HomeMy WebLinkAboutIcy Creek Power Recovery Study 1994Icy Creek Power Recovery Study
prepared for:
City of Unalaska
prepared by:
Polarconsult Alaska, Inc.
April 18, 1994
polarconsult alaska, inc.
ENGINEERS • SURVEYORS • ENERGY CONSULTANTS
City of Unalaska
P.O. Box 89
Unalaska, Alaska 99685
P.O. NBR 21207
Icy Creek Power Recovery Study
Transmittal and Invoice
Dear Mr. Sturgulewski:
April 20, 1994
Enclosed are three copies, one unbound, for the study for the power recovery section of
our work. You will note that the results show there are positive benefits to be obtained by
using power recovery turbines. Further, if there is a large dam located near the existing
intake there is the potential to derive peaking benefits and reduce some of the air quality
hassles, and costs.
The time line to construct these plants is in the order of one year as it takes time to get the
turbines. The second item which takes time is the controls and switchgear.
The amount left on our invoice is $3,475. Although this report took more time then this,
this is what we committed for.
Invoice #94056 amount $3,475
If there are questions or you \vish to discuss the study or the options call us. We do not
charge for telephone calls. Thank-you for your patience.
(!1/:urs
Earle V. Ausman
Attachments: Report
d\network\jobsUnallaska\IR940420
1503 WEST 33RD AVENUE • SUITE 310 • ANCHORAGE, ALASKA 99503
PHONE (907) 258-2420 • TELEFAX (907) 258-2419
polarconsult alaska
Table of Contents
1. SUMMARY ------------------------------------------------------------------------------1
2. I NTRODUCTJON --------------------------------------------------------------------1
3. SYSTEM----------------------------------------------------------------------------------2
4. WATER FLOWS ----------------------------------------------------------------------2
5. POWER GENERA TED----------------------------------------------------------------3
6. MACH IN ERY ---------------------------------------------------------------------------4
6.1 Turbines----------------------------------------------------------------------------4
6.2 Sources -----------------------------------------------------------------------------------4
6.3 Generator----------------------------------------------------------------------------------5
6.4 Controls ------------------------------------------------------------------------------------------5
7. COSTS--------------------------------------------------------------------------------------6
8. ECONOMICS-------------------------------------------------------------------------------7
9. CONCLUSIONS AND RECOMMENDATIONS------------------------------------9
APPENDI}( A-----------------------------------------------------------------------------------A
Figure 1 Monthly Creek Flow and precipitation-------------------------------------------------------A
Figure 2 Option 1, Real Data-----------------------------------------------------------A
Figure 3 Option 1, Adjusted Data-------------------------------------------------------------------A
Figure 4 Option 2, Real Data--------------------------------------------------------------------------A
Figure 5 Option 2, Adjusted Data--------------------------------------------------------------------A
Figure 6 Option 3, Real Data----------------------------------------------------------------A
Figure 7 Option 2 Present Value as a Function of Discount Rate Using Adjusted Data--------------A
AflflE:N[)I){ E3----------------------------------------------------------------------------------------E3
Attachments Information on Turgo, Francis, and Ossberger turbines ---------------------------------B
Figure 8 Option 2 Present Value as a Function of Fuel Cost Using Adjusted Data-------------------B
AflflE:N[)I){ C:----------------------------------------------------------------------------------------C:
Drawing H-1 General Specifications and Flow Diagrams----------------------------------------C
Drawing H-2 Turbine Details---------------------------------------------------------------C
Icy Creek Power Recovery Study
polarconsult alaska
1. Summary
The City's major source of water is Icy Creek. The intake reservoir is at 513 feet of
elevation but the bulk of the served community is slightly above sea level. There is
excess energy available from this high head source. Much of this energy is now being
destroyed by pressure reduction valves. Turbines can be placed into the system that will
recover this energy as electricity. These turbines would be near the new chlorine tank
and would tap into the existing pipeline.
There are 3 options to recover power. The first two utilize water that is excess to the
system, and the third uses water flowing to the community to generate electricity. The
analysis showed Option 2, using actual data will cost about $500,000 to construct and
will have a present worth value of$1,770,422. Adjusting for past rainfall, the values will
be $425,000 and $1,239,976 respectively. These values will be enhanced if a larger dam
is built.
Added capacity may be desirable for peaking. So an addition of new pipe or upgrading
the old wood stave could increase capacity and perhaps replace a diesel generator or two.
2. Introduction
The City ofUnalaska acquires the bulk of its water from Icy Creek, also called Pyramid
Creek. This creek is located several miles south of the main portion of the community.
The water is acquired from a small impoundment at elevation 513 feet. The water flows
by gravity to the users. There is an opportunity to capture energy from the excess head in
·the system that is now being lost in pressure reduction valves. In addition, Icy Creek
flows are in excess of those needed for water supply a substantial amount of the time.
This excess water can be bypassed upstream of the chlorination plant and used to
generate electricity.
Costs are low when turbines are fitted to a system that is already constructed and operated
for water purposes. The additions that are required are the turbine, generator, some
valves, a small amount of pipe, controls and electrical gear, and a small simple building.
Since intake and pipeline operation and maintenance costs are paid for by the water
system the electrical generation plant is not expensive to operate.
The amount of power from the system is limited by the amount of water that is practical
to get through a 24 inch ductile iron pipe.
If the pipeline were paralleled or the old wood stave upgraded, and the proposed larger
reservoir built, the system could be larger, and would provide much more energy than is
shown in these studies. The larger system can provide substantial amounts of peak power
to the community. The new reservoir will store some 150 or so cfs days. The upper 10
Icy Creek Power Recovery Study Page 1 of9
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feet of the reservoir except in low water conditions can be operated to provide almost a
constant flow to the power recovery turbines and can be used for peaking as well.
