United States
                    Environmental Protection
                    Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
                    Research and Development
EPA/600/SR-92/007 Feb. 1992
& EPA       Project  Summary
                     Demonstration of  Fuel Cells to
                     Recover Energy from  Landfill
                     Gas:  Phase  I  Final  Report:
                     Conceptual  Study
                    G. J. Sandelli
                       International Fuel Cells Corporation
                    is conducting a U.S.  EPA-sponsored
                    program to demonstrate energy recov-
                    ery from landfill gas using a commer-
                    cial phosphoric acid  fuel cell power
                    plant. The U.S. EPA  Is Interested in
                    fuel cells for this application because
                    it  is potentially one  of the cleanest
                    energy conversion technologies avail-
                    able. The report discusses the results
                    of Phase I, a conceptual design, cost,
                    and evaluation study. The conceptual
                    design of the fuel cell energy recovery
                    concept is described and its economic
                    and environmental feasibility  is pro-
                    jected. A preliminary design  of the
                    project demonstration was established
                    from the commercial concept. It ad-
                    dresses the key demonstration issues
                    facing commercialization of the  con-
                    cept. Candidate demonstration sites
                    were evaluated, which led to selection
                    and EPA approval of the demonstra-
                    tion site.
                       A plan for Phase II  activities is dis-
                    cussed. Phase II will include construc-
                    tion  and  testing of a landfill gas
                    pretreatment system which will render
                    landfill gas suitable for use in the fuel
                    cell. Phase III will be demonstration of
                    the energy recovery concept.
                       This Project Summary was devel-
                    oped by EPA's Air and Energy Engi-
                    neering Research Laboratory, Research
                    Triangle Park, NC, to announce key find-
                    ings of the research project that is fully
                    documented In a separate report of the
                    same title (see Project Report ordering
                    Information at back).
 Introduction
   The  U.S. Environmental Protection
 Agency (EPA) has proposed standards and
 guidelines for the control of air emissions
 from municipal solid waste landfills. Al-
 though not directly  controlled under the
 proposal, the collection and  disposal of
 waste methane, a significant contributor to
 the greenhouse effect, would result from
 the emission regulations. This EPA action
 will provide an opportunity for energy re-
 covery from the waste methane that could
 further benefit  the environment. Energy
 produced from landfill gas could offset the
 use of foreign oil, and air emissions affect-
 ing global warming, acid rain, and other
 health and environmental issues.
   International Fuel Cells Corporation
 (IFC) was awarded a contract by the U.S.
 EPA to demonstrate energy recovery from
 landfill gas using a commercial phosphoric
 acid fuel cell. IFC is conducting a three-
 phase program to show that fuel cell en-
 ergy  recovery is  economically and
 environmentally feasible in commercial
 operation. Work was initiated in January
 1991. The  project report discusses the
 results of Phase I, a conceptual design,
 cost, and evaluation study, which ad-
 dressed the problems associated with land-
 fill gas as the feedstock for fuel cell
 operation.
   Phase II of the program includes con-
 struction and testing of the  landfill gas
 pretreatment module to be used  in the
 demonstration. Its objective will be to de-
 termine the effectiveness of the pretreat-
 ment system design to remove critical fuel
 cell catalyst  poisons such as sulfur and
                                                                    Printed on Recycled Paper

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halkies. A challenge  test is planned to
show the feasibility of using the pretreat-
ment process at any landfill in conjunction
with the fuel cell energy recovery concept.
A  preliminary  description of the gas
pretreater is presented.
   Phase III of the program will be demon-
stration of the  fuel cell energy recovery
concept. The demonstrator will operate at
Panrose Station, an existing landfill gas-
to-enargy facility owned by Pacific Energy
in Sun Valley, California. Penrose Station
is an 8.9 MW internal combustion engine
facility supplied with landfill gas from four
landfills. The electricity  produced by the
demonstration will  be  sold to the  electric
utility grid.
   Phase II activities began in September
1991, and  Phase III activities are sched-
uled to begin in January 1993.

