ALTERNATIVE ELECTRICAL ENERGY SOURCES
FOR MAINE
W.J. Jones
Appendix
M. Ruane
E
FUEL CELLS
W.J. Jones
Prepared for the Central Maine Power Company.
Report No. MIT-EL 77-101
MIT Energy Laboratory
July 1977
This appendix is one of thirteen volumes; the remaining volumes are as
follows: A. Conversion of Biomass; B. Conservation; C. Geothermal
Energy Conversion; D. Ocean Thermal Energy Conversion; F. Solar Energy
Conversion; G. Conversion of Solid Wastes; H. Storage of Energy;
I. Wave Energy Conversion; J. Ocean and Riverine Current Energy Conversion; K. Wind Energy Conversion, and L. Environmental Impacts.
I
Acknowledgments
Initial literature reviews and drafts of the various technical
appendices were prepared by the following people:
Appendix A
Conversion of Biomass - C. Glaser, M. Ruane
Appendix
B
Conservation - P. Carpenter, W.J. Jones, S. Raskin, R. Tabors
Appendix
C
Geothermal Energy Conversion - A. Waterflow
Appendix
D
Ocean Thermal Energy Conversion - M. Ruane
Appendix
E
Fuel Cells - W.J, Jones
Appendix
F
Solar Energy Conversion
Appendix G
S. Finger, J. Geary, W.J. Jones
Conversion of Solid Wastes
M. Ruane
Appendix
H
Storage of Energy - M. Ruane
Appendix
I
Wave Energy Conversion - J. Mays
Appendix
J
Ocean and Riverine Current Energy Conversion - J. Mays
Appendix K
Appendix
L
Wind Energy Conversion - T. Labuszewski
Environmental
Impacts
J. Gruhl
3
Numerous people shared reports and data with us and provided comments on
the draft material. We hope that everyone has been acknowledged through the
references n the technical sections, but if we missed anyone, thank you!
Ms. Alice Sanderson patiently weathered out many drafts and prepared the
final document.
I
Preface
The Energy Laboratory of the Mass. Inst. of Tech. was retained by
the Central Maine
Power Company to evaluate several technologies
as possible alternatives
(a 600 MWe coal fired
of Sears Island #1
to the construction
generating plant
scheduled for startup in
1986). This is an appendix to Report MIT-EL 77-010 which presents
the results of the study for one of the technologies.
The assessments were made for the Central Maine Power
the basis that a technology should be:
1) an alternative
to a base-load
power generation
facility.
electric
Base-load is
defined as ability to furnish up to a rated
capacity output for 6 57 0 hrs. per year.
2) not restricted to a
single plant.
It
may be several plants within the state of
Maine.
The combined
output, when viewed
in isolation, must be a separate, "standalone", source of power.
3) available to deliver energy
by
1 98 5.
Company
on
I·
_
_ I
_
_
APPENDIX E
FUEL CELLS
Page
1.0
2.0
E-1
INTRODUCTION
1.1
Attractiveness
E-1
1.2
Limitations
E-2
1.3
History
E-2
1.4
Current Status of Fuel Cells
E-2
THERMODYNAMICS OF ELECTROCHEMICAL FUEL CELLS
2.1
E-6
Introduction
2.1.1
Why a Fuel Cell?
2.1.1.1
2.1.2
Indirect Method of Electricity Generation
Direct Method of Electricity Generation
2.2 Thermodynamics of some Fuel Cells
3.0
E-6
E-6
E-6
E-6
E-8
2.2.1
Fuels (general)
E-8
2.2.2
Hydrogen/oxygen
E-8
2.2.3
Other fuels (carbonaceous)
E-8
2.2.4
Electrolytes
E-9
2.2.5
Catalyst
E-9
2.3
Reformer
E-10
2.4
Carbon Monoxide Cell
E-1 0
2.5
Molten Carbonate Cell
E-ll
1
2.5.1
Introduction
E-ll1
2.5.2
Operation
E-12
THE UT/IGT SYSTEMS
E-14
3.1
Introduction
E-14
3.2
Fuel Cell Section
E-14
3.3
Bottoming Cycle
E-14
3.4
Power Conditioning (Inverter)
E-14
3.5
Fuel (coal gasification)
E-15
3.5.1
Introduction
E-15
3.5.2
Coal Gasification
E-15
4.0
ENVIRONMENTAL IMPACT
E-16
5.0
U.S. Government Support
E-23
5.1
Overall Program
E-23
5.2
Demonstration
E-23
5.3
Research
E-23
5.4
Comment
E-23
Page
6.0
7.0
STATUS OF OTHER TYPES OF FUEL CELLS
E-24
6.1
Methanol-Air Fuel Cell Battery
E-24
6.2
Tungsten Carbide/Carbon Fuel Cells
E-24
ECONOMIC EVALUATION
E-25
7.1
General
E-25
7.2
1st Generation UT/IGT/NU
E-25
7.3
Second Generation/Molten Carbonate Cell
E-25
7.3.1
Burns & Roe
E-25
7.3.2
Hart & Womack
E-25
7.3.3
Bockris and Scrinivasan
E-25
7.3.4
Westinghouse/NASA
E-28
7.4
Economics of Pollution Abatement
E-28
7.5
Conclusion - Economics Evaluation
E-28
8.0
CONCLUSION
E-37
9.0
TECHNICAL NOTE - HYDROGEN ECONOMY
E-38
9.1
General
E-38
9.2
Production of Hydrogen
E-38
9.2.1
Fossil Fuel Processes
E-38
9.2.2
Electrolysis
E-38
9.2.3
Chemical Disassociation
E-40
9.2.4
Direct Disassociation
E-40
9.2.5
Transportation
E-40
9.2.6
Storage
E-40
9.2.7
Markets
E-40
9.3
10.0
9.2.7.1
General
E-40
9.2.7.2
Fuel Cells
E-42
9.2.7.3
Other Commercial Uses of Hydrogen
E-42
Conclusion- Prospects for Hydrogen
REFERENCES
E-42
E-43
LIST OF TABLES
Page
Table 1.1
The Status of Fuel Cell Batteries
Table 4.1
Comparative Air Pollutant Levels of 1000 MWe Powerplants
Table 4.2
Annual Environmental Impacts from Operation of 1000 MWe
at 0.75 Load Factors
E-3, E-4
E-16
Coal-Fired Fuel Cell Powerplant with Load Factor of 0.75
E-17
Table 4.3
Emissions and Effluents from Fuel Cell Powerplant
E-18
Table 4.4
Chemicals Used in Recirculative Cooling Water Systems
E-19
Table 4.5
Powerplant Performance Summnary,Gaseous and Thermal
Table 4.6
Base Case Estimate of Potential Trace Elements
Emissions
E-20
Discharged to Atmosphere Without Scrubber
E-21
Table 4.7
Powerplant Performance Summary Liquid and Solid Waste
E-22
Table 7.1
Major Component Relative Cost Comparison
E-27
Table 7.2
Westinghouse Values of All Relevant Parameters for Low
and High Temperature Fuel Cell Powerplants
E-34
Table 7.3
Plant Capital Cost Estimate Summary (638 MWe Plant)
E-35
Table 7.4
Composite Capital Cost Estimate
E-36
Table 9.1
Comparison of the Manufacturing Costs of Hydrogen
from Several Processes
E-39
i
LIST OF FIGURES
Page
Figure 2.1
Comparison of the Ideal and the Actual Efficiency of
E-7
Thermal Engines and Fuel Cells
Figure 2.2
Principle of Fuel Cell Operation
E-7
Figure 2.3
Construction and Principle of a Hydrogen-Oxygen Cell
E-7
Figure 2.4
Electric Power Plant System Concept:
Coal/
Reformer (Gasification)/ Molten Carbonate Fuel Cell/
E-ll11
Bottoming Cycle
Figure 2.5
The Elemental (Molten Carbonate)Cell
E-13
Figure 7.1
Nuclear vs. Fuel Cell Baseload Expansion
E-26
Figure 7.2
Gas Turbine vs. Fuel Cell Peak Load Expansion
E-26
Figure 7.3
Minimal Capital Cost Points (General Electric)
E-30
Figure 7.4
Capital Costs (Westinghouse)
E-31
Figure 7.5
Cost of Electricity for Several Advanced Generating
E-32
Systems (Westinghouse)
Figure 7.6
Average Cost of Electricity (Summarized)
E-33
Figure 9.
Transportation Costs for H2 by Various Means
E-41
ii
__
1.0
INTRODUCTION
1.1
Attractiveness
The attractiveness of fuel cells as a means of generation of electricity rests with the following characteristics:
a.
Efficiency
Sixty to seventy percent fuel energy conversion efficiencies are
readily obtainable with hydrogen and oxygen as fuels, less with
carbonaceous types.
b.
Flexibility
Cells are connected to form a battery.
Battery banks constitute
modules of specified capacity and voltage.
Modules may be assem-
bled into any of a range of sizes necessary to meet the load
requirements at specific sites.
c.
Manufacture
There are no moving parts and required close tolerances.
Manufacturing
processes are straightforward and simple, amenable to mass production
methods.
d.
Noise
There are no moving parts; electricity is generated silently.
The
inverters (that change the DC to AC) are solid state devices.
e.
Heat
The electrical conversion inefficiencies in a fuel cell are manifested as
heat.
Even with efficiencies of 50% there is considerably less to
dissipate than with conventional power plants.
f.
Capacity
One of the major advantages of fuel cells is their high
overload capacity.
or more.
They are able to stand overloads of 100%
The only factor affected by briefly overloading a cell,
is efficiency.
g.
Idling Requirements
Fuel cells consume fuel and oxidant only when power is drawn from
the system.
Consequently, no fuel is consumed during idle periods
when there is no demand.
h.
Reliability
Although many types of systems are not highly refined at the present
time, it is known from experience with the hydrogen-oxygen cell that
the device has a potential reliability equivalent to a storage battery
at its best.
Without this reliability, fuel cells obviously could
not be considered for use in manned space vehicles.
E-1
1.2
Limitations
The results are, for the most part, proprietary.
about the status and prospects.
It is difficult to obtain detailed information
There is, however, a body of literature which provides enough information
for one to conduct a technology assessment such that one can come to some "ballpark" conclusions about
the status, problems, and speculation as to probable economics.
There are several obstacles to the widespread introduction of fuel cell power plants into commercial utility service:
a.