These studies are limited to the plant which is currently constructed for the water supply
system at Icy Creek. A new reservoir near the old site will increase the head on the
turbines and result in added power output and energy production.
3. System
The water system is currently comprised of a small dam and intake structure which is
tapped by a 24 inch ductile iron pipe. Icy Creek currently does not make use of its other
fork. A previous study has shown it is technically possible to divert water from this fork
to the Icy Creek reservoir. Downstream of the dam about 2, 1 00 feet or so is a drain, or
blowoffvalve in the low point ofthe pipeline. This is a potential site for locating a
turbine to use excess water. In this study this is called Option 1.
Downstream of the blowoff is a large tank which will be used to chlorinate water to
enable the city to meet the surface water treatment act regulations. In this area a turbine
can be located whose sole function is to replace the pressure reduction valves, PRV,
upstream of the tank. This turbine which at present would have a capacity of about 100
kW is called Option 3.
Near the tank, a pipeline can be connected to the 24 inch line and run to a power house on
the banks of Icy Creek just before it enters the rock canyon. This will gain extra head
which will result in increased power output. The disadvantage of the location is that
unlike the previous options the construction will be more difficult as a fairly steep slope
will have to be dealt with. While at the location some ground water was observed and
this may require a drainage interceptor.
Schematics are provided in the report, entitled H-1 and H-2 which show the basic
parameters of the selected systems. Option 3 can be combined with either Option 1 or
Option 2 or utilized by itself.
If conditions are different than those shown in this analysis, most new answers can be
factored. For example, the amount of power produce is a direct function of the head. For
a given machine the power output is related to the 1.5 power of the head, and the turbine
speed, rpms, is related to the square root of the head. The power generated, hence the
income earned, is a direct function of the change of head and the change of flow of water
through the turbine.
4. Water flows
The ability to make long term projections of water flow, hence power is limited because
of the shortness of the record. Further, even rainfall data is not sufficient as there are so
Icy Creek Power Recovery Study Page 2 of9
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many threshold conditions which can change the out come with very small variations in
their values.
It has been recommended and believed implemented that recording stream gages be
installed at the project. In time these will yield the desired data which will increase
projection accuracy.
Updated data for 1993 provides nearly two years of consistent data for icy creek
streamflows. Unfortunately this is not enough to correlate yearly average stream flows
with the total yearly precipitation.
As mentioned in a previous report, monthly data is difficult to correlate. Referring to the
Figure 1, one can see that there is some correlation between the two data sets. However,
the spring runoff and winter snow accumulation cause there to be no mathematical
correlation between the two sets of data.
Hindered by a lack of data, two separate analysis where performed for estimating power
output from each of the three turbine options. The first analysis used all existing data.
The second analysis used 1993 data as a base data set for obtaining 11 years of record.
The data was adjusted by dividing the rainfall for the base year (1993) and then
multiplying by the rainfall for each of the years 1983 through 1993. This linear scaling of
the streamflow data may be somewhat conservative since it scales the base flow and the
peaks equally. In reality, a dry year would reduce the spring runoff peak and may not
effect the base flow to any great degree.
The results for each option show the optimum turbine size for each data set used. Option
3 uses water that is consumed by the town and therefore is unaffected by rainfall. It only
depends on the city usage.
5. Power generated
The power generated was calculated based on using the water flow, calculating the head
loss, and multiplying times a representative turbine generator curve. The maximum flow
through the pipe ranged from 36 to 39 cfs which was based on a maximum of 15 percent
head loss. The turbine was limited to a tum down of 30 percent gate as it was assumed
that all units would be of the Francis type. The reason for this is at partial gates this type
of turbine can cavitate which will reduce its life. If the unit for Option 2 is a Turgo, or a
Cross Flow then these lower flows can be utilized. See figures 2 through 6 which plot
kWh generated versus turbine capacity.
Machine efficiency was assumed to be 92% for the generator and about 86% for the
turbine. No losses were added for transmission or for the transformers. Since this
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generation is located at the far end of the City's system there should be some help created
by backing out the amps in the system hence reducing system losses.
6. Machinery
6. 1 Turbines
The machinery selected for the system is discussed in this section. The size of the
machines selected were obtained from data shown on Figures 2 to 6. The size that was
selected achieves near maximum kWh with a minimum machine size.
For Option 1 a turbine which discharges to the atmosphere can used. The types that can
be used are Francis, Cross Flow and potentially a Turgo impulse turbine. The Francis or
Cross Flow would be the best machines. The Francis is more efficient and turns at a
higher speed. Further, it can be fitted with a draft tube which recovers exhaust energy
and allows the machine to be sited at a higher elevation. Its disadvantage is that it has a
partial flow cut off and requires accurate mill work and sturdy foundations. The Cross
Flow has good efficiency over a broad range of flows, it is easy to maintain, easy to erect,
but requires a speed increaser to drive the generator at a reasonable rpm. The Cross Flow
can be fitted with a draft tube but more likely will not be for your project. See
miscellaneous equipment information in the appendix.
· Option 2 with about 300 feet of gross head has the most choices. The turbine can be
Francis, Cross Flow or Turgo. The first two turbines have been previously discussed.
The Turgo is an impulse turbine with excellent efficiency and partial flow characteristics.
This wheels inventor and major manufacturer is Gilkes in England. Gilkes is the only
manufacturer that this machine should be purchased from. A Turgo is extremely reliable
and will last a long time. However, it is expensive, about $400,000.
For Option 3 there are only two choices, a Francis turbine with variable flow or pumps.
