HomeMy WebLinkAboutPROPOSAL - CITY OF SITKA - HEAT PUMPSPROPOSAL FOR ECONOMIC EVALUATION - HEAT PUMPS CITY OF SITKA 12/14/09 PAGE 1 OF 6
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PROPOSAL FOR ENGINEERING SERVICES
PREPARED FOR THE CITY OF SITKA
DECEMBER 14, 2009
ECONOMIC EVALUATION OF WATER SOURCE HEAT PUMPS
TO REPLACE HEATING OIL USAGE FOR SPACE HEATING AND DOMESTIC HOT WATER
FOR THE AIRPORT TERMINAL AND WASTEWATER TREATMENT PLANT (WWTP)
LOCATED ON JAPONSKI ISLAND
Prepared By Andy Baker, PE YourCleanEnergy LLC
308 G Street #212 Anchorage Alaska 99501 907-274-2007
PROPOSAL FOR ECONOMIC EVALUATION - HEAT PUMPS CITY OF SITKA 12/14/09 PAGE 2 OF 6
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BACKGROUND
In 2009, The City of Sitka will incur the following estimated annual costs to heat space and domestic hot
water in the WWTP and Airport Terminal Building (based average heating oil usage from 2003-2008):
Facility Heating Oil Usage (Gal) Cost of Heating Oil ($/Gal) Total Heating Cost
Airport 18,000 $2.60 $46,800
WWTP 10,600 $2.60 $27,560
---------- ---------- -------- -----------
Total 28,600 $2.60 $74,360
The heating oil consumption of the Airport Terminal and WWTP accounts for 49% of the total
heating oil consumed by all eight major City buildings included in the August 2009 CBS Energy
Audit. Due to global demand for crude oil products, the cost of heating oil is expected to escalate at a
minimum rate of 6% per year ov er the next 20 years. All of the heating oil used in Sitka must imported,
delivered and stored at costs also tied to this escalation of crude oil prices. Burning of heating oil also
introduces the liability of pollution and carbon emissions that may carry additional costs in the future as
efforts are increased to mitigate climate change. The City is motivated to evaluate other options for
providing heat to these and other City facilities for the next 30 years that are more cost effective and are
derived from carbon free renewable energy where technically and economically feasible.
There exists an increasingly self-evident opportunity to shift the cost of heating the Airport
Terminal and WWTP buildings from heating oil to water source heat pumps powered by
affordable, stable, and local hydroelectricity. An additional benefit that can be derived from heat
pump systems is that the future liability to the City of fossil fuel pollution and CO2 production can be
essentially eliminated because grid electricity in Sitka is at most times generated from 100% clean hydro.
The viability of heat pumps is greatly influenced by the temperature of the source water, as higher source
temperatures deliver higher pump efficiency. The final effluent from the WWTP (1.5 million gallons
average flow) and unlimited sea water from Sitka Sound are two significant heat sources available on
Japonski Island, see chart below for average monthly temperatures for each source water:
PROPOSAL FOR ECONOMIC EVALUATION - HEAT PUMPS CITY OF SITKA 12/14/09 PAGE 3 OF 6
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Final effluent from the WWTP and sea water from Sitka Sound are both carbon free renewable
heat sources available on Japonski Island that can be evaluated to determine the economic
viability of heat pumps to serve the WWTP and the Airport. The amount of heat that can be
recovered each year by extracting 4 degrees F from the WWTP effluent currently discharged in to the
ocean is 18,000 million BTU/year. This is three times greater than the total amount of useful energy
produced each year from heating oil in all eight City buildings (6,000 million BTU). The concept of using
one sixth of the recoverable WWTP waste heat (3,000 million BTU) to supply heat pump systems
for the Airport and WWTP is both technically and economically worthy of consideration.
The use of WWTP effluent as a heat source for buildings is already a proven practice in the lower
48, Canada and Europe. A high profile example of this practice is the new Olympic Athlete’s Village in
Whistler, BC, where a district loop to all buildings is su pplied by recovered heat from the Whistler WWTP.
Recovery of heat can be achieved with the use of in line filtration and plate and frame heat exchangers
designed for minimal fouling from suspended solids and organic matter. The filters and heat exchangers
will likely be equipped with Clean-In-Place (CIP) back flushing systems that operate on automatic
sequence. Once heat is extracted from the wastewater, the effluent it is simply returned to the outfall pipe
for discharge at the ocean floor as already permitted.
