HomeMy WebLinkAboutEska Recon Report 01-10-2013Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 1 of 11
Eska Creek Preliminary Feasibility Analysis
Introduction
This report examines the feasibility issues of energy and economics for a 1.8 MW hydroelectric project
on Eska Creek (project). The Project is located near Sutton, AK and would use Eska Creek as a source for
energy production. The preliminary analysis includes
• Site reconnaissance to identify locations for the intake, pipeline, and powerhouse in conjunction
with mapping,
• Discussion of environmental, land use, and permitting,
• Collection of hydrology data and an estimation of the available water for power production,
• Conceptual project configuration and size, and
• Preliminary opinion of project cost and economic viability
Project Location and Description
Figure 1, at the end of the report, shows the location of the project and watershed basin based on USGS
63k quad maps. The project is generally located in the Matanuska Susitna Borough on state owned
mental health trust land with existing mining and geological exploration activities underway related to
coal extraction. The area is also a significant resource for recreation and subsistence activities with
established motorized trails.
The selection of the intake site was determined from on the ground reconnaissance efforts that
identified pipeline and access routing resulting in the intake location shown in Figure 1. The location for
the powerhouse was chosen based on the limits of anadromous fish habitat, land ownership, location of
exiting power transmission lines, and general topography. An alternative powerhouse location, at a
higher elevation with a shorter pipeline, was also examined but eliminated after evaluation.
Photos showing the proposed location of the intake, the general pipeline area, and Eska Creek near the
powerhouse site are included at the end of the report.
Compatibility with Existing Use
The project is located above mapped anadromous fish habitat. Eska Creek is cataloged as stream
number 247-50-10220-2095 by ADF&G with coho salmon present and chum salmon spawning identified
as the species and use. The original nomination states that the fish presence extends up to “rail grade”
indicating that the steeper stream gradient precludes further access. Culverts exist in the vicinity of the
upper limit that do not appear to present a barrier (see attached photos). The presence of resident
species is unknown. Also, there are no water rights filings related to the conservation of habitat. The
initial analysis adopts the optimal assumption that no environmental flow releases would be required at
the intake to support aquatic life in the bypassed reach of Eska Creek.
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 2 of 11
The project is located in an area designated as a moose range. The area is also utilized extensively for
recreation. Neither of these uses would be incompatible with the project. The most significant existing
land use activity is the existing and proposed coal mining operations.
Usibelli has an existing lease for coal mining and exploration that covers most of the project footprint.
Specific development plans were not investigated at this time. The impact of coal resource extraction
can range from completely prohibiting project development to enhancing the project the prospect for
development. Identifying the compatibility of the project with existing coal mining authorizations and
planned developments must be investigated should further feasibility efforts continue.
Permitting the project would require leasing or easement applications with the State of Alaska. The
state land use noticing and permitting process would be the forum for public review and comment for
any proposed development. The project would also require additional stream gaging to satisfy state
water rights permitting. Additional aquatic habitat investigations would also be required to initiate the
state fish habitat permitting. The project is not likely to require significant federal permits although a
FERC jurisdictional determination and corps of engineers permit will be needed.
Hydrology
This investigation included performing hydrology data collection at the Eska gage site established just
downstream of the culverts for the lower road crossing (see Figure 1). The purpose of the data collection
was to provide a preliminary assessment of Eska Creek hydrology in relation to nearby drainages with
extensive gaging records. The location was chosen for the ease of access and a stream cross section with
good low flow resolution.
On December 18, 2011, a Campbell Scientific pressure transducer and data logger were installed at the
Eska gage site. The installation utilized a conduit to submerge the pressure transducer in the stream
under the ice and snow. The Eska gage was set to log at 15 minute intervals and the first reading
averaged 1.15 feet of water over the gage with a temperature of 33.1 degrees F. Flow measurements
were taken using a dye tracer method. The figure below shows the flow readings, corresponding gage
depths, and the derivation of the stage discharge relationship.
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 3 of 11
Date Stage (ft)
Discharge
Measurement
Temperature
(deg F)
12/18/11 16:01 1.15 7.4 33
4/7/12 15:17 0.83 5.5 33
4/14/12 14:31 1.09 12.1 34
5/28/12 13:29 1.44 46.1 42
y = 0.2824ln(x) + 0.3627
R² = 0.9963
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
0.0 10.0 20.0 30.0 40.0 50.0
Stage (ft)
Discharge (cfs)
Eska Creek Stage Discharge Curve
Discharge Measurement (cfs)
Excluded Discharge Measurements
Stage Discharge Equation
The discharge measurement of 12/18/2011 was left out of the stage discharge calculation due to
suspected errors in the flow measurement. The discharge calculations are presumed valid within a stage
range of 0.7 to 1.5 feet.
