EXAMPLES OF INDUSTRIAL USES OF GEOTHERMAL ENERGY IN THE USA

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EXAMPLES OF INDUSTRIAL USES OF GEOTHERMAL ENERGY
IN THE USA

• John W. Lund
• Director, Geo-Heat Center
• Oregon Institute of Technology
• Klamath Falls, OR, USA

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INTRODUCTION

• Industrial applications agricultural drying
• Few in number in the U.S.
• Large scale operations dominate
• Gold ore heap leaching
• Onion dehydration
• Zinc ore extraction
• Selected uses will be presented

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ENERGY USE

• Installed capacity 38 MWt
• Annual energy use 518 TJ (144 GWh)
• Mainly due to agricultural drying
• Enhanced petroleum recovery using injected
  geothermal water NE Wyoming and adjacent
  states estimated at 8,600 TJ/yr (2,390 GWh) and
  approx. 250 MWt
• However, no reliable data available
• Reference Lund, et al., GRC Trans. 1990

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ZINC EXTRACTION 1

• CalEnergy Operating Corp. 200 million Mineral
  Recovery Project
• Located on the shore of the Salton Sea in
  southern California Imperial Valley
• CalEnergy operates 10 geothermal power plants
  347 MWe
• Unit 5 49 MWe uses waste brine from 4
  existing plants
• Constructed to fuel zinc project electricity

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CalEnergys Zinc Plant Imperial Valley, CA
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ZINC EXTRACTION 2

• Prior to plants construction spent brine from 8
  plants was injected at 182oC (360oF)
• Unit 5 (49 MWe triple flash) 20 MWe used for
  zinc recovery operation
• Which 30 MW of heat energy
• This reduces the brine temperature to 116oC
  (240oF)
• 1,200 TJ/yr (333 GWh) used in the process
• (electrical energy thermal equivalent process
  steam)

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ZINC EXTRACTION 3

• The mineral recovery project will produce 30,000
  tonnes (33,000 tons) of 99.99 pure zinc annually
  for Cominco Ltd.
• This comes from 9,000 tonnes/hr (9,900 tons/hr)
  of brine that contains 550 to 600 mg/L (ppm) of
  zinc
• Zinc sells for around US0.50/lb (1.10/kg)
  about US33 million/yr
• Also, looked at extracting high grade silica
  manganese in the future

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ZINC EXTRACTION 4

• Process uses existing technology of ion exchange
• But, also employs solvent extraction and
  electrowinning to extract the zinc from the
  brine
• The zinc builds up on cathodes and removed in 24
  hours
• Melted into one ton ingots
• Only operated at 40 capacity

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Overview of CalEnergys Zinc Plant
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HEAP LEACHING 1

• Used in gold recovery from Nevada mines
• Process consists of dripping a dilute sodium
  cyanide solution over a crushed ore pile or heap
• The gold, in solution, drains from the heap and
  extracted by a charcoal process producing a bar
  of impure gold (doré).
• The cyanide solution is then recycled

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HEAP LEACHING 2

• Operation can recover up to 95 of gold
• Also, used for silver extraction
• Under normal circumstances in Nevada
  operation takes place mid-March to late- October
  (min. production temp. 4oC - 40oF)
• Using geothermal energy
• Recovered enhanced by 5 to 17 by accelerating
  the chemical reaction
• Year-around operation possible

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Heap leaching flow diagram with geothermal
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HEAP LEACHING 3

• Two mines in Nevada have used geothermal
• Round Mountain
• 86,000 tonnes (95,000 tons) of ore/day
• 1g/tonne (0.035 oz/ton) 21,000 kg (46,000 lbs)
  of gold in 2001
• Geothermal _at_ 82oC and 69 L/s (180oF and 1,100
  gpm)
• 14.1 MWt and 208 TJ/yr (57 GWh)

