HomeMy WebLinkAbout150913-FalsePassCostMemopolarconsult alaska, inc.
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Anchorage, Alaska 99503-3638
Phone: (907) 258-2420
FAX: (907) 258-2419
M EMORANDUM
150913-FALSEPASSCOSTMEMO.DOC
DATE: September 13, 2015
TO: Bob Christensen, Living Systems Design, LLC
FROM: Joel Groves, P.E.
SUBJECT: Preliminary Project Performance and Development Cost Estimates for Unga Man
Creek Hydro near False Pass, AK
CC:
Unga Man Creek is under consideration for hydropower development to provide electricity to
the community of False Pass. Reconnaissance-level cost estimates, development schedules,
and performance estimates are provided to assist in economic evaluation of the project.
1. Preliminary Estimates of Project Design Parameters
Preliminary estimates of project design parameters are presented in Table 1.
It must be emphasized that the preliminary design parameters in Table 1 are reconnaissance-
level estimates and they may change significantly as the project is studied and better
information becomes available. In particular, the appropriate and feasible design flow could
change significantly, which would result in a proportionate change in project installed capacity
and significant changes in capacity factor, annual energy generation, and other project
performance parameters.
Table 1: Preliminary Design Parameters for Unga Man Creek Hydro Project
Design Parameter Preliminary Estimated Value
Design Flow 1 12 cubic feet per second (cfs)
Gross Head 200 feet (ft.)
Net Head 180 ft.
Penstock 2 4,600 ft.
Installed Capacity 125 kilowatts (kW)
Resource Capacity Factor 1 85%
Annual Energy 1 936,000 kilowatt-hours (kWh)
Utility Load Supplied by Hydro 1 86%
Transmission Line 2 3,000 ft. 7.2/12.4 kilovolts (kV)
Access Road 2 4,600 ft.
Notes:
1. See Section 2 of this letter report for assumptions made to estimate design flow, capacity factor, annual
energy generation and portion of utility load supplied by the hydro project.
2. Based on estimated lengths presented in Renewable Energy Resource Assessment for the Communities of
Cold Bay, False Pass, and Nelson Lagoon, YourCleanEnergy, LLC. May 18, 2010.
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0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
Jan 10 Jan 11 Jan 12 Jan 13 Jan 14 Jan 15 Jan 16Monthly kWh at Generation-100
-75
-50
-25
0
25
50
75
100
125
150
Monthly Peak Load (kW)Monthly kWh Gen
Monthly Peak Load (kW)
2. Preliminary Estimate of Project Performance
2.1. Existing Utility Load
Recent False Pass electric utility load data is shown in Figure 1. In the last five years, total load
at generation has ranged from approximately 450,000 to 710,000 kilowatt-hours (kWh). Peak
load at generation for fiscal year (FY) 2015 was 145 kilowatts (kW).1
Figure 1: Monthly kWh at Generation, FY 2011 through FY 2015
Data provided by City of False Pass.
The utility’s hourly load data is modeled using the Alaska Village Load Calculator (AVLC).2
Figure 2 presents actual monthly load data over the past five years (FY 2011 through FY 2015),
average monthly load over this same time period, and the modeled monthly load using the
AVLC. Table 2 presents average and modeled monthly load data for the utility.
Table 2: Five-Year Average and Modeled Monthly Utility Load at Generation
Month Model Monthly kWh at Generation Actual Five Year Average Monthly kWh at Generation
Jan 59,268 52,356
Feb 54,568 51,394
Mar 58,332 57,511
Apr 53,340 56,485
May 49,493 59,551
Jun 44,699 50,204
July 45,036 50,706
Aug 47,937 44,744
Sept 48,548 42,687
Oct 54,954 54,262
Nov 53,352 54,300
Dec 60,446 53,287
Annual Total 629,972 (rounded to 630,000 kWh) 627,487
1 The fiscal year runs from July 1 to June 30, so FY 2015 is July 1, 2014 through June 30, 2015.
2 The Alaska Village Electric Load Calculator, NREL/TP-500-36824, NREL, Golden Colorado, Sept. 2004.
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10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonthly kWh at GenerationActual Monthly Load at Generation
Model Monthly Load at Generation
5-Year Average Actual monthly Load at Generation
0
10
20
30
40
50
60
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecFlow at Diversion Site (cfs)Average Daily Flow
Average Daily Flow Less Habitat Flow
Average Daily Project Flow
Figure 2: Actual and Modeled Utility Load at Generation
2.2. Hydro Generation
Preliminary estimated average annual hydro project generation potential is calculated using the
preliminary design parameters listed in Table 1 and estimated average daily discharge at Unga
Man Creek based on the hydrology record for Russell Creek near Cold Bay scaled by relative
drainage basin areas to Unga Man Creek.3 Water availability for hydropower generation
assumes a five cubic feet per second (cfs) in-stream flow reservation to accommodate fish
habitat that may exist along the project bypass reach. The need for and amount of in-stream
flow reservation would be determined during the permitting process. Estimated daily flow and
available project flow is shown in Figure 3.
