Solar Thermal Cooling

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• Solar Thermal Cooling
• and Hot Water
• Michael Goggin
• Natural Energy Technologies
• Solar Conference 2007

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Solar Thermal Cooling/Hot Water

• Solar thermal energy heats water in rooftop
  collectors
• Hot water can be used for domestic/process hot
  water or to drive absorption chiller for space
  cooling
• Hot or chilled water can be stored to mitigate
  insolation/load variation

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How Absorption Chillers Work

• Transfers thermal energy from the heat source to
  the heat sink through an absorbent fluid and a
  refrigerant.
• The absorption chiller creates refrigerative
  effect by absorbing and then releasing water
  vapor into and out of a lithium bromide solution.
• Proven technology in cogeneration systems for
  decades.

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Favorable Factors for STC High Insolation
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Large Cooling Load
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High Electric Rates
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Strong Incentives
MN 25 by 2025 (Xcel 30 by 2020)
ME 30 by 2000 10 by 2017 - new RE
VT RE meets load growth by 2012
WA 15 by 2020

• NH 23.8 in 2025

ND 10 by 2015
WI requirement varies by utility 10 by 2015
goal
MA 4 by 2009 1 annual increase
MT 15 by 2015
OR 25 by 2025 (large utilities) 5 - 10 by
2025 (smaller utilities)
RI 16 by 2020
CT 23 by 2020
IA 105 MW

• NV 20 by 2015

• NY 24 by 2013

• NJ 22.5 by 2021

• CO 20 by 2020 (IOUs)
• 10 by 2020 (co-ops large munis)

IL 25 by 2025

• PA 18¹ by 2020

CA 20 by 2010
MO 11 by 2020

• MD 9.5 in 2022

• NC 12.5 by 2021 (IOUs)
• 10 by 2018 (co-ops munis)

• AZ 15 by 2025

• DE 20 by 2019

• DC 11 by 2022

• NM 20 by 2020 (IOUs)
• 10 by 2020 (co-ops)

VA 12 by 2022
TX 5,880 MW by 2015
State RPS
HI 20 by 2020
State Goal

• Minimum solar or customer-sited RE requirement
• Increased credit for solar or customer-sited RE
• ¹PA 8 Tier I / 10 Tier II (includes
  non-renewables)

Solar water heating eligible
DSIRE www.dsireusa.org


September 2007
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Performance/Economic Modeling

• Performance Inputs
• National Renewable Energy Laboratory hourly solar
  insolation data
• Collector performance curves from independent
  certification agency
• Hourly ambient temperature data
• Building energy demand profile
• Economic Inputs
• Equipment costs
• Installation costs
• Energy prices
• Incentives
• Outputs
• Identification of optimal technologies for
  collectors and chillers
• Identification of optimal size for collector
  array and chillers

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Example Output Hourly Profile
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Seasonal Profile
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Payback/Savings
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Benefits

• Economic savings
• Free fuel
• Peak shaving during expensive electric rate
  periods
• 30 ITC from EPAct 05
• Hedge against rising energy prices
• Use existing HVAC infrastructure
• Policy factors
• Large number of state, local, and utility
  incentives
• Growing market for renewable energy credits for
  compliance with state renewable standards
• Environmental benefits
• Fewer GHG emissions and other pollutants
• Water savings in arid Southwest

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For More Information

• Dick Partridge
• 562-833-2629
• Doug Hinrichs
• 301-219-7647
• Michael Goggin
• 240-223-5552