X-/EPA
                               United States
                               Environmental Protection
                               Agency
                               Industrial Environmental Research
                               Laboratory
                               Cincinnati OH 45268
                               Research and Development
                               EPA-600/S7-81-133 Sept. 1981
Project Summary
                               Environmental  and  Economic
                               Comparison  of  Advanced
                               Processes for Conversion of
                               Coal  and  Biomass  into
                               Clean  Energy
                               R. A. Stenzel, B. T. Kown, M. C. Weekes, J. D. Ruby, B. R. Gilbert, C. M. Harper,
                               Y. J. Yim, and R. T. Milligan
                                 Biomass and coal conversion into
                               clean energy is compared on an econ-
                               omic and environmental basis in three
                               regional scenarios: (1) electric power
                               from direct combustion of wood
                               versus conventional coal combustion
                               in the south central U.S., (2) synthetic
                               pipeline gas from anaerobic digestion
                               of wheat straw and manure versus
                               high-Btu  gasification of coal
                               (HYGAS®)  in  the midwest,  and (3)
                               synthetic fuel oil from wood liquefac-
                               tion versus coal liquefaction (H-Coal®)
                               in the northeast. Conceptual commer-
                               cial-scale plants are described. Capital
                               and operating  costs are presented for
                               each of the six plants, and the biomass
                               versus coal economics are compared.
                               General environmental impacts of bio-
                               mass and coal resource collection are
                               assessed and compared  in the
                               scenario contexts. Plant environmen-
                               tal emissions were estimated where
                               possible, and  relative environmental
                               impacts are discussed. Conclusions
                               are given about the conversion con-
                               cepts which seem the more promising
                               routes  to clean energy,  and areas
                               needing further study are identified.
                                 This Project Summary was develop-
                               ed by EPA's Industrial Environmental
                               Research Laboratory. Cincinnati. OH.
                               to announce  key  findings  of  the
                               research project that is fully docu-
                               mented in a separate report of the
                               same title (see Project Report ordering
                               information at back).

                               Introduction and Summary
                                 This  report presents the results of
                               three environmental and economic
                               comparisons of biomass and coal con-
                               version into clean energy. The study
                               was initiated to help develop priorities
                               for assessing conversion technologies
                               capable of producing clean energy from
                               biomass and coal resources. Electric
                               power, synthetic pipeline gas (SPG), and
                               synthetic fuel oil were chosen as repre-
                               sentative clean  energy products which
                               can be produced from both biomass and
                               coal. Representative coal conversion
                               technologies were  to serve as base
                               cases to which biomass conversion
                               technologies were  to be  compared.
                               Three regional scenarios, each with a
                               biomass-coal plant pair, were selected
                               from a  number  of possible candidates.
                               Conceptual  designs of commercial-
                               scale plants were compared in these
                               regional scenarios:

                                 • A 50 MWe wood-fired power plant
                                   versus a  500 MWe  coal-fired
                                   power plant in the south central
                                   U.S.

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  •  A7 MM SCFD(6.7 billion Btu/day)
     biogas plant (anaerobic digestion
     of  wheat  straw  and  manure)
     versus a  274  MM  SCFD (250
     billion  Btu/  day)  high-Btu
     gasification  plant (steam-oxygen
     HYGAS®) in the midwest.

  •  A  1764  BPD wood-oil liquefac-
     tion  plant versus a 66,856 BPD
     coal liquefaction plant (H-Coal®)
     in the northeast.

  In the scenarios, biomass residue is
collected  locally from  forestland
(chipped forest residue), from farmland
(wheat straw), and from feedlots (cattle
manure). Coal is strip-mined in the first
two scenarios  and deep-mined in the
third. As plant feedstocks, the biomass
materials  have lower sulfur and ash
contents,  lower heating values,  and
lower bulk densities (except  manure)
than coal.
  The  plant capacities  chosen  are
representative   of  commercial  scales
being proposed for biomass residue and
coal   conversion.  The   disparity   in
biomass-coal plant capacities is almost
inherent;  hence,  the higher  capacity
coal conversion plants  have a distinct
economy-of-scale advantage. The direct
combustion  and the  liquefaction pro-
cesses  for  biomass  conversion  are
similar to their coal conversion counter-
parts. A biological conversion process,
anaerobic digestion, is compared with a
thermal  conversion  process,  steam-
oxygen  gasification.  Estimated  plant
thermal efficiencies (based on net prod-
uct output) are compared below:
          Power    SPG
Fuel
Oil
Biomass
Conversion 21.6%    31.9%   42.1%
Coal
Conversion 35.1%    69.1%   65.5%

