GENERATOR HEAT RECOVERY
CONSIDERATIONS IN ARCTIC
VILLAGE APPLICATIONS
LCDR William Fraser, P.E.
Who We Are
Alaska Native Tribal
Health Consortium
Division of
Environmental
Health &
Engineering
June 2011
ANTHC
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Non-profit, statewide organization
Provides a range of medical and
community health services for more than
125,000 Alaska Natives.
Part of the Alaska Tribal Health System,
which is owned and managed by the 229
federally recognized tribes in Alaska and
by their respective regional health
organizations.
ANTHC History
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1970s-1990s: Regional health
organizations in Alaska
Passage of P.L. 105-83 established
ANTHC, the only THO established by
statute
December 1997: ANTHC incorporated as
non-profit 501(c)(3)
June 1998: Initial contract with IHS.
ANTHC History

October 1998: Contract expanded to
include Environmental Health &
Engineering
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October 1998: ANTHC becomes a P.L.
93-638 Title III Self-Governance entity,
signing the Alaska Tribal Health Compact
DEHE
Designs and Constructs Health and
Sanitation Facilities
 Provides operations support
 Monitors & develops standards for
mitigating climate change impacts
 Health impact studies
 Environmental Grants & training

Water & Sewer- Why?
What does this have to do with
Heat Recovery?
Hospitalizations are 5 times higher in
communities w/o piped water & sewer.
 Typical Fuel consumption for an Arctic
WTP w/ piped water & sewer: 800025,000 Gal / Year Fuel Oil
 Fuel Prices between $6.00 & $8.00 / Gal.
and rising.
 Heat recovery can help make it affordable.

Extreme Climate
High Energy Use
HEAT RECOVERY FROM POWER
PLANTS

2 basic types:
 Jacket
recovery
 Stack recovery
Small Scale: 50 KW to 3500 KW
 Ideal for space heat and process heat
 Considered a fuel saver, not a primary
source of heat.

Kwigillingok Generator Facility
ADVANTAGES OF HEAT
RECOVERY
Very green- reduces carbon footprint.
 Can dramatically increase the economic
viability of a community water system.
 Adds additional redundancy to the building
heating system.

DISADVANTAGES OF HEAT
RECOVERY
Requires an agreement with the power
utility, often with a charge for waste heat.
 Usually increases the complexity of the
heating system, especially in Washeterias.
 Requires additional maintenance and
coordination between power utility and
building owner.

Other Solutions
SO YOU WANT TO BE GREEN
What do you need to know before you
start?
 Estimating available waste heat
 Deciding on a heat recovery strategy
 Selecting system components

WHAT DO YOU NEED TO KNOW
BEFORE YOU START?
Who owns the generators and what are
their conditions?
 Do you have a viable path between the
waste heat source and the building?
 What type of building are you serving?
 Are there other buildings served by the
waste heat?
 What type of monitoring do you want?
 Who is going to maintain it?

ESTIMATING AVAILABLE
WASTE HEAT
QA = QGEN – QPIPE - QO
QA:
Minimum available waste heat for your building
QGEN:
Average generator output during peak heating season (typically much
less than rated capacity) in BTUs / Hour
QPIPE:
Heat loss from distribution piping during peak heating season. Typically
about 50-60 BTUH / LF
QO:
Heat used by other buildings on the waste heat system (sometimes this is
prioritized by order of connection, so be careful)
HEAT RECOVERY RULES OF
THUMB:
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Generator Output: 1/3 Electricity, 1/3 Jacket
heat, 1/3 Stack loss
1300-2000 BTU / KW-Hr (Available Jacket Heat)
100,000 BTU delivered heat = 1 gallon of diesel
Annual Fuel Saved = .3 x Power plant annual
fuel used x 0.6
Pumping Energy Costs <= 10% Fuel Value
BREAK EVEN TEMPERATURE
DIFFERENCE
TBR =
TBR:
PPUMP:
CE:
COIL:
UAHX:
GPM:
PPUMP x CE x 100
COIL x UAHX
+
PPUMP x CE x 100
900 x GPM x COIL
Break even temperature difference between Generator Heating Supply
and Building Heating Return (Deg F)
Pump power (W)
Electrical cost ($ / kWh)
Fuel cost ($ / Gallon) (80% efficiency assumed)
Heat exchanger U factor multiplied by HX area (BTU/ Hr x Deg F)
Heat exchanger glycol flow rate (GPM)
(This formula only applies in special case of counterflow HX with matching flow rates and
sufficient heating demand to use all of the waste heat)
ESTIMATING WASTE HEAT
DEMAND
QD = QBLG + QPROC
QD:
Waste heat demand (typically does not include dryers)
QBLG:
Building envelope heat losses (must engineer heating system for lower
temperatures than typical heating systems)
QPROC:
Heat required by process systems (includes circulation loops, raw water
heat add, storage tanks, etc. This is where waste heat really shines)
SELECTING A HEAT RECOVERY
STRATEGY

Direct heat add to potable water:
 Double
wall shell and tube, independent of
boiler system (Kiana)

Small system with single boiler:
 Pipe
heat exchanger in series with boiler
(Chenega Bay)

Large system with multiple boilers:
 Pipe
heat exchanger in primary / secondary
arrangement (Kwigillingok)
GENERATOR HEAT
RECOVERY ARRANGEMENT
RECOVERED HEAT INTO
POTABLE WATER
HEAT EXCHANGER IN SERIES
WITH BOILER
PRIMARY / SECONDARY HEAT
EXCHANGER DIAGRAM
Minto Heat Recovery
WASTE HEAT CONTROLLER
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Turns on at 8 Deg F
difference
Turns off at 4 Deg F
difference
Built in HOA switch.
Provides 1p/2t switch
which can handle a 1
HP pump.
BTU METER
Plate / Frame Heat Exchanger
Brazed Plate Heat Exchangers
Shell & Tube Heat Exchangers
Typical pumps
AMOT Valve
DESIGN COMMENTS
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Use Brazed Plate or Plate / Frame heat exchangers
Provide controls to ensure heat is not transferred back to generator
cooling system.
Provide controls to minimize electric power consumption
Provide BTU monitoring if being billed by local utility
Provide pressure relief on pipeline
Provide strainers on both sides of heat exchanger (reduces cleaning
of heat exchanger).
Provide air separator on pipeline side of system.
Provide glycol system monitoring and makeup.
Provide expansion compensation
Don’t use HDPE pipe. Copper, Steel, PEX, Stainless steel.
Monitor pipeline for leaks and pressure.
Questions?