The option of using seawater as a source of heat for buildings on Japonski Island is also worthy of
consideration if a larger heating district is served so that economy of scale can be achieved. The
seawater temperature in Sitka Sound has a profile very similar to Resurrection Bay in Seward
where a successful sea water heat pump project at the SeaLife Center received federal grant
funds after an evaluation was completed by YourCleanEnergy. A system that combines heat
recovery from both WWTP effluent and seawater would enable optimal use of WWTP waste heat and
could serve a large district with economic efficiency on Japonski Island. It is evident however that the
initial cost of a seawater intake may be significant as the intake must extend offshore to a depth of 60 feet
to ensure temperature stability during the winter heating season.
An accounting of recent federal and state grant funding allocations show a clear preference
towards projects that provide innovative and cost effective means to reduce or eliminate fossil
fuel consumption and carbon emissions. Two specific examples of heat pump projects that received
federal grant funding in 2009 in Alaska to reduce heating oil consumption are the Alaska SeaLife Center
and the Auke Bay Lab (NOAA) in Juneau.
Heat pumps using WWTP effluent or seawater at 60 foot depth are predicted to maintain a
Coefficient of Performance of at least 3.0 to deliver heat at 130F to buildings. This means that for
every unit of electric energy that is consum ed by the heat pump, at least three units of heat will be
delivered. Two thirds of the heat energy is then provided by the source water that is heated with
renewable energy at no cost to the City. While the capital cost of heat pump systems and district loops
can be significant, there is high probability that grant funds can be secured in the present political climate
to reduce this cost. Once constructed, the return on investment of a heat pump project is driven primarily
by the savings of heating oil not consumed and the by relatively low cost of heat pump operation as
compared to alternative fuels:
Heating System Efficiency Fuel Unit BTU/ unit fuel $/unit fuel $/million BTU
Oil Boiler 0.82 gallon 134,000 $2.60 $23.66
Natural Gas 0.85 CCF 103,000 $1.05 $11.99
Electricity 1 kwh 3412.97 $0.10 $29.30
Sea Water Heat Pump COP = 3.0 kwh 10240 $0.10 $9.77
PROPOSAL FOR ECONOMIC EVALUATION - HEAT PUMPS CITY OF SITKA 12/14/09 PAGE 4 OF 6
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Typically water source heat pumps will deliver heat to buildings in the range of 130F so that domestic hot
water and radiant floor systems can be supplied. If an additional heat pump is installed inside the
building, the delivery temperature to building heat systems can be increased up to 180F if necessary. If
an entire building is converted to low temperature heat, the overall heating efficiency of a heat pump
system is optimized, this is now common design practice in both Europe and Canada.
In this proposal, the cost of integrating heat from a heat pump system into the Airport Terminal and the
WWTP facility will be evaluated to determine what temperature of delivery will be most cost effective over
a 30 year life cycle. The buildings currently have oil fired boilers delivering medium temperature heat
(180 F) to a combination of forced air duct coils, fin tube radiator baseboards, and hot water heater tanks.
While electric resistance heating has been employed recently in some City buildings (City Hall) the large
demand loads imposed by this practice have introduced concerns for Sitka’s electrical infrastructure,
specifically the need for increased repairs, capacity upgrades and maintenance. This is another
significant reason why the City would like to evaluate the long term viability of water source heat pumps
as an alternative to future electric resistance heat for the Airport Terminal and WWTP.
PROPOSAL FOR ECONOMIC EVALUATION - HEAT PUMPS CITY OF SITKA 12/14/09 PAGE 5 OF 6
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SCOPE:
1. Provide introduction, purpose of the economic evaluation, and a brief discussion of the function
and history of the City buildings to be evaluated (Airport Terminal, WWTP). Express goals that
the City has for both increasing energy efficiency and evaluating cost effective clean energy
alternatives to fuel oil and grid electricity. Identify the financial and public relations benefits that
can be derived by the City by using water source heat pumps.
2. Evaluate trends of City grid electricity and bulk heating oil costs from the past five years; and
estimate escalation rates to be used for electricity and heating oil for a 30 year life cycle cost
evaluation.
3. Evaluate monthly usage of fuel oil and electricity for each building from the past five years and
estimate future usage for a design life of 30 years. Discuss results of recent energy audits
completed for these buildings, improvements that are planned, and anticipated reduction in
heating loads after improvements are made.
