EPA 600/7-81-034
                                         March 1981
          GREENHOUSE PRODUCTION OF
               BEDDING AND FOLIAGE
         PLANTS WITH INDUSTRIAL HEAT
                     by
                I.  J.  Crumbly

         Fort Valley State College
           Fort Valley, GA  31030
               IERL-RTP-1047a
              EPA 600/D-80-014
        EPA Project Officer T.  J.  Brna

Industrial Environmental Research  Laboratory
       Research Triangle Park,  NC   27711

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                           ABSTRACT
     Potential beneficial  use of industrial waste heat for the production
of bedding and foliage plants was  evaluated  via use of conventionally and
warm water heated greenhouses in Fort Valley,  Georgia.  Each greenhouse
was 9.1 m X 21.9 m (30 ft  X 72 ft)  and a  plastic covered quonset.  The
research greenhouse was heated and  cooled using simulated warm condenser
cooling water, while the control greenhouse had conventional heating and
cooling in the 9-month test program.   During  1979, cultivars of 10 leading
ornamental bedding plants, 8 species  of foliage plants, and tomatoes as
bedding plants were studied for  growth rate,  survivability, time of
flowering, and susceptibility to disease  in the humid greenhouses.

     No statistically significant difference  in growth rate for 7 of 10
ornamental and 2 of 8 foliage plants  was  observed in the two greenhouses.
Tomatoes, coleus and geraniums grown  in the conventional greenhouse had
statistically significant  higher growth rates.  Syngonium podophyllum
and Philodendron pertussum grown in the waste  heat research greenhouse
had statistically significant higher  growth rates.  Ornamental bedding
plants grown in the conventional  greenhouse flowered approximately 7.6
days earlier.   No significant difference  in survivability among foliage
plants and 8 of 10 ornamentals was  seen in either greenhouse.  Browallia
and coleus survived better in the conventional greenhouse.  No diseases
were evident in either greenhouse.

     Heating and cooling of the  waste heat research greenhouse was
satisfactory,  despite the  fin-tube  heat exchanger being oversized for
the available  warm water flow.   Environmental  control was adequate; at
no time was condensation observed on  the  foliage of plants grown in
either greenhouse.   Preliminary  economics  indicate that industrial
waste heat can be an attractive  alternative to natural gas and fuel
oil for greenhouse heating.
                        DISCLAIMER


        This report has been reviewed by the Industrial Environ-
     mental Research Laboratory (RTF), U.S.  Environmental
     Protection Agency, and approved for publication.  Approval
     does not signify that the contents necessarily reflect the views
     and  policies of the Agency, nor does mention of trade names
     or commercial products constitute endorsement or recommen-
     dation for use.
                                   11

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                          TABLE OF CONTENTS
                                                                     Page

Abstract  	      i j
List of Figures  	       v
List of Tables  	      vi
List of Abbreviations  	     vii
Acknowledgements  	    viii

SECTION 1.   INTRODUCTION  	       1

     BACKGROUND  	       1

     OBJECTIVES  	       2

     A DESCRIPTION OF THE RESEARCH FACILITIES 	       3

SECTION 2.  CONCLUSIONS	       7

     HORTICULTURAL 	       7

     ECONOMIC	       8

     ENGINEERING  	       8

SECTION 3.  RECOMMENDATIONS	.,..      10

SECTION 4.  HORTICULTURAL STUDIES 	      11

     BEDDING PLANTS	      H

         DRY WEIGHTS (THE WHOLE PLANT)	      11

         DRY WEIGHTS (AERIAL PLANT PARTS)	      13

         FLOWERING DATES IN PAKS AND POTS	      14

         SURVIVAL RATE	      15

     FOLIAGE PLANTS 	      16

         DRY WEIGHTS (AERIAL PLANT PARTS) 	      16

         SURVIVAL RATE	      17

SECTION 5.  GREENHOUSE PERFORMANCE 	      18

     HEATING	      19

     COOLING 	      24

     RELATIVE HUMIDITY 	       28


                                   iii

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                                                                    Page



SECTION 6.   ECONOMIC APPROACH AND MARKETING STUDIES 	       31



    ECONOMIC APPROACH 	       31



    CONSTRUCTION COST 	       31



         BASIC COST (MATERIALS)	       31



         BACK-UP HEATING SYSTEM  	       32



    GREENHOUSE ENERGY REQUIREMENTS	       34



    CURRENT COST FOR ENERGY	       34



         COST FOR FOSSIL FUEL 	       34



         PROJECTED COST OF WASTE HEAT 	       35



         PROJECTED SAVINGS BY USING WASTE HEAT	       35



    MARKETING STUDIES	       37



         BEDDING PLANTS 	       37



         FOLIAGE PLANTS	       37



         POTTED CHRYSANTHEMUMS AND POINSETTIAS 	       38



         ECONOMIC INCENTIVE TO USE WASTE HEAT	       38



         REFERENCES	       39
                                    IV

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                         LIST OF FIGURES
                                                               Page

  1        A schematic  representation  of  the  waste  heat
          research  greenhouse  	     5

  2        A schematic  representation  of  the  conventional
          greenhouse 	     6

  3        The  arrangement of bedding  plant species  in the
          waste  heat research  greenhouse	   12

  4        Average low  night air temperature  from
          February  1 through February 24, 1979  	   20

  5        Average high daytime air temperature from
          February  1 through February 24, 1979  	   21

  6        Comparative air temperature history of 24-hour
          period in the waste heat research  greehouse
          during an ice-snow storm on February 18, 1979 ....   22

  7        Comparative air temperature histories over a
          four-day period in January, 1979   	   23

  8        Average high greenhouse temperatures with water
          heated to 43.loc (109.6°F) in the waste heat
          research greehouse from July 1  through July 4,
          1379	   25

  9        Comparative cooling during 24-hour cycles
          between waste heat greenhouse and conven-
          tional  greenhouse using water heated to 43.1°C
          (109.60F)   	   26

10       Average high  temperatures reached in green-
         houses  using  water heated to 51.2°C (I24.6°F)
         in the  waste  heat research greenhouse
         simulating the  temperature of effluent water
         from a  closed cycle plant (August 14-17,  1979) 	   27

11       Potential  for sensible  heat exchange from effluent
         water to air  during evaporative cooling  in the
         waste heat research greenhouse  from August 29
         through September 3,  1979	   29
                               V

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                          LIST OF TABLES
Table                                                             Page

  1     MEAN DRY WEIGHT (g) OF 8 WHOLE PLANTS/REPLICATION,
        APRIL 1, 1979	  .  .    13
  2     SPRAY DATES OF B-NINE GROWTH RETARDANT 	  ...    13

  3     MEAN DRY WEIGHT (g) OF 20 AERIAL PLANT PARTS/
        REPLICATION, APRIL 12, 1979	.  .  .    14

  4     FLOWERING DATES OF BIDDING PLANTS IN PAKS   	    15

  5     MEAN SURVIVAL RATE BASED ON 4 FLATS/REPLICATION
        (128 PLANTS), APRIL 10, 1979	    15

  6     SPECIES AND CULTIVARS	.  .  .    16

  7     MEAN DRY WEIGHT (g) OF AERIAL PLANT PARTS,
        AUGUST 23, 1979	    16

  8     MEAN DRY WEIGHT (g) OF AERIAL PLANT PARTS,
        SEPTEMBER 19, 1979	    17

  9     MEAN SURVIVABILITY BASED ON 100 PLANTS/REPLICATION,
        AUGUST 23, 1979	    17

 10     AVERAGE MONTHLY TEMPERATURE OF EFFLUENT WATER  AT
        BROWN'S FERRY NUCLEAR POWER PLANT LOCATED  IN NORTH
        ALABAMA	    is

 11     PERCENT RELATIVE HUMIDITY WITH EFFLUENT WATER
        TEMPERATURE SET AT 51.7°C (i25.0°F)  	    30

 12     COMPARATIVE CONSTRUCTION COST BETWEEN  THE  CONVEN-
        TIONAL GREENHOUSE AND THE WASTE HEAT GREENHOUSE
        WITHOUT BACK-UP HEATING SYSTEM 	  .......    33

 13     PROJECTED COST OF BACK-UP HEATING SYSTEM WITH  AN
        OUTPUT OF 4.5 GJ/HR/.4 HECTARE (4.3 MBTU/HR/ACRE).  ...    33

 14     A PROJECTED COMPARATIVE CONSTRUCTION COST  BETWEEN A
        CONVENTIONAL GREENHOUSE AND A WASTE HEAT GREENHOUSE
        BASED ON .4 HECTARE (1  ACRE)  BACK-UP HEATING SYSTEM   .  .    34

 15     ESTIMATED POTENTIAL ANNUAL SAVINGS IN  ENERGY COST
        USING THREE PRICES FOR WASTE  HEAT COMPARED  TO
        NATURAL GAS AND NO.  2 FUEL OIL AND THE NUMBER  OF
        YEARS REQUIRED TO BREAK EVEN    	    36
                                 VI

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         LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS

Btu
°C
OF
ft
gal
gal /mi n
Gj
g
hr
in
I
1/min
1/s
Mj
MW
m
m/s
mph
MBtu
No.
Tj
British thermal unit
degrees Celsius
degrees Fahrenheit
foot
gallon
gallons per min
gigajoules (one billion joules)
gram
hour
inch
liter
liters per minute
liters per second
megajoules (one million joules)
megawatt
meter
meters per second
miles per hour
million British thermal units
number
square foot
square inch
square meter
terajoules (one trillion joules)
                           Vll

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                       ACKNOWLEDGEMENTS
     The author would like to give thanks to Dr. Gerald Williams,
Dr. Porter Russ, Dr. Earl Burns, Dr. Johnny Carter, Mr. Carl Madewell
and Mr. Robert Pile of the Tennessee Valley Authority for their
support and cooperation.  From Fort Valley State College, the author
is appreciative to Mr. Merchant E. Singleton and Dr. Robert Steele
for their technical assistance and to Ms. Clara Tarver and Mrs
Consiwilla Cobb Studstill for their clerical help.  The author'also
wishes to thank Dr. Theodore G. Brna of the Environmental Protection
Agency for his suggestions in preparing the manuscript herein.
                               Vlll

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                                SECTION  1

                               INTRODUCTION
 BACKGROUND
     Water  is used  in the power plant  industry for cooling purposes and
energy  added to this water  is described as waste heat.   In the past,
the normal  procedure has been to dump  discharged cooling water coming
from power  plants back  into rivers,  lakes and cooling ponds where the
energy  added is dissipated.  Most recently, to prevent adverse environ-
mental  impacts of waste heat and to  prevent large water withdrawals
associated  with harm to aquatic life,  the power plant industry has been
forced  to build expensive cooling towers.

