GEOTHERMAL INTERNATIONAL · Geothermal Utility Costs: $298,438 • $0.70 psf Savings from...

transcript

GI Endurant, LLC

One East Oak Hill Drive, Suite 304 Westmont, IL 60559

Tel: 312-405-9489

Rob Olden

Director of Engineering

rjo@ginorthamerica.com

www.ginorthamerica.com

GEOTHERMAL

INTERNATIONAL

Agenda

1. Introduction

2.Overcoming oversizing

– Why detailed analysis?

3.Design case studies

– Integrating innovative HVAC and geothermal

– Optimizing importance

– Importance of commissioning

4.Construction economics

– Considerations for geothermal

Problem Statement

“ Note: Geothermal field sized in excess of connected load to accommodate for diffusion, maintaining thermal performance for unbalanced load.”

- General note on actual geothermal bid drawing • Added vertical costs • Added horizontal costs • Added coordination (including code setback review) costs • Added spoils management • Added chamber costs • Added pumping costs • Added pipe material costs • Added labor

Why do fields get oversized?

Geothermal heat exchangers behave……

…..differently from cooling towers.

Overcoming Oversizing

Cooling tower selection criteria

• Ground Conductivity • Thermal Diffusivity • BHE depth • BHE spacing • Equipment type • Equipment efficiency • Equipment arrangement • Sequence of operations • Occupancy schedule • Hydronic design • Pump selection • Outside air • Infiltration • Load diversity • Hourly loads • Annual drift

Time (1 Year)

Hour 1 Hour 8760

• Ground Conductivity • Thermal Diffusivity • BHE depth • BHE spacing • Equipment type • Equipment efficiency • Equipment arrangement • Sequence of operations • Occupancy schedule • Hydronic design • Pump selection • Outside air • Infiltration • Load diversity • Hourly loads • Annual drift

Engineering uncertainty leads to oversizing

Overcoming Oversizing

Why Detailed Analysis?

• Projects installed to date

– 1150 Boreholes totaling 470,750 linear feet

– 2,799,481 million square feet served

– 6742 tons ( 23.7MWatts) of cooling capacity

Achieved overall average of 18%

reduction in geothermal field size

when performance spec was used

Average project “linear feet per

ton” is 70’ vs 150’-200’

177 122 163

319 32 21 0 0

Supply Temperature Range

Hydronic Supply Temperature

2920 2737

229 103 226

1009 1081

48 7 0 0 0

Supply Temperature Range

Hydronic Supply Temperature

$450,000 Saved

145 boreholes at 450 feet deep 115 boreholes at 450 feet deep

Why Detailed Analysis?

• To improve the economics of geothermal

• A scientific alternative to rule of thumb design that enables the following:

1. Integrating innovative HVAC systems

Generating equipment SOO

2. Optimizing performance

3. Optimizing commissioning

1. Integrating Innovative HVAC Systems

• Raising the bar to allow study of geothermal system design innovations

– Central Plant Systems

– Hybrid Cooling (cooling towers, chillers, etc)

– Hybrid Heating (boilers, solar thermal, etc)

– Industrial and process loads

– Differing geothermal sources

Cascading central-plant chiller system simulation with hybrid cooling and heating

One New Change, London

Reinforcing

Vertical

Structural Integration

Mansfield Hospital

Largest Lake Loop System in

Europe

• 1,400 tons Heating

• 1,600 tons Cooling

• 140 steel heat exchangers

• 650,000 SQFT Lake

• Completed: 2009

• Annual C02 savings: 2,029

2. Optimizing Performance

• Identify the most efficient control sequences

– Minimize energy consumption

– Maintain long-term system stability

• Hypothesizing vs. guessing

• Allows future calibration and optimization based on real building data

Metered energy use tracks with simulated energy use after calibration

Walgreens Case Study

12,000 sq. ft. • Completed 2010 • Oak Park IL

Total GHVAC Cost: $370,000 ($180,000 geo premium)

ARRA Incentives: $161,245 (ITC & Depr)

4.6 year payback • 1st 20 years energy savings: $155,800

Conventional Utility Costs: $17,570 • $1.37 psf

Geothermal Utility Costs: $11,772 • $0.92 psf

Savings from Geothermal: $5,798 • $0.45 psf

Walgreens Case Study

Oak Park prototype system includes • Four geothermal boreholes • Geothermal heat pumps • Water-cooled refrigeration • Supplemental (hybrid) boilers • Supplemental (hybrid) cooling tower • Geothermal M&V

Total KJ comparison: 27,059,065 to 26,933,983 = 0.46% error

Simulation Analysis Accuracy

10,000

20,000

30,000

40,000

50,000

60,000

70,000

Date/Time

SYSTEM MEASURED SYSTEM SIMULATION

Model Calibration

Initial Simulation Calibrated Simulation

Energy Savings 52% 53%

Cost Savings 33% 31%

Real Data from Monitoring

System

Plugged into Simulation Model matches recorded

Supported Initial Performance Estimates

Model Calibration

Commissioning Reports

Eliminated power spike

during morning warm-up period by 50%

Reduced night-time energy use by 30%

Early detection prevented future failures and maintenance emergencies.