High capital costs
b.
Requirement for "pure" fuels (an absence of chemicals that "poison" the cells)
c.
Resultant high cost of electricity (COE)
1.3
History
The fuel cell history has its roots deep in the past of science research.
In 1808 Sir Humphrey
Davy demonstrated that water, when an electrical current was passed through it, could be decomposed
into hydrogen and oxygen at the electrodes through which the electricity was delivered to the water.
H2 0 + electricity
-
H2 + 1/2 02
In 1839 Sir William Grove turned the process around; he combined hydrogen and oxygen in such
a way as to produce water and electricity.
H
> H2 0 + electricity
+ 1/2 02
In theory, this process can be carried on with about 90% efficiency.
The only products are
water and electricity.
Work along the lines of developing Grove's experiment into a practical electrical generation
process culminated in 1959 at two demonstrations:
fuel cells operating a fork lift truck in England
and a tractor in the U.S.A.
In the NASA Gemini and Apollo spacecraft program, the astronauts carried along tanks of chemically pure oxygen and hydrogen (both in liquid form) which were used with fuel cells to produce
electricity.
For terrestrial, commercial, applications, those fuel cells and requirement for hydrogen and
oxygen are not cost competitive.
All current effort is directed towards development of fuel cells
that consume carbonaceous, fossil derived (mainly coal) fuels.
1.4
Current Status of Fuel Cells
The tremendous research and development effort expended on fuel cell development for the NASA
space and the Department of Defense programs was aimed at special applications and has been very
successful.
This development work has led to the accumulation of considerable understanding of the
chemistry and technology useful to the evolution of commercial fuel cells.
Table 1.1 gives a listing
of fuel cell developments as of April 1969 and indicates that almost all of the work has been for
government-based special applications.
However, this table does not show some of the work aimed at
civil applications since these developments are, for the most part, proprietary.
E-2
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In the United States, the former United Aircraft Corp., (Pratt and Whitney Aircraft Div.) and
several other companies (among these are Esso Research and Engineering Co., the Institute of Gas
Technology, TRW, and Battelle Memorial Institute) have initiated full cell development programs.
This non-governmental effort has been directed entirely toward the development of hydrocarbon-air
fuel cell powerplants for commercial electrical utility use.
Since 1967, more than $50 million has been expended at United Technologies*
grams to develop fuel cell powerplants for utility service.
towards this goal.
in specific pro-
This constitutes the principle effort
More than half of the funding of the first development program has been pro-
vided by a group of natural gas and utility companies in a program called "TARGET."**
The concurrent
program, since 1971, has involved ten electric utility companies and the Edison Electric Institute.
The EEI portion has been assumed by the Electric Power Research Institute (EPRI).
About one-third of the total investment has gone into the technology associated with cost
evaluation and reduction of cost and operating life considerations.
The remainder has been spent in developing experimental fuel cell powerplants, in producing
and field testing prototype powerplants, and in building a technology base to make the powerplant
concept more versatile (e.g., allowing for the use of many different liquid and gaseous fossil fuels,
scaling of cell and reformer component elements to multi-megawatt size, and improving efficiency of
ancillary components).
These latter efforts are difficult and costly in an engineering sense, but
do not require many significant advances in the present state-of-the-art to ensure success.
Small-scale, commercial-type fuel cell powerplants were build in 1971-1972 and have demonstrated
in actual field test operation the ability to satisfy all of the functional requirements for electric
utility service.
These 12.5KW powerplants operate on air to obtain the required oxidant and either
gaseous or sulfur-free distillate fuels.
Several powerplants are now in operation and shortly a total
of sixty powerplants will be operational in various installations as part of the TARGET program.
Data from the initial installations have verified that fuel cell powerplants have minimal air
pollution, can reject their waste heat to air, are quiet, and are highly efficient at both rated
power and at part load.
These units operate unattended and have a minimum of scheduled maintenance.
Both voltage regulation and AC frequency control are equal to or superior to electric utility standards.
Rapid response to load change from zero to full power has been demonstrated to be less than
one cycle.
The.noise level is no greater than a home humidifier since the basic energy conversion
process is static, and the only moving parts are circulators for processing and cooling air.
Clean natural gas, and clean very light petroleum distillate fuels (alchohols, naptha, etc.)
required for the operation of this generation of fuel cells are, since the embargo of 1973/1974,
not considered available or economical for use in fuel cell power plants that would constitute part
of the generation mix of the 1980's.
The future large scale use of fuel cells in electrical generation depends upon the development
of fuel cells that can operate, economically, on fuels derived from coal.
It is toward this goal
that research and development efforts, both private and government, are directed.
There are different engineering problems associated with the design of a self-contained fuel
cell/steam turbine electric power plant which are believed to be solveable.
The cost competitiveness
of such a facility can not be estimated until the technological questions have been answered.
*Formerly United Aircraft, Pratt & Whitney Division
**Team to Advance Research for Gas Energy Transformation
E-5
2.0
THERMODYNAMICS OF ELECTROCHEMICAL FUEL CELLS
2.1
Introduction
Most thermodynamic aspects of electrochemical fuel cells are related to the thermodynamic
aspects of chemical galvanic cells.
A galvanic cell consists basically of two electrodes in con-
tact with an electrolyte and combined in such a manner that an electric current flows over an external wire connected to the two electrodes.
A galvanic cell is "reversible" in that depending upon the direction of flow of electrons in
the external circuit the galvanic cell may be "charged" or "discharged."
"Charged" and "discharged"
can also refer to the chemical composition of the electrolyte or electrodes.
because of the choice o
Some galvanic cells,
electrolyte, cannot be "charged."
Fuel cells are dynamic devices in which continuous feed streams of reactants (fuels)and exit
streams of the "combustion" products are involved while a flow of electrons takes place between the
electrodes.
Thermodynamic treatment is somehwat more complex than that for a typical primary or
secondary battery.
The fuel cell is not "reversible."
The precise thermodynamics and electrochemical kinetics of electrolytes, reactants, etc., is
beyond the scope of this paper.
The inquisitive reader is referred to the bibliography.
Portions
of fuel cell technology will be briefly discussed to the extent that the fundamentals of operation
and characteristics are appreciated to the degree necessary to understand the application, present
status problems, and the magnitude of the constraints to favorable cost-effectiveness.
2.1.1
Why a Fuel Cell?
2.1.1.1
Most of
Indirect Method of Electricity Generation
he electricity consumed today is generated by the combustion of fossil fuels. An
increasing portion is by fission (nuclear) reactions.
The remainder is derived from hydro-electric
plants.
Fossil fuels (gas, coal, oil) are hydrocarbons which are oxidized (burned) by atmospheric oxygen; the heat generated is converted to mechanical energy in an engine.
turn, is converted into electrical energy.
The mechanical energy, in
The nuclear reactor, too, generates heat which eventually
becomes electricity.
A greater portion of the original generated heat is not converted into electricity, approximately
66% is wasted.
The unused (rejected) heat and the fuel residues are contaminants that pollute land,
water, and air, and interfere with the global heat balance.
2.1.2
Direct Method of Generation of Electricity
The chemical process which proceeds in a fuel cell results, at once, in electricity.
The direct
method of energy conversion into electricity by use of galvanic elements does not involve the limitations
of the thermal engine.
In ideal cases, it is capable of a conversion efficiency close to 90%.
day, rea;-life, values are around 60%.
Present-
The losses in galvanic cells are determined by the kinetics,
the electrode reaction, the type of physical configuration (geometry) and the electrolyte used.
Figure 2.1 shows a comparison between ideal and real-life efficiencies for thermal engines and
fuel cells.
A fuel cell is illustrated, in principle, in Figure 2.2.
Figure 2.3 shows schematically the construc-
tion and principle of a cell in which hydrogen and oxygen are the reactants and the electrolyte is
potassium hydroxide.
The emf at the terminals of a hydrogen-oxygen fuel cell is approximately 1.2 volts.
E-6
Figure 2.1
ldeal
/
Heat
Fuecell
conversion
c6one'szon
Heat
conllers:on
Fuelcell
Convermon
-1-10-301/
electric
erorgy
30-501/.
I
loss
I
GOverpteela
I
PAi
-1-n0/o
loss .
. -Carnol/
0
I
ilmital
on
losses
10
5S
i
I
10-101
V MIS
Lossor
M
Intrinsiclosses
i
Extrinsiclosses
Figure 1. Comparison
loss
gain
or
gain
f the ideal and the actual efficiency
of thermal engines and fuel cells
Figure 2.2
Figure 2.3
Load
td
ectlbn
Reaction pores
Hz- 2H'4 2e
in pores
Reaction
'I 02+HO+2e-ZOH-
2H'+20H--2H20 -
Finalproduct
Anode
Cathode
Figure 3
Construction and principle of a
hydrogen-oxygen cell
Figure 2 Principle of fuel cell operation'
E-7
2.2
Thermodynamics of Some Fuel Cells
2.2.1
Fuels (General)
Fuel cells may be classified as high, medium or low temperature cells.
a.
High temperature:
b.
Medium temperature:
c.
Low Temperature:
1100 - 1200°F (molten salt electrolyte)
4000 F (Bacon
hydrogen-oxygen cell)
below the boiling point of the aqueous electrolyte
(hydrogen-oxygen cell)
However, the "steering" factor is the type of fuel employed.
of liquids or gases.
The fuels may be any of a number
Hydrogen-oxygen cells are the most highly developed.
zine have been made for the U.S. armed services.
Fuel cells utilizing hydra-
Methyl alchohol, a very high hydrogen content fuel,
has been used as batteries in river signal buoys and power sources for television relay stations.
Fuel cells are currently classified by the fuel required since this is what is of primary national
interest.
The cell technology and configuration and operating temperature follows fuel choice.
a.
Gaseous:
b.
Liquid:
c.
Carbon based (gas or liquid derived from coal)
2.2.2
(hydrogen, methane, etc.)
(alchohol, naphtha, and other hydrocarbons of light molecular structure)
Hydrogen/oxygen
Hydrogen and oxygen are the ideal fuels.
They are, however, "manufactured" fueld in the sense
that they are not available in pure form in nature.
They must be extracted from chemical compounds
or mixtures.
Hydrogen has serious disadvantages, among which only high cost and difficulties in handling and
storage need be mentioned at this point.
A somewhat more detailed treatment exists in a technical
note to this paper.
