United States
         Environmental Protection
          Industrial Environmental Research  EPA-600/7-79-1Q5a
          Laboratory         April 1979
          Research Triangle Park NC 27711
Comparative Assessment
of Residential Energy
Supply Systems That
Use Fuel Cells
(Executive Summary)

R&D Program Report


Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional  grouping  was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

    1. Environmental Health Effects Research

    2. Environmental Protection Technology

    3. Ecological Research

    4. Environmental Monitoring

    5. Socioeconomic Environmental Studies

    6. Scientific and Technical Assessment Reports  (STAR)

    7. Interagency Energy-Environment Research and Development

    8. "Special" Reports

    9. Miscellaneous Reports

This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND  DEVELOPMENT series. Reports in this series result from the
effort funded  under the  17-agency Federal  Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants  associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments  of,  and development of, control technologies for energy
systems; and integrated assessments of a wide-range of energy-related environ-
mental issues.
                       EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for  publication. Approval does not signify that the contents necessarily reflect
the  views and policies of the Government, nor does mention of trade names or
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This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.


                                                       April 1979
   Comparative Assessment of Residential
Energy Supply Systems  That Use  Fuel  Cells
                  (Executive Summary)

          R.V. Steele, D.C. Bomberger, K.M. Clark, R.F. Goldstein, R.L Hays, M.E. Gray
               G. Ciprios, R.J. Bellows, H.H. Horowitz, C.W. Snyder (Exxon)
                           SRI International
                         333 Ravenswood Avenue
                        Menlo Park, California 94025
                         Contract No. 68-02-2180
                       Program Element No. EHB534
                      EPA Project Officer: Gary L Johnson

                   Industrial Environmental Research Laboratory
                     Office of Energy, Minerals, and Industry
                      Research Triangle Park, NC 27711
                             Prepared for

                      Office of Research and Development
                          Washington, DC 20460

What Are Fuel Cells?
Are Fuel Cells Commercially
Available Today?
Fuel  cells  are  devices  capable  of converting  the
chemical  energy  stored  in  a  fuel  directly  into
electrical energy without a step involving combustion.
Hydrogen  contained in the fuel is chemically combined
with oxygen  from  the air  to produce  water and  an
electric  current  that  can  be  regulated  and  used.
Fundamentally, the process is just the  inverse of the
electrolysis  of  water  into   its  component  parts,  a
process often demonstrated  in high  school chemistry
classes.   Practically,  a  fuel  cell  consists  of  two
electrodes, a  catalyst used to  promote  the  chemical
reaction, and an electrolyte (a chemical  substance that
conducts  electricity)  separating  the electrodes.   As
might  be suspected,  a  device  of  such fundamental
simplicity was first conceived long ago—in  1839  by Sir
William Grove, a British jurist.

Although  old   in  concept,  as  practical devices  for
producing electricity  in significant amounts, fuel cells
are in  their  infancy.  For  space missions, fuel cells
have  been shown to  be ideal  power sources, partly
because they convert on-board stores of hydrogen  and
oxygen   to   electrical   power  without   producing
excessive   heat  or   vibration-producing   mechanical
motion.  In  fact, they  provided electrical power  in
Gemini   and   Apollo  spacecraft,   but   were   still
considered novel and exotic devices.

                                 Made in  limited quantities, and to extreme reliability
                                 standards, fuel cells for space craft are understandably
                                 expensive.  Nevertheless,  much has been  learned  from
                                 the space program  about  fuel cells and that knowledge
                                 is   beginning  to   find   earthbound   applications   in
                                 much-improved and less costly devices.

                                 More than 60 small  (12.5 kW)  fuel-cell  power plants
                                 were  field tested  in  1972 and 1973.   A 40-kW device
                                 was  demonstrated  in  1975, and now  work is underway
                                 to demonstrate a 4.5-MW fuel cell in the Consolidated
                                 Edison (New York) utility system by 1980.  Fuel-cell
                                 technology  has  come  a long  way  and  is  nearing
                                 commercial readiness.

Do Fuel Cells Possess             Much of  the present interest in fuel cells derives  from
Attractive Attributes?            their  unusually  low  environmental impact and  their
                                 high efficiency.   Because no combustion  is  involved,
                                 even  fuel cells  that  use  common fuels produce  very
                                 low  emissions  of  nitrogen  or   sulfur   oxides;  the
                                 emissions are many  times  below federal  standards.
                                 Moreover,  fuel cells  generally consume no  water and
                                 operate very quietly.

                                 As a result of its environmental good- neighborliness, a
                                 fuel-cell  power  plant can easily be located very near
                                 the  power demands  it serves,  thereby lessening the
                                 need for high voltage electric transmission lines.

