DEVELOPMENT OF DIRECT-USE GEOTHERMAL … 09.30 Direct Uses...Feasibility studies – both...
Transcript of DEVELOPMENT OF DIRECT-USE GEOTHERMAL … 09.30 Direct Uses...Feasibility studies – both...
Tonya “Toni” Boyd
used with permission
Dr. John W. Lund, PE
Emeritus Director
Geo-Heat Center
DEVELOPMENT OF DIRECT-USE
GEOTHERMAL PROJECTS
GEO-HEAT CENTER BACKGROUND
Established in 1975
Based on the Oregon Institute of Technology campus
– a geothermally heated campus with 192oF water
With addition of two geothermal power plants (2
MWe) and a 2 MWe solar array, the campus will be
100% on renewable energy – the first in the world!
Technical assistance provided to persons, private
firms and governments in all 50 states and 60
countries.
Funded mainly by the U.S. Department of Energy –
Office of Geothermal Technologies
SERVICES PROVIDED BY GHC
Technical assistance – direct-use, small scale electric
power generation and geothermal heat pumps.
Feasibility studies – both engineering and economic
Information dissemination – Quarterly Bulletin,
technical papers, and conferences proceedings.
Data bases – 12,000 well/springs in 16 western
states.
Outreach – training, speakers, booths, and site visits.
Geothermal Direct-Use Engineering and Design
Guidebook – 454 pages – most available on-line
WEBSITE ACTIVITIES
http://geoheat.oit.edu
Over 1900 files (320 MB of information)
Example of yearly activity:
Average hits/day 11,000
Average users/day 2,000
Average downloaded PDF files/day 4,000
68% of users from the U.S.
10% of users are international
22% of users are from unknown locations
INTRODUCTION TO DIRECT-USE
Direct-use geothermal provides heat and/or cooling
to buildings, greenhouses, aquaculture ponds and
industrial processes.
Need to match the resource with the needs of the
user to be successful
Economics and markets are important
Each project is unique!!!
Each project needs a leader or champion (“hero”)!!!
INTRODUCTION 2 Development of a projects should be
approached in phases to minimize risk
Size of the project determines the amount of exploration and development that can be economically justified. For a single home – the risk is high with minimum
information economically available
Larger projects can justified more investigations and resource characterization, thus reducing the risk (i.e. district heating and industrial process applications) - a feasibility study is appropriate and may be necessary
ADVANTAGES OF DIRECT-USE OF
GEOTHERMAL ENERGY
Can use low- to intermediate temperature resources (< 300oF)
These resources are more wide-spread (80+ countries) and are often at shallow depths
Direct heat use (no conversion – high efficiency)
Use conventional water-well drilling equipment
Use conventional, off-the-shelf equipment
(allow for temperature and chemistry of fluid)
Minimum start-up-time
Quicker return on investment (as compared to power projects)
SELECTING THE USE
“I have this resource, what do I do with it?”
Information needed to answer this question:
What is the extent and depth of the resource
What is the temperature and flow rate?
What is the chemistry of the resource?
What are the potential markets and income?
Do you have the experience or can you hire it?
Do you have the financing – ROI ok?
Do you own or can you lease the resource?
IN SUMMARY: DIRECT-USE HEATING AND
COOLING PROJECTS INCLUDES:
Swimming, bathing and balneology
Space heating and cooling Including district (heating/cooling) systems
Agriculture applications Greenhouse and covered ground heating
Aquaculture applications Fish pond and raceway heating
Industrial processes Including food and grain drying
Mineral extraction and processing
SPAS AND POOLS
Use of low temperature resource <140oF
Temperature and mineral content important
Drinking the water and using muds also important
<85oF for pools and <110oF for spa water
Water used directly desirable – flow through
May need to be treated (chlorine)
Secondary water heated through HE
Mixing required with higher temperature resource
Covered and uncovered pools ( 1:2.5 heat needs)
SPACE AND DISTRICT HEATING Heating (and cooling) of individual buildings or a group of
buildings
District heating requires a high thermal load density >0.7 million Btu/hr/acre or a favorability ratio of 2.5 (ratio of resource available/resource utilized)
Peaking with fossil fuel often economically viable as geothermal can provide 50% of the load 80 to 90% of the time.