  It is apparent that these three bio-
mass processes have relatively low con-
version   efficiencies.   In  the  wood
conversion processes,  the  feedstock
properties  are  a  disadvantage—low
heating  values  (high  moisture  and
oxygen contents) and low bulk densities
mean  that  more  material  must  be
handled per unit of energy content than
for coal. Energy consumption and losses
are  high.  The anaerobic  digestion
process suffers  from  a low methane
production rate and incomplete biomass
conversion. This process  does yield a
            digester residue that may be a valuable
            byproduct if it can be used as an animal
            feed.
              Improvements  in  conversion  effi-
            ciencies are important if these particu-
            lar  biomass  processes  are to  be
            competitive with  the coal processes.
            Worthwhile ideas for improving  feed-
            stock   properties  (preprocessing   of
            biomass) should be  given attention, as
            such  ideas could  lead  to increased
            process conversion efficiencies.
              Economic  comparisons   of  the
            biomass and coal conversion  concepts
            are presented in Figures 1, 2,  and 3 for
            utility and private financial methods,
            using the  ERDA-AGA Cost Guidelines.
            These  figures  illustrate that  the bio-
            mass-derived   energy   products  are
            about 50 percent (power) to 300 percent
            (SPG) more expensive to produce than
            the  corresponding  coal-derived  pro-
            ducts  from  much  larger  conversion
            plants.  Synthetic fuel  oil from  wood
            liquefaction is about  2.5 times  more
            costly than oil from the H-Coal® process.
            In  these  scenarios  at  least,   the
            economic  disparities  result   from  a
            combination of less desirable feedstock
            properties,  smaller  biomass  plant
            capacities, and lower process conver-
            sion efficiencies. In  many economic
            situations,  both   direct-fired  plants
                                        would  produce  electric  power  more
                                        cheaply than it  could be  produced in
                                        conventional power plants firing any of
                                        the four synthetic fuels.
                                          Figure  1 shows that the cost of elec-
                                        tricity from  a  wood-fired  plant is  not
                                        competitive with that from a large coal-
                                        fired generating station if wood and coal
                                        prices are about the same on a $/MM
                                        Btu basis. Fora high coal cost/low wood
                                        cost scenario, a small wood-fired plant
                                        could be  economic as  evidenced by
                                        existing  power boilers burning wood
                                        wastes in many pulp and paper mills in
                                        the northeast.
                                          The  biomass-derived  synthetic gas
                                        and  oil  are just  not close  to being
                                        competitive with the coal  derived syn-
                                        thetic fuels, as Figures 2 and 3 illustrate.
                                          Pollution control costs will be high for
                                        the  large   coal   conversion plants,
                                        probably  5 to  10  percent of the total
                                        plant capital costs. These large expendi-
                                        tures,  however,   do not  shift  the
                                        economic   advantage   to   biomass
                                        conversion,  as the foregoing figures
                                        show.
                                          Environmental impacts  of plant con-
                                        struction  and  operation were consid-
                                        ered  separately  from    impacts  of
                                        resource  collection.   Resources
                                        consumed by the plants and emissions
                                        of conventional  pollutants were esti-
                              0.50
                                Wood Cost. $/MMBTU
                           1.00      1.50      2.00     2.50
                                                                             3.00
                  125
      100

|
\

1      75
is
.*-


il      50

                   25
                                5
                              I
                             10
                                                                    Private

                                                                    Utility
 I
20
       15
  Wood Cost. $/Ton
 I
25
30
                            10
                                    20
                                  Coal Cost, $/7on
                              30     40     50
  60
                          70
       80
                              0.50
                          1.00
   7.50     2.00     2.50
Coal Cost, $/MMBTU
              3.00
            Figure 1.     Economic comparisons of wood and coal to power.