                                 The ability  to site  fuel-cell power  plants  locally is
                                 much  enhanced by their modular design (which allows
                                 off-site  manufacturing)  and  their  rapid  installation.
                                 Accordingly,  electric  power  utilities  may soon have
                                 commercially  available a  device that enables system
                                 expansion in small increments.
How Might Fuel Cells Fit
into Electric Power Systems?
Besides  being suitable for  small,  dispersed,  locally
sited  power  stations, fuel cells can  easily operate  in
applications  that  require output  to  follow  demand
closely.  In fact,  electric utility interest  in fuel cells
often   centers   on   mid-1980s    deployment    for
load-following.  Again,  because  of  their  cleanliness,
fuel cells  may be installed in buildings or residential
complexes where  the combined production of electric
power and heat  could be used  to  satisfy heating and
cooling demands  in  an integrated (or "cogeneration")
fashion.   The  fuel-cell-derived  electricity would  be
used  to  operate  heat pumps  to  provide cooling and
supplemental heating.
Can Fuel Cells Use Coal
or Coal-Derived Fuels?
Fuel  cells,  like  most   fuel-consuming  devices  are
indifferent to the origin of the fuel—as long as in final
form it  conforms to the chemical requirements of  the
device.  Accordingly, natural gas, petroleum products,
or similar fuels are perfectly acceptable in fuel cells
provided that the fuels are  first reformed to hydrogen
and   carbon   dioxide    and   that   harmful    sulfur
contamination is removed before the  fuels enter  the
fuel cell proper.

                                 Fuel  cells,  therefore, can  have a  place in a largely
                                 coal-based U.S. energy future.

What Are Leading Coal-Based     Already, U.S. electrical power  is largely generated in
Alternatives to Fuel Cells?        coal-fired plants and the federal government is pushing
                                 for even  more in an  effort to save  relatively  scarce
                                 and  expensive oil  and  natural gas  for  other uses.
                                 Larger, conventional  coal-fired  power  plants,  often
                                 located in remote  areas  and connected  to urban load
                                 centers by  high  voltage  transmission lines, certainly
                                 provide a well-proven alternative  to electric  power
                                 generated from fuel cells.

                                 So-called     "combined-cycle"     electrical    power
                                 generation—a conventional  boiler  and  steam  turbine
                                 generator  supplemented  by a  high-temperature  gas
                                 turbine—is    an     improving    technology   gaining
                                 considerable attention among  utilities.  Certainly,  by
                                 the time  fuel-cell systems  are  perfected sufficiently
                                 to  allow   commercial   deployment,  combined-cycle
                                 systems will  already  be  in  use and  fuel-cell systems
                                 will have to compete with them.

                                 Much of the U.S.  space heating demand  is  met  by the
                                 combustion   of   natural  gas.   Because   so   many
                                 consumer-owned  heaters  are   already  in  place,  gas
                                 utilities have strong  incentive to  supplement natural
                                 gas supplies with coal-derived  substitutes  that  would
                                 not require  alteration of either consumer appliances or

                                 Synthetic  natural gas, (SNG)  derived  from coal, then,
                                 offers strong competition for  the electric heating  role
                                 a fuel-cell/heat pump combination could play in the
                                 market place.
Can Fuel Cells be Compared
with the Alternative
Because fuel cells must compete with so many electric
power   and   heat-producing   fuel   and   technology
combinations,    the    relative    advantages    and
disadvantages of  fuel  cells have proven  difficult  to
discern  clearly.  Consequently, as a part of its mission
to preserve  and enchance  environmental quality, the
U.S. Environmental Protection  Agency  commissioned
this study precisely to learn more about what might  be
expected  from  fuel  cells  when  actually  deployed  in
utility systems.
                                 To    address   this    question,   SRI    International
                                 conceptually designed  twelve  energy systems  able  to
                                 provide   residential   heating  and   cooling   using
                                 technologies projected  to be available toward  the end
                                 of this century.  Only  a few  systems used fuel cells.
                                 As   in  most  comparisons,  some  constraints  were
                                 imposed   to   eliminate   unnecessarily   confusing
                                 complexities while providing a uniform  framework for
                                 comparison.  Accordingly, all systems use western coal
                                 as the primary energy  resource, and all residences are
                                 assumed to have identical heating  and cooling demands
                                 typical  of the  mid-continent United  States.   After
                                 winnowing   out    the   clearly    least   attractive
                                 combinations, we selected  five systems and compared
                                 them in great detail.