     If means can be developed so that this warmed water could be
utilized to heat and cool greenhouses  and extend the growing season of
certain horticultural and field crops, it would help conserve energy
while improving water quality.  Three  other advantages are (1) a normal
waste product would have economic potential to the power plant, (2) a
reduction in the cost of crop production could be passed on to the
consumer, and (3) the country would  realize a slight-to-moderate reduction
in thermal  pollution depending on size, kind of industry and location.

     The Environmental Protection Agency estimates that the U. S. will
require approximately 757 billion liters (200 billion gallons) of fresh
water daily to cool the condenser steam of power plants required to
produce the thousand billion kilowatt  hours needed annually by 1980 (2).
Such water will  be essentially free  of contaminants, and it will be
discharged at 29° to 49°C (85° to 120°F).

     The annual  quantity of waste heat presently available in the U.  S.
is approximately 10,500 quadrillion  joules (10 quad* Btu) equivalent to
254 gigaliters (1.6 billion barrels) of fuel  oil  (8).  This represents an
annual   amount of energy slightly less than 20% of all the energy used
annually in 1971.   However, this is  a low-grade (low temperature) form of
energy, and opportunities to use it  beneficially are limited.  Within
30 years, the electrical power industry will  require the disposal of
about 21 quadrillion joules (20 trillion Btu)  of waste heat per day (6),
One nuclear power plant having a 1,000 MW capacity can supply enough  waste
heat to accommodate 400 hectares (1,000)acres  of conventional greenhouses


     Greenhouses require large amounts of energy to maintain  adequate
temperatures for crop production.   The amount  of energy required will
vary with location, type of greenhouse, energy conservation measures,
and crop.   In the  Tennessee Valley area, the  energy required  for green-
house crop production may exceed 13.1 Tj/hectare  (12,4 billion  Btu/hectare)
or 5.3  Tj/,4 hectare (5 billion  Btu/acre)  and  in  Minnesota  19,3 Tj/hectare
(18.3 billion Btu/hectare)  or 7.8 TJ/.4 hectare (7.4 billion  Btu/
acre)  (4).   The  U.  S.  Department of Agriculture reported in 1974 that

*1 quad = 1015
                                     \

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108,914,015 m2 (357,329,446 ft2) or 3>320 hectares (8,203 acres) were used
for greenhouse space (5).  By conservative estimates, the greenhouse
industry has grown by 5 percent each year since 1974 with a current esti-
mate of 4,237 hectares (10,469 acres).  The average energy requirement for
greenhouses in the U. S. can probably be estimated by using the average
Btu requirement for greenhouse production in Minnesota and the Tennessee
Valley area which is approximately 16.1  Tj/hectare (15.3 billion Btu/hectare)
or 6.5 Tj/,4 hectare (6.2 billion Btu/acre).  Based on this assumption, the
greenhouse industry uses in excess of 66 quadrillion joules (64 trillion Btu)
annually.  The fuel equivalent of this amount of energy could be beneficially
used in the U. S. alone by utilizing waste heat.  In addition, should most
of the greenhouses throughout the world eventually change to waste heat,
the energy saving will  be even more substantial on a global scale.

     Currently, 30 to 40 percent of the cost of greenhouse crop production
is used for energy and is increasing, while natural  gas and fuel oil sup-
plies are becoming less available for greenhouse heating.  Since most green-
houses are heated with natural gas, the present cost for 67 quadrillion
joules (64 trillion Btu) at $3.04/Gj ($3.20/million Btu) for natural gas
exceeds $204 million annually.  The cost of 67 quadrillion joules (64
trillion Btu) supplied by No.  2 fuel oil at $6.45/Gj ($6.80/mi11ion Btu)
would exceed $433 million.  Using waste heat at $.96/Gj ($1.02/million Btu),
the cost of 67 quadrillion joules (64 trillion Btu)  would be $61.4 million.
In addition to conserving fossil  fuels,  the cost for energy could be
reduced by 232 percent or $142.6 million over the use of natural gas and
$371  million or 605 percent over the use of No. 2 fuel  oil  if waste heat
was used, while at the same time environmental pollution would be reduced
through the reduced combustion of fuel.


OBJECTIVES

     This study investigated the potential  beneficial  use of industrial
waste heat for greenhouse production of bedding plants, cut flowers,
and foliage plants.  The research facilities consisted of a conventional
greenhouse and a greenhouse modified to  use simulated waste heat.

     The major overall  objectives of this research were:  (1)   to test
a feasible way to utilize waste heat, thereby conserving energy, (2)  to
test the suitability of the greenhouse environment for the production
of ornamental  and vegetable bedding crops,  cut flowers and foliage
plants, and (3)  to evaluate the overall economics of the system.  The
more specific and detailed objectives are listed below:

                   Horticultural  Objectives

     1.  To compare the quantitative growth data between the crops
         grown in the control  greenhouse and the crops grown in
         the simulated waste heat greenhouse on the  production of
         bedding plants,  foliage plants  and cut flowers.

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      2.   To  evaluate  the  incidence  of  diseases  between  the  crops
          grown  in  the control greenhouse  and crops grown  in  the
          simulated waste  heat research greenhouse under high
          relative  humidity  (90-100%) conditions.

                            Economic Objectives

      1.   To  compare the annual cost of production for each  crop
          produced  in  the  conventional  greenhouse and the  simulated
          waste  heat greenhouse.

      2.   To  evaluate  the  economic implications  of two production
          management systems in both greenhouses,

      3.   To  conduct limited market tests  to determine consumer
          acceptance of waste heat greenhouse production.

                          Engineering Objectives

      1.   To  compare controlled-environment data of the  control
          greenhouse with  that of the simulated waste heat green-
          house  for the entire year with reference to heating,
          cooling and  dehumidification.

      2.   To  determine the responses of the control greenhouse with
          that of the  simulated waste heat greenhouse resulting
          from changes initiated by a relatively sophisticated con-
          trol system  as well as changes from external pertubations,


A DESCRIPTION OF THE  RESEARCH FACILITIES

     The  research facilities consisted of two quonset-type plastic
greenhouses, each 9.1  m X 21.9 m (30 ft X 72 ft).  The plastic covering
for each  greenhouse consisted of a double layer of Monsanto 602-6 mil
polyethylene plastic.   One greenhouse served as a control  and the other
greenhouse served as  the waste heat research greenhouse,

     The  control greenhouse was not modified in any manner.  It has a
climate control  system equipped with fans, shutters,  plastic convection
tube, two natural gas  heating units, and controls to  provide a suitable
greenhouse environment.

     In £he control greenhouse, cooling is provided by an  evaporative
Kool-cel  pad located  at one end of the greenhouse and two exhaust
fans located at  the opposite end of the greenhouse.   Heat  is supplied
by two natural  gas heaters with a heating capacity of 111  Mj (105,000
Btu) per hour.   The heat is disseminated by a fan through  a 0,61  m
(24 in) polyethylene convection tube with punched holes  to bring  about
even distribution of heat throughout the greenhouse,

*Trade Mark, ACME Engineering and Manufacturing Corporation

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     The waste heat research greenhouse, on the other hand, is modified.
Both heating and cooling are supplied by evaporation from a 4.3 m X 2.7 m
(14 ft X 9 ft) Kool-cel pad through which air is circulated by two large
exhaust fans.  For cooling, air is drawn through the Kool-cel  pad and
discharged directly outside.  Exactly 0.61 m (2 ft) of the Kool-cel pad is
located in the attic plenum.  Intake louvers are located at one end of the
attic plenum.  Since much of the heat from warm water is dissipated in the
top 0.61 m (2 ft) of the Kool-cel  pad, much of the heat is discharged out
of the attic before it reaches the growing area of the greenhouse.  This
modification in the design of the waste heat research greenhouse permits
the use of warm water during the summer months when the temperature of
industrial waste water, especially from power plants, is at its highest;
and yet, it will provide excellent evaporative cooling in the  growing area
of the greenhouse;

     Heating in the waste heat research greenhouse is provided by recircu-
lating air through the attic plenum over the Kool-cel pad and/or the fin-
tube system.

     Simulation of waste heat for the waste heat research greenhouse is
supplied by a 105 KW electric water heater (boiler).  The simulated
temperatures of water were based on the average monthly temperatures of
effluent condenser cooling water of each month of the year as  obtained
from the Tennessee Valley Authority's Browns Ferry Nuclear Power Plant
located in Northern Alabama.

     Located 1.2 m (4 ft) downstream from the Kool-cel  pad is  the fin-
tube system.  The fin-tube system consists of two staggered rows of
0.05 m (2 in) radiation tubes 5.49 m (18 ft) lonq.  The fins on the tubes  are
0.1  m X 0.1  m (4 in X 4 in).  Warm water is pumped through this system
of fin-tubes to provide a dry heat exchange and to aid  in  dehumidification.

     The floor in each greenhouse  consists of a concrete walkway 1.2 m
(4 ft) wide located in the center of the house with the remaining part
of the floor being covered with 0.1 m (4 in) of gravel.

     Figure 1 and Figure 2 are schematic representations of the waste heat
research greenhouse and control  greenhouse, respectively.

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          ATTIC  VENT  FAN
             RECIRCULATION
               SHUTTERS^
            -IlllJIIh
                                               HI-
              HEATING

              COOLING
          EXHAUST
          SHUTTERS
POLYETHYLENE CEILING
                                  —AIR FLOW
                                       (FAN)
                               GROWING AREA
 WATER
 HEATER
            FIN-TUBE  -\
            EXCHANGER   \
Figure 1.   A schematic  representation of the waste heat research greenhouse.

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                                                Hh
                                                                    HEATERS
                           CONVECTION TUBE
             O    O    O    O     O     O
                                                  o   o     o
                    EXHAUST SHUTTERS
                           AIR FLOW
                             (FAN)
CONVECTION-TUBE FAN


       KOOL-CEL PAD
                                              GROWING  AREA
                                                                 SUMP
Figure 2.   A schematic  representation  of the conventional greenhouse.

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                              SECTION 2

                             CONCLUSIONS
HORTICULTURAL

     Cultivars of the following bedding plant species were transplanted
in late January and in early February of 1979 in the conventional green-
house and in the waste heat greenhouse:  begonia, browallia, coleus,
geranuim, impatiens, marigold, pansy, petunia, salvia, tomato, and
verbena.