The restriction on this system are a variable back pressure will be imposed on the turbine
which depends on the depth of water in the tank. Further restricting the machine is the
variation in head from head losses and reservoir elevation. A simple pump could be used
as a low cost turbine but its efficiency would not be high. It could be arranged to turn on
whenever needed and could be provided with almost a constant flow: A pump can
perform better if a large reservoir is constructed as flow rates will be more uniform to the
tank.
6.2 Sources
Sources for turbines are Gilkes in England who can supply Francis or Turgo impulse
wheels. Francis turbines can be obtained from China. The safe source of supply for the
Cross Flow is Ossberger in Germany. Although the Chinese turbines are not as pretty
Icy Creek Power Recovery Study Page 4 of9
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they are rugged and conservatively constructed. The Chinese are difficult to
communicate with but their turbines are about 5 times less costly. The reason is the
Chinese believe in small dispersed power and construct 1 ,OOOs of standard units per year.
For this study we priced Chinese Francis turbines.
6.3 Generator
The generators for the system is assumed to be of the induction type. They are also
assumed to be 3 phase machines, and they are for all intents identical with a similar
capacity induction motor. Generators of this type tum above synchronous speed. The
amount above this speed depends on slip. One of Polarconsult' s generators turned at
1210 rpm, synchronous speed is 1,200 rpm, which is unusual. Generally the slip will be
greater. The induction generator also draws reactive power off of the line. In most cases
this means that to keep reactive amperage down capacitors are added to the system.
The induction generator has the advantage that it will not generate power if it is not
connected to the line. This is an advantage as linemen will not have to isolate this source.
It is a disadvantage if standby power is important If that is the case a synchronous
generator can be used. However this type of machine requires some form of governing.
The two major types are the mechanical flow control governor or an electronic load
governor which adds load to the system.
The induction generator will usually be equipped with capacitors to decrease reactive
power. Generally the power factor is held to 90 percent or less to prevent the possibility
of self excitation if the generator looses its load. An induction generator is a very robust
machine; it can withstand over speed and it has no controls, brushes or voltage regulator.
This would be the machine to choose provided the plant it is not intended to be used for
peaking and standby power for this end of the community.
6.4 Controls
The controls used for an induction generator are simple. An induction generator can be
put on line manually by opening the gate and when the turbine nears synchronous speed
close the breaker or the contactor. The contactor and or breaker can be wired to drop off
line if there is a loss of power or some type of condition occurs which is outside of preset
parameters. These parameters could include, over and under, speed, voltage, or over
current. At this time an automatic valve would close or there would be a closure of the
turbine gates or nozzles. This same sequence could also be provided by a PLC,
programmable logic controller, or computer. In this system a speed device provides
information to a computer or relay that closes a contactor when the generator approaches
synchronous speed. The generator then develops the amount of slip, as required to
ley Creek Power Recovery Study Page 5 of9
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overcome the turbine torque. Company's that make this type of gear can provide all of
the essential functions in one small master computer.
A synchronous machine is more critical. To synchronize, the turbine speed has to have a
close match to the system speed and the electrical phases aligned prior to connection .
With smaller machines this can be easily accomplished by reducing the excitation and
bringing the machine through synchronous speed. As the proper speed is approached, the
machine is connected and then the excitation raised. This will result in the generator
pulling the turbine into the proper speed. The controls to accomplish this are similar but
more complicated than those for an induction machine, and as a result will be more
costly.
In addition to electrical and governing controls, controls will be needed to determine what
water flows are appropriate for the system. For Option 1 and 2 a head level control can
be used at the reservoir which will open the turbine gates the amount required to hold the
water level just below the spillway. This system can be programmed to take advantage of
some of the reservoir capacity.
When the large reservoir is constructed it is reasonable to make calculations and develop
ruling curves to determine how the operations of the hydro and the water supply can best
be integrated to achieve the maximum electrical production with the optimum protection
of the water supply. This work is generally done with computer studies. The algorithms
can be programmed into a PLC, computer, or control setpoints and values can be
dispatched from Public Works as is most desirable.
7. Costs
The costs for the various options are provided in this section. These costs are based on
the City hiring the workers and avoiding title 36 wages which are required for contract
work. These costs are based on using Chinese turbines, and the balance North American
equipment. The pipe is all steel with welded joints, the buildings are metal or wood on a
concrete foundation. The building cost is assumed to be $100 per square foot, the
concrete $800 per in place cy. Labor rates were assumed to be $40 per hour for welding
and pipe fitting, and $35 per hour for skilled labor. In addition, an experienced mill
wright was factored for two days working time to align the units. Materials are the most
significant cost for this type of project. To the construction costs are added engineering
near 10%, local administration near 15%, local supervision for 2 months and a risk factor
of20%.
Icy Creek Power Recovery Study Page 6 of9
polarconsult alaska
Item Description Option 1 Option 2 ·Option3
Pipe, valves and Welding $YJ2000 . ' $40,000 $28,000
Building $32,0oo $ 32,000 $.32,000
Turbine $40,000 $40,000 $20,000
Generator s4t),ooo $40,000 $13,000
Transformer $il5,000 $21,000 $6,000
Switchgear $'2,4,000 $24,000 $16,000
Balance freight, labor, etc. ${51,000. $79,000 ··s 28,ooo
Subtotal $t214,0()() $ 276,000 $143,000
Local Supervision $~!13.; (}()() .• $ 13,000 $>13,000
Engineering $ .. 25,000 $30,000 $20,000
Local Administration $36,000 $45,000 $27,000
Contingencies $50,000 $61,000 $40,000
Total $.338,000 $425,000 $243,000
What is not included in the cost estimate are the costs of any extension of the 3 phase
power system to the plant. Three phase is strongly advised for the system and power
lines have to be extended in any event to the chlorination plant. This amount should be
added to the cost of the plant which will reduce the present worth of the plant after
payoff. The City knows the cost of line extensions so this figure can readily be
determined.