For very special purposes or where money is not a constraint, a pure hydrogen/oxygen fuel cell
is used.
In the space research program, for example, or at isolated terrestrial research or data
acquisition sites.
There are, in addition, those applications, such as radio relay stations and
meteorological monitoring and transmitting stations for which the fuel cell is the only viable alternative.
More importantly, a hydrogen/oxygen fuel cell contains an alkaline electrolyte.
The alkaline
fuel cell is highly sensitive to carbon dioxide and thus to cheap, carbon-containing fuels.
As a
matter of fact, even in terrestrial applications one uses oxygen instead of air because the carbon
dioxide present in air (about 0.03 percent) can and does give trouble either by precipitating solids
in the electrodes or by reacting with the bulk electrolyte.
Scrubbing the air to remove the carbon
dioxide or frequent changes of electrolyte is often necessary.
Nitrogen in the air too can, under some conditions with some fuel cells, give trouble.
2.2.3
Other fuels (carbonaceous)
The best fuel, if one can't have pure hydrogen to start with, is a gaseous fuel that contains
plenty of hydrogen.
Among the simple combustible gases there is a noticeable predominance of hydro-
gen in methane (CH4 ), ethane (C2 H6 ), butane (C4 H1 0 ), etc.
It is easier to extract the hydrogen from
such gases than it is from hydrocarbon liquids or solids.
Natural gas is used in some thermal engine
electrical generation plants.
Because a natural gas operated fuel cell offers almost twice as much
conversion efficiency, the gas industry took an early interest in the fuel cell.
In 1967 a group of twenty-eight gas and combination gas and electric utilities formed the Team
to Advance Research for Gas Energy Transformation or "TARGET" to develop fuel-cell power plants for
the generation of electric power using natural gas as the hydrogen-providing fuel and air for the
oxygen supply.
E-8
__
__
__
In this system the hydrogen-rich gas is processed in a "reformer" to convert the gas in hydrogen
and carbon dioxide before introduction into the fuel cell.
There is an energy conversion loss in the
"reformer" stage due to oxidation of the carbon and use of some of the reformed gas in maintenance of
the reformer process itself, (the energy conversion is about 75% efficient).
The concept proved to be
a viable one and several pilot plants were built.
Natural gas is now
in short supply.
Petroleum, from which the more desirable light hydrocarbon
fuels can be derived has become expensive and for a number of other reasons, among them our desire to
reduce imports, is not a desired source of fuel for the generation of electricity in the 1980's and
beyond.
However, the most common available fossil fuel is coal.
Therefore, current effort in the U.S.
is to develop fuel cell systems which can use fuels derived from coal.
2.2.4
Electrolytes
The type of electrolyte used in a cell is governed by the fuel to be consumed.
The electrolyte
can be acid or alkaline, solid or aqueous, etc.
The first aqueous fuel cells developed with reasonable performance were hydrogen/oxygen cells.
These cells operated with a KOH (potassium hydroxide) electrolyte at about 60-80°C (140-1760 F).
Noble
metals were used as catalysts; platinum in particular.
It was natural that the initial work with hydrocarbons was carried out under the same conditions.
Success was very limited.
The main obstacle to the use of an alkaline electrolyte in a carbonaceous fuel cell is the reaction of the electrolyte with CO 2 to form the carbonate salt.
CO2 + 2KOH -
) K2 C0 3 + H2 0
To keep the electrolyte active, the K2 CO3 would have to be regenerated back to KOH, a process
that would consume about 30% of the cell's output power.
In addition, expensive and cumbersome equip-
ment would be needed.
A hydorcarbon cell must operate in an electrolyte such as acid or equilibrium carbonate solutions.
The electrolyte must ve such that its composition does not change during cell reaction or at
least reaches a steady state from which there is no further change.
Experiments were conducted with acidic electrolytes and some success is reported.
Problems exist
however, among them being that corrosion limits the choices of the catalysts for both the fuel and the
oxygen polarization.
Losses are high and catalysis is slow at low temperatures.
These latter two are
common to aqueous solutions.
2.2.5
Catalyst
The catalyst participates in at least three functions of the electrode process:
electron transfer, and surface reaction.
adsorption,
Nickel, palladium, and platinum are the most active catalysts
for the anodic oxidation of H2 , CO, hydrocarvons and alcohols.
The life of a fuel cell is partly
limited by the life of the catalyst.
To date;,much of the low temperature fuel cell research has been centered on the search for adequate catalysts.
By its nature this research has been semi-empirical although guided by general prin-
ciples of catalysis developed by individual investigators.
stated.
More specific rules and laws have not been
It is unfortunate that in spite of advances in solid state physics, kinetics and theory of
catalysis, the preparation of catalysts for a given reaction remains an art.
Catalysts have been found that are satisfactory for hydrogen-oxygen fuel cells using alkaline
electrolytes.
Catalysis for carbonaceous fuels, however, are much more prone to poisons in the fuels.
E-9
- -
2.3
Rformer
Fossil fuels have to be processed to a form useable in the fuel cell. This process is called
reformation.
In the reformer, as the equipment is called, the fuel is changed into a gas stream,
if originally a liquid, and the carbon oxidized so that Co and H2 are fed to the cell.
The composition of the gas stream is dependent upon the:
a.
fuel source (petroleum, natural gas, coal, "wastes", etc.)
b.
reformer process, (steam, heat, sulphur removal, and the economics)
c.
requirements of the fuel cell (hydrogen/CO,
2
d.
load response requirements.
hydrogen/CO, CO/CO2, etc.)
This may be met by buffer ("surge")storage tanks.
A coal to carbon monixide fuel cell to electricity system from a practical standpoint is that
which refers to the original solid fuel form which the gas is generated and the electricity produced.
C + CO 2 = 2C0 Gas Generation
2C0 + 02
C + 02
-
2C02 Fuel Cell reaction
= CO2
Overall process
Reformers in fuel cell systems are considered to have about 70 - 75% conversion efficiency.
2.4
Carbon Monoxide cell
The significance of the carbon monoxide cell is related to attempts to utilize carbonaceous fuels
in a more active form, either as carbon monoxide or in the form of "water gas" obtained by the reaction
of methane with water.
The individual reactions for a carbon monoxide cell are:
at the cathode
at the anode
2e + 1/2 02 + CO2 + CO 3
CO + C023 -
202 + 2e
The overall reaction is described as:
-
CO + CO 3
CO 2 + 2e
The presence of an appropriate catalyst in the fuel gas line or at the electrode itself, alone
with water results in a reaction
H2 0 + CO = H2 + CO 2
Hydrocarbons and partially oxidized hydrocarbons (such as alcohols, aldenhydes, etc.) in a high
temperature cell go through a more indirect process
CnH2n + 2
H 2 +02-
=
CnH2 n + H2
= H2 0 + 2e
E-10
ii
CnH2n + nH 2 0 = nCO + 2nH 2
CO + H2 = C
2
+ H2
2.5 Molten Carbonate Fuel Cell
2.5.1
Introduction
The Energy Conversion Alternative Study (ECAS) concluded that one of the most promising fuel
cell concepts is the molten carbonate electrolyte type.
The fuel is the low heating value gas (LHVG)
obtainable from an adjacent coal gasification facility.
The electrolyte contains Li2 CO3 , Na 2 C0 3 , and
K2 C0.3
The overall reaction is identical to very efficient combustion in that only H2 0 and CO2 are
the major products.
If a sulfur bearing coal is the feedstock, then scrubbers must be employed in the
gasification (reformer) step before the fuel cess and the extracted sulfur present a disposal problem.
0
0
The molten carbonate cell is a high temperature device, 700 C (1300 F).
The heat generated in
the fuel cell can be used in a bottoming cycle (conventional steam/turbine generation plant).
The conversion efficiency for the fuel cell/bottoming cycle electricity generation can be 66%.
The overall stat nn efficiency, taking into account losses in the conversion of coal to gas, is 50%.
A system concept t shown in Figure 2.4.
Figure 2.4
AC
Power
m
I
a-c electricity
a-c electricity
I
r
m
I
Inverter
Generator -
I
%
mechanical energy
d-c electricity
r
.
.
l_
,
Goal
Synthetic
Gas
Coal
Gasifier &
-
Bottoming
Cycle
(Steam or Gas
Turbine)
heat
Fuel
Cell
s
-
(H 2 & CO)
Desulfurizer
-
~,
m
heated
Ah
4-am-- Air
~~~~~~~~~~~~~~--
4"Het- J
c
Compressor
Sulphur
Compounds
Electric Power Plant System Concept:
coal/reformer-(gasification)/molten carbonate fuel cell/bottoming cycle
E-11
2.5.2
Molten Carbonate Fuel Cell Operation
0
0
iolten carbonate fuel cells operate at about 500 to 800 C (932-1470 F) using as electrolytes
mixtures of lithium, sodium, and potassium carbonates and porous nickel electrodes.
The elemental cell model is shown in Figure 2.5.
In this system, the carbonate electrolyte
serves to transfer oxide ions from the cathode, which consumes oxygen from the air, to the anode,
which combines this oxygen with the fuel, H2 and CO.
At the anode:
H2 + C0 3 --) H2 0 + CO2 + 2e
CO + CO 3 -At
2C02 + 2e
the cathode:
1/2 Os + CO 2 + 2
) CO3
The advantages of this type of fuel cell over others are:
a.
Catalysis is normally not a problem due to the high temperature of operation.
As a consequence, noble metals are not required to effect the desired reactions.
b.
0
0
The waste heat, because of its high temperature (500-800 C or 932-1470 F) can be used to
generate steam or can be used in the reformation of hydrocarbon fuels and bottoming cycle.
c.
The electrolyte is non-acidic, less corrosive than acidic electrolytes.
d.
Because carbon monoxide is part of the operation, a carbonaceous fuel (coal derived)
is useable.
Nox produced from air fixation in the fuel cell operation is minimal in this system due to the
0
0
low temperature of operation (700-750 C or 1300-1400 F).
The major environmental problems are associated with ash, and sulfur compounds from the post
gasification scrubber handling and disposal.
Water treatment and cooling tower operation for the steam plant are also problems which will
influence cost of operation and siting considerations.
There is, however, substantial uncertainty regarding:
a.
Operation of the fluidized bed gasifier such that the gas produced be free
of tars or contaminating hydrocarbons
b.