AFTER FIX BEFORE FIX

3. Importance of Commissioning

Central Plant Office Case Study

93,116 sq. ft. • Completed 2011 • Mundelein IL

Total GHVAC Cost: $2,620,000 ($970,000 geo premium)

ARRA Incentives: $880,828 (ITC & Depr.)

1.5 year payback • 1st 20 years energy savings: $1,600,000

2xParallel DHR Chiller/Heaters serving hydronic VAV. Boiler for back up 100% Geothermal

Heating Load

TC ° F TH ° F

Cooling Load

rator C

Cooling Tower

Chiller Plant

Geo field maintains (warms) the

evaporator to support the load on the condenser side

Geo field maintains (cools) the

condenser to support the load on the evaporator side

Central Chilled Water Plant

Heating Load

TC ° F TH ° F

Cooling Load

rator C

Chiller Plant

Central Chilled Water Plant

1200 Ton Office Case Study

423,158 sq. ft. • Completed 2012 • Glenview IL

Total GHVAC Cost: $12,050,000 ($1,971,000 geo premium)

ARRA Incentives: $1,205,000 (Only ITC)

4.25 year payback • 1st 20 years energy savings: $4,620,500

50% Geothermal HVAC Hybrid

2x Conventional RTU in parallel with 2xGeothermal Heat pump RTU Serving VAV electric reheat system. Geothermal only heats at night.

Snow melt and data centers are connected to geothermal source loop.

Campus Retrofit Case Study

166,000 sq. ft. • Countryside, IL • Completed 2011 Distributed rooftop heat pumps • Radiant heat • Central chiller/heater • Central staging pumping station • Advanced air filtration • Snowmelt • Hydronic VAV

Central Plant: “6 Pipe”

• Control to Leaving Water Set Points in Heating and in Cooling Simultaneously.

– Chilled Water Temps to 38 F

– Hot Water Temps to 140 F

– Resultant source flows are mixed and sent to the field.

Design Conclusion

1.We need to change our paradigm with geothermal design

2.Performance Specs enable innovation and increased value

3.Analysis should remain alive for comparison after commission

4.Upfront commissioning is vital

Construction Economics

1.Advanced analysis of hybrid geo enables:

DESIGNING TO THE BUDGET

OPTIMIZE PAYBACK

SENSITIVITY STUDIES

2.Understanding the costs:

– Why deeper boreholes?

– Spoils management

– Manifold chambers

– Setbacks

– Conductivity testing

Why deeper boreholes

1.Deeper boreholes are not always better

– Shallow bedrock (>150’)

– Land area is tight

– Pumping design

– Pressure testing

2.Benefits:

– Reduces horizontal costs (25% of total job)

– Less site coordination

– Better conductivity

• Schedule • Spacial constraints • Trade coordinat • Winter operation

Drill Rig Considerations

• Spoils containment • Landfill testing • Liquid spoil management

• Formations may favor mud rotary

• Temporary vs permanent casing

• Test well data should be included in bid documents

Spoils management

1.Site logistics

– Managing fluids on the ground

– Custom dumpsters or confined pits on site

– Other trades in close proximity

2.Testing

– MWRD

– Landfill (CCDD vs. subtitle D)

3.Questions to ask

– Can spoils be recycled on site

– Drilling experience given the logistical constraints

Manifold Chambers

Plastic Chambers

Grade Accessible

Factory assembled

No structural impacts

3.5’ below grade

No penetrations

$22,000

22 BHE’s/Chamber

Concrete Chambers

Ladder required

Assembly required on site

Concrete structure

5’-8’ below grade

Multiple penetrations

$85,000

No max limit

CAD Details

Code Requirements

• Civil site utilities can dramatically worsen geothermal payback

– Ductile iron for all storm sewer

– Backflow preventers on permeable paver systems

– Drilling under slabs

• Code is antiquated and needs to be revised to enable closed loop geothermal construction

Conductivity Testing

• Important to enact, but be careful: – Location may be non-compliant with code setbacks

– Conductivity is fairly consistent in this area • Lake Forest 52.4-52.8/1.89/1.26

• North Chicago 55/1.65/1

• Downtown Chicago 54.6-55.9/1.94/1.35

• South Chicago 54.5/1.50/1.01

• Hyde Park 55.1-56.2/1.94/1.36

– Geothermal analysis must model all of the energy flows accurately

– Why not operate with sensitivity study and require test on first production borehole to confirm

Conclusion

• Higher resolution analysis + Hybrid geothermal = smaller fields and safer operation

• Analysis + monitoring = smarter ongoing operation

• Performance specifications will reduce the variance in geothermal bids and open the market to innovation

GEOTHERMAL INTERNATIONAL · Geothermal Utility Costs: $298,438 • $0.70 psf Savings from...

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