Polarconsult owns its own hydro plant. The plant consists of 4,200 feet o 12" pipeline,
intake and desanding box, power house built off of a cliff, all equipment similar to Option
3 but with a more expensive 1 phase generator, 4,600 feet of direct buried power cable, a
telemetered metering system, 8,600 feet of access trail and pipeline bench, and 8,600 feet
of buried 2 pair telephone cable. This plant was constructed near Palmer for less than
$210,000. The majority of the cost and labor was in the pipeline and intake which will
not be needed for this plant.
8. Economics
The economic analysis is based on the present value of the project upon payoff. The
present value simply means what the money is worth today. For example, the present
value of the loan to build the hydro project would be the amount of the loan. The present
value of the income from the hydro project is the amount that the future income is worth
today.
The discount rate is the interest rate that is used to move money through time. It is also
used as the loan interest rate. Typically, the discount rate is the potential interest that
money can earn minus the inflation rate. For this project, we have chosen a discount rate
of 5%. This is based on the assumption that tax free bonds or a mixture of tax free bonds
and grants can be used. See Figure 7 for Option 2 Adjusted Data Case where the discount
rate varies.
Icy Creek Power Recovery Study Page 7 of9
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Income will increase when the price of electricity increases. These increases will be
caused by inflation of equipment, labor and fuel and by the absolute increase in fuel
prices over time. As an example, the hydro will put out the same amount of power each
month on average. If the cost of that power remains the same, then the income from the
hydro will be constant. If the cost of power increases, then the income from the hydro
also increases. For this analysis, we have estimated an increase of 1.5% per year in the
cost of electricity. This means that if the price of electricity is now 7 cents per kWh then
in 30 years the price of electricity will be 11 cents per kWh. See Figure 8 for Option 2,
Adjusted Data Case where the future price of electricity varies.
The factors that determine whether this project is profitable (having a positive present
value) are the loan amount, the loan payback period, the discount rate, the price of
electricity, the increase in the price of electricity, the amount of power produced by the
hydro, the amount of power produced by the hydro that is utilized (or sold), and the
maintenance cost of the hydro. For this analysis, it is assumed that all of the power
produced by the hydro is utilized and that the maintenance costs are 10% of the initial
hydro income. The values used for the this analysis are as follows:
Initial hydro cost (loan amount)----------------------Varies with option
Hydro loan payback time (yr.)------------------------------30 years
Discount rate (annual) -------------------------------------------5. 0%
Price of electricity ($/kWh)-------------------------------------0.07
Fuel cost increase rate -------------------------------------------1.5%
Yearly average power produced (kWh)-------------Varies with option
Amount of power produced that is sold---------------------100%
Hydro O&M cost (per month)----------------------10% of hydro income
Given those assumptions, the analysis of the different options yields the following results.
Option 1 Option li . . Option 2 Option 2 Option3
Data set used .real data adjusted data: <Treal:data adjusted data real data
Initial hydro cost (loan amount) $400,000 $330,000 ·ssoo~i>oo $425,000 $243,000
Hydro monthly payments $2,138 $1,764' ·. :$2,'6:73 $2,272. . $1,299
Average monthly income from hydro $7,992 $5,192' · .. $h375 $8,342 $2,211
<.c·,, •.:'·
Hydro O&M cost (per month) $799 $519' $1;138 $834 $221
Present worth of hydro after loan $1,195,117 $706,244· $1;770,422 $1,239,976 $198,277
payback
The results of the economic analysis show that all of the options are profitable based on
the assumptions made.
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9. Conclusions and Recommendations
It is concluded that a power recovery plant located near the chlorination tank has positive
financial benefits. Even based on factored water flows, the present worth values of
Option 1 yields $706,244 and Option 2 yields $1,239,976. To these amounts can be
added Option 3 at $193,000.
What is not incorporated into these calculations is the new darn which will result in an
increase of head and enable the flows to be smoothed so there will be a greater power
output. The value of the head increase for a dam with a surface elevation of 560 feet will
result in an increase in revenue of22% for Option I, and 16% for Option 2 and about
26% for Option 3.
Also what is not incorporated is a possibility of using the system to shave peaks and the
advantage that will accrue to Unalaska in helping meet the new stringent air quality
requirements. These values would be the subject of a more detailed analysis.
Costs are always a factor in the construction of a system such as this. It is very easy on a
small job to load it up with overhead and wasted effort. The assumption is the work is
done efficiently and professionally, and the overhead is kept to a minimum and the crew
starts and completes the work in a short period of time during the summer.
The City should consider if this system provides them with a rate of return commensurate
with the risks. If this is the case, the design and construction of this plant will take about
one year. The major time requirement is to purchase and deliver the turbine.
If the City believes it desirable to consider expanding the facility to incorporate peaking
turbines with a new dam it is likely a parallel pipeline will have to be built to provide the
most effective system.
If the City does not wish to take the risk they can allow private enterprise to build the
plant with a purchase option at a latter date or a percentage of the gross revenue generated
by power sales.
Icy Creek Power Recovery Study Page 9 of9
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Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Appendix A
Monthly Creek Flow and precipitation
Option 1, Real Data
Option 1, Adjusted Data
Option 2, Real Data
Option 2, Adjusted Data
Option 3, Real Data
Option 2 Present Value as a Function of Discount Rate Using
Adjusted Data
FIGURE 1
Monthly Creek Flow and Precipitation
80 T 12
70 + l I \ I __:;_ Flow ( cfs)
--11-Precip (in) 1 +10 -60 ~ I -u = '-' .... ._,
~ 8 = 0 0 -50 ·-~ -e:: ~ -....
