Life Cycle Cost Analysis of Gated Spillways and Fuse Plugs1068751/FULLTEXT01.pdf · Gated Spillways are usually constructed in Sweden. The Gated Spillways operate using civil, mechanical

Life Cycle Cost Analysis of Gated

Spillways and Fuse Plugs

Muhammad Tabish Parray

Master of Science Thesis KTH School of Industrial Engineering and Management

Department of Energy Technology Division of Applied Thermodynamics and Refrigeration

SE-100 44 STOCKHOLM

2

Master of Science Thesis

EGI_2016-101 MSC

Life Cycle Cost Analysis of Gated Spillways and Fuse Plugs

Muhammad Tabish Parray Approved Examiner

Prof. Björn E. Palm

Supervisors

Erik Nordström Magnus Svensson Hans Bjerhag

Commissioner

Fortum AB

Contact Person

Hans Bjerhag

3

Abstract This study aimed to evaluate Gated Spillways and Fuse Plugs from an economic perspective. Life Cycle Cost Analysis was carried out for both these alternatives.

A literature review was carried out to know more about the hydropower plants at Fortum. Various methodologies for Life Cycle Cost Analysis were investigated. Also a study was carried out to identify the Gated Spillways and Fuse Plugs to be investigated. Various costs associated with them were also identified.

Data was collected from the archives at Fortum and also via communication with experts. The deterministic analysis of data was carried out using a model built in Excel. Also probabilistic analysis of the data was carried out using Monte Carlo Simulation. The final results showed that Fuse Plugs are cheaper than Gated Spillways. Also for Gated Spillways, the initial costs are higher than the various other costs throughout its lifetime. The Civil costs are also higher as compared to Mechanical, Electrical and other Miscellaneous costs.

4

Acknowledgement This thesis was carried out during the spring and summer of 2016 at Fortum, Sweden. The thesis involved a lot of data collection and interviews with experts. I would like to thank all the people, who despite their busy schedules managed to answer my question and point me in the right direction.

I would firstly like to thank all the people at Vita Villan for helping me out and providing a wonderful environment to work in. A special thanks goes to Karl-Erik Löwén for guiding and mentoring me at all the stages of the project.

The thesis is the culmination of my master’s program in Sustainable Energy Engineering, and I would like to extend my heartfelt gratitude to the Swedish Institute and its staff for the heart-warming support I received from them over these two years.

Finally I would like to thank my supervisors at Fortum, Hans Bjerhag and Magnus Svensson, my supervisor at KTH Erik Nordström and Prof. Björn Palm for their support, guidance and advice throughout the thesis work.

Stockholm, November 2015

Tabish Parray

5

Contents Abstract ....................................................................................................................................... 3

Acknowledgement ....................................................................................................................... 4

Contents ...................................................................................................................................... 5

Abbreviations ............................................................................................................................... 7

List of Figures ............................................................................................................................... 8

List of Tables ................................................................................................................................ 9

1 Introduction........................................................................................................................ 10

2 Background......................................................................................................................... 11

2.1 Statement of Purpose............................................................................................................ 11

3 Literature Study and Interviews ........................................................................................... 12

3.1 Hydropower in Sweden ......................................................................................................... 12

3.2 Rivers Fortum uses for hydropower ...................................................................................... 13

3.3 Dams ...................................................................................................................................... 14

3.4 Type of Gated Spillways ........................................................................................................ 14

3.5 Fuse Plug ................................................................................................................................ 18

3.5.1 Usage of Fuse Plugs in Sweden ..................................................................................... 19

3.5.2 Usage of Fuse Plugs outside Sweden ............................................................................ 19

3.6 Life Cycle Cost Analysis .......................................................................................................... 20

3.6.1 Construction Cost Index (Anläggningskostnadsindex) .................................................. 21

3.6.2 Monte Carlo Simulation ................................................................................................ 21

3.7 Interviews .............................................................................................................................. 22

4 Methodology ...................................................................................................................... 23

4.1 Modelling framework and structure ..................................................................................... 23

4.2 Selection of Spillway Dams .................................................................................................... 23

4.3 Costs Considered ................................................................................................................... 24