4. For the WWTP, evaluate daily and monthly treated wastewater temperatures and flows from the
past five years. Identify possible methods of using heat from treated wastewater flow to
supplement a sea water heat pump system if it were located adjacent to this facility.
5. Identify several possible locations for sea water intakes, and for these locations evaluate
seawater temperature data (if available) from the past five years. Estimate the BTU’s of heat that
could be extracted from raw seawater each month at various pumping rates using a plate & frame
heat exchanger and a glycol loop that then supplies a heat pump system.
6. Identify proven commercial heat pump equipment that can utilize a glycol loop heated by sea
water during the heating season to supply low temperature heat (130F) supply to each of the
buildings. Evaluate Coefficient of Performance (COP) of heat pumps selected and estimated
electrical energy input for annual operation. Provide results of heat pump mfg’s software
simulation given monthly sea water temperatures and the requirement to maintain a 130F glycol
building heat loop through the entire heating season.
7. Three basic concept alternatives will be included for evaluation in this proposal:
A. Recover heat from WWTP effluent with heat pump to cover all heating loads now met by fuel
oil appliances in the WWTP facility.
B. Recover heat from WWTP effluent with heat pump to cover all heating loads now met by fuel
oil appliances in both the WWTP facility and the Airport Terminal. This option would require a
buried pipe loop to transfer heat from the WWTP site to the Airport Terminal.
C. Recover heat from both WWTP effluent and a new sea water intake and use heat pumps to
deliver heat to the WWTP, Airport and other selected buildings via a district loop. This option
is intended to establish a cost of heat basis for comparison to the proposed Coast Guard
biofuel option for Japonski Island.
8. For each alternative, provide site plan, piping schematic and site photos to illustrate the location
of basic equipment; routing of piping; indicate estimated sizes and capacities of pumps, piping,
heat exchanger, heat pumps. Identify modifications and cost required to integrate delivered heat
into existing building heat systems.
PROPOSAL FOR ECONOMIC EVALUATION - HEAT PUMPS CITY OF SITKA 12/14/09 PAGE 6 OF 6
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9. For each alternative illustrated, perform 30 year life cycle cost evaluation which compares present
worth of capital cost, electricity used by circulation pumps and heat pumps, anticipated
maintenance/replacement costs, and heating fuel saved.
10. Compile an Executive Summary which lists alternative heat pump systems, the associated
Capital Investment Required, Net Present Worth, and Years to Payback.
11. Produce deliverable report in pdf format which includes data from above items, graphs, color
photos and technical information in a simple easy to read format that begins with the executive
summary and recommendations of improvement options evaluated.
COST FOR ENGINEERING SERVICES:
Total time effort = 176 hours @ $120/hour = $21,120; this cost includes a two week (88 hour) technical
evaluation site visit to Sitka where temporary office space will be provided; two week home office time (80
hours) to compile the report; and one day (8 hour) return visit to present results with power point slide
show and conduct facility tour with City staff.
50% of total cost to be billed upon completion of technical site visit (approx 88 hours = $10,560). Balance
of fee ($9,600) less final presentation time effort will be billed upon delivery of final report. Delivery of
final report will precede presentation visit. Presentation visit will be scheduled at least two weeks in
advance. Invoice for presentation time (8 hours = $960) will be billed upon completion of presentation.
Final report will be delivered in pdf format. Two printed and comb bound color copies of the final report
will also be provided. Additional hard copies of the final report can be provided at $1 per page at the time
of delivery, or can be printed in color by the City from the pdf file.
Round trip air travel (ANC–SIT) for the technical site visit trip, and return presentation trip, will be paid in
advance by the City. Cost for local accommodation, car rental and meals will be reimbursed to the
Consultant at a rate of $200 per day for a maximum of 15 total days.
SCHEDULE:
Technical site visit to Sitka will take place within four weeks of Notice to Proceed. Delivery of final report
to City will be completed within two months of Notice to Proceed. Presentation visit will be scheduled by
City within one month following delivery of Final Report, on a date agreed to by the City and Consultant,
with at least two weeks advance notice to Consultant.
EXECUTION OF CONTRACT AGREEMENT:
Owner: c/o Jim Dinley, Municipal Administrator Consultant: Andy Baker, PE
Address: City and Borough of Sitka YourCleanEnergy LLC
100 Lincoln Street 308 G Street #212
Sitka, Alaska 99835 Anchorage, AK 99517
Phone: 907-747-1808 907-274-2007
Signed: ___________________________ Signed:_______________________
Date: ____________________________ Date:_________________________