(1;1 c. f:: ·-u u (1;1
40 6 ""' (1;1 ~ bJ) » eo; -""' -= (1;1 -~ 30 = 0
...Q 4 2;
-= --1\ e:: = -0 1\ 0
2; 20 E--4
2
I .. I ' I \. ~ ---I I
10
0 ··-···-+--0
12/28/91 416192 7/15/92 10/23/92 1/31/93 5/11/93 8119/93 11/27/93 317194
Date
1,400,000 -~
1,380,000 -
1,360,000 ~----
-.c
31: 1,340,000 .111: -'a
<ll u 1,320,000 ::l
t--~
'a
0 .. a. 1,300,000 .. t----
<ll
31:
0
a. 1 ,280,000
.1!:-..
Ia
<ll 1,260,000 >-----
<ll
C)
Ia ..
<ll 1,240,000 > ---
<
1,220,000
1,200,000
1,180,000
300
I
I~
I
1/
-
-----
----
FIGURE 2
Option 1, Real Data
~~~, ..
~------~ ~ ----vn
·---/ v
---
---
-r
/
...
f---
---
--
-
h
/ ~ --
" 1\
------\-= '
--
'
'
--
350 400 450 500 550 600 650 700
Turbine Size (kw)
2,000,000
1,950,000
-..c:
~ ~1,900,000
c
0 :;::;
(.)
:I
'C
0
0:1 ,850,000 ...
Gl
~ a.
>-;:
:g1,800,000
>
1,750,000
1,700,000
,~---
-----
---
450 500
-
FIGURE 4
Option 2, Real Data
---
//\ v ~ ~' ~-~~ / -----------
I
·~ J \
I --------·---
I
------------·----------
--~·----·········------------'
550 600 650 700 750 800 850 900 950
Turbine Size (kw)
1,440,000
1,420,000
:c
!1,400,000
c
0
:;::l
0 ::s
"C
0 a: 1 ,380,000 ...
~
D..
>--.:
m1.36o.ooo
>-
1,340,000
1,320,000
FIGURE 5
Option 2, Adjusted Data
--t----~-7---·-.Y.. --~---+-----·-----·----+
\
~
•
~ ·-···!--·-· --+-----+---· ---+-----;
400 450 500 550 600 650 700 750 BOO
Turbine Size (kw)
390,000
380,000
:2 370,000
3: =-c
0 :;:: 360,000 C.) ::s
'0
0 ...
D. ... cu
3: 350,000
0
D.
>--.::: cu cu >-340,000
330,000
320,000
--·~··"-'-·--;---------
FIGURE 6
Option 3
---
-
/ ~-~""-
e--I ~ ----
/ r----~--
[\ v
I f----v ---------;
I
r-------.1-
55 65 75 85 95 105 115 125
Turbine Size (kw)
--~
-
--
135 145
polarconsult alaska
Appendix 8
Attachments Information on Turgo, Francis, and Ossberger turbines
Figure 8 Option 2 Present Value as a Function of Fuel Cost Using
Adjusted Data
Icy Creek Power Recovery Study
What is a Turgo Impulse
Turbine?
The concept behind the Turgo Impulse
design was to provide a simple Impulse type
machine having a considerably higher specific
speed than the single Jet Pelton. The design
allows a larger jet of water to be directed at an
angle onto a runner of small diameter, hence an
average specific speed of151mperial units-
65 metric units is available. ·
The first Gilkes Turgo Impulse Turbine was
installed in Scotland in 1919. Since then,
turbines of this exclusive Gilkes design have
been operating in over 60 countries, many of
them repeat orders and most ofthe 1720 units
manufactured are still operating
The fact that the machine can operate at
heads from 50 feet (15M) to 1000 feet (300M)
indicates the universal application, allowing
installations of Impulse turbines in what was
previously exclusive Francis turbine territory.
Gilkes, with their inhouse Research and
Development Department and test facilities
have continuously improved and uprated the
original design. We have a design team
exclusively engaged to ensure that we maintain
this position as a market leader.
Like all equipment of outstanding
performance or design, attempts have been
made to copy the Gilkes Turgo Impulse turbine
but only Gilkes can back the design with 60
years of manufacturing, installation and
servicing experience.
PELTON
TURGO
... ·):~";!'-o'·• ..
The Advantages of the GILKES
Turgo Impulse Turbine ·
When considering a hydro-electric
installation, even very competent engineers
tend to overlook the considerable difference
between water turbines and other types of
motive power units.
The quality engineered water turbine,
should be good for at least 50 years of
operation, with the minimum of down time
and spares requirement In addition to this, the
costs of the mechanical components (turbine-
generator -governor) are generally only a very
small proportion of the total hydro plant
installation , when one considers the water
storage facility, pipelines, powerhouse, switch
gear and transmission lines. It is, therefore, vital
that the correct priorities are recognised. The
water turbine must be of a proven design, from
a well established manufacturer:
capable of producing its rated output
have a high efficiency
serviced with the minimum of downtime
must be the right type of turbine for the
prevailing heaa, flow rates and other site
conditions.
The Gilkes Turgo Impulse turbine has the
following major advantages relative to other
Impulse and Reaction turbines over a very wide
range of head conditions.
1) Being of the Impulse pattern, no fine clearances are
involved which means that the turbine can operate on silt
laden water over long periods with the minimum of wear.
When this does occur, wear at the spear tip and nozzle can
be easily repaired and after longer periodsthe runner can
be repaired by welding if required. Turgo Impulse turbines
are very popular at mining power plants, being able to
provide a long life when operating on mining tailings. The
overall efficiency is unaffected by normal wear.
2) All working parts, including the governing deflector are
easily accessible through the detachabl e top cover or
throu gh the tailrace pit M anholes are provid ed for routin e
inspection.
