HomeMy WebLinkAboutCity of Homer Energy Recovery Project Feasibility Study - Nov 2021 - REF Grant 7014006Feasibility Study
City of Homer Energy Recovery Project
Prepared for
City of Homer, AK
November 17, 2021
Prepared by
InPipe Energy Inc.
Contents
Section A: Executive Summary .................................................................................................................... 3
Purpose...................................................................................................................................................... 3
Location.................................................................................................................................................... 3
Designfeatures..........................................................................................................................................4
Capacity....................................................................................................................................................4
Capitalcost................................................................................................................................................4
SectionB: Economic Feasibility...................................................................................................................4
ProjectSite and Region.............................................................................................................................4
Access................................................................................................................................................... 5
Labor..................................................................................................................................................... 5
WaterSupply............................................................................................................................................ 5
Projected Environmental impacts/benefits................................................................................................5
Section C: Technical Feasibility...................................................................................................................5
HydraulicsData-set...................................................................................................................................5
HydraulicAnalysis....................................................................................................................................6
TurbineSelection......................................................................................................................................6
Energyproduction methodology...............................................................................................................7
EstimatedProject Cost..............................................................................................................................7
Section D: Financial Feasibility....................................................................................................................8
SectionE: Recommendation.........................................................................................................................8
References..................................................................................................................................................... 9
2
Section A: Executive Summary
The purpose of this document is to provide a Feasibility Study for the proposed City of Homer
Energy Recovery Project.
This project has the following characteristics:
Purpose
The project's objective is to convert the energy from the pressure head and flow volume at three
sites in a City of Homer water pipeline to electricity that will be utilized to reduce operating
costs for its water distribution infrastructure.
Location
The project sites are located in vaults in the City's eastern trunk/pipeline that house pressure
reducing valves (PRVs) and related equipment. See Figure E. Site coordinates are:
• PRV04-EF Fireweed Ave.: Latitude: 59.66458, Longitude:-151.52532
• PRV05-SK East Hill Rd.: Latitude: 59.6625, Longitude:-151.52255
• PRV06-PRV06-BT East Hill Rd.: Latitude: 59.65956, Longitude:-151.52017
Figure A below shows the site locations.
Figure A: Location of PRV sites in the City of Homer
Design features
A flow bypass will be installed in City of Homer water pipelines that will direct flow through a
hydroelectric energy recovery unit. This unit will use a pump -style hydro turbine and standard
generator unit. Additionally, pressure transducers, flow control meters, and pressure control
valves are utilized in conjunction with a programmable logic controller (PLC) to monitor and
adjust the delivery pressure in accordance with operational requirements. See Figure E
The hydro energy recovery unit is designed to comply with all utility parallel interconnection rules
including power outage protection and auto shut off. Power generated from the induction
generator flows through an inverter and relay before flowing into the grid.
The system will be controlled by a programmable logic controller. The provided control system is
self-contained including all controllers, relays, ancillary PFCCs and a PLC system. It will be
connected to a SCADA communication system using Modbus TCP Ethernet or Ethernet I/P
protocols.
Before the unit is installed, the pipeline can be hot tapped with closed isolation valves. This
allows for installation without the need to shut down flow to the water pipeline. All connections
are bolted flanges and adjustments are made via dismantling joints. Once fully installed, the
energy recovery unit is energized by allowing water flow through the system.
Capacity
The proposed project is designed to have an energy generation capacity of X kilowatts (M).
This is based on the available head and flow rate through the pipeline.
Capital cost
The total capital cost for the installed project is $600,000.
Based on the technical, financial and managerial review of the proposed project's capabilities
and requirements, it is the opinion of the Reviewer that the proposed project is feasible and a
beneficial alternative to the use of a traditional pressure valve at the project site due to the added
electricity generation capability of the hydroelectric energy recovery system.
Section B: Economic Feasibility
The net benefit of this proposed project, taking into consideration the overall benefits and costs,
is demonstrated in this section. The Reviewer finds that the proposed project is economically
feasible based on the following considerations:
Project Site and Region
The project site is well suited for the size and scope of construction and operations associated
with the installation and long-term operation of the energy recovery system.
4
Access
The Fireweed Ave. and East Hill Rd. runs in close proximity to the site and allows for easy site
access. Electric distribution line owned by Homer Electric, the utility that provides electricity in
the project area, is also adjacent to the site with an existing meter present at the project location.
Labor
The project shall utilize skilled City of Humer Public Works Dept. staff. There exists a
significant base of skilled labor in the region due to the local network of commercial water and
electricity providers and users in the immediate vicinity as well as in the greater Kenai Peninsula
region.
Water Supply
The long-term economic viability of the project his highly dependent on a continuous supply of
water. The Homer Water and Sewer Master Plans states that water demand and deliveries are
forecast to grow at approximately 3% annually. This plan also states that the available water
supply sources for the Public Works Dept. Department significantly exceed demand. Given this,
there should be adequate water flow to supply the proposed project for a project life of twenty
years or greater. Due to the trend in demand growth, it is expected that flows will increase to the
benefit of the proposed project in terms of increased electricity production.
Projected Environmental impacts/benefits
The project comprises a minor equipment addition to an existing facility and does not result in
significant negative environmental impacts associated with the construction or operation of the
proposed project. The average carbon dioxide emissions for electricity generators in Homer are
1.34 lbs. CO2/kWh according to the City of Homer Climate Action Plan Implementation
Project2. Because this project will produce no CO2/kWh, the proposed project would offset
approximately 1,800 Metric Tons of CO2 over a thirty-year period.