However, district heating is capital intensive – especially the distribution network (pipelines) – 35 to 75% of total
Typical savings of 30 to 50% compared to natural gas, and higher when compared to electricity
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80006000400020000
PEAKING BOILER (6%)
GEOTHERMAL HEAT PUMP(31%)
GEOTHERMAL (63%) DOMESTICHOT
WATER
HOURS PER YEAR
(oC)
Fossil fuel
Geothermal
Meeting peak demand with fossil fuel
DOWNHOLE HEAT EXCHANGERS
Used by homes – individual or shared in:
Klamath Falls, Oregon
Rotorua and Taupo, New Zealand
Cesme, Turkey
Closed loop of pipe in well (coil or DHE)
Clean secondary water used
Only heat extracted from well
Wells 10 to 12 inches in diameter
Casing 2 inches smaller - clearance
DHE with promoter pipe DHE with perforated casing
DOWNHOLE HEAT EXCHANGER DESIGN
perforations
Both create a vertical convection cell of heated water
KLAMATH FALLS, OREGON
DISTRICT HEATING SYSTEM
Completed 1983 – $2.33 million – DOE-PON
Two wells – 367/900 ft. deep 219/212oF
700 /765 gpm – max
Pipeline: 4,040 ft. – 8 inch steel Preinsulated – direct buried & sidewalk utilidor
Heat Exchanger building – 2 plate heat exchangers - each 10.0 million Btu/hr
Injection well – 1,235 ft, deep 2,500 ft. from production zone
Production Well
Injection Well
Geo Production
District Heat Supply and Return
Heated Buildings
Greenhouse
Snowmelt
Klamath Falls district heating system
IFA Nursery – 4 acres – trees seedlings
OTHER KLAMATH FALLS
GEOTHERMAL USES ON THE
DISTRICT HEATING SYSTEM
GREENHOUSES
A variety of crops can be raised: vegetables, flowers, house plants, trees
Various heating systems can be used
Geothermal reduces costs and allows operation in colder climates
Temperate climate zone: 100 Btu/ft2/hr
5 acre facility: 22 million Btu/hr (6.5 MWt) peak
Annual requirement with LF of 0.45 = 100billion Btu/yr (28 million kWhr/yr)
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32 50 68 86 104
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Temperature 0C
Temperature 0F
CUCUMBER
LETTUCE TOMATO
AQUACULTURE
Raising catfish, bass, tilapia, shrimp and tropical fish and even alligators
Temperature of water from 55 to 90oF
Increase growth rate by 50 to 100%
Water quality and disease control important when using the geothermal water directly
Outdoor pond in temperate climate zone: 250 Btu/hr/ft2
5 acre facility: 50 million Btu/hr (15 MWt) peak
With LF of 0.60 = 260 billion Btu/yr (77 million kWhr/yr)
Temperature 0C
Temperature 0F
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Cows
68 86 104
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Trout
Shrimp Catfish
Chickens
INDUSTRIAL
Generally require higher temperatures as compared
to space heating : >200oF.
High energy consumption
Year-around operation
Drying of timber, extracting minerals, concrete block
curing, leather tanning, milk pasteurization, borate
and boric acid production, and dehydration of
vegetables and fruit are examples
They also tend to have high load factors in the range
of 0.4 to 0.7 – which reduce the unit cost of energy.
Food processing Cementdrying
LumberFurniture
Pulp and paper
Aggregatedrying
Leather
Concrete blockcuring
Metal parts washing
PasteurizationSoil warming
Aqua-culture
Biogasprocesses
Malt beverages
Distilled liquor
Fruit & vege-table drying
Mushroomculture
Blanching andcooking
Beet sugarextraction
Soft drinks
Greenhousing
0C
0F
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660 930
1500 2000
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0F
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1500 2000
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Application temperature (0F, 0C)
REFRIGERATION/SNOW MELTING Lithium bromide system (most common – uses water
as the refrigerant) Supplies chilled water for space and process cooling –
above the freezing point
The higher temperature, the more efficient (can use geothermal fluids below 200oF)– however, >240oF better for 100% efficiency)
Units are now available down to 176oF @ 100% efficiency
Ammonia absorption used for refrigeration below freezing normally large capacity and require geothermal temperatures above 250oF – only one in operation worldwide (Alaska) @ 165oF; however, using 40oF cooling water from a stream (large ΔT).