3) Speed-load control is usually carried out by jet deflector,
governor operated. This method of governing ensures that
there are no pipeline shock loads even on full load
rejection. Where water economy is of paramount
importance, the deflector governing can be augmented by
follow-up closure of the spear, the rate of closure being
designed to be compatible with the pipeline design rating.
This gives the Turgo Impulse a very considerable advantage
over medium to high head Francis turbine installations
which require uprated pipelines, surge faci lities or relief.
valves.
4) There is no danger of cavitation damage to the runner or
casing.
5) The performance curve is extremely flat giving high
efficiency over wide flow and load variations. This is
particularly important where the turbines are used on sites
subject to seasonal flow changes or in conjunction with
municipal water supply or irrigation schemes. The twin jet
version available in the high capacity range provides for
even wider flow variations whilst maintaining high
efficiencies.
6) . The large jet diameter relative to runner mean effective
diameter provides a machine capab le of passing large
quantities of water when the turbines are be ing used as a
flow regulating device in addition to a power generation
machine. .
7) The high spedfic speed characteristic generally means that
a more compact and cheaper generator can be used even
when compared with multi jet Peltons.
8) These features all indicate that the Gilkes Turgo Impulse
turbine must be seriously considered where one is looking
for a medium to high head machine of proven efficiency,
reliability and simple maintenance. ·
ASK US TO PUT YOU IN TOUCH WITH SATISFIED USERS.
The OSSBERGER"''Turbine
The OSSBERGER Cross-Flow Turbine is protected by US and Foreign Patent Documents and its
innovative design makes it superior in performance, operation and reliability, compared to
other similar turbine types.
Range of Application : Heads 4 to 650ft (1 to 200m)
Waterflows 1 to 530 cfs (.03 to 15 mo/s)
Outputs 1 to 1500 kW per unit
Figure 1: Horizontal Admission
Principle and Flow Pattern
The OSSBERGER turbine is a radial impulse-type
turbine with partial admission. Its specific speed .
makes it a low-speed turbine. The jet of wat er wh1ch
is given a rectangular cross-section by the gUide-vane
system , flows through the ring of blades on the barrel-
shaped rotor , first from outside to inside and then ,
after crossing the interior of the runner, from inside to
outside again .
In practice , this flow pattern has the additional advan-
tage that leaves , grass and melting snow , which are
forced between the blades of the rotor as the water
enters , are washed out again after half a revolution of
the rotor by the outgoing water , assisted by the
centrifugal forces . The self-clean ing rotor therefore
never becomes blocked.
If the nature of the water-cours e should require it,
OSSBERGER turbines can be built in multi-section
configuration , the normal section ratio being 1 :2.
The sm all guide vane section is used with low water
supplies , the large section with medium f~ow~.and
both sections together for full flow. By th1s diviSion
into se ction s , any w ater supply in the rang_e .from 1/6
to 1/1 full flow is handled with optimum efhc1ency .
This explains why OSSBERGER turbines are espe-
cially suitabl e for the efficient utiliz ation of water flows
subj ect to wide fluctuations .
Casing . .
The all -steel casing of OSSBERGER turbmes !S
extr emely robust , yet lighter th an cast-Iron ca s1ngs,
shock and frost resistant, with the sidewalls made m
steel casting.
Rotor
The heart of the turbine , the rotor , is fitted with blad e s
wh ic h ar e made of preci sion drawn se ctional steel by
a prov en method and ar e fitted and we ld ed at both
ends int o end dis cs. Depend in g on 1t s s1ze. th e rot o r
is fitted with up to 37 such blades . The blades , wh ich
are curved only in radial di rection , produce no axial
thrust , thereby obviating the need for thrust bearings
or labyrinth bearings with all their inherent disadvan-
tages. In long ro tors the blades are suppo rt ed by
several intermediate discs . Although the use of
precision drawn blade sections e nsures almost
perfect balancing, the rotors are carefully balanced
before f inal assembly.
Bearings
The main bearings in OSSBERGER turbines are
equipped with standard self-alig ni ng roller-beari ng
inserts . Roll e r bearings in water tu rbines have
indisputable advantages if the ingress of leakage
water o r condensation is prevented by the design o f
the bearing housing , as outboard bearings . This is, in
fact , the outstanding feature of the patented
OSSBERGER turbine bearing design. At the same
time, the rotor is positivel y centered in re lation to th e
turbine casing. Sealing components which require no
maintenance complete this ingenious technical
solution. Apart from a change of grease about once a
year, the bearings require virtually no maintenance.
Guide Vanes
In divided OSSBERGER turbines, water admission is
controlled by two balanced guide-vanes. These
divide the stream of water and direct it so as to enter
the rotor smoothly, irrespective of the guide-vane
aperture. Since the two variable-pitch guide-vanes
are precision mounted in the turbine casing they
eliminate the need for shut off valves between pen-
stock pipe and turbine, at heads up to 150 feet. The
two guide-vanes can be adjusted individually by
control levers linked with the automatic or manual
control system. These control levers or guide-vane
arms are equipped with dead weights for failsafe
turbine shut-down, if used in conjuction with the
OSSBERGER hydraulic regulator.
The OSSBERGER· Cross-Flow Turbine
compared to other Turbine types
Figure 4: Specific Speed
Draft Tube .
As already mentioned, OSSBERG~R turbmes are
basically impulse turbines. In med1um and low head
ranges, however, a draft tube is essent1al m order to
utilize the full head, !rom headwater _level to ta1lwater
level. Impulse turbines, equipped w1th draft tubes,
require regulation of the suction head and the water
column in the draft tube, especially if they need to
operate efficiently over a flow range from 15 to 1 00%
of full flow. A simple, frictionless, air inlet valve for
controlling the vacuum in the turbine casing solves
this problem in the OSSBERGER turbine, so that
even intake heads of as little as 4 feet can be used.