Section C: Technical Feasibility
The Reviewer has examined the data and methodology utilized to evaluate the project equipment
configuration and projected energy production. The projected energy production was based on
the following:
Hydraulics Data -set
The upstream/downstream pressure and volumetric flow rate data was provided by the City of
Homer's Public Works Dept.
Hydraulic Analysis
The data was analyzed to determine the pressure differentials between the inlet and outlet at the
currently operating pressure control valve. At the site, the pressure differential was found to be
consistent with flow rates. Figure B summarizes the monthly flow rate through the East Trunk.
450
400
350
300
A 250
200
09 150
3
100
50
0
Figure B — Monthly Flow Rates - East Trunk Pipeline
289
208
324
266 252
230 211
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Month
Pressure data for each station is summarized in Table I below
PRV04-EF — Fireweed Ave. 86
32 56
29 70
50 95
56
70
95
PRV05-SK-East Hill Rd. 103
PRV06-BT- East Hill Rd. 149
The average inlet pressure was determined to be 74 psig (128 ft. Avg. Head). The average
outlet pressure was determined to be 50 psi.
Turbine Selection
Each hydro -turbine (pump as turbine) original equipment manufacturer publishes a
performance/output curve based upon experimentally observed values. The equipment selection
for the proposed project was made by selecting the standard turbine with optimal performance
for the range of hydraulic conditions present at the project site.
rel
Energy production methodology
The project energy production was calculated by applying the performance/output curve for the
selected turbine against the hourly hydraulic data. The estimated annual energy production for
the proposed project is 93,000 kilowatt-hours (kWh) Figure F shows the combined site
production per month based on the production calculations.
12,000
10,000
8,000
a
0
6,000
ow
4,000
on
s,
W 2,000
0
Figure C — Project Energy Production by Month
1 n 4nn 10,700 10,500
5,500 5,500 6,000
8,000
7,800
6,700
5.900
JAN FEB MAR APR MAY JUN JUL AUG SLP OCT NOV DEC
Month
The equipment configuration is designed to accommodate the hydro -turbine selected by the
above process. The flow meter and pressure transducer are standard equipment that have been
selected to provide operating data to the system PLC. The standard pressure reduction valve has
been specified to accommodate the pressure and flow range in the representative historic data -
set.
Estimated Project Cost
The Reviewer has examined the estimated costs to develop and construct the proposed project.
The assessment of the development costs is based on the need to complete the following
activities:
• Regulatory flings: The project will file for the eligible exemptions from FERC (Federal
Energy Regulatory Commission).
7
Interconnection agreement: The project will create the supporting electrical drawings
and complete the application process to Homer Electric for the project interconnection.
Final design and permit review: the project will complete and file the required
mechanical and electrical drawings.
Project sourcing: The project will finalize equipment procurement and installation
vendor contracts
The hydroelectric energy recovery system costs are derived based on the combined costs of the
bill of materials. Installation costs were reviewed estimated based onsite surveys and comparable
installations to confirm the project's estimate of $600,000 for the three planned sites.
The Reviewer has assessed the design and development process. The relative simplicity, small
scale and the use of standard/off-the-shelf components reduces project risk. Similar to other
distributed generation projects of its type, the risks identified can include (but are not necessarily
limited to) timing for completion related to both the availability of component, and the electric
utility's interconnection review process.
Section D: Financial Feasibility
The Reviewer finds that the financial projections for the project are a function of two principal
drivers that are both stable and reliable. Unlike other renewable sources that have production
profiles that depend on intermittent resources that cannot be forecast accurately (e.g., solar and
wind), the proposed project production correlates directly with predictable and well documented
water pipeline flows. Additionally, the cost savings are based on the well document utility
electric tariffs/charges. These two combined factors contribute to a stable, long-term revenue
profile for the proposed project.
Because the project is not dependent on either production tax credit or investment tax credit
incentives, the project will not be burdened with the complexity and cost associated with tax
equity structures.
Section E: Recommendation
The Reviewer finds that the proposed project is feasible and low risk due to several factors:
• Energy resource: The hydraulic data (provided by a municipal water dept.) that provides
the basis for the energy forecast is consistent and stable in terms of the pressure
differential and flow rates over an annual cycle.
• Energy conversion method: The method of conversion chosen for this project utilizes
types of pumps and control valves that are widely used in water pipeline application. The
method of selection of such equipment meets standard industry practices.
• Existing supporting infrastructure: The project utilizes existing water and electrical
utility infrastructure already present at the project site.
• Team experience: The management has a demonstrated track record in water
infrastructure projects
Eta
• Fit with the Alaska Energy Authority Renewable Energy Fund: The site is located in
a municipality that is a leader in climate -related and energy management projects and has
potential to demonstrate an important source of distributed renewable energy that shows
high potential for economic development in rural communities as well as urban areas.
References
1) Homer Water and Sewer Master Plan (July 2006)
2) City of Homer Climate Action Plan Implementation Project Final Report (December 2009)
Figure D — Existing pressure control valves and low flow bypasses at City of Homer
PRV5 (left) and PRV6 (right) sites
Figure E — Example of energy recovery system (Skagit, PUD site in Mt. Vernon, WA)
0