The efficiency of the hot-gas iron oxide fixed-bed desulfurization process
c.
The ability to control regeneration of sulfide beds
d.
The effect on fuel cell life of the probable contaminants in the fuel gas
as produced
Unresolved problems at any of these processing steps could require significant process additions
to control potential environmental problems, adding to capital requirements and increasing the project
cost of electricity.
E-12
Figure 2.5
THE ELEMENTAL (MOLTEN CARBONATE) CELL
Fuel Vent
Oxidant Inlet
e- -+ CO3)
(H2 + C03=
L/
H2
2
+ Co 2
Ion Conductor and
Electron Insulator
Electrochemically Combines H and 0
To Release Electrical Power Directly
E-13
3.0
THE UT/IGT SYSTEM
3.1
Introduction
The major effort in fuel cell system development in the U.S. involves a molten carbonate fuel
cell.
The system is to use coal which is processed in a reformer stage to produce a low heating value
gas (H2 and CO) for the fuel cell.
The waste heat of the fuel cell is employed in a conventional
thermal (turbine/electric) plant.
Overall efficiencies of 50% from coal to electricity are projected.
turbine coal fired plant can operate at about 39%.
Boers*2
1
A modern conventional steam
is credited with early research on the devices
upon which current fuel cell technology is based.
A consortium of United Technologies, the Institute of Gas Technology, several electrical utilities,
and the Electric Power Research Institute have invested to date over 50 million dollars for research.
The consortium has published few details of the results of their investigations and no information on
which one may base cost estimates.
3.2
It is expected to be operational by 1980.
Fuel Cell Section
In the system as envisaged by UT, each fuel cell unit will have an output of 4.5 megawatts.
The
size will be 7.0 m high by 4 m in diameter (23 ft. x 13.5 ft.) and weigh about 84 metric tons (93 U.S.
tons).
The thermodynamic efficiency of the cell itself can be as high as 57%.
used as process heat for generation
of electricity
The 43% loss can
in a conventional
be
thermal cycle
system or in the conversion of the coal to a fuel gas for the cell.
Fuel consumed in the projected fuel cell system will amount to 85% of the total hydrogen plus
carbon monoxide in the feed gas.
The useful life of the system is projected to be 40,000 hours (5 years).
Considerable technical progress has increased the probability that this fuel cell power plant can
be successfully commercialized.
We have some reservations about the availability of clean (sulfur and
heavy metal free) coal should Mr. Carter's proposals for massive conversion to coal by industry and
electrical utilities be implemented.
3.3
These are discussed later in the paper.
Bottoming Cycle
As outlined above, the use of a high-temperature fuel cell system in a power plant permits the
designer to increase the overall plant efficiency by integration with a "bottoming cycle." (See Fig. 4)
The "bottoming cycle" refers to the process of removing the heat from the fuel cell with a liquid,
water, or other two-phase fluid, by means of a heat exchanger.
The fluid, which is flashed to a "gas"
stage at high pressure, is delivered to the turbine, which, in turn, drives an electrical generator.
The "bottoming cycle" design is a relatively straightforward engineering task with more or less
established trade-off criteria which permit optimization for cost-effectiveness.
Since this paper is
to primarily consider the fuel cell portion of a power plant we will not discuss the "bottoming cycle"
any further except to include the cost estimates in overall system evaluation.
3.4
Power Conditioning (Inverter)
Fuel cell electrical output is direct current.
other processes can use the DC output directly.
alternating current.
In the
Electroplating, aluminum smelting and a number of
Nearly all other customers for electricity require
United States the frequency is 60 hertz (cycles per second).
conditioners, or inverters, are necessary for the conversion of the DC output to AC.
This can be
accomplished at about 95% efficiency.
In general, there are at least seven power conversion schemes that can be considered:
1.
chopper-inverter
E-14
· ___
________
Power
2.
inverter
3.
buck-boost inverter
4.
complementary inverters
5.
high frequency link
6.
hydbrid (high frequency + simple line-commutated inverter)
7.
force commutated inverter
The AC output of the converter must be compatible with the electrical grid (transmission and distribution
lines, switchgear, transformers, other generating platns, etc.).
The frequency of the output and the vol-
tage levels at the point of coupling must be exactly the same.
In addition any transients on the line (sudden changes of voltage or load due to short circuits,
lightning discharges, switching, etc.) must not damage the fuel cell plant or any disturbances originating at the fuel cell plant must be similar to those of conventional plants for which apparatus and
system design parameters exist to minimize damage to equipment or interruption of electrical supply.
13
of the economic and technical aspects of the above
The Westinghouse Company has conducted a study
seven schemes and found that the number 7, force commutated inverter, is the optimum.
The major point ot be mentioned here is that the state-of-the-art indicates an upper limit of
approximately 2 kilovolts output from fuel cell batteries.
Because of transformer primary current con-
siderations, this constraint limits use of the force commutated type of inverter system to powerplants
of small size, 25 megawatts or less.
3.5
For the larger plants, systems 1 through 3 offer the best possibilites.
Fuel
3.5.1
Introduction
Petroleum-derived products naphtha, benzene, etc. are the most desireable carbonaceous fuels.
first family of fuel cells systems developed at UT have been designed for these types.
The
It is apparent
that now they are too expensive, or valuable, forlarge-scale use in fuel cell power plant operation.
The plant design, therefore uses coal as the source of fuel.
3.5.2
Coal Gasification (Requirements)
All coal-fired powerplants require coal preparation facilities at the site.
consider, then, is the storage and grinding area.
The first area to
Leaks and spills are to be expected, facilities
should be provided for cleaning up and hosing down the area so as to wash dust to a collecting pond
before it becomes airborne.
The fuel cell requires a gas, so the coal must be converted (reformed) into gas.
Existing gasi-
fiers require as feedstock, that the coal be crushed to, but not finer than, about 6.4 mm (1.6 inches).
Vapor effluents from coal crushing may contain sulfur compounds, combustibles, and other trace components
from coal, and may be odoriferous.
Depending on its composition, the vapors may have to be scrubbed or
incinerated prior to discharge.
The gasification process will be one of several being developed by other industries.
The require-
ment for a "pure" gas input will necessitate that the product gas be cleaned of sulphur and heavy metal
contaminants before use.
If it were a conventional power plant one might consider "post combustion"
scrubbing, which does offer some opportunities for overall conversion efficiency.
The gasification process is accompanied by a number of discharges of sulfur compounds, NOx , trace
elements, contaminated water, and heat.
Sulfur is removed from the synthesis gas immediately after coal
gasification, and thus is not a problem associated with the fuel cell or steam generation portion of the
plant.
E-15
4.0
ENVIRONMENTAL IMPACT
4.1
Introduction
Because of the efficiencies in the range of 50-55%, fuel cells would consume about 2/3 of the
fossil fuel of a conventional facility, thus consumptive use of land for extraction purposes would
be less.
Thermal pollution of the fuel cell section is thus proportionately less than at a coal
facility and air pollutants are limited to CO2 and small fractions of other pollutants, see Table 4.1.
(Meyer, Jones & Kessler, 1975).
Other beneficial effects of fuel cells result from a quietness, size and low waste level which
enable small installations to be sited locally reducing transmission needs to one-third or less of
conventional needs.
Table 4.1 presents a general fuel cycle view of important pollutants, Tables 4.2, 4.3, and 4.4
show lists of specific concerns and chemicals emitted, and Tables 4.5, 4.6, and 4.7 show quantification
of effluents (Kalfodelis, et al., 1976) from a large fuel cell facility that includes a coal gasification
plant.
TABLE 4.1
Comparative Air Pollutant Levels of
1000 MWe Powerplants at 0.75 Load Factor
Gas-fired station
Sulfur dioxide (lbs)
Fuel Cells
1970
2
Nitrogen oxides (lbs)
26300
1660
Hydrocarbons (lbs)
18400
1500
Particulates (lbs)
660
.2
E-16
TABLE 4.2
ANNUAL ENVIRONMENTAL IMPACTS FROM OPERATION OF 1000 MWe COAL-FIRED
FUEL CELL POWER PLANT WITH LOAD FACTOR OF 0.75a
Impact
Land, sq. mi.
Water, tons
Air,
Extraction
(surface)
32.9
23900
curies
0
BTU
O
tons
u
curies
0
Solid or liquid
waste,
tons
1.82 x 106
Processing
Transport
Conversion
.2
2.3
.6
2570
0
0
0
0
3200
1.8 x 104
0
0
813
0
45
26300
0
2.0 x lO1 3
870
2.2 x 104+
0
3.0 x 105
0
2.1 x 106
0
.206
.016
1.53
Injuries
9.3
1.7
15.6
1.09
Workdays
lost
330
66.
1560
120.
Occupational
Deaths
Total
2.0 x 1013
0
curies
Transmission
0
.009
a Assumed similar to a gas-fired facility in conversion aspects and to a coal facility in
extraction and transport aspect.
E-17
0
1.76 +
27.7 +
2080. +
TABLE 4.3
EMISSIONS AND EFFLUENTS FROM FUEL CELL POWERPLANT
Emissions to Atmosphere
Potential Concerns
Wind action on coal storage and handling
Dust, fire, odors
Wind action on ash
Dust
Water vapor from coal grinding
Dust, H2 S
Cleaned flue gas
NO x , plume disperions, dust, SO x , P.O.M.
Vacuum pump on steam condenser
Minor
Air and mist from cooling tower
Plume, mist deposition, trace chemicals
Possible fugitive dust from area and
iron oxide preparation
Dust nuisance
Transients due to upsets, cleaning, etc.