In this case, an elbow draft tube can be designed, to
further reduce the civil structural costs. The air intake
into the turbine housing creates an air-water mixture
in the draft tube, providing a beneficial side effect to
the environment by increasing the oxygen content of
the outflowing water in the tailrace. Depending on the
ratio of the suction head (draft tube length) to the total
head, the turbine efficiency may reduce by approxi-
mately 3% in comparison with Figure 6.
Operating Characteristics
Due to their inherent design features, OSSBERGER
turbines are not affected by cavitation, provided the
suction head (draft tube length) is not extended
"beyond" the vapor pressure of water, irrespective of
the head under which they work.
A turbine setting below tailwater level wit~ associated
high civil structural costs, as mandated w1th other
turbine types, is not required with OSSBERGER
turbines. The runaway speed of OSSBERGER
turbines at rated head is approximately 1.8 times the
nominal speed which allows the use of standard
generators.
Efficiency
Figure 6: Efficiency Curve of an OSSBERGER Turbine
with divided guide vanes (Ratio 1 :2), without draft tube.
OSSBERGER Turbine Efficiency:
Water Flow: 15 30 60 90 100 %
Efficiency: 86 87 87 87 87 %
Figure 6 clearly illustrates the superiority of the
OSSBERGER turbine in the partial load range. Small
rivers and water courses often have a reduced water
flow for several months of the year. Whether or not
power can be gene~at~d during tha~ time dep~nds on
efficiency charactenst1cs of t~e. particular turbme. .
Turbines with a high peak effiCiency but a poor P?rtlal
load behavior produce less annual power output 1n
run-of-river power stations with a fluctuating water
supply than turbines with a flat efficiency curve, such
as the OSSBERGER.
Even with extensive head fluctuations, e.g. down-
stream of storage reservoirs, the efficiencies of
OSSBERGER turbines are inherently better than
those of high-speed turbines.
The mean overall efficiency of very small turbines (up
to 400 series) and at low head sites is guaranteed
over the whole admission range at a lower rate as
shown in Figure 6.
Turbine Regulation
An unco icated simple power producer such as the
OSSBE ER turbine needs an equally reliable
regulation system. On their search for such a system,
the OSSBERGER engineers found that a proportional
control valve was too sensitive and once more, new,
but well-proven technologies were investigated. It
was discovered that the Askania jet-tube system was
best adapted for this duty. One of its outstanding
features were the requirement standards on the
quality and cleanliness of the hydraulic oil which was
about ten times less likely to cause problems than
with the usual proportional valves.
The OSSBERGER regulator/governor basically
consists of the following mostly standardized compo-
nents:
-hydraulic power unit (HPU) with jet-tube assembly,
oil pump supply system, hot wired solenoid valves
for failsafe turbine shut-down and input signal
conversion into hydraulic pressure deflection.
-turbine control panel (TCP) for wall mounting with
indicators and operational devices.
-servo motor (hydraulic cylinder) for each guide
vane.
-tache-generator directly mounted on turbine or
generator shaft for speed indication.
-level sensor with galvanized support stand for
installation at intake.
-guide vane position feed-back signal with position
potentiometers.
The OSSBERGER regulators are used for automatic
control of the sub-divided OSSBERGER turbine
according to the flow rate (respectively water level),
generator speed, or intake pressure. The guide vane
position of the turbine is regulated by the hydraulic oil
flow either directed into the opening or closing ports of
the hydraulic servo cylinders. Water flow through the
turbine is therefore continuously regulated according
to the input signal.
The A-regulator is used in connection with induction
generators for asynchronous operation, whereby the
run-of-the-river concept mandates the guide vane
opening, maximizing generation by using the water
level signal at the intake to control the turbine open-
ing. The A-regulator offers the following features:
-automatic start-up
-automatic paralleling with utility grid
-automatic turbine regulation
-automatic shutdown at grid failure and restart
The OSSBERGER S-regulator/governor is used with
synchronous generators to operate either grid-parallel
or independently for stand-alone units. For isolated
operation, the generator speed is controlled by the
PID-governor to maintain constant frequency and
stable operation from zero to full load. Jf combined
with water level regulation, the turbine will start on
spee~ control followed by the synchronizing process
at wh1ch time the main circuit breaker will connect to
th.e public grid. At this point the water level regulator
WI." take over since the generator is locked into the
gnd ~ystem and speed regulation is not further
requrred.
For smaller stand-alone units an electronic load
controller with load dump can be used for single and
three phase generators to replace the PID-governor.
The combination of an OSSBERGER turbine with its
dedicated control system will ensure continued
trouble-free operation, proven by many thousand
installations around the world.
Turbine Control
I A-Regulator h _j S-Govemor ~---~~----~~-~G--~&r-~ ~~~-----n----~
I Manual Control I j Water Level Control / .... 1 _sp_e_ed_c_o_ntr_o_l _,
Run·of·the-River
(Maximize Generation)
I .L I ....------' ........_ ___ ,
Grid-parallel Grid·parallel and
operation only isolated operation && \7\7 I Induction Generator I r Synctlronous Generator l
<;] ~--<]____j "'
!.___Ut_i_lity_G_n_·d _ _,j .... l __ u_mr_ty_G_rid _ ___,l j lsolat~ Grid
Grid provides
excitation.
No power gen-
eration without
grid power.
Automatic shut·
down and re-start
Sell Excitation.
Power factor
improvement.
Self Excitation.
Stand-alone
operation.
Stable Operation
from zero to tull
load.
Figure 7: OSSBERGER Regulator Types
Front Cover Photographs
TOP LEFT The Georgetown Divide Public Utility Water Agency m
California uses their Irrigation system to generate electncity with an
OSSBERGER Turbine to operate efficiently between 180 and 260
feet.. A 600 rpm induction generator is directly coupled to the
turbme shaft. An automated by-pass valve is provided. to maintain
the water flow at times of power outage and grid failure.