     The data included in this report suggest that the growth rate of
the bedding plant species grown in this study are not adversely affected
by the waste heat greenhouse environment.

     With the exception of browallia and coleus, the survival rate for
all other species of bedding plants grown in the waste heat research
greenhouse was comparable to the survival rate of those species grown
in the conventional greenhouse.

     It was found that the plants grown in the conventional greenhouse
flowered approximately 7,6 days earlier than those grown in the waste
heat research greenhouse.  However, this may be insignificant when
considering the amount of money saved in fuel cost,

     The following species of foliage plants were transplanted in each
greenhouse from June 12, 1979, through July 14, 1979:  Ardisia humilis,
Asparagus meyerii, Begonia Caribbean mix, Djzyotheca elegantissima,
Hypoestes sanguinolenta, Philodendron pertussum, Schefflera compacta,
and Syngonum podophyllum.

     All of the above species grown in the waste heat research greenhouse,
with the exception of Ardisia humilis, showed a better growth rate than
those grown in the conventional greenhouse.   The growth of Syngonium
podophyllum (nephthytis green) and Philodendron pertussum was statistic-
ally significantly better in the waste heat research greenhouse than in
the conventional  greenhouse.

     The waste heat research greenhouse environment  seems to be highly
suited for growing foliage plants.  This is probably brought about by
the higher percent relative humidity in the waste heat research green-
house than in the conventional greenhouse.   Most foliage plants grow
better under a high percent relative humidity.

     In regards to survival rate, there were no statistically signifi-
cant differences  in survival rate between any of the species grown in
the conventional  greenhouse and the waste heat research greenhouse.  No
diseases were found in either greenhouse.

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 ECONOMIC


     Because data were analyzed from only one crop of bedding plants
 and one crop of foliage plants, the economic conclusions made herein
 are of a preliminary nature.

     This study revealed that the waste heat greenhouse equipped with
 a backup heating system would initially cost $84,506 to $90,605/.4
 hectare (1 acre) or $208,730 to $233,794/hectare more to construct than
 the same size conventional greenhouse.

     If waste heat can be supplied for $0.96/Gj ($1.02/MBtu) as compared
 to $3.04/Gj ($3.20/MBtu) and $6.45/Gj ($6.80/MBtu) for natural gas and
 No. 2 fuel oil, respectively, it may result in a savings of $13,520/.4
 hectare (1 acre) or $33,394/hectare when compared to natural gas and
 $35,685/.4 hectare (1 acre) or $88,142/hectare when compared to No. 2
 fuel oil.

     Considering the current increasing price rates for natural gas
 and No. 2 fuel oil, the number of years required to break even for the
 cost of using waste heat to heat a greenhouse can probably be reduced
 to 3 to 4 years relative to heating with natural gas and 1  to 2 years
 for heating with No.  2 fuel oil  by 1985.

     With reference to marketing and consumer acceptance, customers
 did not show any preference in buying plants grown in the conventional
 greenhouse over those grown in the waste heat research greenhouse.
 The quality of plants grown in the waste heat research greenhouse was
 equal  to the quality of those grown in the conventional  greenhouse.


 ENGINEERING

     The engineering performance of the waste heat research greenhouse
was compared with the conventional greenhouse in regards to heating,
 cooling and relative humidity.

     In regards to maintaining heat, the waste heat research greenhouse
was able to maintain an average low nighttime temperature of 12.0°C
 (53.6°F) over a 24-day period during the month of February while using
water heated to 21.8°C (71.2°F)  with a flow rate of 109 liters/minute
 (24 gallons/minute).   The average low outside temperature for the same
 period was 2.6°C (36.7°F).   Bedding plants grown in the waste heat
 research greenhouse did not suffer any adverse effects when compared to
 those grown in the conventional  greenhouse.   The waste heat research
 greenhouse is quite capable of providing a suitable winter-time tempera-
 ture for the species  of bedding plants tested in this project.

     With reference to cooling,  over a 4-day period the waste heat
research greenhouse in July was  able to maintain an average high day-
 time temperature of 30.0°C (86.0°F) in comparison to 29.4°C (85°F)
maintained by the conventional greenhouse.   The temperature of the

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entering effluent water used to cool the waste heat research greenhouse
during this period was 43. PC (109.6°F).  The average outside temper-
ature for the same four-day period was 38.6°C (101.5°F).  These data
indicate that warm effluent water can be used effectively to cool
greenhouses, provided that much of the heat associated with the effluent
water can be dissipated from the greenhouse through an attic before
reaching the growing area.

     For the most part, the relative humidity averaged only a few percent
higher in the waste heat research greenhouse than it did in the conventional
greenhouse.  At no time was there condensation of water vapor observed on
the foliage of plants grown in the waste heat research greenhouse or the
conventional greenhouse.

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                               SECTION 3

                            RECOMMENDATIONS
It is recommended that:
     (1)  The industry associated with the production of thermal  water
          (waste heat) and the greenhouse industry apply the findings
          of this project to help eliminate thermal  pollution of  our
          waterways while benefitting both industries.

     (2)  A longer study period (4 to 5 years)  be given  to  the evaluation
          of the crops observed in this study to  help verify the  results
          stated herein.

     (3)  A longer study period (4 to 5 years)  be given  to  further
          evaluate the greenhouse design and control  of  the greenhouse
          environment.

     (4)  Additional  research  be  given to finding those  species of
          bedding plants  and foliage  plants that  are  best suited  to
          the environment of a waste  heat greenhouse.

     (5)  The growth  response  of  woody ornamentals be tested  with waste
          heat.

     (6)  More research  be  given  to the economic  evaluation in comparing
          waste  heat  greenhouse crop  production with  that of  conventional
          greenhouse  crop production.
                                 10

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                               SECTION 4

                         HORTICULTURAL STUDIES
     Horticultural studies began in January, 1979.  All horticultural
studies followed the time table listed below:

     1.  January through April of 1979, cultivars of the 10
         leading ornamental bedding plant crops along with the
         2 leading vegetable bedding plant crops were grown in
         each greenhouse.

     2.  May through September of 1979, cultivars of the leading
         species of foliage plants and plants adapted for hanging
         baskets were grown in each greenhouse.

     The greenhouses were not completed in time to schedule a fall crop
(August through December of 1978).  Therefore, this report contains data
collected on bedding plants grown in each greenhouse from January, 1979,
through April, 1979, and foliage plants grown June, 1979, through
September, 1979.

     Both the conventional greenhouse and the waste heat research green-
house were operated as a commercial-type enterprise, and all  parts of
the system were evaluated, both from the standpoint of mechanical opera-
tion and as a satisfactory structure for plant growth.

Bedding Plants

     All bedding plants were grown from super seddings obtained from the
Ball Seed Company of Chicago, Illinois.  Jiffy Mix Plus served as the
soil medium.

     Seedlings for each species and cultivar were transplanted to cell
paks (32/tray), with the exception of geraniums which were transplanted
into O.lm (4 in) standard pots.  After transplanting, trays and pots for
each species were equally divided, and half were placed into  the conven-
tional  greenhouse and the other half placed in the waste heat research
greenhouse.

     Figure 3 depicts the arrangement of the bedding plant species in
both greenhouses.  The statistical design used for the analysis of
variance was the randomized complete-block design (10).  A 1.2m (4 ft)
space was placed between each block (replication).

     Dry Weights (the whole plant).  Table 1  depicts the mean dry weight
of the whole plant for all species, except peppers.   (The pepper seedlings
were lost in both greenhouses due to mice).  The growth rate  of geraniums,
petunias, and verbenas in the conventional greenhouse was statistically
greater as compared with the same species grown in the waste  heat research
greenhouse.  Although begonias, browallias, coleus,  impatiens, marigolds,

                                  11

-------
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Figure 3.   The arrangement  of bedding  plant species  in the waste heat  research greenhouse.

-------
 pansies,  salvias  and  tomatoes grown  in  the conventional greenhouse
 showed  a  slightly better  growth  than  those grown  in  the waste  heat
 research  greenhouse,  the  differences  in growth  rates were  not  statis-
 tically significant.

 TABLE 1.  MEAN  DRY WEIGHT (g) of 8 WHOLE PLANTS/REPLICATION,
          APRIL 1, 1979Z
SPECIES

Begonia
Browallia
Coleus
Geranium
Impatiens
Marigold
Pansy
Petunia
Sal via
Tomato
Verbena
DAYS FROM
TRANSPLANTING

     50
     48
     49
     47
     49
     50
     40
     49
     48
     40
     40
CONVENTIONAL
GREENHOUSE
            WASTE HEAT
            RESEARCH GREENHOUSE
   11.
    8.
    7.
   17,
   12.
   14.
   11.
   17.
   13.
   17.
25a
OOa
87a
25a
87a
90a
50a
50a
OOa
50a
10.
 6.
 6.
13.
11.
14.
10.
14.
12.
15.
87a
37a
25a
25b
37a
OOa
25a
87b
25a
30a
   13.70a
                 10.37b
zMeans sharing uncommon letters are significant at the 5% level.

     Table 2 shows the dates plants were treated with a 0.5% solution
of B-nine, a growth retardant.  The different species of bedding plants
were sprayed with the growth retardant when they showed signs of stretch-
ing.  B-nine was applied with a 7.57 1 (2 gal) sprayer.  Some difficulty
was experienced with obtaining a uniform flow from the sprayer.  This
nonuniform application of B-nine probably resulted in some variation in
growth rate noted among species grown in the same greenhouse as well as
differences noted among species grown in separate greenhouses.

TABLE 2.  SPRAY DATES OF B-NINE GROWTH RETARDANT
SPECIES

Browallia
Coleus
Geranium
Impatiens
Pansy
Petunia
Salvia
Verbena
                 SPRAY DATES

                 3-27-79
                 3-13-79  &  4-16-79
                 3-17-79, 3-27-79 &  4-16-79
                 3-12-79  &  3-27-79
                 3-13-79
                 3-12-79
                 3-12-79
                 3-12-79  &  3-27-79
     Dry Weight (aerial plant parts).  Table 3 shows the mean dry weight
of the aerial parts of each species.  Coleus and tomato plants grown in
the conventional greenhouse showed a statistically significant better
growth rate than those grown in the waste heat research greenhouse.
                                   13

-------
 Petunias grown  in  the  waste  heat research  greenhouse  showed  a  growth
 rate significantly better than  those  grown in  the  conventional  green-
 house,  but better  growth  was probably due  to a heavier  application  of
 B-nine  in the conventional greenhouse.