Dust, smoke, fumes
Potential noise and odors
Machinery, maintenance
Effluents - Liquids and Solids
Rain runoff - coal and waste areas
Suspended and dissolved matter
Ash slurry
Ground water contamination
Slurry of waste from sulfur recovery
cleanup
Ground water contamination and land use
Sludge and chemicals from water treating
Minor
Waste electrolyte
Ground water contamination
Trace Elements
Leaching associated with disposal of ash
Soluble toxic elements
Fate of volatile toxic elements in coal
feed
Contamination of local air and water;
effect on fuel cell life
Emissions as gas and P.M. and P.O.M. with
stack gas
Hazards to life
E-18
TABLE 4.4
CHEMICALS USED IN RECIRCULATIVE
COOLING WATER SYSTEMS
Chemical
Use
Corrosion inhibition or scale prevention
in cooling towers
Organic phosphates
Sodium phosphates
Chromates
Zinc salts
Synthetic organics
Biocides in cooling towers
Chlorine
Hydrochlorous acid
Sodium hypochlorite
Calcium hypochlorite
Organic chromates
Organic zinc compounds
Chlorophenates
Thiocyanates
Organic sulfurs
pH control in cooling towers
Sulfuric acid
Hydrochloric acid
Dispersing agents in cooling towers
Lignins
Tannins
Polyacrylonitrile
Polyacrylamide
Polyacrylic acids
Polyacrylic acid salts
Biocides in condenser cooling water
systems
Chlorine
Hypochlorites
Sodium pentachlorophenate
E-19
------
TABLE 4.5
POWERPLANT PERFORMANCE SUMMARY
GASEOUS AND THERMAL EMISSIONS
Plant Effluent
0.32
SO2 , pg/J
9
NOx ,
0.52
<.013
g/J
0.30
HC,
pg/J
Negligible
CO,
pg/J
6.8
Particulate,
g/J
Solid
Fuel Standards
<0.039
0.043
Thermal Pollution
Heat Rejected - Cooling Towers
1.830 MJ/kWh
Heat Rejected - Stack
0.30 MJ/kWh
Heat Rejected - Total (1)
3.62 MJ/kWh
(1)
Includes total plant losses
E-20
TABLE 4.6
BASE CASE ESTIMATE OF POTENTIAL TRACE ELEMENTS
DISCHARGED TO ATMOSPHERE WITHOUT SCRUBBER
Average %
Emitted (7)
ppm in Coal
Basis)
(Dry
.
Element
Emittedb
kg/d
Antimony
0.5a
25
0.81
Arsenic
8 - 45
25
13. - 73
Beryllium
0.6 - 7.6
25
1.0 - 12
Boron
13 - 198
25
21 - 320
Bromine
14 .2 a
100
92.0
Cadmiun
0,14a
35
0,32
Chlorine
400 - 1000 a
100
2600 - 6500
Fluorine
50 - 167
100
320 - 1100
Lead
8 - 14
35
18 - 32
Mercury
.04 - .49
90
0.2 - 2.9
Molybdenum
0.6 - .49
25
1.0 - 14
Selenium
2.2a
70
10.0
Vanadium
8.7 - 67
30
17 - 130
Zinc
0 - 53
25
0 - 86
3094 - 8373
TOTAL
a,
Not given in ECAS basis and therefore estimated
b.
Based on a feed rate 6891 t/d of Illinois No. 6 coal
E-21
TABLE 4.7
POWERPLANT PERFORMANCE SUMMARY
LIQUID AND SOLID WASTE
Liquid
Blowdown
Gasifier Boiler
152 m3/h
5.9
Steamplant Boiler
21.1
Cooling Tower
125.0
Sulfur
6.1 t/h
9.1 g/kWh
Solid (Ash)
20 t/h
32 g/kWh
E-22
_
__
0.23 dm 3/kWh
5.0
U.S. GOVERNMENT SUPPORT
5.1
Overall Program
The U.S. Energy Research and Development Administration (ERDA) has established a National Fuel
Cell Program to "commercialize state-of-the-art fuel cell technology in the near term and advance higher
efficiency, lower cost, future competitive technologies..."
1.
Utility Demonstrations:
There are six facets to the program.
Demonstrate, on a utility grid, the viability of electric
utility fuel cell systems which are nearing readiness for commercialization.
2.
Provide technology to lower the cost and increase the
First Generation Technology:
reliability of first generation fuel cell systems.
3.
Second Generation Technology:
Advance the state-of-the-art of molten carbonate fuel
cells in order to achieve the earliest possible commercialization of these fueled,
based loaded systems.
4.
Fuels Utilization:
Broaden the spectrum of fuel cell acceptable fuels to include
the economic usage of No. 1 through No. 6 fuel oils, coal, and solid wastes.
5.
Systems Development:
Develop and demonstrate fuel cell systems for applications
outside of electric utilities including (1) the efficient recovery of waste fuel
sources such as waste hydrogen from industrial processes, hydrogen rich gases
generated from urban waste and sewage sludge and methane-air mixtures recovered
from deep shaft mines; (2) integrated energy systems for residential and commercial buildings and industrial applications; and (3) transportation applications.
6.
Applied Research:
Examine advanced fuel cells systems for application after 1985
and support emerging systems with a sufficient technology base for continuing
improvements.
5.2
Demonstration
The first generation units are the original units developed by UT/IGT which operate on natural
or clean methane gas or naphtha. ERDA's part here is apparently to accelerate the establishment of
demonstration projects even though they may not be entirely cost-effective or use desired fuels.
The demonstration units, 4.8 megawatt, were anticipated for fall '77.
The commercial units, for which there are 56 orders, are 27 megawatt units using clean, special
fuels, and may be available in 1978.
These systems are intended to be co-generation types:
fuel cell
generated electricity with "heat pumped" waste heat for heating, ventilation and air conditioning will
be available.
In the late 1980's it is hoped that 50% efficiency, combined fuel cell/steam generated electricity,
with coal gasification reformers and molten salt cells will have been developed.
5.3
Research
Applied research over a period of 20-50 years will be supported in order to obtain efficiencies
of 60% from advanced fuel cells (solid oxidized).
5.4
Comment
The nature of the agreements between industry and ERDA is not clear.
Industry has invested millions
of dollars in research and states flatly that all information is proprietary and declines to furnish data
E-23
as to the exact status development, or the nature of any impediments to completion of commerical units.
The ERDA program is one and one-half years old.
The schedule of events was not endorsed by any
of the researchers or utility people with whom we have made contact and it was their considered opinion
that making fuel cells operate on hydrogen and oxygen, or very clean gas and air or "special" fuels like
naphtha,
is one thing.
It is quite something else for the electrical generating industry to invest
a few hundred million dollars in a technology for the commerical production of electricity, in competition with other proven technologies.
Of particular concern is the requirement for clean natural
fuels or the production of special composition (hydrogen rich) fuels or the production of special
com-
position (hydrogen rich) fuels from fossil fuels which are already in short supply and very expensive.
Even the coal-based units will require "low" sulfur coals.
6.0
STATUS OF OTHER TYPES OF FUEL CELLS
6.1
Methanol-Air Fuel Cell Battery
The Esso Research and Engineering Company of Linden, New Jersey, has designed a methanol-air fuel
cell battery (low-temperature) for the U.S. Army for military communications.
furic acid and the output was rated 60 watts at 6 volts.
The electrolyte is sul-
Life tests have been on the order of 400 hours
over a 6-month period and it is anticipated that the cells should operate satisfactorily for longer
periods of time.
The performance of this size of cell for the intended application may be considered satisfactory.
Certainly there is no similarity between the military mission, "electricity at any cost," and a commercial bulk power central station electricity plant.
6.2
Extrapolation is not possible.
Tungsten Carbide/Carbon Fuel Cells
In West Germany there is considerable effort being expended on the development of tungsten carbide/
carbon fuel cells.
It is the opinion of researchers at the AEG-Telefunken Corp., German Federal Republic,
that the tungsten carbide/carbon fuel cell has the greatest potential from the point of view of economics
and applicability.
The logic leading to their preference for this low-temperature cell over others stems
from the sensitivity of alkaline fuel cells to carbon dioxide and thus to cheap, carbon-containing fuels,
the necessity for the utilization of noble metal electrodes in fuel cells with acidic electrolites and the
sensitivity of metallic catalysts to poisons.
In a series of papers (Pohl,
1972; Bohn, 1968; and Bohn, 1973) they describe their investigations
and conclude that the tungsten carbide/carbon fuel cell is the most economical for West German purposes.
The current status, progress since 1973, could not be determined.
E-24
P
7.0
ECONOMIC EVALUATION
7.1 General
Because technology has yet to be clearly defined for
key elements in a commercial fuel cell facility, particularly the molten carbonate fuel cells
and because proprietary development is involved in
each of the gasification, sulfur recovery, and fuel
cell areas, the developers themselves are considered
best placed to estimate costs from the present technology
base. The estimates vary between wide limits.
We will discuss what we believe to be the best available
study. As a general rule, however, it may be
expected that estimated costs will rise as development
proceeds to commercialization.
7.2 UT/IGT/NU 1st Generation Fuel Cell
Plant
In 1972, Northeast Utilities Service Company, (an electrical
utility), conducted an economic study9
of the natural gas fueled fuel cell power plant
as part of the generation mix of their system.
The results
were contained in a paper presented at the winter
meeting of a professional engineers society meeting.
The results indicated that fuel cells could provide
an economically competitive generating source depending,
among other things, on the intended duty cycle, and
the cost of fuel at the point of use.
Two of the figures that illustrated results are reproduced,
Figures 7.1 and 7.2. In Figure 7.1,
the range of nuclear installed cost of $425/KW. 1977 costs
are about $900/KW. Fuel cost, if one assumes
that the fuel cell would be naphtha, is over $2.00 per million
BTU (see Figure 7.2).
The fuel cell that is planned for use in the 1985
time frame would not use a petroleum derived
hydrocarbon but one from coal. Neither the cell,
nor the coal gasification process has been developed.
The uncertainty and hazard of projecting costs in
underlined by the Northeast Utilities experience.
7.3 Molten Carbonate Cell (Second Generation)
All conceptions of power plants utilizing this type of cell
include a coal conversion facility adjacent
to the fuel cell or fuel cell/bottoming cycle power generation
plant.
7.3.1 Burns and Roe
Burns and Roe, Inc. 13,14
15
have developed the cost estimate for the molten carbonate fuel
integrated facility from data supplied by UTC(UL)-IGT for a plant which
generates 638 MWe.
The model plant is complete and self-sufficient, using coal, water,
air, and water-treating chemicals as raw materials. Certain chemical additions will also be required
at the catalytic facilities
included in the system, including iron oxide at the desulfurizer,
catalyst at the sulfur recovery plant,
and electrolyte conditioners at the fuel cells.
Catalytic tail gas treatment may also be included and
require chemical additions.
The presentation includes breakdowns for the installed costs of land and
improvements, fuel
handling and processing, fuel cell system, electrical plant equipment,
and the steam plant-bottoming
cycle. The overall plant capital cost estimate summary is reproduced
as Table 7.1.