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00

I
 §
 0
        20
        15
        10
                          Straw or Manure Cost, $/MMBTU
                  0.50      1.00      1.50     2.00     2.50     300
                   I	I	I	I	I	I
              Straw   10
                                   20
                                   -4-
                                                30
                            40    Straw
              Manure  246
                           Straw and Manure Cost. $/Ton
                                                                 Manure
                                  Coal Cost, $/Ton
                              20        30        40
                               i	i	i
                                                              Private

                                                              Utility

                                                              50
                                       60
                                        i
                  0.50
                                             2.00
                      2.50
Figure 2.
              1.00     1.50

               Coal Cost, $/MMBTU

Economic comparison of straw/manure and coal to SPG.
3.00
                               Wood Cost, $/MMBTU
                 0.50
                           1.00
I
o
s^
o
*w

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      •  The anaerobic digestion and wood
         liquefaction  processes  are  not
         promising routes to low cost syn-
         thetic fuels in view of the superior
         HYGAS® and H-Coal®  process
         economics.

      •  In  certain  localities,  power
         generation  from wood may be
         economically   competitive   with
         power generation from coal if the
         coal/wood  price  ratio  is  high
         enough.

      •  The  small  biomass  conversion
         plants do not appear to have an
         overall environmental advantage
         over  their coal conversion plant
         counterparts on a relative basis;
         however, more and better quanti-
         tative emission data  need to be
         developed in order to better assess
         the probable impacts of both the
         biomass  and  coal  conversion
         technologies.

      •  Managed  properly, biomass
         residue  collection  should  have
         less  severe environmental
         impacts than coal  mining,  even
         though  much  more land  area
         would be affected by  residue col-
         lection.

      From these comparisons, it is evident
    tiat the coal conversion  processes are
    more likely to become major routes to
    clean fuels than these biomass conver-
    sion processes,  primarily  because of
    better economics. Other  biomass feed-
    stock/conversion process/energy
    product scenarios  could prove  to be
    more favorable in this type of biomass-
    coal  comparison.  A combination  of
    three factors is desirable:
          •  a relatively  low-priced biomass
             feed material,

          •  a process that has a relatively high
             conversion efficiency, and

          •  a higher-priced product than fuel
             oil or fuel  gas.

          Steam  and power  production from
        low-cost residues and co-firing of wood
        and fossil fuels  appear to be promising
        ways of using biomass resources in a
        number of localities in the U.S. Biomass
        conversion into  more valuable products
        (chemicals,  fertilizers,  animal  feeds)
        should also be a promising area  of
        study.
      Both  biomass and coal conversion
    would  have  adverse  environmental
    impacts, and there is continuing need to
    better define  the  likely  impacts of
    resource  collection,  conversion,  and
    product usage.
      The coal conversion plants need to be
    large in order to produce competitively
    priced clean energy. If the coal conver-
    sion plants could be scaled-down to the
    same low capacities as their biomass
    plant counterparts, it is likely that the
    coal-derived energy products would be
    more  costly   than  the   respective
    biomass-derived  products.  In  some
    localized scenarios, biomass conversion
    could have an economic advantage over
    coal conversion on a small scale.

U S GOVERNMENT PRINTING OFFICE, 1981 — 757-012/7313
           R. A. Stemel, B. T. Kown. M. C. Weekes, J. D. Ruby, B. R. Gilbert, C. M. Harper,
             Y. J. Yim, and R. T. Milligan are with Bechtel National, Inc., P. 0. Box 3965,
             San Francisco, CA 94119.
           Thomas J. Powers is the EPA Project Officer (see below).
           The complete report, entitled "Environmental and Economic Comparison of
             Advanced Processes for Conversion of Coal and Biomass into Clean Energy,"
             (Order No. PB 81-234 239; Cost: $29.00, 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:
                  Industrial Environmental Research Laboratory
                   U.S. Environmental Protection Agency
                   Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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