 TABLE 3.   MEAN  DRY WEIGHT (g) OF 20 AERIAL PLANT PARTS/REPLICATION,
           APRIL 12,  19792
 SPECIES

 Begonia
 Browallia
 Coleus
 Geranium
 Impatiens
 Marigold
 Pansy
 Petunia
 Sal via
 Tomato
 Verbena
DAYS FROM
TRANSPLANTING

     61
     59
     60
     58
     60
     61
     51
     60
     59
     51
     51
CONVENTIONAL
GREENHOUSE

   19.75a
   12.90
    9.63a
   40.87a
   Sl.OOa
   24.50a
   22.12a
   25.50a
   22.37a
   45.00a
   23.50a
WASTE HEAT
RESEARCH GREENHOUSE

     19.37a
      9.30a
      6.63b
     42.51a
     29.00a
     25.50a
     22.12a
     37.75b
     20.12a
     42.50b
     23.50a
zMeans sharing uncommon letters are significant at the 5% level.

     Geraniums and marigolds grown in the waste heat research greenhouse
showed a slightly better growth rate (but not statistically) than those
grown in the conventional greenhouse.  The reverse was true for begonias,
browallias, impatiens and salvias.  Pansies and verbenas showed equal
growth rates in both greenhouses.

     Flowering Dates in Paks and Pots.   Table 4 depicts and compares the
number of days required to flower in paks and pots for each species in
each greenhouse.  The plants grown in the waste heat research greenhouse
flowered on the average of 7.6 days (approximately one week) later than
those grown in the conventional greenhouse.  The greatest difference in
flowering was noted in the geraniums which flowered 9 days earlier in
the conventional greenhouse.  Begonias, browallias, impatiens, and mari-
golds flowered 8 days earlier in the conventional  greenhouse.  Pansies,
petunias, salvias, and verbenas grown in the conventional greenhouse
flowered 7 days earlier than those grown in the waste heat research
greenhouse.

     Tomatoes are not listed in Table 4 because tomato bedding plants
were sold according to plant size.  Tomato plants  had reached a saleable
size in both greenhouses at the end of 4 weeks.
                                    14

-------
 TABLE 4.  FLOWERING DATES OF BEDDING PLANTS IN PAKS
 SPECIES
    CONVENTIONAL
    GREENHOUSE
   WASTE HEAT
   RESEARCH GREENHOUSE
       DAYS DIFFERENCE
       IN BLOOMING
            TIME FROM               TIME FROM
            TRANSPLANTING   DATE OF TRANSPLANTING   DATE OF
            TO BLOOM (DAYS) BLOOM   TO BLOOM  DAYS) BLOOM
Begonia
Browallia
Geranium
Impatiens
Marigold
Pansy
Petunia
Sal via
Verbena
31
61
79
33
23
36
39
38
45
3-13-79
4-12-79
4-30-79
3-16-79
3-5-79
3-28-79
3-21-79
3-20-79
4-6-79
39
69
88
41
31
43
46
45
52
3-21-79
4-20-79
5-9-79
3-24-79
3-13-79
4-4-79
3-28-79
3-27-79
4-13-79
8
8
9
8
8
7
7
7
7
      Survival  Rate.   Table  5  shows  the  survival  rate  for  each  species  of
 bedding  plants  in  the conventional  greenhouse  and  the waste  heat  research
 greenhouse.  Only  two species,  browallia  and coleus,  showed  a  statistically
 significant  better survival rate  in  the conventional  greenhouse than  in  the
 waste heat research  greenhouse.   Browallia  had an  81.0% survival  rate  in
 the  conventional greenhouse and 66.0% in  the waste heat research  green-
 house.   Coleus  had an 89.5% survival rate in the conventional  greenhouse
 compared to  78.0%  in  the waste  heat  research greenhouse.   For  all other
 species,  the survival  rate was  not  statistically significantly different
 between  the  two greenhouses.

 TABLE 5.  MEAN  SURVIVAL RATE  BASED ON 4 FLATS/REPLICATION  (128 PLANTS)
          APRIL 10,  1979Z
SPECIES

Begonia
Browallia
Coleus
Geranium
Impatiens
Marigold
Pansy
Petunia
Sal via
Tomato
Verbena
DAYS FROM
TRANSPLANTING

     59
     57
     58
     56
     57
     59
     49
     58
     57
     49
     49
CONVENTIONAL
GREENHOUSE

   95.5
   81. Oa
   89.5a
   98.8a
  100.Oa
   98.7a
   99.2a
  100.Oa
   96.2a
  100.Oa
   97.5a
WASTE HEAT
RESEARCH GREENHOUSE

     91.7a
     66.Ob
     78.Ob
     98.4a
    100.Oa
     96.7a
     99.5a
    100.Oa
     97.5a
    100.Oa
     97.5a
zMeans sharing uncommon letters are significant at the 5% level
                                   15

-------
 Foliage Plants

      Foliage plants were grown in both greenhouses from June 12, 1979
 through September, 1979.  Table 6 shows the species and cultivars that
 were grown in both greenhouses.

 TABLE 6.  SPECIES AND CULTIVARS

      SPECIES                           TRANSPLANTING DATE

 Ardisia humilis                             7_14_79
 Asparagus  meyerii                          7-14-79
 Begonia Caribbean mix                      6_2i-7g
 Dizyotheca elegantissima                   6-21-79
 Hypoestes  sanguinolenta                     7-5-79
 Philodendron pertussum                     7-5-79
 Schefflera compacta                        7-5-79
 Syngonium  podophyllum                      6-21-79

      Foliage plants were also  obtained  from Ball Seed  Company  as  super
 seedlings.   All  seedlings  did  not  arrive  on the  same date,  and  trans-
 planting took place from June  12,  1979, through  July 14,  1979.

      Dry weight  (aerial  plant  parts).   Dry  weights  were taken August 23,
 1979, on Dizyotheca elegantissima  (false  aralia). Ardisia  humilis,
 Begonia  Caribbean mix, Syngonium podophyllum (nephthytis  green) and
 Hypoestes  sanguinolenta  (polka  dot plant).

      For comparison,  Table 7 depicts the  mean dry  weight  for the  five
 species  of  foliage  plants grown in both greenhouses.   With  the exception
 of Ardisia  humilis, the  remaining species grew better  in  the waste heat
 research greenhouse than they did in the  conventional  greenhouse.  Syngo-
 mum  podophyllum  (nephthytis green) grew  significantly better in  the
 waste heat  research greenhouse  than it did  in the  conventional greenhouse.

 TABLE 7.  MEAN DRY  WEIGHT (g) OF AERIAL PLANT PARTS, AUGUST 23, 1979Z

               PLANTS/      DAYS FROM      CONVENTIONAL  WASTE HEAT
 SPECIES        REPLICATION  TRANSPLANTING  GREENHOUSE    RESEARCH GREENHOUSE

 Dizyotheca
 elegantissima     10            63           6.38a           7 12a
Ardisia humilis    10            40           3.74a           3.66a
Begonia Carrifa-
 bean mix          10            63          19.72a          21.43a
Syngonium
 podophyllum       20            63          34.80a          43.70b
Hypoestes
 sanguinolenta     20            63         100.20a          92.20a

zMeans sharing uncommon letters are significant at  the  5% level.

                                   16

-------
      The mean dry weight for Asparagus meyerrL Philodendron pertussum
 and Schefflera compacta were taken on September 19, 1979.  Table 8 shows
 that Philodendron pertussum grew significantly better in the waste heat
 research greenhouse than in the conventional greenhouse.  Although the
 growth rates were not significantly better, both Asparagus meyerii and
 Schefflera compacta grew better in the waste heat research greenhouse
 than in the conventional greenhouse.  These data indicate that foliage
 plants responded well to the waste heat greenhouse environment.

 TABLE 8.   MEAN DRY WEIGHT (g) OF AERIAL PLANT PARTS, SEPTEMBER 19, 1979Z

                PLANTS/      DAYS FROM      CONVENTIONAL  WASTE HEAT
 SPECIES        REPLICATION  TRANSPLANTING  GREENHOUSE    RESEARCH GREENHOUSE

 Asparagus
  meyerii            10            67           5.31a           5.75a
 Philodendron
  Pertussum          5            76          19.32a          22.60b
 Schefflera
  compacta           5            76          12.45a          13.96a

 zMeans  sharing uncommon  letters  are significant at  the  5% level.

      Survival  Rate.   Table  9  shows  the  survival  rate for each  species
 grown  in  both  greenhouses.   In regards  to  survival  rate,  the waste  heat
 research  greenhouse  provided  a favorable environment equal  to  that  of  the
 conventional greenhouse.  As  a result of using  normal disease  preventive
 practices  which were  identical for  each greenhouse,  no  evidence of  any
 diseased  plants was  found.

 TABLE 9.   MEAN SURVIVABILITY  BASED  ON 100  PLANTS/REPLICATION
           AUGUST  23,  1979Z

               DAYS  FROM            CONVENTIONAL      WASTE  HEAT
 SPECIES        TRANSPLANTING        GREENHOUSE        RESEARCH GREENHOUSE

 Dizyotheca
 elegantissima       63              100.Oa              100 Oa
 Ardisia humilis      40              100.Oa              100 Oa
 Asparagus meyexjj_   40              100.Oa              loo'oa
 Caribbean mix
 be9onia             63               97.3a               96.8a
 Syngonium
 podophyllum         63              100.Oa              loo oa
 Philodendron
 pertussum           49              100.Oa              100 Oa
Hypoestes
 sanguinolenta       49              100.Oa              loo oa
Schefflera
 comPacta            49              loo.Oa              100.Oa

zMeans sharing  uncommon letters  are significant at the 5% level.

                                   17

-------
                                SECTION  5

                         GREENHOUSE  PERFORMANCE
      Histories  for  temperature  and  percent  relative  humidity were
 compared  for  the  conventional greenhouse  and  the waste  heat research
 greenhouse.   Temperature was  recorded  by  a  Bendix  hygro-thermograph,
 and  the percent relative humidity was  measured with  a hand psychro-
 meter.  Both  temperature and  the percent  relative  humidity readings
 were taken on the floor in  the  center  of  each greenhouse and on the
 outside of the  greenhouses.