In order to perform an average annual energy production estimate for the project a synthesized annual
hydrograph was developed using the gaged data and the median daily flows for the Little Susitna River
which has a 63 year gaging record performed by the USGS (USGS site number 15290000). Adjustments
to the Little Susitna River median daily values to arrive at a synthesized hydrograph for the project
included proportioning based on the basin area, averaging with the Eska gaged flows, and flattening of
the summer runoff profile to account for the generally higher elevation of the project basin versus the
Little Susitna basin. The hydrograph below shows the synthesized result for the Eska gage site location.
The actual hydrograph used for the project used this hydrograph scaled by the basin area of the intake
versus the basin area of the Eska gage site.
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 4 of 11
0
20
40
60
80
100
120
140
Flow (cfs)Date
Eska Gage Avg Daily Measured Discharge
Little Su Median Scaled to Eska Gage Basin Area
Eska Gage Site Estimated Median Hydrology
Future hydrology data collection should be done near the intake if at all possible to identify whether the
high altitude sub basin area may exhibit significantly different runoff characteristics than the lower basin
and with those of nearby comparison basins. The intake site would be accessible during the summer by
ATV and hiking about 1/4 mile. Winter access will likely require helicopter use although snow machines
are capable of reaching the intake site under favorable snow conditions.
Project Concept
The conceptual project configuration used in this analysis consists of a small concrete diversion
structure for the intake, a combination of buried HDPE and steel pipeline located in a constructed access
trail, a small powerhouse with a single turbine, switchgear, and a transformer connected directly to the
existing distribution line. Not included in the cost, and likely a project requirement, is upgrading the
existing transmission to three phases.
A number of different hydraulic capacities and pipeline sizes were evaluated in the project concept. The
sizing analysis settled on a project with a hydraulic capacity of 22 cfs and nominal pipeline diameters of
22” and 20” with a peak output of 1.8 MW as the baseline size for the cost estimate and economic
analysis. With a single turbine most of the project sizes would not be operational during the lowest
flows of late winter and spring. The sizing analysis is shown in the table and chart below.
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 5 of 11
Hydraulic
Capacity (cfs)
Annual Energy
(kWh)
Pipe wt
(tons)
Nominal Pipe
Dia (inches)
Velocity
(fps)Headloss
15 6.1E+06 241 18 8.9 132
17 6.5E+06 241 18 10.1 168
19 7.2E+06 302 20 9.2 124
21 7.6E+06 302 20 10.2 150
23 7.8E+06 302 20 11.2 178
25 8.5E+06 353 22 10.1 131
27 8.7E+06 353 22 10.9 151
29 9.2E+06 419 24 9.9 113
31 9.3E+06 419 24 10.6 128
33 9.4E+06 419 24 11.2 145
35 9.5E+06 419 24 11.9 162
200
250
300
350
400
450
4.0E+06
5.0E+06
6.0E+06
7.0E+06
8.0E+06
9.0E+06
1.0E+07
15 20 25 30 35 Pipe Weight (tons)Annual Energy Output (kWh)Hydraulic Capacity (cfs)
Annual Energy (kWh)Pipe wt (tons)
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 6 of 11
The daily project output based on the information from above is shown in the following chart.
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Power (kW)Date
Cost Estimate
A preliminary opinion of cost for the project is included in this analysis and is based on existing cost
estimates for similar projects and is shown in the table below.
