ENERGYCONVERSION OPTIONS FOR ENERGYEFFICIENT CEA EMPHASIS ON FUEL CELLS

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ENERGY-CONVERSION OPTIONS FOR ENERGY-EFFICIENT
CEA- EMPHASIS ON FUEL CELLS -

• Norman R. Scott
• and
• Corinne J. Rutzke
• Cornell University, Ithaca, NY

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Agricultural Importance

• Agriculture as a source for food, natural raw
  materials for bioindustries and energy will
  increasingly be a major engine to drive our
  transition to a sustainable world.

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AGRICULTURE TODAY

• Combination of family-owned and corporation-owned
  enterprises
• Located away from population centers
• Products are transported to processing centers
  located near interstate trucking transportation
  lines

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THE FUTURE OF AGRICULTURE

• Integrated, sustainable systems
• Agricultural production systems that are
• energy suppliers and
• economic drivers for the surrounding community
• Located near or in population centers

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PUTTING THE PIECES TOGETHER
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INNOVATIONS ARE DRIVEN BY

• Environmental concerns
• Distributed electric generation
• Sustainable communities
• Entrepreneurship opportunities
• National policy

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Future Benefits Conclusions
Dairy Farm
Input
Output
Dairy Operation
Water
Milk
Absorption Chiller/
milk
Plate Heat
Refrigerator
Exchanger
M
fish
Algal
Fish
a
Supple-
Lagoon
Cow
Pond
Tanks
r
mentals
veggies
k
Greenhouse
Screw
e
compost
Compost
Separator
Sun
t
s
Raw Manure
Digester
Pretreatment
On farm
Cropland
H
S
2
Electric Grid
Scrubber
Irrigation
G R I D
System
electricity
Fuel Cell/
Inverter
Cogeneration
Heating
CO

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Electrical Storage
System
Separator
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ENERGY CONVERTERS

• Diesel engine
• Microturbines
• Fuel cells

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WHAT IS A FUEL CELL?

• an electrochemical energy conversion device
• converts hydrogen and oxygen into water,
  producing electricity and heat in the process
• can be recharged (using hydrogen and oxygen)
• provides a DC (direct current) voltage
• can be used to power motors, lights or electrical
  appliances
• several different types of fuel cells, each using
  a different chemistry
• usually classified (named) by the type of
  electrolyte used

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HOW DOES A FUEL CELL WORK?

• Chemistry of a Fuel Cell
• Anode side
• 2H2 gt 4H 4e-
• Cathode side
• O2 4H 4e- gt 2H2O
• Net reaction
• 2H2 O2 gt 2H2O

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HOW DOES A FUEL CELL WORK?
membrane with catalyst
anode
cathode
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HOW DOES A FUEL CELL WORK?
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HOW DOES A FUEL CELL WORK?
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HOW DOES A FUEL CELL WORK?
e-
e-
pressurized hydrogen gas
Membrane allows H to cross, and prevents e-
from crossing
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HOW DOES A FUEL CELL WORK?
cathode
membrane
anode
catalyst
O
e-
e-
pressurized hydrogen gas
Electrons are attracted to cathode and current is
generated
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HOW DOES A FUEL CELL WORK?
H2O
...and water is formed
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FUEL CELL STACK
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HOW DOES A FUEL CELL WORK?
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CHALLENGES WITH FUEL CELLS

• Production of/access to clean hydrogen fuel
• Reduction of H2S contamination
• Storage and distribution of hydrogen
• Hydrogen gas contains little energy per unit
  volume (compared to a liquid fuel like gasoline
  or methanol).
• A device called a reformer turns hydrocarbon or
  alcohol fuels into hydrogen
• Reformers are not perfect
• generate heat and produce other gases besides
  hydrogen.
• the hydrogen that comes out of them is not pure
• lowers the efficiency of the fuel cell.

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FUELCELL ENERGYS 250 kW DIRECT FUEL CELL POWER
PLANT
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200 kW UTC POWER PLANT IN CENTRAL PARK, NEW YORK
CITY
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UTC FUEL CELLS TIMES SQUARE INSTALLATION, NEW
YORK CITY
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IS IT ECONOMICALLY FEASIBLE TO USE FUEL CELLS
FOR PROTECTED HORTICULTURE ENERGY NEEDS?
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ENERGY USE AT TWO NEW YORK STATE GREENHOUSES

• Cornell CEA Greenhouse
• lettuce production facility
• (CEA Commercial
• Demonstration Project)

Underwood Farms Shushan, New York Family-owned
hydroponic tomato greenhouse
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Cornell CEA Demonstration GH ENERGY USE
EQUIPMENT LIST
Office Environmental controls computer,
business computer, printer, alarm system, office
light, answering machine Restroom Overhead light
and fan Walk-in cooler Air chiller and
lights Headhouse Overhead lights, freezer,
radio, coffee maker,
microwave, vacuum seeder, seeder light, EC and
pH meters, electronic scale, O2
switch valve Growth room Water-cooled lamps,
chiller, fan, compressor, Air conditioner,
timers, pumps, CO2 meter Furnace room Overhead
lights, boilers (headhouse, pond
pump, main circulation pumps, boiler
pump) exhaust fan, hot
water heater Greenhouse Pond pumps, overhead
fans, HPS lamps, Walkway
lamps, exhaust fans, shade motor, vent motor,
pad pump, water solenoids, CO2
meter
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CEA Greenhouse Electricity Usage
Eliminated from average - Unusual
circumstances 1999 - aphid infestation shut down
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CEA GREENHOUSE ENERGY USE for PRODUCTION OF 1200
HEADS LETTUCE PER DAY CONTINUOUS PRODUCTION
FOOD-GRADE GH
Year 12 mo-Average kWh 12
mo-Average Therms
(electricity) (natural
gas) 1999 448,090 20,742 2000
663,680 38,544 2001 608,165
26,821 2002 515,360 28,898 2003
366,720 (thru Aug) 20,252 (thru Aug)
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CEA GREENHOUSE ENERGY USE for PRODUCTION OF 1200
HEADS LETTUCE PER DAY CONTINUOUS PRODUCTION
FOOD-GRADE GH
5y-Average kWH
5y-Average Therms
(electricity) (natural
gas) per Year 602,442 29,777 per Month
46,423 2,481 per Day
1,498 82 per Hour 62
3 per 5oz. Head 1.3 0.1
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Underwood Farms GH ENERGY USE EQUIPMENT LIST
Headhouse Overhead lights, radio Growth
room 3 High Pressure Sodium (HPS) 600 W lamps,
timer Furnace room
Overhead lights, coal-furnace boiler pump
Greenhouse Hydroponic
pumps, 144 HPS 600W lamps, exhaust fans, vent
motor, weather station