      The  flow rate  of warm  water was set  at 109 1/min (24 gal/min)
 in the waste  heat research  greenhouse; the  same flow rate was used
 for  both  winter and summer.

      The  temperature of power plant effluent water will vary according
 to whether the  power plant  is operating on a closed  cycle or an open
 cycle and also  according to each month of the year.  Table 10 shows
 the  temperature of  effluent water for  both a closed  cycle and an open
 cycle power plant at the TVA's  Browns  Ferry nuclear  power plant located
 in north  Alabama.   As shown in  Table 10, the temperature of effluent
 water will be higher from a power plant operating on a closed cycle
 than  from a power plant operating on an open cycle.
TABLE 10.
MONTH

January
February
March
April
May
June
July
August
September
October
November
December
AVERAGE MONTHLY TEMPERATURE OF EFFLUENT WATER AT BROWN'S
FERRY NUCLEAR POWER PLANT LOCATED IN NORTH ALABAMA9
                                     CLOSED CYCLE
                                     TEMPERATURE
OPEN CYCLE
TEMPERATURE
C
21.30
21.80
24.40
31.30
35.80
40.60
43.10
43.20
40.60
35.70
29.10
24.40
F
70.34
71.24
75.92
88.34
96.44
105.08
109.58
109.76
105.08
96.26
84.38
75.92
C
43.10
43.90
45.10
47.20
49.00
50.50
51.20
51 . 20
49.90
47.70
45.40
F
109.58
111.00
113.18
116.96
120.20
122.90
124.16
124.16
121.82
117.86
113.72
                                  43.20
109.76
aEarl Burns.  Personal Communication.  TVA.  October, 1978.

     In this study, the temperature of water used in the waste heat research
greenhouse simulated the temperature of effluent water coming from an open
cycle power plant throughout the year, with the exception for short periods
when the temperature of effluent water coming from a closed  cycle plant was
simulated for testing purposes only.
                                   1!

-------
 HEATING

      During  February,  1979, the  temperature of effluent water from
 open  cycle operation was 21.8°C  (71.2°F) as shown in Table 10.  The
 water used in  the waste heat  research greenhouse was heated to this
 temperature.   Each greenhouse had the nighttime temperature set at
 15.5°C (60°F)  and a daytime temperature setting at 21.1°C (70°F).

      During  a  24-day period in February, the waste heat research
 greenhouse maintained  an average low night temperature of 12.0°C
 (53.6°F).  The conventional greenhouse average low night temperature
 was 14.1UC (57.4°F).   This was a difference of 2.1°C (3.8°F).  The
 average  low  outside night temperature for this period was 2.6°C
 (36.7°F) as  depicted by Figure 4.

      It  is important to note  here that the temperature control box in
 each  greenhouse was located approximately 1.2 m (4 ft) above floor level.
 However, the hygro-thermographs  recorded the temperatures at floor
 level  where  bedding plants are commonly grown in greenhouses.  Temper-
 ature  stratification is common in greenhouses and is the major reason
 for the  difference between the greenhouse set temperature and the
 temperatures recorded  at floor level.

      Figure  5 depicts  the average high daytime temperature maintained
 in the waste heat research greenhouse and the conventional greenhouse
 along  with the average high outside temperature for the same 24-day
 period in February.  The waste heat research greenhouse maintained an
 average  high temperature of 18.4°C (65.1°F), whereas the conventional
 greenhouse maintained  an average high temperature of 21.6°C (70.9°F).
 The average  high outside temperature for the period was 12.6°C (54.7°F).

     One of  the coldest days of the year was February 18,  1979.   On
 that date, there was an ice-snow storm.   Wind speed reached above
 17.9 m/s (40 mph) and  the outside temperature reached a low of -4.4°C
 (24°F) (Figure 6).   The lowest temperature reached in the  waste  heat
 research greenhouse was 8.9°C (48°F).  This was less than  2°C difference
 in the lowest temperature recorded in the conventional  greenhouse which
was 10.6°C (51°F).

     Figure  7 shows the 24-hour per day temperature histories for both
 greenhouses over a  4-day period in January.

     The waste heat research greenhouse fin-tube heat exchanger  system
was designed to provide adequate dry heat.   The fin-tube heat exchanger
system consisted of 18 fin  tubes, 0,05 m (2 in) diameter by 5.49 m (18 ft)
length, 0.05 m (2 in)  square plate fins,  with 2 fins/0.03  m (1  in).   However
the 1/3 hp pump provided only enough water to fill  the  bottom 4  fin tubes
with warm water.   Therefore, the heat in  the waste research greenhouse was
obtained by pumping water over the pad.
                                   19

-------
IN3
o
          30
     n>

     -o
     05
     -5
     DJ
     n>
      o
     o
         10
                                                                                                           86
                                                                                                           68
WASTE HEAT
GREENHOUSE
       14.1.

-(53.6°F)
                          CONVENTIONAL
                           GREENHOUSE
-(57.4°F)
                                                                                                           50
n>

-a
n>
-5
DJ
t-t-
C
-s
ro
                                                                          2.6_OUISIDL___(36.70F)
                                                                                                           32
    Figure 4.  Average low  night  air temperature from February  1  through February 24, 1979.

-------
      40  -
      30
-s
QJ
     20
     10
                                                                             •104
                                                                               86
                 18.4-
WASTE HEAT
GREENHOUSE
                         CONVENTIONAL
                  21-6_	GREENHOUSE
68
-s
QJ
H-
c:
-s
                                                                     1? fi.   OUTSIDE
                                                                 J54.7°F)
                                                                               50
Figure 5.  Average high daytime air temperature  from February 1  through February 24, 1979.

-------
          30
          20
ro
     ro

    T3
     ro
     -s
     ro
     o
    o
          10
                 8.9-
                      -4.4*
         -10
OUTSIDE    (24.QQF)
                        WASTE  HEAT

                        GREENHOUSE
     10.6-

-(48.QOF)
                                                                                CONVENTIONAL

                                                                                 GREENHOUSE
                                                                                                            86
                                                                                                           68
                                                                                                           50
0)

-a
ro
-s
a>
,t-i-
c:

ro
                                                                                                           32
                                                                                                           14
     Figure  6.   Comparative  air temperature history of 24-hour period in the waste  heat  research  greenhouse
                during  an  ice-snow storm on February 18, 1979.

-------
IX)
OJ
           ro
           3
           TD
           ro

           G)
           rp
            o
           o
                                      CONVENTIONAL  GREENHOUSE
                            	  WASTE  HEAT  GREENHOUSE

                                      OUTSIDE
                   0 4 8 12  16  20 24  4

                       January  21
8  12 16 20 24  48   12  16   20  24   48  12  16  20

  January 22       January 23        January  24
                                                          
                                                          n

                                                          -d
                                                                                                   -5
                                                                                                   QJ
     Figure 7.  Comparative air  temperature  histories  over a four-day period in January, 1979,

-------
COOLING
     Both greenhouses were covered with an 80 percent K-shade cloth
to provide favorable light conditions for foliage plants and to aid
in cooling.  Figure 8 shows the average high temperature for both
greenhouses during a hot 4-day period in July using warm water heated
to 43.1°C (109.6°F) to cool the waste heat research greenhouse.  During
this 4-day period, the average high temperature in the waste heat
research greenhouse was 30°C (86°F) and 29.4°C (85°F) in the conven-
tional greenhouse.  The average high outside temperature covering the
same period was 38.6°C (101.5°F).  Figure 9 shows cooling for 24 hours
per day during the same 4-day period in July.

     As mentioned previously, the temperature of effluent water
coming from a closed cycle power plant is higher than the temperature
of effluent water coming from an open cycle power plant.  To test
the effectiveness of cooling a greenhouse with the higher temperature
effluent water coming from a closed cycle power plant and under high
relative humidity conditions, the hot water heater was set at 51.2°C
(124.2°F) for several days during July and August.

     Figure 10 shows the temperatures maintained by each greenhouse
and the outside temperature for a 4-day period during August while
using the higher temperature water in the waste heat research green-
house.  The average high temperature reached in the waste heat research
greenhouse during this 4-day period was 27.2°C (81°F) and 25.4°C
(77.8°F) in the control greenhouse.  This represented only a difference
of 1.8°C (3.2°F) between the control greenhouse and the waste heat
research greenhouse.  The average high temperature reached outside of
the greenhouses was 34.6°C (94.3°F) for the same 4-day period.

     It is important to note that evaporative cooling is limited by
the attainment of 100% relative humidity in a greenhouse and the rela-
tive humidity of the outside air supplied to the evaporative cooler.
As mentioned in the next section, the relative humidity in the waste
heat research greenhouse was generally higher than the relative humidity
in the conventional greenhouse.  However, the noted differences in
relative humidity between the two greenhouses were generally small.
Therefore, if the relative humidity can be controlled, the data repre-
sented by Figure 10 indicate that the higher temperature effluent water
from a closed cycle power plant can be used effectively to cool green-
houses during the hot summer months.

     An effort was made to determine the rate of sensible heat exchange
from effluent water to air.  The temperature of effluent water (from
the hot water heater), the temperature of the effluent water 0.61 m
(2 ft) below the top of the evaporative pad (attic level),  and the
temperature of the effluent water at the base of the evaporative pad
2.7m (9 ft) below the top of the evaporative pad, were taken.  The
average temperature of effluent water for each of the above points

                                   24

-------
0)
3
T3
rt>
-5
Q)
(-+
c:
-~>
o>
      40
      30
20
      10
                                                                      38.6-
                                                                              OUTSIDE
                        WASTE HEAT
                 ?n n   GREENHOUSE
                               -(86.0°F)
                                           29.4
CONVENTIONAL
 GREENHOUSE  (g5.nQF)
                                                                                    •(101.5°F)
                                                                                                       104
                                                                                                        86
                                                     68
                                                                                                  50
                                                                                                       32
                                                                                                        rp
                                                                                                        -5
                                                                                                        -5
                                                                                                        o>
Figure 8.   Average  high greenhouse temperatures with water  heated  to  43.1°C (109.6°F) in the waste
            heat  research greenhouse from July 1 through July  4,  1979.

-------
en
      CO

      T3
      CO
      -s
      01
      -s
      CO
       o
      :o
            50
            40
            30
            20-
                                   OUTSIDE


                                   WASTE HEAT GREENHOUSE
                  	  CONVENTIONAL GREENHOUSE
            10
         122
         104
          86
          68
MM  50
                   4  8 12 16 20 24  4  8  12 16 20 24  4  8 12 16 20 24  4  8  12  16  20  24
CO

-a
a>
-s
QJ
cf
C

ro
  Figure  9.   Comparative  cooling during 24-hour cycles between waste heat greenhouse  and
             conventional  greenhouse using water heated to 43.1°C (109.6°F).