Item Labor Labor Cost Equip Cost Materials
Cost Ship Cost Total Cost
CONSTRUCTION SUPPORT 3,750 $ 356,000
$ 360,000
MOBILIZATION
$ 250,000 $ 250,000
POWERHOUSE 1,350 $ 110,000
$ 250,000
$ 360,000
INTAKE 2,400 $ 190,000
$ 88,000
$ 280,000
PIPELINE 2,400 $ 190,000
$ 992,000
$ 1,180,000
ACCESS TRAILS 1,980 $ 152,000
$ 321,000
$ 470,000
TURBINE AND GENERATOR 540 $ 51,000
$ 950,000
$ 1,000,000
TRANSMISSION
EQUIPMENT $ 403,000 $ 120,000 $ 520,000
SUBTOTAL, Direct Costs 12,400 $ 1,049,000 $ 403,000 $ 2,721,000 $ 250,000 $ 4,420,000
Contingency
25%
$ 1,110,000
Contractor profit
15%
$ 660,000
SUBTOTAL, Construction $ 6,190,000
SUBTOTAL, Construction
$ 6,190,000
Construction interest
$ 140,000
Feasibility and Permitting
6%
$ 350,000
Engineering
4%
$ 250,000
Inspection and testing
3%
$ 180,000
Owner admin 2% $ 100,000
TOTAL PROJECT $ 7,210,000
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 7 of 11
Economic Analysis
The economic analysis evaluates future revenue and costs by estimating those costs and calculating
present day values using estimated economic trends. For this analysis a schedule of cash flows has been
generated over the economic term. Future cash flows are discounted to determine their Present Value
for comparison. It should be understood that the high variability of the economic factors coupled with
the uncertainty of the necessary assumptions for future estimations makes accurate economic analysis
difficult in the early stages of project development. For this analysis the major economic factors of
concern are:
• The present day capital cost and financing terms including the economic term of the analysis,
the loan term, the project life, cost of capital, and discount rate. The estimates for these factors
are presented in the economic summary table. A weighted cost of capital is used based on a 5%
borrowing rate for 75% of the capital cost and an 8.5% rate of return for the remaining 25%. Pre
construction costs are not included in the project financing.
• The actual annual revenue generated by the project is dependent on competing generation
sources, climate and hydrology, and project reliability. This has been estimated using the annual
average energy generation, as shown in the hydrology section, and a fixed rate for energy. The
project would deliver power to Matanuska Electric Association, a southcentral utility, at
wholesale rates equal to the avoided cost of existing generation which is currently $0.067/kWh.
• The actual annual costs incurred to operate and maintain the project (parts, labor, taxes, fees,
insurance, credits, etc) are estimated throughout the project life in accordance with the
schedule below. Construction start is assumed to occur after 5 years of predevelopment work.
Project Operation Cost Schedule
Description Interval Cost
Taxes, insurance, fees Annual $40,000
Parts, labor, and administration Annual $60,000
Turbine and Generator Overhaul 15 years $260,000
Intake and power transmission replacement 20 years $580,000
Pipeline 50 years $1,200,000
The results of the economic evaluation are shown in the summary table below. The negative Net
Present Value (NPV) incidates the project is not viable given the current set of assumptions.
Project Cost Estimate $7,210,000
Financed Construction Cost $6,510,000
Construction Cost Financing Term 20 years
Construction Cost Weighted Finance Rate 5.88%
Annual Finance Payment $562,000
Annual Energy Production 7,720,000 kWh
Energy Rate $0.067 /kWh
Annual Revenue $517,000
Annual Operation Cost $100,000
Economic Life 30 years
Economic Discount Rate 5.0%
Net Present Value (NPV) -$1,630,000
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 8 of 11
Conclusion
The initial analysis indicates that the project is not economically viable at this time. However, this could
change in the next several years if the cost of natural gas (avoided cost of energy) rises as is likely the
case for alternative fuel or energy sources that will be needed to replace dwindling Cook Inlet natural
gas supplies. Analysis shows that an avoided cost rate of $0.0875/kWh would result in a NPV of 0. Higher
sales rates have already been agreed upon with the Fire Island wind farm obtaining approximately
$0.10/kWh, a rate that would make this project potentially beneficial.
It is concluded that the project is not recommended at this time. If energy rates rise significantly and
additional investigation is pursued, the following areas require further analysis:
• Investigate compatibility with mining operations,
• Perform additional hydrology data collection and analysis focusing on establishing flows at the
intake,
• Investigate aquatic habitat concerns,
• Improve on the project concept and cost estimate, and
• Investigate transmission connection requirements.
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 9 of 11
Figure 1 – Project Location
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 10 of 11
Photos
Photo of culverts taken from Eska gage site.
Photo of Eska Creek near powerhouse site.
Bering Pacific Engineering Eska Creek Hydroelectric Project Report
AEA Grant Agreement 7040063
1/10/2013 Page 11 of 11
Photo showing pipeline terrain taken from near intake site looking towards powerhouse site.
Photo looking down on intake site.