorenewables via Biological Processes ......... 166
6.4.1 Hydrogen Production via Microbial
Fermentation of Biomass ........................... 170
6.4.2 Anaerobic Hydrogen Production ..................... 170
6.4.3 Biophotolytic Hydrogen Production .................. 172
6.4.4 Dark Fermentative Hydrogen Production .............. 174
6.5 Hydrogen from Biorenewables via Thermochemical Processes ... 176
6.5.1 Potential of Renewable Hydrogen Production .......... 178
6.5.2 Production of Hydrogen from Biomass via Pyrolysis .... 179
6.5.3 Production of Hydrogen from Biomass via Gasification .. 186
6.5.4 Hydrogen from Biomass via Non-Conventional Processes 195
6.5.5 Hydrogen from Biomass Gasification by Steam
Reforming ...................................... 197
6.5.6 Hydrogen from Biomass via Air–Steam Gasification ..... 199
6.5.7 Hydrogen from Biomass by Supercritical Water
Gasification ..................................... 202
6.5.8 Hydrogen-rich Gas from Shells via Supercritical Water
Extraction ...................................... 206
6.5.9 Production of Hydrogen from Mosses and Algae
via Pyrolysis and Steam Gasification ................. 208
Summary ................................................... 214

References .................................................. 214

Chapter 7 Fuel Cells .................................................. 221
7.1 Introduction ............................................ 221
7.1.1 History of Fuel Cells .............................. 222
7.2 Fundamentals of a Fuel Cell ............................... 224
7.3 Different Types of Fuel Cells .............................. 226
7.3.1 Proton Exchange Membrane Fuel Cells (PEMFCs) ...... 226
7.3.2 Direct Use of Methanol in Fuel Cells ................. 228
7.3.3 Characteristics of Main Types of Fuel Cells ............ 230
7.4 Catalysts Used in Fuel Cells ............................... 231
7.5 Use of Alternative Fuel in Fuel Cells ........................ 233