-------
            40
                                                      104
34.6_
                             OUTSIDE
            30
[ND
      ro
      3
      -a
      ro
      -s
      CU
      . o
      -o
                             WASTE HEAT
                      97 9   GREENHOUSE    («l.nQF)
            20
            10
CONVENTIONAL
 GREEMHOUSF
                                                                                                (Q/I
                                                                                                              86
                                                                                                             68
                                         rt>

                                         T3
                                         rt>
                                         -s
                                         CD
                                         c-t-
                                                                                                                    ro
                                                                                                             50
                                                                                                             32
     Figure  10.  Average  high  temperatures reached in greenhouses using water  heated  to 51.2°C (124.6°F)
                 the waste  heat  research greenhouse simulating the temperature of  effluent water from a
                 closed cycle  plant (August 14-17, 1979).

-------
over a 6-day period  (August 29, through September 3, 1979) is depicted
in Figure  11.  There is a total average drop in temperature of 27.5°C
(49.50F) from the temperature of the effluent water to the base of the
evaporative pad and a 21.1°C (38.0°F) drop in temperature from the tem-
perature of the effluent water just 0.61 m (2 ft) below the top of the
evaporative pad.  This indicated that 77 percent of the total amount of
heat dissipated from effluent water by evaporative cooling occurred in
the top 0.61 m (2 ft) of the evaporative pad.  Since the top 0.61 m (2 ft)
of the evaporative pad was  above the attic level, it meant that over
three-fourths of the heat from the warm effluent water was exhausted out
of the attic plenum and never entered the growing area of the greenhouse.
This also meant that the attic plenum was effective in dissipating the
excess heat associated with effluent water from the growing area of the
greenhouse during the warm months of the year.  Furthermore, it permitted
the use of a greater volume of warm effluent water during the warm months
of the year without adversely affecting greenhouse crop production.  The
greater the volume of warm water used by a greenhouse operator during
the summer months, the more beneficial it is to the power plant.


RELATIVE HUMIDITY

     Due to the large cost over-run on the construction of the two
greenhouses, funds were not available to purchase three recording
hygrometers.  A hand psychrometer was purchased during the spring of
1979.  Therefore, data concerning the relative humidity were taken
during the spring and summer months only.

     All  psychrometric readings were taken at floor level  in the
center of each greenhouse.   Table 11 shows the relative humidity for
each greenhouse and the outside for a 10-day period during the month
of August under various environmental conditions and at different times
during the 24-hour day.  Table 11  shows that the relative humidity was
generally higher in the waste heat research greenhouse than it was in
the conventional  greenhouse.  However, in some instances there was
either no difference or only small  differences between the relative
humidity in the waste heat research greenhouse and conventional  green-
house at the time the psychrometric readings were taken.   At no time
was there any observed condensation of water vapor on foliage of plants
grown in either greenhouse.   The high relative humidity did not pose a
problem in either greenhouse.

     It is important to note that each psychrometric reading in Table
11 took approximately 3 minutes.   The psychrometric readings were made
by using a slide rule humidity calculator.   Although extreme care was
used in taking the relative humidity readings from the slide rule
humidity calculator, there is  a possibility that some errors could
have been made.   This is  probably exemplified by the 12:00 a.m.  and
3:00 p.m.  relative humidity readings taken on 8-23-79 for  both green-
houses as well  as for the relative  humidity readings taken on 8-25-79
and 8-26-79 for the waste heat research greenhouse as depicted in
Table 11.   The relative humidity of the outside air and the prevailing

                                 28             :

-------
             53.7-
                 TEMPERATURE  OF
                 EFFLUENT WATER
      50
      40 —
  fD
  -a
  fD
  a>
  03
  O
  o
      30
      20
      10
•(128.7°F)
    TEMPERATURE OF
    EFFLUENT WATER
    AT ATTIC LEVEL
                                32.6
                                                      (90.7°F)
                         TEMPERATURE OF
                         EFFLUENT WATER
                         AT BASE OF PAD
       OUTSIDE
28.6 TEMPERATURE
                                                       26.2
                                        (79.1°F)
                                                                                                        22
                                                                                                        04
                                                                                                        86
                                  -a
                                  ro
                                  -s
                                                                                                              fD
                                                                                                        68
                                                                                                        50
Figure 11.  Potential for sensible heat exchange from effluent water to air during evaporative cooling
            in the waste heat research greenhouse from August 29 through September 3, 1979.

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 TABLE  11.
PERCENT RELATIVE HUMIDITY WITH EFFLUENT WATER TEMPERATURE
SET AT 51.7°C (125.0°F)
 DATE
  TIME
8-15-79
8-17-79
8-17-79
8-18-79
8-19-79
8-20-79
8-21-79
8-22-79
8-23-79
8-23-79
8-23-79
8-25-79
'8-26-79
8-26-79
5:00 p.m
12:40 p.m
6:10 p.m
2:00 p.m
2:00 p.m
1:20 p.m
12:00 a.m
12:00 a.m
12:00 a.m
3:30 p.m
11 :30 p.m
12:30 p.m
1:00 p.m
8:00 p.m
WASTE HEAT
RESEARCH
GREENHOUSE

    80
    83
    92
    70
    68
    80
    92
    96
    96
    96
   100
    80
    82
    96
CONVENTIONAL
GREENHOUSE

   80
   82
   87
   70
   65
   80
   92
   92
   98
   92
  100
   72
   70
   96
         OUTSIDE
OUTSIDE  CONDITIONS

  62      cloudy
  68      cloudy
  68      cloudy
  52      partly cloudy
  46      clear-sunny
  56      partly cloudy
  80      midnight
  78      midnight
 100      midnight-raining
 100      raining
 100      night-raining
  78      partly cloudy
  72      partly cloudy
  84      cloudy
environmental conditions at the time the relative humidity readings
were taken on the previously mentioned dates do not support the rela-
tive humidity readings found in the greenhouses and are probably
erroneous.

     The relative humidity in a greenhouse can quickly change as
the external environmental conditions change (such as sunlight, cloud
cover or rain).  A better evaluation could have been given on the
comparison between the relative humidity in the waste heat research
greenhouse and the conventional greenhouse with a 24-hour per day
recording hygrometer.

     Although psychrometric determinations were not made during the
winter months due to the lack of a psychrometer, visual observations
were noted.  When fogging was observed in the waste heat research
greenhouse in the winter, it always occurred at night or during the
daytime when the cloud cover was heavy.  The fog always formed about
4 feet above the floor level and upward to the attic.  The foliage
of bedding plants, which were grown on the floor of each greenhouse,
never showed any signs of condensation of water vapor.

     Fog formation in the winter months can be eliminated from a
waste heat greenhouse by the use of dry heat exchangers such as a
fin-tube system.  As noted earlier, the pump installed to circulate
water through the 18 radiation fin-tubes has only sufficient capacity
to circulate water through the bottom 4 of these tubes.  Therefore,
only 22 percent of the radiation fin-tube system was providing heat
or participating in the heating and drying process.
                                  30

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                            SECTION  6

             ECONOMIC APPROACH AND MARKETING STUDIES
 ECONOMIC APPROACH

     Because data were analyzed from only one crop of bedding  plants
 and one crop of foliage  plants, the economic projections made  herein
 are of a preliminary nature.

     The economic approach  in this study is based on a comparison
 between a year-round commercial waste heat greenhouse operation with
 that of a conventional greenhouse operation.  The projected savings
 in fossil fuel and cost  of  greenhouse production are on a  .4 hectare
 (1 acre) basis.

     The economics discussed in this study are based on one crop of
 bedding plants (winter and  spring of 1979), one crop of foliage plants
 (spring and summer of 1979), and a projected crop of potted chrysan-
 themums and poinsettias  (summer and fall of 1979).  A costrreturn for
 each type of greenhouse  operation is based on 0.093 m2 (ft2) of space
 used per flat base and per  pot base for certain crops grown in this
 study with reference to  an  annual savings in fossil fuel and the cost
 of fossil energy for the greenhouse production of these crops.

     The economic data in this study are based on the following:  (1)
 the difference in construction cost of a .4 hectare (1 acre) waste
 heat greenhouse compared to a .4 hectare (1 acre) conventional green-
 house, (2) the cost of a back-up heating system for a .4 hectare (1
 acre) waste heat greenhouse, (3) the average annual energy (Gj) require-
ment needed to heat a .4 hectare (1 acre) greenhouse in the U. S., (4)
 the current cost/Gj for  natural gas and No. 2 fuel oil, (5) the projected
 cost for the waste heat, and (6) the wholesale value of certain crops
grown in this study.
CONSTRUCTION COST

     Basic Cost.  The cost of construction materials used to build the
9.1 m X 21.9 m  (30 ft X 72 ft or 2,160 ft2) conventional greenhouse
was $5,264 or $26.24/m2 ($2.44/ft2).  This cost is equivalent to
$106,157/.4 hectare (1 acre) or $262,207/hectare.  The cost of erecting
the 201 m2 (2,160 ft2) conventional greenhouse was $7.96/m2 ($0.74/ft2)
or $1,600 which is equivalent to $32,267/.4 hectare (1 acre) or $79,6987
hectare.  The combined total cost of construction materials and the
erection of the 201 m2 (2,160 ft2) conventional greenhouse was $6,863
or$34.19/m2($3.18/ft2).  This cost is equivalent to $138,404/.4 hectare
(1 acre) or $341,858/hectare.

     The cost of construction materials for the 9.1 m X 21.9 m (30 ft X
72 ft or 2,160 ft2) waste heat research greenhouse was $8,098 or

                                   31

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 $40.32/m2  ($3.75/ft2).   This  cost  is  equivalent  to  $163,3107.4  hectare
 (1  acre) or  $403,375/hectare.  The  cost  of erecting  the 201 m2  (2,160
 ft2) waste heat  research greenhouse was  $2,532 or $12.58/m2 ($1.17/ft2)
 which  is equivalent  to  $51,062/.4  hectare  (1 acre)  or  $126,123/hectare.
 The combined total cost of  construction  materials and  erection  of the
 201 m2 (2,160 ft^) waste heat  research greenhouse was  $10,630 or
 $52.90/m2  ($4.92/ft2).   This  cost  is  equivalent  to  $214,372/.4  hectare
 (1  acre) or  $529,499/hectare.