Figure 3: Preliminary Estimate of Average Daily and Available Project Flow in Unga Man Creek
3 Preliminary estimated hydrology for Unga Man Creek is discussed in Preliminary Hydrology Estimate for
Hydropower Development at Unga Man and Waterfall Creeks near False Pass, AK. Letter Report,
Polarconsult Alaska, Inc. September 11, 2015.
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2.3 Hydro Project Performance
Daily utility load data described in Section 2.1 is compared against daily hydro generation
capability in Section 2.34 to estimate how much of the utility’s load the hydro can be expected
to carry. A basic generation dispatch model is used to determine which of the utility’s
generation plants (diesel and/or hydro) would be used to meet system load on a daily basis.
The model assumes that the hydro is governed with a 20 kW load bank, and that the diesel and
hydro plants have an integrated supervisory control and data acquisition (SCADA) system that
supports automated switching and paralleling. The SCADA would make dispatch decisions on a
continuous basis based on changing utility load and water availability. Since only daily data is
available for analysis, the following dispatch logic is used in the generation dispatch model to
approximate actual SCADA dispatch decisions:
1. On days when the available hydro capacity exceeds the utility peak load by more than
20 kW (assumed load bank governor capacity), the hydro is assumed to carry 100% of
utility load with the diesel plant turned off for the entire day.
2. On days when the available hydro capacity is more than the peak load by less than 20
kW, the diesel plant is assumed to operate for two hours with the smallest gen-set
loaded at 40% of its capacity. For the False Pass diesel plant, this base diesel loading is
approximately 50 kW.
3. On days when the available hydro capacity is less than 100% of the daily peak load but
greater than daily average load, the diesel plant is assumed to operate for 12 hours with
the smallest gen-set running at 40%.
4. On days when the available hydro capacity is less than the daily average load, the diesel
plant is assumed to operate all day, with the smallest gen-set running at 40% or as-
needed to meet utility demand.
Preliminary estimated performance of the Unga Man Creek hydro is summarized in Table 3.
Table 3: Preliminary Estimated Performance for Unga Man Creek Hydro Project
Parameter Estimated Value 2
Hydro Generation Used to Supply Utility Load 540,000 kWh (58%)
Hydro Generation to Load Bank Governor 1 175,000 kWh (18%)
Hydro Generation not Used (Available for Interruptible Loads) 221,000 kWh (24%)
Total Hydro Energy Generation 936,000 kWh (100%)
Utility Load Supplied by Hydro Plant 540,000 kWh (86%)
Utility Load Supplied by Diesel Plant 90,000 kWh (14%)
Total Utility Load 630,000 kWh (100%)
Percentage of Time All Diesels are turned off 73%
1. Load bank governor size assumed at 20 kW. Load bank could be used for space or water heating.
2. Model results have been rounded to nearest 1,000.
4 Section 2.3 only provides an annualized summary of hydrology statistics. Estimated hydro performance is
calculated using the actual daily flow records for Russell Creek, as adjusted to the Unga Man basin, over the
25-year period of record.
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0
10
20
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40
50
60
70
80
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140
150
1/1/07 2/1/07 3/1/07 4/1/07 5/1/07 6/1/07 7/1/07 8/1/07 9/1/07 10/1/07 11/1/07 12/1/07Daily kWExcess Hydro Energy Available
Hydro to Load Bank Governor
Utility Load Met by Diesel
Utility Load Met by Hydro
Daily Peak Utility Load
Total Utility Load
0
10
20
30
40
50
60
70
80
90
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110
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150
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016Daily kWExcess Hydro Energy Available
Hydro to Load Bank Governor
Utility Load Met by Diesel
Utility Load Met by Hydro
Total Utility Load
Estimated hydro performance, based on Russell Creek hydrology and model utility load, is
presented in Figure 4. Annual performance for a typical year (2007) is shown in Figure 5.
Figure 4: Estimated Hydro Project Performance, 1996 to 2015
Figure 5: Estimated Hydro Project Performance in a Typical Year (2007)
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3. Development Schedule and Cost
Developing the hydro project would occur in the following stages:
1. Feasibility study.
2. Design and permitting.
3. Construction.
Preliminary estimated schedule and cost for these steps is summarized in Table 4. Narrative of
the purpose and effort involved in each step, and basis for the estimated schedule and cost,
follow.