7.3.2 Hart and Womak
An economic assessment of molten carbonate fuel cells for large-scale
power production with propane feed to an integrated reformer-molten carbonate fuel cell system
was published by Hart and Womak
in 1967.17 They concluded that initial capital costs for the system
would be at least 25% higher than
for a coal-fired steam turbine generator system of similar life. Since
the fuel cell life was expected
to be short (ptimistically 5 years compared to perhaps 10 to
20 years for a gas turbine and 20 to 30
years for a steam turbine), they concluded that such a fuel cell plant
was not economically attractive.
7.3.3 Bockris and Srinivasan
Bockris and Srinivasan conducted a study 2 0 from different sources of
recent (1969) and future fuel
cell costs. A projected cost for the molten carbonate cell system attributed
to Broers is $600/KW for
large-scale production using gas and a reformer.
E-25
_
_
I
I
FUEL CELL FUELCOST
FUEL CELL INSTALLEDCOST ~ SMW
Nuclear vs. Fuel Cell Baseload Expansion
Figure 7.1
II
I
i
l! CS
IGa
,2
I
SC
_
l
1go
12o
_ _ _ _
14o 11M
1i0
FUEL CELL INSTALLED COST- IlW
Gas Turbine
vs.
Fuel Cell Peak Load Expansion
Figure 7.2
Figures 7.1 and 7.2 apapted from Northeast Utilities/United Technologies data.
E-26
TABLE 7.1
MAJOR COMPONENT RELATIVE COST COMPARISON
(In Mid-1975 Dollars Per kWe)
Westinghouse
(Parametric Point
MC4 from Ref. 8)
Fuel
UTC - IGT
(Reference 10)
150
82
Power Conditioning
63
38
Steam Bottoming
36
34
249
154
1 Capital costs developed for a 900 MWe fuel cell power plant, exclusive of indirect costs, which
develops 1170 MW AC output.
2 This basis for fuel cell power plant, exclusive of indirect costs, with 638 MW total
net output.
Source:
Burns & Roe, Inc. 13, 14, 15
E-27
7.3.4
Westinghouse
The effect of ten plant and operating variables on the cost of electricity was investigated by
Westinghouse 6ibrmolten carbonate fuel cell systems in their parametric assessment study.
These were
the effect of power plant size, fuel cell life, cell output degradation, current density at fuel cell
electrodes, electrolyte thickness, temperature of the fuel cell, replacement of air by oxygen, oxygen
plant size, fuel type, and recovery of waste heat from the fuel cell by a steam turbine generator
system.
The approaches used by Westinghouse to calculate the capital costs of the fuel cell subsystems
analyzed in its study are detailed in that report.
Westinghouse emphasizes that cost techniques are,
at best, aoproximate, in the absence of design details for the fuel cell models.
In Table 7.3 are presented the final overall component
capital cost breakdowns estimated by Westing-
house for a 900 MW fuel cell power plant (which, however, develops 1170 MW AC output), compared with
those employed in the UGT-IGT Burns and Roe basis for a 638 ME facility.
Note that the system estimated
by Westinghouse operates on medium heating value gas, for which no related capital charge was developed.
But again, the UL-IGT estimates appear extremely optimistic, notwithstanding the fact that they were
estimated for a system which was only about half the size of the system considered by Westinghouse.
In an oral presentation made by a study team at NASA of NASA's evaluation of ECAS conceptual
designs were made.
Cost estimates generated by GE, Westinghouse, and UTC for Category 2, Furnace and
Solids Handling, and for Category 4, Bottoming Cycle Equipment were compared.
Because UTC estimates were consistently low relative to those of GE and Westinghouse in these
categories, Exxon prepared 53 , for purposes of comparison, a composite capital cost estimate patterned
after UTC's presentation in which the GE estimates were used for these categories.
estimate for the molten carbonate system increased from $590 to $774 per kWe.
The capital cost
In addition, Westinghouse's
value for the fuel cell equipment (about double the UTC estimate) was assumed, total investment in
increased to 600 million dollars or to about $945 per kWe (see Table 7.4).
7.4
Economics of Pollution Abatement
It is difficult to attempt to separate investment and operating costs chargeable to environmental
control facilities in an assessment of this powetplant. The gasifier concept, the desulfurization and
sulfur recovery processes, and the fuel cell method for generation of electricity have all been included
in the design in the expectation that emissions to the environment from the overall plant will be lower
than from competing power generation facilities.
Even the steambottoming cycle, whose function is to
maintain overall generation efficiency above current practice, may be considered to be a thermal pollution control device because it converts a portion of fuel cell waste heat, that would normally be thermal pollution, into electricity.
recovery, and fuel cell areas.
Proprietary development is involved in the gasificiation, sulfur
In addition, it is extremely difficult to estimate costs from the present
technology base because, as a general rule, it may be expected that any estimated costs will rise as
development proceeds to commercialization.
7.5 Conclusion - Economic Evaluation
Commercial availability of carbonaceous fuels (coal derived) fired fuel cell systems is not anticipated before the year 1990 and, in some cases, 2000.
To estimate the cost of electricity, in 1986 dollars,
for a system which is still being developed is curious exercise.
Some workers, however, have estimated
that the figure would be between 55 and 70 mills per kW hour.
These cost comparisons serve to point out difficulties in making cost projections of technology
that has not been at least tested on a pilot demonstration unit.
Factors not associated with a specific
technology may also drastically change the incentive for commercialization.
E-28
For example, no one had
foreseen the unprecedented increases in fuel costs and the government policy of discouragement of
use of the desirable fuels which have occurred within the past five years.
On the other hand, molten carbonate fuel cell power capability has been improved considerably since the early sixties.
The ultimate consideration, of course, is what the interplay
among stricter regulations on emissions from power plants, which drive up capital costs (and may
introduce inefficiencies into the systems), the improvements in technology (which reduce costs),
and hopefully, increase efficiency, and the costs of fuels, to which larger fractions of all labor
and material costs are becoming more significantly comparable, will be on the viability of the
proposed system.
The ECAS study (54) is the most recent (1976) and comprehensive study that addressed the
economics of fuel cell power plants.
report.
Figures 4.8 through 7.6 and Table 7.2 are adapted from that
We have not attempted to duplicate the efforts of the investigators.
been possible for us to even check the results.
It would not have
The original data were in constant 1974 dollars.
We have added a scale equivalent 1986 dollars (5% inflation).
Figure 4.7 is an illustration of the estimates of the General Electric Company's "Minimum
Capital Cost Points" for power plants.
We have marked the figure for the cost of open cycle gas
turbine (presently used for peaking) and the cost for the high temperature fuel cell.
displays the estimates of the Westinghouse Corporation estimates.
Figure 7.4
The reader's attention is in-
vited to the particular data points for open cycle gas turbine (a conventional contemporary peaking
unit) for the molten carbonate fuel cell/steam plants.
The cost of electricity, as estimated by the Westinghouse Corporation, for several advanced
generaling systems, is listed in Figure 7.5.
Conventional peaking turbine generated electricity
costs and molten carbonate fuel cell generated electricity are indicated by the dotted lines.
The relative efficiencies and range costs of electricity for several systems are plotted
in Figure 7.6.
The estimate for cost of electricity as generated by a molten carbonate cell
ranges between 55 and 70 mills per kilowatt hour in 1986 dollars.
Table 7.2 summarizes the values of all relevant parameters for high and low temperature
fuel cell power plants.
Availability."
The interesting item here is the last one, "Estimated Date of Commercial
No fuel cell systems, in their opinion, will be available before 1990, and some
not until after the year 2000.
E-29
System
Case
Advancedsteam
11
Open-cyclegasturbine
22
Open-cycle
gas turbinclorganic
36
Combined
cycle air cooled)
8
Combined
cycle water cooled)
5
Closed-cycle
gas turbine trecuperated)
6
Closed-cycle
gasturbineforganic
40
Closed-cycle
gas turbinelsteam
46
Supercriticalcarbondioxide
47
Liquid-metalRankine
9
Open-cycle
MHD
12
Closd-cycleMHD
13
Liquid-metal,MHD
6
Lov-temperaturefuel cells
S
High-temperaturefuel cells
4
NE
0
200
400
:-
600
g00
1000
I
1200
1400
875
Capital cost, $/kWe (1974 dollars)
i
I
I
0
400
800
General Electric results
I
I
I
I
1200
1600
2000
1650
Minimum capital cost points
1986 dollars, 5%/yr. inflation
MIT calculation
Figure 7.3
*Adapted from (54).
E-30
-
-
------
--
I
2400
I
2800
I
3200
Case
Sysiem
Advanced
stlcm(atmospheric 69
furnal
.
Advancd
steam
(Af6i
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cmpents
-i
seam(pressAdanced
urizedoilerl
6 lanceof plant
M tontingency
E] Escalation
andinterest
49
Advanced
steam
PIFBI
Open-cycle
gasturbine
Isimple
cycle)
Open-cycle
gasturtine
trecuperatled
1
16
Z v/////
'
/
Open-cyck
gas
turbinelorganic
-.:.~
Cobtined
cycle
Clased-cycl
gasturbine
ncuperated)
Clased-cycle
gas
lurbinelslam
Clsed-cycle
gas
turbinelorganic
=ch-s
m//cass2I
ULutl-! tIRankine
Oten-cycle
MHiD
dirct
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cll liredllstem
13
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121lhse
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ona~~~~~j,,~....
. .:.
OpencycleMIID
(diretr
coalliredllstam
I
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MIlDLBTU
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2
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MlsDhslm
12
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acid
Iull clls
11
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20
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II
AI
IIO ai
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1
I
II
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1
I
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1
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Capital cost,
1
I
Im c
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I
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I . I
1300VI 1O0
I
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$/kW (1974 dollars)
Westinghouse results
I
·
200
i
I
-
·
600
m
I
I
1400
1000
I
I
d
1800
,
I
I
2200
1986 dollars, 5%/yr. inflation
MIT calculation
Figure 7.4
*Adapted
from (54).