4.4 Assumptions .......................................................................................................................... 25

4.5 Calculations ........................................................................................................................... 26

5 Results and Discussions ....................................................................................................... 28

5.1 Costs of Gated Spillways with respect to Spillage Capacity .................................................. 28

5.2 Costs of Fuse Plugs with respect to Spillage Capacity ........................................................... 29

5.3 Comparison between Fuse Plugs and Gated Spillways ......................................................... 30

5.4 Comparison of cost breakdown for Gated Spillways and Fuse Plugs .................................... 31

6

5.5 Electricity Costs and comparison with Total Operational Costs ............................................ 33

5.6 Monte Carlo Analysis for Cost of Gated Spillways ................................................................ 34

5.7 Fuse Plug triggering ............................................................................................................... 37

6 Conclusions ......................................................................................................................... 38

7 Recommendation for Future Work ...................................................................................... 39

References ................................................................................................................................. 40

Appendices…………………………………………………………………………………………………………………………………..42

7

Abbreviations

LCC- Life Cycle Cost LCCA - Life Cycle Cost Analysis ICC - Initial Construction Cost LCOE - Levelised Cost of Electricity PERT - Project Evaluation and Review Technique FDU – Detailed Dam Safety Evaluation (Fördjupad Dammsäkerhetsutvärdering) FDI – Indepth Inspection (Fördjupad Inspektion) PFMA - Possible Failure Mode Analysis NA- Not Available Dam Classification – The dams are classified into 4 consequence classes as follows1 Consequence

Class Consequence of dam failure expressed as a probability level of claims

experience

1+

Probability of • Loss / damage / inoperability due to large volumes of water on people's lives, people's homes, cultural facilities and workplaces and severe strain on society by the cumulative effect of the damage along the river, is high • Serious disturbances in the country's electricity supply is high • Serious disruptions in transport and transport is high • The destruction or extensive damage to other vital public facilities is high • Significant loss of biodiversity is high • Very large economic damage is high

1

The probability of loss of life or serious injury is not negligible or The probability is noteworthy due to serious damage to the: • socially important facilities • significant biodiversity loss or There is also a high probability of major economic damage.

2

The probability is not negligible, considerable damage to the: • community facilities • biological diversity or • economic damage

3 (The probability of injury is negligible as above) High Consequence Dam- Dams that fall under Class 1+ and Class 1 are referred to as high consequence dams. Dimensioning Flood- The maximum flood that a hydraulic structure can safely pass without any significant damage to its structure. Design Flood Classification- Design Floods are classified into two classes (Svensk Energi, Svenska Kraftnät och SveMin, 2007)

Flood Class Marginal consequences if failure during floods I • Fatalities, major damages large.

• Design for 10000 year flood achieved by exceeding the retention level in reservoir or increasing spillage capacity. • Able to deal with 100 year flood at retention level.

II • No fatalities, major damages low • Designed for 100 year flood.

1 RIDAS- Power Companies guidelines for dam safety

8

List of Figures Figure 1 Major Rivers Fortum uses for Power Generation ................................................................... 13 Figure 2 Sector Gate .............................................................................................................................. 14 Figure 3 Segment Gate (www.wikiwand.com 2016) ............................................................................. 15 Figure 4 Wheel Gate (Main Engineers 2016) ........................................................................................ 15 Figure 5 Flap Gate (CMCHydro 2016) .................................................................................................... 16 Figure 6 Drum Gate ............................................................................................................................... 16 Figure 7 Bottom Gate (Kuhlin 2016) ...................................................................................................... 17 Figure 8 Fuse Plug Structure .................................................................................................................. 18 Figure 9 Working of a Fuse Plug (Laboratory of Hydraulics 2014) ........................................................ 18 Figure 10 Vittjärv Fuse Plug (Google Maps 2016) ................................................................................. 19 Figure 11 Monte Carlo Simulation for Multiple Input Variables (ADCATS 2016) .................................. 22 Figure 12 Triangular Probability Distribution (Structured Data LLC 2016) ............................................ 26 Figure 13 LCC for various Gated Spillways ............................................................................................ 28 Figure 14 ICC of Fuse Plugs .................................................................................................................... 29 Figure 15 LCC of Fuse Plugs ................................................................................................................... 29 Figure 16 LCC comparison between Gated Spillways and Fuse Plugs ................................................... 30 Figure 17 LCC Breakdown for various Gated Spillways ......................................................................... 31 Figure 18 LCC breakdown for various Gated Spillways ......................................................................... 32 Figure 19 LCC breakdown for Vittjärv Fuse Plug ................................................................................... 32 Figure 20 Electricity Costs vs Other Costs (kSEK) .................................................................................. 33 Figure 21 Avestaforsen LCC Probability Distribution ............................................................................ 34 Figure 22 Vittjärv LCC Probability Distribution Collected ...................................................................... 35 Figure 23 Avestaforsen LCC Probability Distribution (80%-120%) ........................................................ 36 Figure 24 Avestaforsen LCC Probability Distribution (60%-120%) ........................................................ 36 Figure 25 LCC comparison of Fuse Plugs for different scenarios .......................................................... 37

