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

Levels of exploration and

reservoir confirmation

Proposed

well

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?

Courtesy of the

Geothermal

Education

Office

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)

Colorado, Hungary, New Zealand and Arkansas

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

-20

-15

-10

0

-5

5

10

15

100

75

50

25

0

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

Downhole heat exchangers – 600 in KF

Black

iron

pipe

vs.

PEX

pipe

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

Klamath Falls district heating system

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)

0 5 10 15 20 25 3530 40

32 50 68 86 104

0

25

50

75

100

125

Temperature 0C

Temperature 0F

CUCUMBER

LETTUCE TOMATO

Greenhouse heating systems

Greenhouses shapes

and designs

USA, Iceland and

Hungary

Osarian greenhouses, Kenya – 1,000,000 roses/day shipped overseas

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

0 10 20 30 40

32

Cows

68 86 104

100

80

60

40

20

0

50

Trout

Shrimp Catfish

Chickens

Typical

aquaculture

facilities

“Gone Fishing” – African Cichlids

Eels,

Slovakia

Alligators,

Idaho Tilapia and cat fish

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

100

500

380

1000

660 930

1500 2000

1210

2500

1490

3000

0C

0F

100

500

380

1000

660 930

1500 2000

1210

2500

1490

3000

Application temperature (0F, 0C)

Industrial applications

Heap leaching, milk pasteurization, onion dehydration, timber drying

Tomato drying - Greece

140ºF

geo.

30 lb/hr

4 t/yr

dried

Air flow HE

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

Klamath Falls snow melting system

New geothermal snowmelt system on campus

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

Combined heat and power project example

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

THANK YOU