For all  the comparisons, we examined the entire chain

of the system, starting with the coal mine and ending

with the heating and cooling of residences, to be  sure

that the claimed environmental advantages of the fuel

cells at the point of electric power generation  did not

distract   us   from   some   important  environmental

impacts  elsewhere in the system.  Our five  surviving

systems, four of  which use  heat pumps for heating and

cooling are:
o   System  1—A  coal-fired   power  plant  supplies
    electricity and  a coal gasification plant supplies
    SNG   to   residences;  electricity   powers   air
    conditioners and SNG is burned in gas furnaces.

o   System 2—A  26-MW fuel-cell power  plant  fueled
    by   coal-derived  SNG   supplies  electricity   to
    residences with heat pumps.

o   System 3—A  26-MW fuel-cell power  plant  fueled
    by  coal-derived  naphtha  supplies  electricity  to
    residences with heat pumps.

o   System 4—A  combined-cycle  power  plant  fueled
    by  coal-derived  fuel oil supplies  electricity  to
    residences with heat pumps.

o   System 5—A  100-kW  fuel-cell power plant  fueled
    by  coal-derived SNG, sited  in a housing complex,
    supplies   electricity  to  townhouses  with   heat
    pumps; heat recovered from  the fuel cell supplies
    supplemental space heating and hot water.

Of these  five,  the  first  one  most  resembles  the

existing  order  in  the utility industry, and  the  fourth

constitutes an  already  evident evolutionary change of

the industry.

What do the Comparisons
The  scorecard for the  various  systems is  mixed—no
single  system  stands   out  as  superior  in  all  the
attributes  that  will ultimately  decide  which systems
will  be deployed.  Nevertheless,  some very interesting
facts emerge about energy systems that use fuel cells.
Which System Costs the
Consumer More?
Are There Differences in the
Capital Investment Required?
 Which Has the Best System
The   three   fuel-cell  systems  provide  heating  and
cooling  to  our  standard  residences at  considerably
higher cost that the  two more  conventional  systems.
In fact,  the  annual  energy bill to  a consumer  using
System 5 is over 63%  higher than for one using System
1, the most  conventional and  lowest cost option.  The
order of cost, from the least  expensive system to the
most expensive, is 1,4,2,3,5.

The  scorecard for the capital  intensiveness  of the five
systems  largely follows  the  pattern  of the annual cost
to  consumers.  In  order,  from  least to  most capital
intensive, are Systems 1, 4, 3, 2, 5.  Because  capital is
itself a  scarce resource, utilities most likely  will show
most interest in Systems 1 and 4.

Because all five systems contain at least one element
not  yet  proven in  commercial service, such  things as
reliability,  the  degree  of redundancy  needed   in  a
system,  and the ability to  integrate smoothly the new
devices  into a system are  difficult  to assess, more so
than for most other comparison attributes. We judge,
however  that, overall, the  most conventional  system is
 most  likely  to  give the  best  performance. System
performance, from  best  to  worst  comes in this order:
Systems 1, 2, 4, 3, 5.

Which System is Most
What About Air Quality?
Are There Differences in
Water Quality?
When making a comparison of system efficiency, we
were careful to  account for energy losses at every step
in proceeding from the coal mine  to the heated  and
cooled   residence.    All   fuel-cell   systems    are
considerably   more   efficient    than   the   most
conventional system,  System 1.  Indeed,  System  5 is
75% efficient, while System 1 is only 41% efficient.
Systems 2, 3, and  4 possess nearly equal efficiencies in
the 64% to 67% range.  This  attribute is particularly
important because  it shows that the systems using fuel
cells required less  coal to accomplish the same end—a
virtue  that, besides conserving resources, carries  over
into lessened environmental impact.

Because  maintenance  of  air  quality  around  electric
power   generation   plants  is   a  vexing  and  costly
problem, the relative  scores for this indicator  could
prove  especially important  to utilities in  the  years
ahead.  We  weighted equally pollutants emitted at the
fuel production site  and the  fuel consumption   site
(both   overwhelm    the   emissions    from    fuel
transportation).  Again, all  three systems using  fuel
cells  are  superior  to the  two  more  conventional
systems, with System  5 being the cleanest and System
1 emitting the most pollutants.  In order, from  least to
most polluting are  Systems 5, 2,  3, 4,1.

For  this indicator  we  weighted  equally effluents  and
water consumption at the  fuel production and the fuel
consumption locations.

                                 All  three  fuel-cell  systems are cleaner than the two
                                 more  conventional  systems.  Again,  System  5  is the
                                 cleanest,  but  this   time  System  4  degrades  water
                                 quality the most. In order of  cleanliness  are Systems
                                 U} Zy «5j ly 4*
How Do They Compare on
Solid Waste?
Most  solid  waste  for this  set  of  five  systems  is
produced as ash in converting the coal to a more useful
energy  form.   Consequently, scores  in  this category
essentially mirror the  overall system energy efficiency
ratings—the most efficient  System 5 also produces the
least  solid  waste  and the least  efficient System  1
produces  the  most solid  waste.  Systems  2, 3, 4 are
nearly tied, and  produce  about the same intermediate
What About Land Use, Noise
and Aesthetics?
Is There a Pattern in the
The   three  parameters  are  closely  linked  because
aesthetics  and human exposure to noise produced  are
greatly affected by  location and  the  amount  of land
occupied  or  disturbed.  Overall,  least  obtrusive  is
System 5 and the most obtrusive is System 1.