     The average cost of construction materials  for  the conventional
 greenhouse was $26.24/m2 ($2.44/ft2)  compared to $40.32/m2 ($3.75/ft)
 for the construction materials of the waste heat research greenhouse.
 This represents  $57,1537.4  hectare  (1 acre) or $141,168/hectare or
 54  percent more  for  the cost of construction materials for the waste
 heat research greenhouse compared to  the conventional  greenhouse.  This
 added  cost for a waste  heat greenhouse is primarily  due to the added
 fin-tube heater  system,  attic  fans, attic intake louvers, and attic
 exhaust shutters.

     The erection cost  for  the conventional greenhouse was less than the
 erection cost for the waste heat research greenhouse by about 58 percent.
 The erection  cost of the 201 m2 (2,160 ft2) conventional greenhouse was
 $7.96/m2 ($0.74/ft2) compared  to $12.58/m2 ($1.17/ft2) for the same size
 waste  heat research greenhouse.  This represents an  increase of $18,7957
 .4  hectare (1 acre) or  $46,425/hectare or 58 percent more for the erection
 cost of a waste heat greenhouse compared to that of a  conventional green-
 house.  Like  the difference in cost of construction materials, the added
 difference in the erection cost of  a waste heat greenhouse is primarily
 due to installing the fin-tube heating system, the attic intake louvers,
 the attic exhaust fans,  and attic exhaust shutters.

     Although the waste  heat research greenhouse used  in this study did
 not have a back-up heating system,  according to the analysis of data, it
 cost $34.19 m2 ($3.18/ft2) to construct a conventional greenhouse as
 compared to  $52.90/m2 ($4.92/ft2) for a waste heat greenhouse; this
means  that the basic waste heat greenhouse will  cost approximately 55
 percent more  to construct than a conventional  greenhouse.   Thus, the
 basic waste  heat greenhouse will  cost $187,641/hectare or $75,968/.4
 hectare (1  acre) more to construct than will  the conventional  greenhouse
 (Table 12).

     Back-Up  Heating System.  Since the waste heat research greenhouse
 used in this  study does  not have a back-up heating system, such a heat-
 ing system was not used  in computing the previous cost.  However, a
commercial  waste heat greenhouse operator would need a back-up heating
system in the event the  power plant could not deliver warm effluent
water to the greenhouse.  The cost of a back-up heating system having
the equivalent capacity of 4.5 Gj/hr/.4 hectare (4.3 MBtu/hr/acre) will
cost approximately $15,000 for oil  and $8,500 for natural  gas  (Table 13).
This represents an additional  $3.66/m2 ($0.34/ft2)  for the oil-fired
back-up heating system or $2.15/m2  ($0.20/ft2)  for a gas-fired back-up
system.  This additional cost should be added to the previous  $52.90/m2

                                  32

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TABLE 12.  COMPARATIVE CONSTRUCTION COST BETWEEN THE CONVENTIONAL GREEN-
           HOUSE AND THE WASTE HEAT RESEARCH GREENHOUSE WITHOUT BACK-UP
           HEATING SYSTEM
Conventional
9.1m X 21.9m
Greenhouse
(30 ft X 72 ft)
Waste Heat Research
9.1m X 21.9m (30 ft
Greenhouse
X 72 ft)
Difference
Cost of Materials:
per square meter
per square foot
per .4 hectare
per hectare
Erection Cost:
per square meter
per square foot
per .4 hectare
per hectare
Combined Cost:
per square meter
per square foot
per .4 hectare
per hectare
TABLE 13. PROJECTED
4.5 Gj/HR/
Conventional
Natural Gas:
per square meter
per square foot
per .4 hectare
per hectare
No. 2 Fuel Oil:
per square meter
per square foot
per .4 hectare
per hectare
$ 5,264.00
26.24
2.44
106,157.00
262,207.00
$ 1,600.00
7.96
0.74
32,267.00
79,698.00
$ 6,863.00
34.19
3.18
138,404.00
341,858.00
COST OF BACK-UP
.4 HECTARE (4.3
Greenhouse
0.00
$0.00
0.00
0.00
0.00

$0.00
0.00
0.00
0.00
$ 8,098.00
40.32
3.75
163,310.00
403,375.00
$ 2,532.00
12.58
1.17
51,062.00
126,123.00
$ 10,630.00
52.90
4.92
214,372.00
529,499.00
$ 2,834.00
14.08
1.31
57,153.00
141,168.00
$ 932.00
4.62
0.43
18,795.00
46,425.00
$ 3,767.00
18.71
1.74
75,968.00
187,641.00
HEATING SYSTEM WITH AN OUTPUT OF
MBTU/HR/ACRE)
Waste Heat Research

$ 2.15
0.20
8,500.00
20,995.00

$ 3.66
0.34
15,000.00
37,050.00
Greenhouse




                                  33

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 ($4.92/ft2)  cost for a waste heat greenhouse.   Adding the cost of a
 back-up heating  system, the  cost of constructing a waste heat greenhouse
 would  range  from $55.15 to  $56.56/m2 ($5.12 to $5.26/ft2) (Table 14).
 This cost is equivalent to  $223,027 to  $229,126/.4 hectare (1  acre)
 or  $550,877  to $565,941/hectare  for the construction  of a waste heat
 greenhouse compared  to $138,521/.4 hectare  (1  acre) or $342,147/hectare
 for a  conventional greenhouse.   The waste heat greenhouse would initially
 cost $84,506 to  $90,605/.4  hectare (1 acre) or $208,730 to $223,794/
 hectare more to  construct than the same size conventional greenhouse.

 TABLE  14.  A PROJECTED COMPARATIVE CONSTRUCTION COST  BETWEEN  A
           CONVENTIONAL GREENHOUSE AND  A WASTE HEAT GREENHOUSE
           BASED ON  .4 HECTARE (1  ACRE) BACK-UP HEATING SYSTEM
      Conventional Greenhouse
                                         Waste  Heat  Greenhouse
Natural
per
per
per
per
square
square
meter
foot
.4 hectare
hectare

$

138,
342,
34.
3.
521.
147.
19
18
00
00
$

223
550
55
5
,027
,877
gas
.05
.12
.00
.00
No. 2 Fuel Oil
$ 56
5
229,126
565,941
.56
.26
.00
.00
Greenhouse Energy Requirements

     The amount of energy required to maintain an adequate temperature
for greenhouse crop production will vary with location, type of green-
house, energy conservation measures, and crop but may range from 5.3 Tj
to 7.8 TJ/.4 hectare (5 to 7.4 billion Btu/acre) with about 6.5 TJ/.4
hectare (6.2 billion Btu/acre) being average (2).  The average annual
energy requirement for .4 hectare (1 acre) in Fort Valley, Georgia, is
about 5.2 Tj (5 billion Btu).  As previously mentioned, the minimum
greenhouse temperature may vary according to the crops grown; however,
the above greenhouse energy requirements are based on maintaining a
minimum temperature ranging from 12.8°C to 15.6°C (550F to 600F).

Current Cost for Energy

     Cost for Fossil Fuel.   Thirty to forty percent of the cost of
greenhouse crop production  is for energy and is increasing everyday.
Most greenhouses are heated by natural  gas; No. 2 fuel oil ranks
second.

     The cost to maintain adequate temperatures for greenhouse crop
production will  vary according to the kind of fuel  used.   For the Fort
Valley,  Georgia area,  the average current cost/Gj for natural  gas is
$3.04 ($3.20/MBtu),  whereas the present average cost/Gj using Mo. 2
fuel  oil  is $6.45 ($6.80/MBtu).  Thus,  the annual cost of fuel  (6.5 Tj/
.4 hectare or 6.2 billion Btu/acre) when supplied by natural  gas is
$19,760/.4 hectare (1  acre) or $48,807/hectare and  $41,925/.4 hectare
(1 acre)  or $103,555/hectare when supplied by No. 2 fuel  oil.
                                   34

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      Projected Cost of Waste Heat.   Although  several  suggestions  have
 been  made,  presently,  no general  conclusions  are  possible  for  what  waste
 heat  should cost.   One suggestion was  made  that waste heat should cost
 $0.19/Gj  ($0.20/MBtu)  (1).   However, perhaps  a more  realistic  cost  should
 be  based  on the cost of retrofitting a power  plant with  a  greenhouse
 heating capability  and allocating the  cost  of retrofitting to  the power
 plant or  greenhouse operator,  or  both.   Because each  site  is expected
 to  have different constraints,  the  break even cost for greenhouse opera-
 tion  is likely to be site specific  and dependent  on  the  market for  green-
 house crops as well  as power plant  variables.

      The  investment and operating cost will vary  with different sites.
 However,  the jfterco demonstration project near Minneapolis, Minnesota
 may serve as a model (3).For  the  Sherco demonstration  project,  the
 calculated  cost to  deliver  the  warm water 1,067 m (3,500 ft) to the
 demonstration  greenhouse and return it to the cooling tower the same
 distance  was about  $0.96/Gj  ($1.02/MBtu)/.4 hectare  (1 acre) based  on
 the projected  installed pipeline  cost  of about $600,000  for a  pipeline
 flow  rate of 442 1/s (7,000  gallons/minute).  Also included in  the
 above cost  to  deliver  the warm  water to  the greenhouse are the  pumping
 costs, $270/year, chlorination  for  bacterial  slime control estimated
 to  be $550/year and total operating cost estimated to be $l,500/year/
 .4  hectare  (1  acre)  greenhouse.

      Projected  Savings  By Using Waste  Heat.   The  projected savings  in
 cost  of greenhouse  crop  production  in  this study  is based  on the  cost of
 $0.96/Gj  ($1.02/MBtu)  for waste heat as  obtained  in the  Sherco  demonstra-
 tion  project (3).   As  previously  mentioned, on an annual basis  the average
 .4  hectare  (1  acre)  greenhouse  in the  U.  S. uses  6.5  Tj  (6.2 billion Btu)/
 .4  hectare  (1  acre), calculated to  be approximately $19,760 or  $48,8077
 hectare when supplied  by natural  gas.  This is equivalent  to $4.88/m2
 ($0.454/ft2).   The  same  amount of energy  supplied by  No. 2 fuel oil  has
 been  calculated to  be  about  $41,9257.4 hectare (1  acre)  or $103,555/hectare.
 This  is equivalent  to  $10.34/m2 ($0.962/ft2).   If waste  heat can  be supplied
 for $0.96/Gj ($1.02/MBtu), the cost to maintain adequate temperature for
 greenhouse  crop production would  be $6,240/.4 hectare  (1 acre)  or $15,413/
 hectare.   This  is equivalent to $1.54/m2  ($0.143/ft2).   This represents a
 savings of  $33,394/hectare of $13,520/.4  hectare  (1  acre) when  compared to
 natural gas  and $88,142/hectare of  $35,685/.4 hectare  (1  acre) when  compared
 to No. 2  fuel oil.

