DOBBIE ENGINEERS LTD - Bay of Connections Moore... · Case Study Aquatic Theme Park Aquatic Theme Park 1. Would Require • Two low temperature supply wells (i.e. Typical Rotorua

DOBBIE ENGINEERS LTD

Direct Use Of Geothermal

Energy

Greg Moore

Direct Use of Geothermal Energy


DOBBIE ENGINEERS DIRECT USE PROJECTS

DOBBIE ENGINEERS DIRECT USE PROJECTS

•Clean steam production plant •Timber drying kilns •Pool heating •Glass house heating •Hotel and hospital heating

3


CONTENTS

1. Evaluation of Energy Source for Direct Use • Determine the extent and Quality of Resource • Determine limitations on Extraction • Identify potential uses for the energy

2. Options for energy extraction • Down Hole Heat Exchangers • Low Temperature Doublet Production System • High temperature and pressure systems

3. Examples of Direct Heat Use 1. Hotel/ Motel Direct Use 2. Mineral Pools and Aquatic Parks 3. Glass Houses 4. Industrial Applications

4. Health and Safety Requirements

4


Determine the extent and Quality of Resource

1. The Depth of the resource will influence well costs • Shallow well, 100 to 200m deep, 100 to 150mm

diameter,$30K to $50K • Deep well, 1500 to 2000m deep, 300 to 450mm

diameter$7M to $10M 2. Fluid Temperature and Pressure will influence the suitable

end use (bathing, space heating, industrial applications) 3. What are acceptable extraction rates? Affect size of

development 4. Chemistry? Is it corrosive, will it cause fouling, is it water,

steam or gas dominated ? These generate the challenges and how we use the resource. 5


How Do We Resolve These Questions

1. Look at other users

2. Use scientific measurements to establish reservoir depth and size, resistivity measurements etc

3. Sample and analyze fluid from natural features

4. Drill slim or test holes to sample the aquifer

5. Perform discharge tests on wells

6


What Are The Production Limitations Discuss with Environment BOP/Environment Waikato Consider existing resource consents Evaluate impacts on natural features and other users Will the gas or liquid discharges generated be significant? Will subsidence be an issue?

7


Identify Potential Uses

8

Lindal diagram ex GNS


Options For Heat Extraction 1. GSHP, Ground Source Heat Pumps

2. DHHE, Down Hole Heat Exchangers

3. Low Temperature Doublet Production Wells

4. Deep Source Production Wells

9


DHHE 10


Down Hole Heat Exchanger Performance 1. Output 20 to 70 kW but up to 150kW seen in Rotorua

2. Typically low temperature heat (40 to 80 oC)

3. Wells are 50 to 100m deep, minimum diameter 150mm,

larger wells overseas

4. Piped secondary fluid pumped through the coil

5. Requires permeability and a horizontal flow in the aquifer, this limits performance and increases risk

DHHE

11


Down Hole Heat Exchanger Typical Uses 1. Most Rotorua applications are one home plus a pool

2. 5 to 10 homes is likely best case scenario

3. Maybe a small Motel 5 to 40 units

4. Pool 20 to 100m2

DHHE

12


Down Hole Heat Exchanger Features 1. Relatively low output

2. Does not extract fluid from the reservoir. Considered more

sustainable and minimizes pressure impacts in the reservoir.

3. Only one well is required, Typical costs $35k to $60k, plus additional $20k - $25k per home connected

4. Output is very dependent on local permeability and horizontal flow in the aquifer. Relatively high risk of variable results

DHHE

13


Low Temperature Doublet Production system 14


Low Temperature Doublet Well Types 15


Low Temperature Doublet System Performance 1. Output 200kW to 1 MW

2. Typically low temperature heat (80 to 160 oC)

3. Wells are typically 50 to 200m deep, diameter 100 - 150mm,

larger wells are possible

4. Typically uses a plate heat exchanger to separate geothermal fluids and heating system fluids

5. Output more predictable than DHHE

Low Temperature Doublet System

16


Low Temperature Doublet Systems

Low Temperature Doublet System Typical Uses 1. 50 to 100 homes

2. Large Hotel 200 to 300 rooms plus conference facility

3. Pool of 500 to 1000m2 (50m Olympic pool or aquatic park)

4. Commercial development (1000 to 10,000 m2)

5. Glass House 500 to 5,000 m2

17


Low Temperature Doublet System Features 1. Moderate output, 120 to 160 oC, 100 to 200 tonnes/day

2. Requires two wells to provide supply and reinjection, can

impact on reservoir pressures

3. Typical costs $100k to $250k for wells and heat exchanger plant, plus additional heating system. Annual energy savings range from $20k/year to $100k/year or more

4. Output is more predictable output than DHHE’s

5. Often use antiscalant dosing to prevent calcium carbonate deposition

Low Temperature Doublet Systems

18


High Temperature & Pressure Systems 19


High Temperature and Pressure Systems 1. Output 2MWT to 50 MWT

2. Typical temperature (180 to 240 oC)

3. Wells are typically 1,000 to 2,500m deep, diameter 200 -

350mm

4. Typically uses a separator to separate geothermal fluids and then uses steam in a shell and tube heat exchanger to heat a secondary fluid.