Table 4: Preliminary Estimated Schedule and Budget for Project Development
Development Stage Schedule Budget
Feasibility Study 1 to 2 years $170,000 to $270,000
Design and Permitting 1 to 3 years $250,000 to $500,000
Construction 1 to 2 years $4,000,000
Start-up 2019 - 2023 $4,430,000 to $4,770,000
3.1 Feasibility Study
Feasibility study phase consists of a comprehensive review of technical, regulatory, financial,
and environmental issues pertaining to the project to determine if it is feasible. The study
would include targeted field work and data collection to fill in critical data gaps including:
- Topographic surveys to measure available project head.
- Field work to identify probable locations of project features.
- Hydrology studies to determine availability of water flow.
- Fisheries studies / agency consultations to determine need for and to quantify any
restrictions on water diversion to protect fish habitat.
- Preliminary wetlands inventory to quantify probable wetland impacts
Feasibility study schedule is driven by the need to collect a minimum one year of stream flow
data on Unga Man Creek to begin characterizing the hydrology.
The feasibility study results are as good as the data fed into the feasibility analysis. The
budgetary range for the feasibility study covers a range of data collection intensity and quality.
There is some discretion in how much money can justifiably be spent collecting data at this
stage of project development. Typically, an increased budget in the feasibility stage offsets
costs in the design / permitting phase.
3.2 Design and Permitting
The scope, budget, and schedule for the design and permitting phase of project development
will depend on the outcome of the feasibility study. Planning estimates are provided.
3.2.1 Scope
Design and permitting typically are conducted in tandem as regulatory agencies need design
information to evaluate the project’s permit terms and conditions, and the design process
requires well-defined permit terms and conditions to complete the project design.
Permitting scope includes working with regulatory agencies to obtain all major permits needed
to construct and operate the project. Typically, these include the following major permits:
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- FERC Declaration of Intention to confirm jurisdictional status
- Land easements or leases
- Wetlands delineation and permitting (U.S. Army Corps of Engineers)
- Cultural resources survey (ADNR SHPO)
- Water Use Permit / Water Rights (ADNR DMLW)
- Fish Habitat Permit (ADFG)
Design scope includes developing engineering plans and specifications suitable for constructing
the project. Design (and/or permitting) may include the following additional or continuing data
collection efforts:
- Detailed topographic survey for project design
- Geotechnical investigations for diversion structure, powerhouse, access roads, power
line extension.
- Continuing stream gauging to further define resource availability and support water
rights application and fish habitat permit
- Fisheries surveys to support fish habitat permit
3.2.2 Budget and Schedule
The budget and schedule ranges covers probable complexity of the resource issues. If resource
agencies require extensive field studies to address resource questions or support permitting
decisions, these studies will increase the cost and time required to complete project permitting
and design.
3.3 Construction
At this time, there is limited available technical information to form a detailed cost estimate for
the project. Instead, recent cost data for generally similar hydro projects is used to provide a
realistic planning budget for project construction.
3.3.1 Construction Budget
Construction of remote Alaska hydro projects in the size class proposed for False Pass at Unga
Man Creek has been costing in the range of $20,000 to $30,000 per kW.
Proximity of False Pass to local marine transport / shipping routes, proximity of the project site
to existing community roads and the existing electric distribution system, and apparent easy
terrain for construction of the access road and penstock installation are all factors that suggest
a relatively lower project cost.
Preliminary review of the creek suggests the diversion structure will be founded on alluvium
with no bedrock present and that the creek experiences significant flood events that the
diversion and tailrace must be designed to withstand. Initial field data indicates presence of
anadromous fish in the bypass reach and potentially at the diversion site, which would require
provisions for fish passage and maintenance of fish flows at the diversion structure. These
factors suggest a relatively higher project cost.
Based on preliminary information, it is recommended that False Pass budget $25,000 per kW
with a 30% contingency at this stage of project development. For a 125 kW project at Unga
Man Creek, the preliminary budget estimate for construction is $4,000,000.
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3.3.2 Construction Schedule
Available data suggests the project could be built by a qualified and experienced contractor in a
single construction season. As is typical of remote Alaska projects, this will require careful
planning and management to procure necessary construction materials and equipment for a
single mobilization.
Depending on the availability of suitably qualified local labor, it may be preferable for the City
to build the project under force account. Force account helps keep labor wages in the
community, and also enhances the community’s familiarly with the hydro and the skills
necessary to maintain it for the long term. Depending on the size of the local labor force, force
account construction may take an additional season.