Commercial Fuel Cell Landfill
Gas to Energy System
Conceptual  Design
   A commercial fuel cell landfill gas to
energy system  concept  was  designed to
provide a modular,  packaged, energy con-
                             version system which can operate on land-
                             fill gases with  a wide  range of composi-
                             tions as typically found in the United States.
                             The complete system incorporates the land-
                             fill gas collection system, a  fuel gas pre-
                             treatment system, and a fuel cell energy
                             conversion  system.  In the fuel gas  pre-
                             treatment system, the raw landfill gas is
                             treated to remove contaminants to a level
                             suitable for the fuel cell energy conversion
                             system. The fuel cell  energy conversion
                             system converts the treated gas to elec-
                             tricity and useful heat.
                                Landfill gas collection systems are pres-
                             ently in use in over 100 landfills in the
                             United States.  These systems have been
                             proven effective for the collection of landfill
                             gas. Therefore these design and evalua-
                             tion studies were focused on the energy
                             conversion concept.

                             Overall System Description
                                The commercial landfill gas to energy
                             conversion system is illustrated in Figure
                             1. The fuel pretreatment system has provi-
                             sions  for handling a wide range of gas
                             contaminants. Multiple pretreatment mod-
ules can be used to accommodate a wide
range of landfill sizes. The wells and col-
lection system collect the raw landfill gas
and deliver  it at  approximately ambient
pressure to the gas pretreatment system.
In the gas pretreatment system the gas is
treated  to remove non-methane organic
compounds (NMOCs) including trace con-
stituents which contain halogen and sulfur
compounds.
   The commercial energy conversion sys-
tem shown in Rgure 1 consists of four fuel
cell power plants. These power plants are
designed to provide 200 kW output when
operating  on landfill gas with  a heating
value of 500 Btu/scf.* The output from the
fuel cell is utility grade ac electric power. It
can be transformed and put into the elec-
tric grid, used directly at nearby facilities,
or used at the landfill itself. The power
plants are capable of recovering  cogen-
eration heat for nearby use or rejecting it to
air.
'1 Btu/scf. 37.3 kJ/sm*
                 Landfill Gas Wells and
                 Collection System
                                         Transformer
    Collection Syt

•«*•> • •,  MIMM t*««"^V
                                                                             Utility
                                                                             Grid
                                                                                            \
                                                                         Multiple Fuel Cell
                                                                         Power Plants
                     Landfill Site
                     Office and
                     Blower
                                     Gas Pretreatment
                                     System
Figure 1.    Fuel cell energy recovery commercial concept

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    As configured in Figure 1. the commer-
 cial system  can process  approximately
 18,000 scf/h* of landfill gas (mitigate 9050
 scf/h of methane) with minimum environ-
 mental impact in terms of liquids, solids, or
 air pollution.

 Fuel Pretreatment System
    The fuel pretreatment system incorpo-
 rates two stages of refrigeration combined
 with three regenerable adsorbent steps.
 The use of staged refrigeration provides
 tolerance to varying landfill gas constitu-
 ents. The first stage significantly reduces
 the water content and removes the bulk of
 the heavier hydrocarbons from the landfill
 gas. This step provides flexibility to accom-
 modate varying landfill characteristics by
 delivering a relatively narrow cut of hydro-
 carbons for the downstream beds in the
 pretreatment  system. The  second refrig-
 eration step removes additional hydrocar-
 bons by  a  proprietary process and
 enhances  the  effectiveness of the acti-
 vated carbon and  molecular sieve beds,
 which remove  the remaining volatile or-
 ganic compounds and hydrogen sutfide in
 the landfill gas. This approach is  more
 flexible than utilizing dry bed adsorbents
 alone and has built-in flexibility for the wide
 range of contaminant concentrations which
 can exist from site to site and even within a
 single site varying with time.
   The three  adsorbents are regenerated
 by  using  heated gas  from the process
 stream. A small portion of the treated land-
 fill gas is heated and then passes through
 the beds to strip the adsorbed contami-
 nants. After exiting the final bed,  the re-
 generation gas is fed into a low nitrogen
 oxide (NOX) incinerator where  it is  com-
 bined with the vaporized condensates from
 the refrigeration processes, and the mix-
 ture is combusted to provide 98% destruc-
 tion of the NMOCs from the raw landfill
 gas.
   The pretreatment system design pro-
 vides flexibility  for operation  on a wide
 range of  landfill gas compositions: it has
 minimal solid wastes,  high thermal effi-
 ciency, and low parasite power require-
 ments. The pretreatment system is based
 upon  modification of an  existing system
 and utilizes commercially available com-
 ponents. The  process train and  operating
 characteristics  need  to be validated by
 demonstration. Key demonstrations  in
 Phase II will include: the achievement of
 low total halide contaminant levels in the
treated gas; effectiveness of the regenera-
tion cycle as affected by regeneration time
* 1 scf/h = 0.028 sm'/Ji
 and temperature; durability of the regener-
 able beds;  and tow environmental  emis-
 sions.

