Transcript Geothermal HVAC for Homes, Farms and Businesses (and schools) Alice Gitchell Richard Stockton College Please feel free to ask questions at any time!

Geothermal HVAC for Homes,
Farms and Businesses
(and schools)
Alice Gitchell
Richard Stockton College
Please feel free to ask questions at
any time!
What’s in the name?
• “Geothermal energy” has historically
referred to geysers and steam from deep in
the earth
• Not found in New Jersey
• Better term is GeoExchange
• Registered trademark of Geothermal Heat
Pump Consortium
• www.geoexchange.org
Why Stockton?
• Long term interest in energy technology
• Most of our heating and cooling is done by
GeoExchange – 1650 T cooling capacity
• “World’s largest” for many years
• Used for research and training
• Moving towards a very advanced system
Stockton campus
The science behind GeoExchange
• Constant temperature found a few feet below
ground surface
• Not making heat (by burning fuel) but moving it
• Heat can be “moved” into a building to warm it,
leaving the ground cooler
• Heat can be discharged into the ground, leaving
your building cooler and the ground a little
warmer
• So how to get to the right TEMPERATURE?
Science behind the heat pump
• A heat pump runs on electricity, does work
and “separates” hot from cold
• Closed system with a gas inside
• Compressing a gas heats it, expanding a gas
cools it
• Take advantage of either “side” of this
closed system
Putting it together
• Water to air heat transfer
• Using electricity to move both air & water
around
• Two common configurations
• Open versus closed loop
Open loop system
• Suitable for house or small business
• Pump well water through heat pump
• Extract heat (winter) or discard heat
(summer)
• Discharge water to another well or other
arrangement (landscaping)
• Can “zone” using multiple small heat
pumps
Components – water to air HVAC
system
• Well
• Heat pump(s)
• Thermostats or building management
system
• Ductwork
• Discharge arrangement for water
Closed loop system
• Put PVC piping into ground for heat exchange
• “Borehole” is the most common configuration –
100 to 400 feet deep
• Fill with water to circulate for heat exchange
• System is isolated from groundwater
• Can be scaled UP
• Borehole field a LONG term investment
Closed loop
Vertical Piping
Advantages – open or closed
system
• Same equipment provides heating and cooling –
less mechanical space required
• Lower operating cost (percentage varies according
to alternatives) - less pollution
• Comfort factors - temperature never goes very
high (so air is less dry) & air moves more slowly
than forced hot air
• Can heat and cool at same time (but not with the
same heat pump)
Advantages (cont.)
• Flexible configuration – inside building and also
in terms of ground coupling
• Quiet
• No equipment exposed to weather or vandalism
• Don’t need certified boiler operators
• “Bragging rights”
• Rebates – go to www.njssb.com click on
equipment, currently $370 per ton
Disadvantages
• Slightly higher initial cost for both equipment and
design
• Construction can be disruptive (for larger projects)
• Unfamiliar to maintenance staff – but maintenance
costs are lower in long run
• Greatest benefits to facilities with high, consistent
loads
• Not economical for cooling only (in NJ)
Important pointers
• Easier with new construction (but retrofits can
work and should be included in comparisons)
• Introduce into planning early – building will be
slightly different
• Check experience of architect and engineer
• Need life cycle cost analysis and energy study
• Geology counts – sand is good but rock is NOT
bad
• Ask for details if you are told “it won’t work”.
What’s next?
• Hybrid systems – when AC and heat demand are
out of balance
• Pond or ocean systems
• Standing column configurations
• Aquifer thermal energy storage (ATES) seasonal
storage common in Europe
• Energy efficiency or carbon reduction credits –
RECs in NJ now limited to renewable generation
of electricity, but this could change
Stockton Projects Completed
(research included)
• Geothermal HVAC
• Photovoltaics – 18 kW on Arts & Sciences
Building, 2 kW on daycare
• Lighting upgrades, motor replacement, etc.
• Energy Alert – human behavior - harvest
easy savings on high demand days
• Fuel cell
Fuel cell
• 200 kW electricity + 900,000 btu heat per hour
• Consumes natural gas, so why do it?
• Bypasses all transmission loss and reduces air
pollution
• “Transitional technology” in the public interest
• Distributed generation less vulnerable to
disruption
• Non interruptible power – critical equipment and
emergency response
Next at Stockton
• Photovoltaics – large scale – flat roofs as a
New Jersey resource
• ATES (800 T cooling capacity) – feasibility
study complete
• Wind (1.5 MWatts) – careful evaluation of
wildlife impacts necessary, technical
advances important