A striking  pattern  emerges  when  we  assemble  the
scores for all categories of comparison. The  fuel-cell
systems  are the  most costly—to  build and install  as
well as in end-use cost to consumers—but are the most
environmentally benign and  consume the least coal to
get the heating and cooling job done.

                                 We  expected from  the outset of this  study that  the
                                 fuel  cells  themselves would be  clean compared  to
                                 alternatives,  but  our  finding  that entire  fuel-cell
                                 systems  from  resource  extraction  to  final  demand
                                 offer overall environmental benefits is new.
Will Fuel Cell Systems
Actually Be Used?
How  the  trade-off between environmental cleanliness
and economic cost will  be valued in  the  next  several
decades will prove crucial to the question of whether
fuel-cell systems  resembling those we have  examined
will actually be deployed in meaningful numbers.  One
thing  is certain:   Fuel-cell systems possess a mixture
of  attributes  much   different   from   the   more
conventional electric  power systems.   As a result,  U.S.
utilities will have  available an important  new electric
power option in the years ahead.
                                 Full  analysis  is  available  in  the  500-page report:
                                 "Comparative   Assessment   of  Residential  Energy
                                 Supply  Systems That use Fuel  Cells," Environmental
                                 Protection Agency, Report No. 600/7-79-105b, 1979.

                               TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse before completing)
                                                     3. RECIPIENT'S ACCESSION NO.
Comparative Assessment of Residential Energy
 Supply Systems That Use  Fuel Cells (Executive
                               6. REPORT DATE
                               April 1979
                               6. PERFORMING ORGANIZATION CODE
         R v. Steele,D. C. Bomberger ,K. M. Clark,
R. F. Goldstein, R. L. Hays, M. E. Gray, G. Ciprios*,
R.J.Bellows*.H.H.Horowitz, and C.W.Snyder*
                               8. PERFORMING ORGANIZATION REPORT NO.
SRI International
333 Ravens wood Avenue
Menlo Park, California 94025
                               10. PROGRAM ELEMENT NO.
                               11. CONTRACT/GRANT NO.
 EPA, Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC 27711
                               13. TYPE OF REPORT AND PERIOD COVERED
                               Final; 9/76 - 1/79	
                               14. SPONSORING AGENCY CODE
^.SUPPLEMENTARY NOTES JERL-RTP project officer is  Gary L. Johnson, MD-63, 919/541-
 2745. (*) Coauthors are Exxon personnel.
16. ABSTRACT The rep0rt gives results of a comparison of residential energy supply sys-
 tems using fuel cells. Twelve energy systems, able to provide residential heating
 and cooling using technologies projected to be available toward the end of this cen-
 tury, were designed conceptually. Only a few systems used fuel cells. All systems
 used Western coal as the primary energy source, and all residences were assumed
 to have identical heating and cooling demands typical of the mid-continent U.S.
 After screening, five systems were analyzed in detail. The entire energy cycle,
 from coal mine to end use, was examined for costs, efficiency, environmental im-
 pact, and applicability.  The five energy systems are: (1) a coal-fired power plant
 supplying electricity and a coal gasification plant supplying SNG; (2) a 26-MW fuel-
 cell power plant fueled by coal-derived SNG supplying electricity; (3) a 26-MW fuel-
 cell power plant fueled by coal-derived naphtha supplying electricity; (4) a combined
 cycle power plant fueled by coal-derived fuel oil supplying electricity; and (5) a
 100-kW fuel-cell power  plant fueled by coal-derived SNG, sited in a housing com-
 plex, supplying electricity to heat pumps, with heat recovered from the fuel cell
 supplying supplemental  space heating and hot water. Results indicate that the fuel
 cell systems are most costly, most efficient, and have least environmental impact.
                             KEY WORDS AND DOCUMENT ANALYSIS
                    >.IDENTIFIERS/OPEN ENDED TERMS C.  COS AT I Field/Group
 Fuel Cells           Coal Gasification
 Energy Conversion   Coal
  Techniques         Naphthas
 Residential Buildings Fuel Oil
 Cooling Systems
Pollution Control
Stationary Sources
Substitute Natural Gas
Natural Gas
Heat Pumos

                                          19. SECURITY CLASS (This Report)
                                            21. NO. OF PAGES

                   20. SECURITY CLASS (Thispage)
                                            22. PRICE
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