 Fuel Cell Power Plant
    The commercial landfill gas energy con-
 version conceptual design incorporates four
 200-kW fuel cell power units. Since each
 of the four units in the concept is identical,
 this discussion  will focus on the design
 issues for a single 200-kW power unit.
    A preliminary design of a fuel cell power
 plant was established to identify the de-
 sign  requirements which allow optimum
 operation on landfill gas. Three issues spe-
 cific to landfill gas operation were identi-
 fied which reflect a departure from a design
 optimized for operation on natural gas. A
 primary issue is to protect the fuel cell from
 sulfur and halide compounds not scrubbed
 from the gas in the fuel pretreatment sys-
 tem. An absorbent bed was incorporated
 into the fuel cell fuel preprocessor design
 which contains both sulfur and halide ab-
 sorbent catalysts. A  second issue is to
 provide mechanical components in the re-
 actant gas supply systems to accommo-
 date the larger flow rates that result from
 use of dilute methane fuel. The third issue
 is an increase in the heat rate of the power
 plant by approximately 10% above that
 anticipated from operation on natural gas.
 This is a result of the  inefficiency of using
 the dilute methane fuel. The inefficiency
 results in an increase in heat recoverable
 from the power plant. Because the effec-
 tive fuel cost is relatively low, this decrease
 in power plant efficiency will not have a
 significant impact on the overall power plant
 economics.
    The landfill gas power plant design pro-
 vides a packaged, truck transportable, self-
 contained fuel cell power plant  with  a
 continuous electrical rating of 200 kW. It is
 designed for automatic, unattended opera-
 tion, and can be remotely monitored. It can
 power electrical loads either in parallel with
 the utility grid or isolated from the grid.

 Environmental and Economic
 Assessment of the Fuel Cell
 Energy Conversion System
   The commercial application of the con-
 cept to the  market described previously
 was assessed.  For the purpose of the
 evaluation,  a site  capable  of supporting
four fuel cell power modules was selected.
The site would produce  approximately
434,000 scf of landfill gas per day. The gas
contains approximately 50% methane with
a heating value of 500 Btu/scf.
   The analysis  of the environmental im-
pact shows that both  the fuel cell and a
flare system can be designed to eliminate
 the methane and the non-methane organic
 compounds from the landfill gas system.
 For the example site considered, the meth-
 ane elimination is essentially complete for
 both systems, and 98% of the NMOCs are
 destroyed. Trace amounts of sulfur oxides
 (SO.)  and NOX will be  emitted in each
 case. With the fuel cell system, however,
 significant reductions of NO, and SO, will
 be achieved due to the fuel cell energy
 generation. This analysis assumes an 80%
 capacity factor for the fuel cell and offset-
 ting emissions from electric utility power
 generation using a coal-fired plant meeting
 New Source Performance Standards. For
 the example site, the fuel cell energy con-
 version system provides  5.6 million kWhr
 of electricity per year, with a net reduction
 of 35.2 tons* per year of NO, and 16.8 tons
 per year of SOS from reduced coal use.
    Economically the fuel cell energy sys-
 tem has the potential for deriving revenues
 from electric sales, thermal sales, and emis-
 sion offsets credits. These revenues can
 be used to off set the investment cost asso-
 ciated with  gas collection, gas pretreat-
 ment, and fuel cell power units. The level
 of these revenues depends upon the value
 of the electricity, the amount and value of
 the heat used, and the value of the emis-
 sions offsets.
    The fuel cell energy conversion system
 was studied to establish the net revenues
 or costs for processing landfill gas to miti-
 gate methane emissions. For this analysis,
 h was assumed that the  fuel cell energy
 conversion system  and the flare system
 would have an overall annual capacity fac-
 tor of 80%. For this analysis, two levels of
 fuel cell installed costs were considered^
 The lower level represents  a fully mature
 cost when the power plant has been ac-
 cepted  into the marketplace, and is rou-
 tinely produced  in  large  quantities. The
 upper level represents  a price level when
 the power plant is being introduced  into
 the marketplace, and  is  produced on a
 moderate and  continuous basis.
    Figure 2 shows the fuel cell revenues
for the most stringent application situation
 (no emission  credits or  thermal energy
 utilization). In  this case, the fuel cell re-
ceives revenues only from the sale of elec-
tricity. Although the emissions are lower
from the  fuel  cell,  no  specific credit or
value is attached to them for this example.
Under these conditions the fuel cell is still
the economic choice for most locations at
the mature product  installed cost. At the
entry level cost the fuel cell  is economical
in those areas  where the value of electric-
                                                                                   * 1 ton = 907 kg