High Temperature & Pressure Systems

20



High Temp. & Pressure System Typical Uses 1. Timber drying kilns (90 to 160 oC) 5 to 10 kilns

2. Large Glass Houses (90 to 160 oC) 5 to 15 Ha

3. Clean Steam Production for product drying or Dairy, 25 to

50 t/hr of steam

4. Aquaculture 2 to 20 Ha

5. Other Process Plants: ethanol distillation, rendering plants, pulp and paper,

21


High Temperature & Pressure System Features

1. High Temperature and Pressure output requires more detailed design to appropriate codes with robust safety systems

2. Requires two wells to provide supply and reinjection

3. Typical costs: $5M to $10M per well, plus separation and heat transfer plant and piping which is variable and may range from $2M to $10M. Capital cost is extensive

4. Some advantages if linked with an existing steam field, production and standby wells can be shared.


22


Case Study Hotel Application

Case Studies

1. Low Temperature Hotel System

2. Low Temperature Mineral Spa System

3. Low Temperature Pool Theme Park Complex

4. High Temperature Glass House application

5. High Temperature Timber Kiln Drying

6. High |Temperature Clean Steam Application.

23


Case Study Hotel Application

Low Temperature Hotel System 1. Minimum two wells (production and reinjection) 2. Fluid 130 to 140 oC, 150 to 200 tonnes/day 3. Typically might heat 200 rooms plus restaurant and

conference facilities, pools? 4. Plate Heat Exchangers transfer energy to space heating

and hot water systems 5. Significant hot water storage is required to meet peak

domestic hot water requirements 6. Geothermal fluid use can be cascade down to finally

heat pools 7. Geothermal System costs $150k to $200k. Annual

might save $300 to $500/year per room plus other savings for public spaces and pools

24


Case Study Hotel System 25


Case Study Hotel System Production Well 26


Case Study Hotel System Reinjection Well 27


Case Study, Hotel System Heat Exchanger Plant Room 28


Case Study Hotel System Heat Exchanger 29


Case Study Hotel System Heat Exchanger 30


Case Study Hotel System, 500kW Heat Exchanger 31


Case Study Hotel System, 7.5 m3 Hot Water Storage Tank 32


Case Study Mineral Pools

Low Temperature Mineral Spa System 1. Require a low temperature geothermal water supply

• Cooled water from a well or heating system • Natural spring or pool

2. Degassing system to remove CO2 and H2S

3. Storage system is needed to meet instantaneous demands

4. Water treatment system is required to adjust temperatures and maintain constant temperatures

5. Systems require regular flushing and cleaning

34


Case Study Mineral Pool Spa 33


Low Temperature Mineral Spa System, Rules 1. Water Quality. NZS 5826 has section on geothermal

pools • Once through water use. Water change rate of at

least one per 4 hours • Empty, scrub and disinfect pools daily

2. Degassing system is essential to remove CO2 and H2S 3. Control temperatures at or below 40 oC, 4. Ensure spaces are well ventilated (see RDC Bylaws) 5. Pools shall overflow via the rim without any low points

to capture gases 6. As no water treatment, heads shall not be immersed 7. Provide a physical barrier between pools and grass or

soils Case Study Mineral Pools 35


Low Temp. Mineral Spa System, Possibilities

1. Cooled geothermal water from one production well, 200 tonnes/day

2. Cooling pond or heat exchange system to cool fluid down

3. Provide gas removal from water by flashing or aeration

4. Sufficient for 15 to 20m2 of pool, or 10 spa pools

5. Can be recycled if filtered and sterilized. Chemical

treatment has been unsuccessful in most cases. Pasteurization has been used.

Case Study Mineral Pools

36


Case Study Aquatic Theme Park 37


Case Study Aquatic Theme Park

Aquatic Theme Park

1. Could provided year round heated complex : • Themed for Rotorua? • Indoor Spa complex • Indoor 25m training pool • Outdoor Spa 70 m2

• Indoor/Outdoor Leisure and Wave Pool 1300m2

• Outdoor 25m pool • Lazyriver/hydroslides • Geothermal Spa • Domestic hotwater and space heating

40


Case Study Hotel System 25



Aquatic Theme Park

1. Would Require • Two low temperature supply wells (i.e. Typical

Rotorua wells 650 to 700kJ/kg 130 to 140 oC) • Reinjection Well • Approximately 400 tonnes/day of geothermal fluid

or 2.5 MW of energy.