Snow melting using PEX pipes under or in pavement : 100 to 150 Btu/hr/ft2 typical
Oregon Institute of Technology – chiller
192oF producing 45oF chilled water @ 600 gpm
1 MWt installed – 500 kWt net
Chena Hot Springs Resort – Ice Museum
Absorption chiller 33 kW
85 gpm @
165oF
geothermal
80 gpm @
40oF river
water.
-4oF @ 55
gpm to
museum
SELECTING THE EQUIPMENT
FOR DIRECT-USE PROJECTS
Geothermal fluids often must be isolated to prevent
corrosion and scaling
Normally need a plate HE to isolate the fluid
Care to prevent oxygen from entering the system
Dissolved gases and species such as boron and
arsenic can be harmful to plants and fish.
Hydrogen sulfide attacks copper and solder.
Carbon dioxide can be used in greenhouses.
Peaking or backup fossil fuel plants often used
PLATE HEATEXCHANGER
ENERGY
USERSYSTEM
INJECTIONWELLHEADEQUIPMENT
PRODUCTIONWELLHEADEQUIPMENT
GEOTHERMAL
1300F(550C)
1400F(600C)
1800F(800C)
1700F(750C)
PEAKING/BACKUP
UNIT
Typical direct-use system equipment
NEW TRENDS
COMBINED HEAT AND POWER PLANTS Low temperature resources used for binary power
production and cascaded for direct use
Temperatures as low as 200oF are being used
Makes efficient use of the resources
Improves economics
Increases employment
CHENA HOT SPRINGS, ALASKA United Technologies
Corporation
200 kWe Carrier converted
vapor-compression cycle
chiller to a Rankine cycle that
uses R-134a refrigerant
Installed in July of 2006
Lowest temperature geothermal
use for power generation in the
world
165oF resource and 40oF
cooling water
OREGON INSTITUTE OF TECHNOLOGY
BINARY POWER PLANT
• 280 kW electric
• 198oF geothermal water
• Cost: $1,000,000
• Provides 10% of campus
electricity
• 2nd power plant planned
@ 1.75 kW
• With solar array - 100% of
campus electrical energy
supplied.
• Water cascaded to heat all of
campus at 165oF
SUMMARY OF POTENTIAL
GEOTHERMAL APPLICATIONS
40 to 90oF: geothermal heat pumps for heating
and cooling
90 to 140oF: spas and pool heating; greenhouse
and aquaculture heating, snow melting; radiant
floor heating
140 to 200oF: space heating using baseboard
hot water and forced-air systems
200 to 300oF: industrial processing, cooling and
refrigeration
>200oF: binary power generation
>350oF: flash steam electric power generation
FUTURE DEVELOPMENTS
Collocated resources and use
Within 5 miles apart
Sites with high heat and cooling load density –
>0.7 million Btu/hr/acre
Food and grain dehydration
Especially in tropical areas where spoilage is common
Greenhouses in colder climates
Aquaculture – to optimize growth even in mild climates
Combined heat and power projects – cascading
Mineral extraction (silica, zinc, gold, etc.)
CONCLUSIONS Many possible direct-uses of geothermal fluids
Number of parameters will limit choices: Temperature, flow rate, chemistry and land availability
Market available, and do you have the expertise to provide the product (i.e. heat and/or flowers/fish, etc.)
Can you get the product to the user economically – (i.e. pipelines or truck/rail/airline transportation)
Availability of capital, income and ROI/payback
Can you attract investors (i.e. minimize the risk)
Alternative to consider – combined heat and power project – to better utilize the resource and help the bottom line