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            3000
            2000
             rooo
        5*5     0
        !U.
        so
            -2000
     Fuel Cell Installed Cost
        Mature Product
                      Market
                      Entry
                      Cost
                         I
    Hare Economic  Gas Collection
        Option       andFlare
      I	I	I
                2.0     4.0     6.0     8.0     10.0    12.0

                       Value Received for Fuel Cell Electricity, kWh
                    14.0
Figure 2.    Comparison of fuel cell to flare for methane mitigation assuming electric revenues
            only.
Hy Is 9 cents per kWh or higher. With the
potential for revenue from thermal energy
or emission offset credits, the economics
become more competitive. Thus the appli-
cability of the concept would become at-
tractive to a broader market.
   Other energy conversion systems could
also produce electric and/or thermal en-
ergy. Both the internal combustion engine
and the gas turbine engine have been
suggested as options for methane mitiga-
tion at landfill sites. For the landfill size
selected for this analysis, the internal com-
bustion engine is more effective than the
gas turbine options for cleanup.  This is
used as the basis for  the  comparisons
provided here.  The internal combustion
engine can provide both heat and electric
energy while consuming the methane at
the landfill gas site. With the present state-
of-the-art technology, however, a lean-bum
internal combustion engine has higher lev-
els of  NO,  emissions than  the fuel cell
unless special precautions are taken  to
clean the  exhaust. For this analysis two
cases were considered. The first case as-
sumes no cleanup of the internal combus-
tion  engine exhaust,  and  the second
assumes that the exhaust is cleaned with
selective catalytic reduction (SCR). Since
the SCR employs a catalyst in the cleanup
system, the landfill gas will have to be
pretreated in a manner similar to the fuel
cell system. For those cases with a SCR
cleanup system, a pretreatment  system
has also been  included as part of the total
system cost.
   Figure 3 shows the results of the eco-
nomic analysis for the fuel cell system and
the internal combustion engine system.
Since both systems can provide electricity,
the comparison between the systems is
based on the cost of electricity generated
from the energy conversion system with
appropriate credit for thermal sales and/or
emission offsets. The fuel cell is competi-
tive at the full mature price when no ex-
haust cleanup  is required with the internal
combustion engines. However, the opera-
tion of the  internal combustion engine at
the landfill site would be quite dirty, and
significant amounts of NO, would be added
to the ambient air compared to the fuel
cell. For many  locations where the fuel cell
would be considered, such as California or
other high emissions areas, the exhaust
cleanup option is required. Consequently,
the fuel cell option would be fully competi-
tive with the internal combustion  engine
option for most cases where on-s'rte cleanup
of the  internal combustion  engine is re-
quired. In areas where a SCR would be
employed to clean up an internal combus-
tion engine exhaust, the fuel cell concept
is competitive at entry level cost.
   Based on the analysis of both the flare
option  and other energy conversion op-
tions, the fuel cell power plant is fully com-
petitive in  all situations in the  mature
production situation. For initial power plant
applications with limited lot production, the
fuel cell power plant is competitive in areas
with high electric rates and/or severe emis-
sions restrictions at the local landfill site.