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HEAP LEACHING 4

• Florida Canyon
• 12,000 tonnes (13,000 tons) of ore/day
• 0.7 g/tonne (0.025 oz/ton) 3,600 kg (8,000 lbs)
  of gold/yr
• Geothermal _at_ 99oC and 23 L/s (210oF and 365 gpm)
• 1.4 MWt and 42 TJ/yr (12 GWh)
• These two mines are presently shut down, due to
• Low prices for gold and silver
• High operating costs
• Royalty charges for use of energy from federal
  lands
• Now being considered for reopening due to changes
  in gold price and BLM royality payment

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Round Mountain, Nevada
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MILK PASTEURIZATION 1

• Medo-Bel Creamery in Klamath Falls, Oregon used
  geothermal heat in milk pasteurization for about
  50 years
• 233-m (765 ft.) deep well _at_ 87oC _at_ 6.3 L/s (189oF
  and 100 gpm)
• Used a 3-section plate heat exchanger
• Minimum temperature needed 78oC (172oF) for 15
  seconds in short term pasteurizer

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Medo-Bel Creamery with plate heat exchanger
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MILK PASTEURIZATION 2

• Plate heat exchangers 3 sections
• 1. Preheats incoming milk at 3oC (37oF) by
  outgoing (pasteurized) milk to 71oC (160oF)
• 2. Pasteurizes milk with geothermal water
• (in at 87oC and out at 77oC)(189 and 171oF)
• 3. Finally, cools hot milk by preheating
  incoming cold milk and then further cooled with
  chilled water back to 3oC (37oF)

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Medo-Bel pasteurization flow diagram
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MILK PASTEURIZATION 3

• Milk processed at rate of 0.84 L/s (13 gpm)
• Total of 225,000 kg (500,000 lbs)
  processed/month
• Also used to batch pasteurize ice cream
• And, to heat 2,800 m3 (30,000 ft2) building
• Cost
• 5 kW pump at 210/month
• Pipe corrosion (800 mg/L sodium sulfate H2O)
• Savings 1,000/month
• 0.3 MWt and 1.0 TJ/yr (0.3 GWh)
• No longer operating

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SLUDGE DIGESTION 1

• City of San Bernardino has a geothermal district
  heating system serving 14 major buildings 13
  MWt
• The city installed a primary anaerobic sewerage
  digester in 1983
• Process uses 58oC (136oF) geothermal fluid which
  replaced methane fuel
• The digester, which uses living anaerobic
  micro-organisms to feed on the organics, uses
  geothermal to assist the process

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SLUDGE DIGESTION 2

• The geothermal design uses an 18.5 m2 (200 ft2)
  spiral plate heat exchanger to transfer 1.6 GJ/hr
  (1.5 million Btu/hr) of heat to the 7,600 m3
  (268,000 ft3) digester tank
• The geothermal water, at 290 mg/L (ppm), flows at
  25 L/s (400 gpm) in at 58oC (136oF) and out at
  53oC (127oF)
• The savings is approx. 30,000/yr
• Expanded to 4 digesters 1.8 MWt 53 TJ/yr (6.4
  GWh)

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Sludge digestion diagram San Bernardino, CA
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AGRICULTURAL DRYING 1

• Two large geothermal onion and garlic dehydrators
  are located in NW Nevada
• These units can each process 4.5 to 6.8 tonnes
  (10,000 to 15,000 lbs) of wet onions/hr drying
  them from 80 to 5 moisture (output 0.9 to 1.4
  tonnes/hr 2,000 to 3,000 lbs/hr)
• 35 MJ/kg used (15,000 Btu/dry lb) 208 TJ/yr (58
  GWh) (100 billion Btu/yr) over 150 days period
• Product used in soups, baked goods, salt,
  seasoning as powders to slices

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AGRICULTURAL DRYING 2

• Single-line, continuous-belt dryer use
• 3.8 m (12.5 ft.) wide
• 58 to 65 m (190 to 215 ft.) long
• 3 to 4 sections (A to D) 96 to 74oC (205 to
  165oF)
• Processing 4.5 to 6.8 tonnes/hr (10,000 to 15,000
  lbs/hr) of wet onions
• Using 2,450 m3/hr (86,500 ft3) of air
• 42 GJ/hr (4.3 million Btu/hr)
• Onions 5 cm to 2 m (2 in. to 6 ft.) deep
• Bryair desiccation unit required in final stage