     Since  this study  revealed that a waste heat greenhouse would initially
cost  $84,506 to $90,605/.4 hectare  (1 acre)  more to  construct than a conven-
tional greenhouse the  same size, the number of years   required to break even
 is an important consideration in an economic analysis.  Two important factors
 in determining the  number of years required to break  even in a waste heat
greenhouse operation are the cost of delivered waste  heat/Gj (MBtu)  and the
kinds  of fossil fuel waste heat is used to replace.

     The  effect  of the cost of delivered waste  heat  on the number of years
required  to break even  is supported  by  the data  in Table  15.   In Table 15,
two  other  hypothetical  costs for waste  heat  are  compared  with  the  cost of

                                   35

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       TABLE  15.    ESTIMATED  POTENTIAL ANNUAL SAVINGS  IN ENERGY COST USING THREE PRICES FOR WASTE HEAT COMPARED
                    TO NATURAL GAS AND NO. 2  FUEL OIL AND THE NUMBER OF YEARS REQUIRED TO BREAK EVEN
CO
cri
BASED ON
COST OF WASTE
HEAT/Gj



$0.96/GJZ
$6,240
$1.50/Gj
$9,750
$2.00/Gj
$13,000
THE AVERAGE ANNUAL GREENHOUSE USE OF 6.5 T
COST OF ENERGY/
Gj SUPPLIED BY
NATURAL GAS


$3.04/Gjx
$19,760
$3.04/Gj
$19,760
$3.04/Gj
$19,760
COST OF ENERGY/
Gj SUPPLIED BY
NO. 2 FUEL OIL


$6,45/Gjw
$41 ,925
$6.45/Gj
$41,925
$6.45/Gj
$41,925
j (6.2 BILLION BTU)/. 4 HECTARE (1 ACRE)
SAVINGS OVER
THE USE OF:
Natural No. 2
Gas Fuel Oil

$2.08/Gj $5.49/Gj
$13,520 $35,685
$1.54/Gj $4.95/Gj
$10,010 $32,175
$1.04/Gj $4.45/Gj
$6,760 $28,952
YEARS REQUIRED TO
BREAK EVEN
THE USE OF>'
Natural
Gas

6.2

8.4

12.5
OVER
*
No. 2
Fuel Oil

2.4

2.6

2.9
                is estimated that a waste heat greenhouse will cost $84,506 to $90,605 more/ .4 hectare (1 acre)
             than a conventional greenhouse.
            zThe cost of waste heat/Gj is based on the Sherco demonstration project.
            xThe cost of natural gas/Gj is based on Fort Valley, Georgia's (1979) price.
            wThe cost of No. 2 fuel oil is based on Fort Valley, Georgia's (1979) price.

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 waste heat/Gj  (MBtu)  established by the Sherco demonstration  project (3).
 Regardless of  the kind of fossil fuel  replaced by waste heat,  there is
 an increase in the number of years  required to break even  as  the cost
 of waste heat/Gj  increases.

      Since different  fossil  fuels vary in  cost,  it is  obvious  that  the
 number of years  required to  break even in  a waste heat greenhouse
 operation is greatly  determined by  the cost of the fuel  replaced by
 waste heat.  As  illustrated  by  the  data in Table 15, the cost/Gj of
 heat supplied  by  natural  gas and No. 2 fuel  oil  is $3.04 and  $6.45,
 respectively.  With waste heat  costing $0.96/Gj, it requires  6.2 years
 to break even  compared to 2.4 years for No.  2  fuel  oil  for a  .4  hectare
 (1  acre) waste heat greenhouse.   Should the price of waste heat  increase
 to $2.00/Gj, the  number of years required  to break even  if waste heat
 is used to replace natural gas  is increased to 12.5 years  as  compared
 to 2.9 years for  No.  2 fuel  oil.

      It is important  to note that inflationary fuel  rates  and  increased
 fuel  costs were neglected in computing the above number  of years required
 to break even  by  using waste heat to replace natural gas and No.  2  fuel
 oil._  Based on past trends,  it  is safe to  expect inflationary  fuel  rates
 and increased  fuel costs  to  continue and thereby reducing  the  number
 years  required to  break even by  operating  a  waste heat greenhouse.   Con-
 sidering the current  increasing  costs  of the two above fossil  fuels,"the'
 number of years required  to  break even  for the cost of retrofitting can
probably be reduced to 3 to 4 years for heating by natural gas and 1 to
2 years for heating by No. 2 fuel oil by 1985.
MARKETING STUDIES

     Bedding Plants.  Marketing studies began on April 6, 1979, and con-
tinued throughout the bedding plant season.  Bedding plants were sold
directly from the greenhouses.  Browallia, coleus, impatiens, marigolds,
pansies, petunias, salvias, and verbenas were sold at a wholesale price
of $4.00/32-plant flat.

     Customers did not show preference in buying plants grown in the con-
ventional greenhouse over those grown in the waste heat research green-
house.  The quality of bedding plants grown in the waste heat research
greenhouse was equal to the quality of those grown in the conventional
greenhouse.

     Bedding plants are usually grown in flats.   A .4 hectare (1 acre)
greenhouse will  provide the space for 21,840 flats, 0.56 m X 0.28rri  (22 in
X 11  in).  Petunias and marigolds are popular bedding plant crops and
were sold at $4.00/flat.   This represents a gross return of $87,360
.4 hectare (1 acre) or $2.00/0.3 m? (/ft2).

     Foliage Plants.  Foliage plant crops are grown and sold in many
different pot sizes.  However, this economic study is based on a 0.08 m
(3 in) pot size.   Hypoestes sanguinolenta (polka dot plant), Caribbean

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begonia mix, and Dizyotheca elegantissima  (false Aralia) can be easily
grown to a saleable size within 4 weeks and can serve easily as late
spring or early summer crops.  A .4 hectare (1 acre) greenhouse can pro-
vide enough space for 599,040 0.08 m  (3 in) pots.

     In this study, the above plants  grown in 0.08 m (3 in) pots were
sold locally to a supermarket at $0.50/pot which was the wholesale price.
If all 599,040 0.08 m (3 in) pots could be sold at $0.50/pot, the gross
return per .4 hectare (1 acre) greenhouse would be $299,520 or $6.88/
0.09m2 (/ft2).

     Certain foliage crops will probably give the greatest economic
return due to rapid crop turn over.

     Potted Chrysanthemums and Poinsettias.  Although experimental data
were never collected for chrysanthemums and poinsettias during the fall
of 1978 (because the greenhouses were not completed in time), they are
commonly grown as fall greenhouse crops.  The average wholesale prices
in 1978/0.15 m (6 in) pot of chrysanthemums and poinsettias were $2.17
and $2.47, respectively (6).  In this study, poinsettias are being used
as the fall crop for economic evaluation.

     Poinsettias are normally grown in 0.15 m (6 in) pots.   It is custo-
mary to allow 0.09  m2 (ft2) for each poinsettias pot base.   The estimated
crop value is $53,797/.4 hectare (1 acre)  or $1.24/0.09  m2 (/ft2).

     Economic Incentive to Use Waste Heat.  Based on the above annual crop
rotation, the projected gross income for a greenhouse operator is $440,677/
.4 hectare (1 acre) or $10.11/Q09m2  (/ft2).  If waste heat can be bought
at $0.96/Gj ($1.02/MBtu), a greenhouse operator can expect to save annually
$13,520/.4 hectare (1 acre) or $33,394/hectare when compared to heating
with natural  gas and $35,685/.4 hectare (1 acre) or $88,142/hectare when
compared to heating with No. 2 fuel oil.  On a /0.09m2 (/ft2) basis, the
estimated savings are $0.310/0.09m2 (/ft2) when compared to heating with
natural  gas and $0.819/0-09m2 (/ft2) when  compared to heating with No. 2
fuel oil.

     The above economic evaluation, however, is based on the greenhouse
operator selling all  of the plants  grown in a .4 hectare (1 acre) green-
house and receiving top prices for each crop which is rarely the case.  If
a greenhouse  operator is unable to  sell all of the plants produced for top
prices,  the need to save on the cost of fuel becomes even more essential
to a profitable operation.   Admittedly, it takes slightly more electricity
to operate a  waste heat greenhouse  than it does to operate a conventional
greenhouse.   This added cost for additional electricity which is required
to operate the fans and back-up heating system in a waste heat greenhouse
is not included in the previous economic analysis.   However, with a saving
in the cost of fuel  ranging from $13,520 to $35,685/.4 hectare (1  acre)
or $33,394 to $88,142/hectare along with the scarcity of fossil  fuel, it
appears  that  the utilization of waste heat in  the greenhouse production of
high cash valued ornamental crops  can be economically feasible.


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                                 REFERENCES


  1.   Beall,  S.  E.,  Jr.,  and G.  Samuels.   The Use of Warm Water For
      Heating and Cooling Plant  and Animal  Enclosures.   1971.
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  2.   Berry,  James W.,  and Herman H.  Miller.   A Demonstration  of
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  3.   Boyd, L. L., G. C.  Ashley,  J.  S.  Hietala,  R.  V. Stanfield,  and
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  4.   Burns,  Earl R., Robert S.  Piles,  and  Carl  E.  Madewell.   Waste
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  5.   Census of Agriculture.  USDA.   1974.  pp.  Ill  38-39.

  6.   Crop Reporting Board.   Floriculture Crops:  Production Area
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  7.   Jensen,  Merle H.   The  Future of Energy-Sources, Ideas.  In:
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 8.  Madewell, C. E.,  L.  D. King, Johnny Carter, J. B.  Martin, and
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 9.  Olszewski,  M.  and  H. R. Bigelow.  Analysis of Potential Imple-
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     Industry.   ORNL,  October,  1978.  pp.  1-27.

10.  Steel,  Robert G.  D., and James H.  Torrie.  Principles and
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     New York,  1960.   pp. 132.
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