• Underwood Greenhouse supplemental lighting
• in winter months only (Nov - Mar)
• during night (off-peak) hours only
• lights set on timer (no daily integral control)

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UDERWOOD FARM TEST SITE - Seedling room LIGHTS ON
TIMER Greenhouse Production area 5280 sq ft
Average Electricity Usage kWh/month
kWh/d TOTAL FARM ON OFF PEAK
USAGE 144 HPS 600W lamps on Timer
25,500 850 No Lamps used
17,000 567 OFF PEAK USAGE
ONLY 144 HPS 600W lamps on Timer
12,750 425 No Lamps used
3,500 117
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Need for Real Numbers

• AA Dairy has been meticulous in obtaining data
  for more than 5 years
• biogas production (total per cow)
• biogas composition (CO2 measurements)
• oil consumption (daily)
• electricity generated on the farm
• electricity sold to the grid
• difference between generated sold is
  electricity used on the farm

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AA DAIRY
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Total biogas production and biogas production per
cow per day
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Engine-generator performance at AA Dairy
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Energy produced and net energy to grid at AA
Dairy
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Electricity Used by AA Dairy and Purchased from
the Grid March 9-12, 2001 (NYSEG Energy
Profiler Online)
Generating Capacity 70 kW
Electricity used (kW)
Electricity purchased (kW)
Time of day_at_ 5 min. intervals
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Bars show Standard Deviation
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140 kW (Fuel cell)
70 kW (IC)
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Fuel Cell Options

• Plug Power (PEM) lt 50kW (typical 4.5kW)
• EcoVillage at Ithaca (multiple households)
• Fuel Cell Energy (MCFC) 250kW
• Good size for 1000 cow unit

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Reducing H2S Concentration

• Dietary influence (limited ability)
• Direct precipitation with iron compound in
  digester (ferric phosphate, ferric oxide)
• Iron sponge (hydrated ferric oxide with
  woodchips)
• Commercial solid-oxide systems (zinc oxide/zinc
  carbonate)
• Activated carbon scrubbers
• Bioscrubbers
• Alkali solution (produce a fertilizer)
• Mixed cow-manure compost/wood chips

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Viability

• fuel cells would be economically viable in
  rural areas, if they were put in specialized uses
  that operate on a continuous basis, use heat
  generated and that will pay a premium for such
  characteristics as low emissions, low noise
  levels, high quality power, modularity of design
  and capacity to use different types of
  hydrogen-based fuels.
• Max Pfeffer

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Simplified Economic Analysis

• Estimation using present value analysis with
  variables
• discount rate, capital costs, operating costs,
  insurance and taxes, purchase price of
  electricity, selling price of electricity, and
  electricity inflation
• diesel engine, microturbine and fuel cell
  comparisons
• calculated using data from AA Dairy

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Economic Sensitivities

• All three energy converters are most sensitive
  to
• 1. The capital cost and
• 2. Price received for electricity produced.
• 3. Price paid for electricity from grid

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Net Present Value Analysis

• Based on 500 Cows
• Diesel Engine- payback in 3 to 7 years
  (depending)
• Microturbines- payback in 3 to 8 years
  (depending)
• Fuel Cell- payback not w/in 10 years (except if
  1200/kW)

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Net Present Value Analysis

• Based on 1000 cows
• Diesel Engine- payback 2 to 7 years (depending)
• Microturbines- payback 3 to 8 years (depending)
• Fuel Cell- payback 3 years (if 1200/kW)
• - payback 9 years (if 2500/kW)
• - payback 11 years (if 5000/kW)

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New York Distribution of Households
Electricity Demand

• Households Households
  Electricity
• 
  Demand
  
  
• 
  gWh_at_5900kWh/hh/yr
• Central cities 3,528,430 50 20,817
• Suburban areas 2,893,313 41 17,070
• Rural Areas 635,117 9 3,747
• TOTAL 7,056,860 41,635

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Comparison of Different Systems in Meeting
Electricity Needs
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Integrated Entrepreneurial Approach

• Obviously reducing capital costs will improve the
  economic scenarios (especially for the fuel
  cell) BUT we suggest that a more potentially
  innovative and economically successful route is
  to create business and community partnerships to
  enhance the value of energy produced, both
  electrical and thermal.
• Examples might include enterprises such as
  greenhouses, aquaculture facilities, algal
  farming, pasteurization on the farm, various food
  and feed processing facilities, and most
  comprehensive of all, providing a communitys
  energy and jobs needs.

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Agricultural Importance

• Agriculture as a source for food, natural raw
  materials for bioindustries and energy will
  increasingly be a major engine to drive our
  transition to a sustainable world.

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http//www.bee.cornell.edu/sustain/fuelcell/index.
htm