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AGRICULTURAL DRYING 3

• Bradys Hot Spring plant first in U.S.
• 132oC (270oF) geothermal fluid
• Only has 3 stages (A thru c)
• 6-months operation season
• 23 tonnes (25 tons) of wet onions are processed
  during season
• 58-m (190-ft) long dryer by 3.8 m (12.5 ft.) wide
• Uses 88 to 49oC (190 to 120oF) air in various
  stages
• Has also processed celery and carrots to extend
  season
• Product trucked from S. California to S. Oregon
  (500 to 1000 km (300 to 600 miles)

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AGRICULTURAL DRYING 4

• Empire Foods plant constructed 1994
• Capacity
• 34 tonnes/day (37 tons/day) onions 38.6
  tonnes/day (42 tons/day) garlic
• 50 to 75 L/s (800 to 1200 gpm) of geothermal
  fluid _at_ 141oC (286oF)
• Cold storage warehouse allows year-round
  operation 2nd line being considered
• Geothermal energy also used for four ORMAT
  1.5-MWe binary units net output 3.6 MWe
• 16oC (29oF) ?T across heat exchanger spent
  fluid being considered for 1 MWe power plant for
  facility use
• Plant now closed due to competition of garlic
  imports from China

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Empire Energy 5 MWe 4 binary units
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SUMMARY

• Industrial use dominated by large facilities
  (onion dehydration, heap leaching, zinc
  processing)
• Small industrial uses include laundries,
  mushroom growing, mineral water processing, and
  an industrial park in Hawaii (experimental work)
• Enhanced petroleum recovery in NE Wyoming using
  injected geothermal water no reliable data
• Total as high as 100 MWt and 2,000 TJ/yr (555
  GWh) 250 MWt and 8,600 TJ/yr (2,390 GWh)
• Today 38 MWt and 518 TJ/yr (144 GWh)

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CONCLUSIONS 1

• A survey in the U.S. found that of 108 industrial
  processes surveyed (representing 80 of U.S.
  industrial energy usage), 97 of all processes
  required heat input in the form of steam at 120oC
  (250oF) or higher.
• An examination of geothermal wells in 8 western
  U.S. states reveals that 99 are 120oC (250oF) or
  less.
• High load factor important (most 0.44 to 0.68)
• Wells above 120oC (250oF) would normally be used
  for electric power generation, however ----
• source K. Rafferty, GHC Bulletin Vol. 24, No.
  3 (Sept., 2003)

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Ref K. Rafferty, 2003
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Ref K. Rafferty, 2003
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CONCLUSION 2

• Consider Power plant vs dehydration plant
• Assumptions
• 150oC (300oF) resource
• 20 MW net binary power plant
• US0.07 per kWh power sales price
• 10-month dehydration operation
• 13,600 tonnes (15,000 tons) annual production (2
  lines)
• US2.20/kg (1.00/lb) dried product wholesale
  price

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CONCLUSIONS 3

• Power plant vs dehydration plant
• Power Dehydration
• plant plant
• Capital Expenditure 50 mill. 15 mill.
• Gross Revenue 11 mill. 18 mill.
• Resource require. 760 L/s 76 L/s
• (12,000 gpm)
  (1,200 gpm)
• Employees 15 75
• source D. Mendive, Geothermal Development
  Assoc., Reno, NV

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CONCLUSIONS 4

• The industries with favorable geothermal heat use
• Plastics (Rayon, Acetate, polypropylene,
  acrylics)
• Rubber (latex)
• Chemical and paper manufacturing
• Dehydration
• Two alternatives to improve the situation
• Use high temperature effluent from geothermal
  power plants
• Use vapor recompression technology (low pressure
  steam compressed to high pressure/temperature)
• Source K. Rafferty, GHC Bulletin Vol. 24, No.3
  (Sept. 2003)

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THANK YOU