TOP RIGHT To minimize construction work for a power plant
rehabilitation, an OSSBERGER Turbine was placed into the
existing turbine pit. The turbine with top intake operates at a head
of 38 feet, to develop 700 kW. This automated station belongs to
Hydro Sherbrooke in Quebec, Canada.
BOTTOM LEFT Adirondack Hydro Development Corp. is the owner
of the Middle Falls Hydro Station in New York. This typical run-of-
the-river hydro installation, operating at a net head of 48 feet. is
featuring two OSSBERGER Cross-Flow Turbines, each one
equipped with divided guide vanes, to enable power generation
year-round. Each turbine is coupled with a single-stage speed
increaser to drive a synchronous generator at 900 rpm. The
installed capacity amounts to 2.3 MW. The OSSBERGER PID·
Governor incorporates speed and water level regulation. to permit
tully automatic, unattended operation.
BOTTOM RIGHT Another Typical run-of-the-river hydro plant, built
by Adirondack Hydro Development Corp .. is rated at 34 feet and a
maximum flow of 250 cfs to generate in excess of 600 kW.
Pictured is the turbine with transition piece from which the cooling
water for the speed increaser is diverted. The draft tube below the
turbine allows full utilization of the draft head below the turbine
runner. Power generation resumes year-round from full flow down
to approx. 12 cis, experienced during dry summer months.
<U = -c: > ..... = <U
<"1.)
<U
I..
~
$1,600,000
$1,500,000
$1,400,000 -
$1,300,000
$1,200,000
$L100,000
,000,000 -~
$900,000
$800,000
0.00%
FIGURE 8
Option 2 Present Value as a Function of
Fuel Cost Using Adjusted Data
I
------~ ........-
~ ~
----·-------~ ~ ·-----·-···-· ~--I
~ -------
-----------~--
0.50% 1.00% 1.50% 2.00%
·Fuel Cost Increase Rate
-~~
-------
-----
2.50% 3.00%
polarconsult alaska
Appendix C
Drawing H-1 General Specifications and Flow Diagrams
Drawing H-2 Turbine Details
Icy Creek Power Recovery Study
INTAKE ELEV 513 0' INTAKE ELEV 513 0'
TOP OF TANK 330 0'
HEAD CONTROLLED
VALVE
(EXISTING)
GROSS HEAD = 214'
RESERVOIR TO TURBINE
TURBINE
DISCHARGE
BLOW-OFF SITE
N T S
INTAKE ELEV 513 0'
TOP OF TANK 330 0'
PRV
HEAD CONTROLLED VALVE
(EXISTING) TURBINE
DISCHARGE
GROSS HEAD = 300
RESERVOIR TO TURBINE
DATE ~/1 5/ NO
ELEV 213 0'
I C Y C R E E K
ICY CREEK BELOW FILTER PLANT
N T S
DATE REVISictlS polarconsu!t
HEAD CONTROLLED VALVE
(EXISTING)
unc
DESIGNED __ EA 1----t---t---------------!
DRA\\N DJ!l 1--+----J-------------J
CHECKED __ EA 1-----t---1----------------1 ENGINEERS e SURVEYORS • ENERGY CONSULTANTS
PRV
FILTER PLANT SITE
N T S
SCALE 1 =1 -()
FILE UH1 1:---t--+-------------1
1503 WEST 33RD AVE SUITE 310
ANCHORAGE ALASKA 99503
PHONE (907) 258-2420
FAX (907) 258-2419
GROSS HEAD= 180'
RESERVOIR TO TURBINE
-----------1---
DRAWING
GENERAL SPECIFICATIONS
AND FLOW DIAGRAMS
PROJECT
DUTCH HARBOR/UNALASKA
HYDROELECTRIC PROJECT
ANCHORAGE~ ALASKA
}
SHEET
Of
N
<(
12" ¢
~ DUCTILE IRON
¢ STEEL ¢ STEEL
12 '/J
24 ¢ DUCTILE IRON
HL11D-wJ-30
TURBINE
P L A N
24" ¢ STEEL
FLOOR
12 ¢ 12 ¢ 16" 1/J
E L E V A T I 0 N
9 5/8"
/
TURBINE AT FILTER PLANT SITE
9 5/8" 9 5/B"
24' ¢ DUCTILE IRON
24" ¢DUCTILE IRON
DATE 4M/ NO DATE REVISIONS
DESIGNED __ EA t------+--+-------------1
DAA~ ~R t------+--+-------------1
~E=D----EA ~-r-+-----------~
poialfconsult aiaska. ~t11c
ENGINEERS o SURVEYORS o ENERGY CONSULTANTS
SCALE 1/4 ~1 -(1
FILE UH1 l----+--+--------------1
1503 WEST 33RD AVE SUITE 310
ANCHORAGE ALASKA 99503
PHONE (907) 258-2420
FAX (907) 256-2419
\
I
WATER DISCHARGE
GRADE
TAILRACE
P L A N
WATER
DISCHARGE
~E T
HL-110-WJ-50
I HL11D-wJ-50
TURBINE
I E L E V A T I 0 N
A1 Az
2 '-9 1/2' 1 '-11 5/8"
A3
3'-3 3/8"
HL11D-wJ-50
TURBINE
A4
1 '-4 1/2"
TYPiCAL TURBINE AT BLQW~OFF ANP AT ICY CREEK
DRAWING
TURB~NE DETAiLS
I
PROJECT
'!DUTCH HARBOR/UNALASKA
I HYDROELECTRIC PROJECT
I
DUTCH HARBOR, ALASKA
SHEET