Demonstration Project
Preliminary Design
   The objective  of the demonstration
project is to validate the economic and
environmental feasibility of  a commercial
fuel cell energy recovery concept  operat-
ing on  landfill gas. A preliminary design of
the demonstration project shown in Figure
4 is described, which  identifies the key
issues to be resolved before demonstra-
tions and describes the major components
of the demonstration project.
   Demonstration project design require-
ments  were derived from the commercial
concept. These requirements were used
to define project site selection criteria, gas
pretreatment system design, and commer-
cial fuel cell modifications to accommodate
landfill gas.
   The site selected for the demonstration
project is the Penrose Station in Sun Val-
ley, California. This site, owned and oper-
ated by Pacific Energy, accepts landfill gas
from four municipal sold waste landfills.
Penrose Station presently  produces 8.9
MW of electricity from landfill gas, using
internal combustion engines. The demon-
stration will operate on a slip stream from
Penrose's gas feed.
   Because Penrose accepts gas from four
fills, some of which contain industrial waste,
the composition and  contaminant levels
vary considerably. Average  methane con-
tent is  44% and the gas typically contains
150 ppmv sulfur and 78 to 95 ppmv halides.
The sulfur contaminant levels are higher
than typically found in municipal solid waste
landfill gas. A successful demonstration at
Penrose will show applicability of the con-
cept to a broad  segment of the market.

Conclusions
   Based on the environmental and eco-
nomic  evaluation of the commercial fuel
cell energy system, the following  can be
concluded:

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      10.0
       8.0
       6.0
       4.0
       2.0
Electricity Sates
Thermal Recovery
Emissions Offsets
                                    With
                                    SCR
                                   Exhaust
                                   Cleanup
                      Mature
                      Product
                       Cost
     No
   Exhaust
   Cleanup
                                 HP272-04
                                 R9117O9
                        Fuel Cell
                      Energy Conv.
                        System
             I.C.E.
          Energy Conv.
             System
Figure 3.     Comparison of fuel cell to internal combustion engine
             energy conversion system.
     The fuel cell landfill gas to energy
     conversion system provides a  net
     reduction in total emissions while si-
     multaneously mitigating the methane
     from the landfill gas.
     Fuel cells will be competitive at initial
     product prices  on  landfill  sites lo-
     cated in high electric cost areas or
     where the thermal energy  can be
     utilized. The fuel  cell Will also be
     attractive where there is a credit for
     the environmental impact of fuel cell
     energy conversion.
     When the projected mature product
     price  is achieved,  fuel cells will be
     competitive for most application sce-
     narios. In .many situations, fuel cells
     will provide net revenues to the land-
     fill owners. This could,  in the long
     term,  result in methane mitigation
     without additional cost to the ultimate
     consumer.
     A demonstration project design was
     established which addresses the key
     technical issues facing  commercial
     application of the fuel  cell energy
               recovery concept to the market. A
               site has been selected for the dem-
               onstration which fairly represents the
               landfill gas market.

          Recommendations
             Phase II of the project, which evaluates
          the gas pretreatment system at the  se-
          lected site, should be conducted to verify
          that landfill gas can  be cleaned to meet
          fuel cell requirements. The pretreatment
          system design needs to  be finalized to
          resolve the remaining cleanup issues and
          construction started as soon as possible in
          Phase II. A challenge test should  be  de-
          fined to evaluate the limits of operating
          capability of the pretreatment system in-
          cluding regeneration and adsorption break-
          through conditions.

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                    Penrose
                     Station
                   Gas Wells
                      and
                   Collection
                     System
                 (PacHic Energy)
                                     Utility
                                     Power
                                     Lines

                                      A
                                                                                               AC Power*"
                                                                                                  to Grid
                                                     Gas-Guard®
                                                   Gas Pretreatment
                                                       System
                                                       (Biogas
                                                   Development Inc.)
   PC25
  Fuel Cell
Power Plant
(ONSICorp.)
                     Landfill
X
x
x
X
x
                                                                   Natural Gas
                                                                   Southern California Gas Company
Flgvn4.     Proposed demonstrator concept
                                                                       if U.S. GOVERNMENT PRINTING OFFICE: IW - 64O-OHO/40167

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GJ. Sandeltiis with International Fuel Cells Corp., South Windsor, CT 06074.
Ronald J. Spiegel is the EPA Project Officer, (see below).
The complete report, entitled "Demonstration of Fuel Cells to Recover Energy from
  Landfill Gas: Phase I Final Report: Conceptual Study," (Order No. PB92-137520/AS;
  Cost: $19.00, subject to change) will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
        Air and Energy  Engineering Research Laboratory
        U.S. Environmental Protection Agency
        Research Triangle Park NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
EPA/600/SR-92/007

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