E-31
2600
2600
4000
4000
Ssstcl
Advance
ste .,prl
:
Case
: Urllarel
I
i
Advanced
slam presurizedboilerl
(69t4
31
Adivarces :-L OFB,
C
FI
Components
odCX
C Capital
F *Fuel
0 · Operating
and
maintenance
1 2
i
fI
Advanced
steam
tF8I
I
31
c
Open-cycle
gasturbineIismplecycle,
26
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gasturbineIrecuperaled)
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96
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1
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27
41
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gasturbine.steam
C
F
0
42
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gaslurbinelorganic
52
Liquid-metal
Rankine
13
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MHO
(direct-indiredct
coal
lired)- base
case1
12
C
|F
I
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I
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C
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110
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Open-cycle
MHDtdirectcoalfired base
case2
Open-cycle
MHD(LBTU
integrated
gasifier)- base
case3
I
s
Closed-cycle
MHO
6
iquid-metal
MHD
12
Phosphoric
acidluelcells
Alkalineuelcells
I
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C II
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carbonate
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.
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F
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a
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30
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40
I
50
I
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Cost of electricity, mills/kW-hr. (1974 dollars)
Westinghouse results
I
0
20
40
60
I
80
100
1986 dollars, 5%/yr. inflation
MIT calculation
Figure 7.5
*Adapted from (54).
E-32
---
120
140
50
. IAA
lUU
I
\
"\ ,/
, Low-temperature
fuel cells
(HBTU
fuel)
40
80
m
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/
I
30
J
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60
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;
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o
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(a)GeneralElectricresults.
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cycle(air cooled
S.-
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V-:"
ill
.20
.30
.40
.50
.I
n.,
/ll
50"
I
f
Overallenergyefficiency
(b) Westinghouse
results.
Average Cost of Electricity
HBTU - High Btu Gas
LMMHD - Liquid Metal Magnelohydrodynamic
OGT
- Open-Cycle Gas Turbine
CCMHD - Closed-Cycle Magnelohydrodynamic
CGT
- Closed-Cycle Gas Turbine
OCMHD - Open-Cycle Magnelohydrodynamic
LMR
- Liquid Metal Rankine
Figure 7.6
Source:54
E-33
TABLE 7.2
- WESTINGHOULFE
VALUESOF ALL RELIVANT PAIIAMETERS FOR LOW- ANDIIIC;I-TEMlPERATUiRF
FUEL-CEL.POWEHI
IIANTS
Iolten
Aqueous
acid system
Paramceer
Solid electrolyte system
carbonate
system
(case 12)
<
g
Case 4
Case 18
Case 19
(case 4)
.
23.4
1255
1161
219
25
900
900
250
900
Fuel
HBTU
mITU
IBTU
IBTU
LBTU
Oxidizer
Fuel-celllife, hr
Voltagedegradation,perccnt
Air
Air
Air
10 000
Air
10000
Air
10 000
10 000
10 000
poweroutput, MWe
Fuel-cellrating, nvW
dc
Temperature, OC
Electrolytetype
85 wt
ElectrOlytethickness, cm
2
Anodecatalyst loading, mg Pt/cm
Cathodetype
2
Cathodecatalyst loading, mgPt/em
Totalplant capital cost, milliondollars:
Fuel processingequipment
Fuel-cellsystem
Steamturbinegenerator
Osygenplant
Heat-recoverysteam generator
Recuperator
Powerconditioning
Capitalcost, $/kWe
Resultbreakdown:
Total major-componentcost, milliondollars
Total major-componentcost, $/kWVe
Balance-of-plantcost, $/kWe
Sitelabor.cost, /kWe
Total direct cost, $/kWe
Indirect costs, $/kWe
Profit andowner ,osts, $/k%'e
cost, $/kWe
Contingency
Ecalation cost, S/kWe
Interest duringconstruction,S/kWe
Total capitalization,S/kWe
Costof electricity, mills/kW-hr
Capitalcomponent
Fuel component
component
Operating-and-maintenance
Total
Fatimatedtime for construction,yr
i EsUmateddate of commercialavailability
-
-
I
-
-
5
5
5
5
650
1000
1000
1000
Paste of Li, Na. K, (ZrO2 ) _x020
2 3 )x
carbonates, and
alkali aluminates
0.05.
0.004
0.1
13 PO4
(ZXO2)
(Zo 2 )l-x(CaO
(Y 20 3 )
0.002
0.004
Nl Ni-ZrO2 - cermet Ni-ZrO2 - cermet
NI-ZrO2 - eermet
Lithiated NiO
In20s/PrCoO3-x
In2 O3 /PrCoO3 -x
%n03/Prcoo3_
x
Cr203
0.002
Cr2O3
0.002
Cr2 0 3
0.002
400
0.56
45.6
47.7
893.28
75.37
161.00
0.3
Interconnection
type
Inlerconnection
thickness, cm
2
Currentdensity, mA/cm
Averagecell voltage, V
Pow-erplant
efficiency, percent
Overallenergyefficiency,percent
L-C
5
190
Pt/C
0.3
Pt/C
Anode type
1064
200
200
0.7
36.0
24.2
8.64
0.645
0.7
54.4
45.7
2.4
0
0
400
0.66
60.2
50.6
539.05
2.41
142.00
11.52
569. 90
2.30
171.00
11.72
0
0
0
15.62
18.4
59.00
0.211
4.20
17.50
11.80
28.00
59.00
269.06
227.74
18.38
29.47
275.58
15.03
22.05
22.05
68.62
79.04
482.370
248.95
215.40
15.57
33.35
264.32
17.01
21.15
21.15
66.35
76.43
93.87
429.58
39.59
137.54
606.71
70.14
456.40
36.40
89.81
96.71
948.31
341.17
327.96
36.98
89.08
454.03
45.43
36.32
38.59
130.94
153.38
858.70
15.25
12.55
16.05
43.85
14.74
11.34
14.16
40.24
29.98
5.47
12.25
47.70
27.15
6.35
18.40
51.89
5
1990+
5.0
3.0
2000+,
2000+
0
0
1.38
20.20
4.84
59.00
4.51
193.74
39.93
42.70
276.37
21.78
22.11
12.44
19.00
19.46
371.16
11.73
25.01
9.85
0.086
0
46. 68
1.5
1990
BOO
0.68
53.2
53.2
205.46
52.36
18.80
-
-
1974 Dollars
E-34
48. 54
.
-
I
5.5
2000+
TABLE 7.3
PLANT CAPITAL COST ESTIMATE SUMMARY
(638 MWe PLANT)
Materials
Balance
Major
Comments of Plant
(M$)
(M$)
Land Improvements
& Structures
1.4
Site Labor
(Direct & Indirect)
(M$)
13
-
Total
$/KW
(M$)
16
31
48
21
50
78
.59
92
Coal Handling, Gasification, Gas Cleanup
& Ash Handling
17
Fuel Cell System
Equipment
42
Steam Plant Bottoming
Cycle Equipment
17
4.2
10
31
49
Electric Plant Equipment
19
4.5
9
33
51
SUBTOTALS
A&E Services &
Contingency
Escalation & Interest
During Construction
6.7
11
96
45
63
204
318
18
12
20
50
78
123
193
377
590
(@ 48%)
TOTAL DOLLARS
Source:
(53)
E-35
TABLE 7.4
COMPOSITE CAPITAL COST ESTIMATE
M$
$/kW
GE
+35
+56
W
+60
+98
91
GE
+27
+42
33
51
UTC
318
326
515
+122
+196
50
78
79
127
+29
+49
254
396
405
642
+151
+245
123
193
195
303
+72
+110
377
590
600
945
+223
+355
$kW
M$
$kW
31
48
31
48
Coal Handling, Gasification, Gas Cleanup, & Ash
Handling
50
78
85
134
Fuel Cell System Equipment
59
92
119
190
31
49
58
33
51
204
Land, Improvements, &
Structures
Steam Plant Bottoming
Cycle Equipment
Electrical Plant
Equipment
A & E Services and
Contingency
Sub-total
Escalation and Interest
During Construction
Total
INCREMENT
Composite
UTC
M$
UTC
E-36
-
-- -
8.0
CONCLUSION
The fuel cell offers excellent opportunities for the generation of electricity at higher effi-
ciency and much less pollution than conventional fossil fuel fired steam turbine driven generation.
The "ideal" fuel cell requires hydrogen and oxygen, two gases that are "manufactured" by expensive processes.
Hydrogen handling storage and transmission requires special technology none of which
has been tested on a scale that would be required for fuel cell generation on a utility sized scale.
Fuel cells that operate from light hydrocarbon fuels have been and are successfully employed in
electric utility generation facilities.
Light hydrocarbons are derived from petroleum.
Current national policy is to discourage use of
such fuels for the generation of electricity.
A type of fuel cell, called the molten carbonate cell, can be designed and manufactured.
It will
operate on coal derived low heating value gas.
A pilot plant has yet to be built and therefore there is no way to estimate the cost of the electricity that would be generated.
There has been sufficient technological progress in the research phase to provide a high degree
of confidence in the ultimate technical success of the concept of an integrated coal gasification plant
(with sulphur scrubbers), fuel cell electricity generation and steam turbine electrical generation
bottoming cycle.
The anticipated dates for completion of pilot plant studies vary from late 1980 to early 1990.
E-37
9.0
TECHNICAL NOTE - HYDROGEN ECONOMY
9.1
General
We dream of the "ideal" fuel/electricity system:
virtually inexhaustible, available at minimum
environmental cost and creating no pollution upon conversion to work or heat.
The hydrogen/oxygen
fuel cell producing electricity is perhpas the closest we come to this dream.
It can be derived from
water, the most abundant chemical with minimum environmental impact.
for 1985 shows that the usual pollutants (CO, S0,2
An analysis for New York City
particulates, hydrocarbons) are reduced to zero
while the NOx is reduced to about 75% of the value that would otherwise be expected.
When one, however, examines methods of production, transportation, and storage we find that the
economic viability of a hydrogen energy system still depends on certain technological advances in the
state of the art.
As the environmental and other cost determining factors of fossil fuels rise, the
economic advantage of a hydrogen economy approaches the stage where serious thought and experimentation
begin to make sense.
The fuel cell has contributed much to the consideration.
to the section of the references that is pertinent to hydrogen.
The reader is referred
Our discussion will be brief.
The current thought centers about producing hydrogen and oxygen by electrolysis with off-peak
electric power (from a nuclear station).
Hydrogen is delivered by pipeline for use as a fuel for inter-
nal and external combusiton and/or use in fuel cells.
The oxygen produced at the nuclear plant would
also be piped to cities, but used for sewerage treatment.