• Cascaded use of geothermal to maximize use

• Fluid cooled to 26 oC to recover all energy • Pools covered at night to minimize losses • Cooled fluid could be used in a geothermal spa

complex

41



Aquatic Theme Park

Features • Year round hot water pools and climate control

• Central Geothermal Heating Plant costs $300k to

$500k. (Pool heating systems extra)

• Annual Energy could be 20,000 to 30,000 GJ

• Energy savings of $300k to $400k per annum

42


Case Study Large Glass House (5 to 15 Ha) 43



Large Glass House 5 to 15 Ha Features

• High Temperature/pressure well. Fluid at 18 barg, 200 oC

• Energy approx 2MW per Ha. (20MW for 10Ha)

• Peak Fluid use 8 tonnes/hr/Ha (fluid at 1200kJ/kg)

• Requires standby capacity and large storage tank to store heat during day to meet peak loads at night

• Capital cost to serve 10 Ha requires deep supply and reinjection well ($1M-$10M each) plus $500k to $1M for central plant and piping








GEOTHERMAL FLUID TO CLEAN STEAM

NTGA CLEAN STEAM PLANT CASE STUDY

•Kawerau plant that generates clean steam suitable for use in paper machines. Could be any clean steam application •Owned by Ngati Tuwharetoa Geothermal Assets •Supplies up to 26 tonnes/hr of 16barg clean steam to SCA Hygiene Australasia's Kawerau tissue paper plant. Enabled SCA to shut down its gas boilers •Commissioned in September 2010

49


COMMISSIONED PLANT 50


FLOW DIAGRAM 2 PHASE GEOTHERMAL TO CLEAN STEAM 53


GEOTHERMAL CONDENSATE STRIPPING PLANT 54


CLEAN STEAM HEAT EXCHANGER 55


56


TIMBER DRYING

TIMBER DRYING CASE STUDY Energy needed to:

•Heat the air (90°C to 140°C) to be circulated in the kilns •Boil water is required to produce a humid atmosphere to precondition or recondition timber

Geothermal energy can be used as separated geothermal steam within the heating coils or to heat pressurised water that passes through the heating coils

58


SEPARATED GEO STEAM IN KILN (KAWERAU)

Production well Reinjection well

Separated Geothermal

Water

Separator

Geothermal Steam Other users

and vent

NCG

Stack

Flash

Vessel Condensate

NCG

Kiln

59


HOT WATER SYSTEM CONVERTED FROM GAS BOILER TO GEO HX

TAUHARA GEOTHERMAL HEAT PLANT •Conversion of Tenon’s 9 timber drying kilns from natural gas to geothermal. Uses two phase fluid and heat exchangers •Contact Energy supplied the geothermal source and the heat plant •Tenon modified the kilns piping to connect to the plant •Loads ranged from 5 to 30MW •Dobbie Engineers designed and commissioned the plant

60


TENON FLOW DIAGRAM WITH GEO HEAT EXCHANGERS

TH6 TH2 TH7 TH8

HEX 2

HEX 1 170C

HEX 3

165C Water

180C Water

150C Water

135C Water

Heat Dump

Heat Dump

Kiln 1

Kiln 2

Kiln 3

13.5 barg 197C

Kiln 4

Kiln 5

Kiln 6

Kiln 7

Kiln 8

Kiln 9

61


TENON HEAT EXCHANGERS

NCG DISCHARGE TO STACK

HX 1 HX 2

Ø400 GEO SUPPLY INSULATED

TIMBER DRYING KILNS

62


Health and Safety 64

Health and Safety Issues For Geothermal Use High Pressure and Temperature Well Drilling and Operation. Covered by Gary Brown later today Pressure Piping and Vessels

• Piping and pressure vessels operating over 65 oC and at pressures above 50 kPa must comply with Pressure Equipment, Cranes and Passenger Ropeways Act

• Requires design, design verification and fabrication in accordance with recognized standards.

• Plant must be maintained and operated in accordance with recognized standards



Health and Safety Non Condensable Gases (CO2 and H2S)

• All plant areas need good ventilation, eliminate low points, hollows etc where gas can accumulate.

• At plant start-up gas levels needs to be considered • Mineral pools are of particular risk if fluids are not

degassed • Geothermal fluid shall not taken into inhabited areas

Hot Pipes over 55 oC should be insulated for personnel protection



Health and Safety Bylaws: Rotorua District Council Geothermal Bylaws. These cover a number of issues including the use of mineral pools, plant locations, drilling geothermal wells, maximum exposures limits for H2S and the safe operation and maintenance of plant.

DOBBIE ENGINEERS LTD

Direct Use Of Geothermal

Energy

Greg Moore


www.dobeng.co.nz PO Box 1055 Rotorua Ph 07 3485 465

http://www.dobeng.co.nz/

Documents

DOBBIE ENGINEERS LTD - Bay of Connections Moore... · Case Study Aquatic Theme Park Aquatic Theme Park 1. Would Require • Two low temperature supply wells (i.e. Typical Rotorua