It has been pointed out that if undergrounding of electric transmission is required in the future,
electrolytic hydrogen, transported in gaseous form in pipelines and converted back to electricity at
the load substation (fuel cells), may provide a less expensive system than transmission of electricity
directly.
Why has not a hydrogen economy been possible; what are the impediments; what will the cost of
petroleum have to be in order for hydrogen to compete?
9.2
Production of Hydrogen
9.2.1
Fossil Fuel Processes
The production of hydrogen from fossil fuels employs either a reformer reaction or an oxidation
reaction. Steam reforming of light hydrocarbons produces carbon monoxide and hydrogen.
In the oxidation
readtion,for heavy petroleum and coal, oxygen is introduced in controlled quantities to produce CO and
H2 which is then converted to C0 2 and H2 .
The oxidation process has an advantage over steam reforming
in that it can process any hydrocarbon feedstock, or coal and no desulfurization is required prior to
the partial oxidation step.
The results of a comparative study of the manufacturing costs for 1990, conducted in 1969, are
tabulated in Table 9.1. Take particular note of the predicted price of fuel oil, natural gas, and coal.
The prices in 1977 are indicated for oil and coal.
9.2.2
So much for long-range economic forecasts.
Electrolysis
Present electrolysis plants required 120 - 140 kwh of electric power for the production of 1000
standard cubic feet (SCF) of hydrogen about 60% efficient as compared to theoretical possibility.
While
advanced designs may be expected to greatly reduce capital costs and operate at higher efficiency, the
operating costs for hydrogen production remain extremely sensitive to electric power costs, which will
increase with time.
Each mil per kwh increase in the cost of electricity adds 12-14 cents per 1000
E-38
TABLE 9.1
COMPARISION OF THE MANUFACTURING COSTS OF HYDROGEN FROM
SEVERAL PROCESSES*
3
Cost, ¢/O1 SCF Hydrogen
Steam
methane
reforming+
Steam
Naphtha
reforming+
Partial
oxidation ,
of fuel oil*
Coal gasification
using steam and
oxygen#
12.4
20.6
13.8
16.0
Utilities**
4.0
4.2
5.1
3.8
Labor at $4/hr
1.2
1.2
1.4
2.8
Overhead, 60% of labor
0.7
0.7
0.8
1.7
Maintenance, and operating
supplies, 4% of capital
investment
1.7
2.0
2.1
4.6
Fixed charges at 9%
3.8
4.5
4.6
10.3
23.8
33.2
27.8
39.2
Raw materials
Total,
103 SCF
Capital investment, $ millions
5.8
6.6
6.9
15.3
*Based on hydrogen production, 40 million standard cubic feet per day; hydrogen delivery pressure,
1700 psig; fixed charges; depreciation 6.7%, local taxes and insurance 2.7%.
+Natural gas at $0.25/10 BTU.
lNaphtha at $20/ton
*Fuel oil at $2/bbl:
150,000 BTU/gal.
1977
#Bituminous coal at $5/ton; 12,700 BTU/lb. 1977
$14.50/bbl
30.00/ton delivered
**Includes electricity, cooling water, and boiler feedwater.
Source:
J.E. Mrochek, "Economics of Hydrogen and Oxygen Production," in Abundant Nuclear Energy,
U.S. Atomic Energy Commission (May, 1969).
E-39
SCF of hydrogen in today's plants.
Electricity, derived from solar energy, is intermittent and periodic.
solar energy provides a constant source of storeable energy.
9.2.3
Hydrogen production from
Such as system is some time away.
Chemical Disassociation
Energy input, in the form of heat, can supply kinetic energy to free the molecules of hydrogen
The idea of "cracking" water by the use of heat is appealing.
and oxygen in water.
Material limitations (direct thermal decomposition takes place at an acceptable rate at temper0
0
atures above 3000 C (5500 F) presently prevent process heat production at temperatures necessary for
the one-step crackign process; the idea of using multi-step processes at lower temperature is being
considered.
In a multi-step process the required work which must be supplied can be reduced to zero
(theoretically) by the selection of a suitable sequence of chemical steps.
Analysis of the msot promising process, Mark - 1 of Euratom's Ispra Laboratories, by the Future's
Group and Funk shows that on a commercial basis, the plant costs are higher and technical problems
much more difficult to solve than commonly estimated.
9.2.4
Direct Disassociation
It is possible to disassociate water by the direct transference of energy in the form of heat or
0
Temperatures are in the range of 2500°C (4500 F) and the efficiency is computed to be about 35%.
light.
Ultraviolet light can disassociate water.
The generation of adequate amounts of ultraviolet
require the existence of a fusion reactor.
The first, high temperature heat is materials prohibited.
For the second, fusion reactors non-
existent.
Transportation
9.2.5
Hydrogen transmission can be accomplished in the same variety of ways which are used for transmitting natural gas.
Costs, assuming solution of the technical problems of welds, valves, pumps, mater-
ials, etc., are solved, as computed by the Futures Group in 1972 are displayed in Figure 7. 2.
9.2.6
Storage
The problem of hydrogen storage must be divided into three subsidiary questions:
the time in
storage, the accessibility, and the volume of hydrogen to be stored.
Hydrogen will leak through much smaller orifices much more readily than natural gas.
to be designed for both long- and short-term variations in demand.
Storage has
For seasonal variations, large volumes
are required; for daily swings in demand, smaller storage volumes are suitable for electric power production.
For vehicle propulsion, very small amounts of fuel must be available on demand.
The storage systems for these different purposes are quite different.
They involve different
vessels, controls, valves, etc. and hydrogen form, i.e., liquid, and high and low pressure gas states.
9.2.7
Markets
9.2.7.1
General
The price of hydrogen does and will depend upon the size and nature and geographical distribution of the market.
Possible customers are:
1.
fuel cells
2.
manned aircraft
E-40
·______L-111---..
----
I
-_
_
,_
I
,,
_____
Figure 9.2
Transportation Costs for H2 By Various Means
_
___
__
. . .
i i
:
. : .
-
+- . .
:
- ..
. -.
50
.
CryogenicPipeline (ii
30
20
r2
I
i
10
I--'
,.
5
·
· ··. :·
·
.:...
'':''
~~
-':-:. :.-::::i-::
C
M
.
!
·
00o
.
qi
i
i~~~~~~~Ri
L-;l]:~~~~~~.
.I
.T:
.
'~~~~~
.~~~~~...
Ox
·
-
:
....
..
..
;-
.i...
.........
-· T... '
...
i. I.:i~ ;..
,
.......d
'
;
!..~
·
·
........:~i
-]
i '
I
.
: ~ . i .
Ii
.
·
k
·
.'30
Inch
Pipelin
(gas)
·
''
·
...
i
:
:
.
M
.
~°:. :::~'; ' ' [1:::. I: L
-
. .
',I
.
:
.
:
-.
.
7
!Ship
.
~I
t :
- -Barge
.
.
..
(liquid)
.
'
-
~~~~~~.
.
:' 1
-
!
77 -77 7
. . i
!
- -
. I
I. f
-
i
0
100
200
300
400
500
600
700
Distance in miles
Source:
The Futures
Group
E-41
--
800
900
-
: I. ---
i
-
7
--
·
i
7-
1000
:
.
.I
; a
.
.
.
.:
3.
rockets
4.
surface transportation
a.
ships
b.
trucks
c.
buses
d.
buses
e.
trains
Hydrogen will have to compete with a well established, safe, and fully understood petroleum economy.
Market penetration, in the absence of strong and sustained government intervention will not take place.
9.2.7.2
Fuel Cells
The "ideal" fuel cell requires pure hydrogen and pure oxygen.
These fuels must be produced.
The production costs cancel the advantages of the "ideal" fuel cell.
Substitution of air for oxygen introduces the serious problem of "poisoning" of the cell by
the relatively small amounts of carbon dioxide in the atmosphere.
If it is desired to operate fuel cells with fuels derived from carbon or hydrocarbon materials,
the desired electrolytes are acidic and electrodes and catalysts that are immune to carbon poisoning.
The
alternative is to process the fuel gas feed stream in a way that all objectionable components are reduced
to the level where economical operation is obtained.
The stage in which the hydrocarbon containing fuels are processed is called "reformer".
"Reform-
ation" introduces the opportunity to include coal, petroleum, natural gas, and synthetics (ammonia, methanol,
hydrogen peroxide, etc.) as fuels for cost competitive fuel cell operation.
9.2.7.3
Other Commercial Uses of Hydrogen
Hydrogen is required in a number of petrochemical, food, metallurgical and other process
industries.
The requirements are met by existing production facilities.
Certainly there are industries
that would purchase hydrogen to replace some of their existing requirements for fuels if the price of
hydrogen were to decrease.
They would not convert until there is an assurance that price will be stable
or only decrease.
9.3
Conclusion - Prospects for Hydrogen
The production of hydrogen presently is very closely coupled to the availability and price of
fossil fuels.
Hydrogen can be produced by use of nuclear reactors.
Nuclear reactors first have to
become available on a scale that results in excess capacity, if only at certain times of the day, to
be diverted to hydrogen production.
A hydrogen economy depends upon the satisfactory solution of formidable technical problems associated with more widespread use of hydrogen.
not known.
At this juncture in time, the cost of the solution is
Just how much hydrogen will be demanded by a fuel cell market is practically impossible to
forecast.
There are no distribution, storage handling, or "combustion" equipments in existence.
A completely
new system, from top to bottom, has to be developed and tested before it can be introduced.
This author believes that the establishment of a significant, greater than 5% of the total energy
economy, hydrogen industry before the next century will require a dedication on the part of the government,
motivated by the external forces which do not exist or can be perceived or should be considered desirable.
There is the very interesting opportunity to make hydrocarbons, liquids (gasoline, jet fuel, etc.,),
and gases (methane, butane, etc.,) by combining hydrogen and carbon (derived from coal).
amounts of coal available.
There are large
If the "greenhouse" effect is of concern, then extraction of carbon from CO2 in
air, about 3% average in 1977 (higher in urban centers and near certain industries) might have very
positive environmental impacts.
The cost of CO 2 pollution abatement by conventional means might be more than
the cost of CO2 use in the synthesis of hydrocarbon fuels.
The opportunity merits serious consideration.
E-42
_I_
*_
IC---·-·ll_.-___1
_
__1.___
__
-_
_
__I
_
10.0
1.
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E-43
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___
_
___
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E-45