9

List of Tables Table 1 Major Rivers used for Hydropower in Sweden (Kuhlin 2016) .................................................. 12 Table 2 Major Rivers Fortum uses for Power Generation ..................................................................... 13 Table 3 Various Gated Spillways and their Spillage Capacities ............................................................. 23 Table 4 Fuse Plugs Considered .............................................................................................................. 24 Table 6 Costs Considered ...................................................................................................................... 24 Table 6 Cost Distribution for Gated Spillways ....................................................................................... 27 Table 7 Cost Distribution for Fuse Plugs ................................................................................................ 27 Table 6 Probability of LCC of Avestaforsen between various values .................................................... 34 Table 9 Probability of LCC of Vittjärv between various values.............................................................. 35 Table 10 Probability of LCC variation for Avestaforsen, while changing Major Refurbishment Cost ... 36

10

1 Introduction Hydropower forms a very important part of the Swedish Energy System and provides around 45% of the total electrical production per year. With an increase in the intermittent renewable energy sources, like wind and solar, and the planned nuclear phase out by the Swedish Government, it will play an increasingly significant part in balancing the Swedish national electric grid.

Most of the dams for these hydropower stations in Sweden have been constructed at least 30 years ago, with some as old as 100 years or more, and have been constructed for floods with a statistical probability of occurring once over a period of 1000 years. However according to the RIDAS guidelines (Svensk Energi, 2012), the Swedish power companies guidelines for dam safety, many of the dams are being refurbished to cope with Class one floods (Svensk Energi, Svenska Kraftnät och SveMin, 2007). This refurbishment involves significant capital investment and increase in the discharge capacity. The dam discharge capacity can be increased by constructing and renovating various types of Gated Spillways and/or fuse plugs, or by increasing the retention level of the dam. Life Cycle Cost Analysis (LCCA) acts as a tool for making more informed decisions regarding these upgrades and refurbishments.

11

2 Background Hydropower plants have a high initial investment cost, although the Levelized Cost Of Electricity (LCOE), the net present value of the unit-cost of electricity over the plants lifetime, for this technology is among the lowest. After the power plant has been constructed, it has various overhead costs like Operation and Maintenance (O&M) costs, Inspection costs etc. which initially are low and increase over time, financial costs which are reduced over time, reinvestment costs that appear at regular intervals (decades), etc. Initial design of a power plant significantly impacts the total costs. Proper initial planning leads to significant minimization of costs over the life cycle of the project.

A Dam constitutes significant percentage of costs of the entire hydropower plant. It serves as a barrage for the water in the reservoir, allowing the water to be diverted to the turbines for generation of electricity. However during high floods or stoppage in power production, water must be allowed to pass through in order to prevent overtopping. For bypassing the water, Gated Spillways are usually constructed in Sweden. The Gated Spillways operate using civil, mechanical and electrical infrastructure. In many cases however, the spillway gates are seldom used and thus there is a risk of malfunction when they are needed. In other cases, where they are frequently used, they may suffer wear and tear, leading to regular inspections and high maintenance costs.

In Sweden, many of the high consequence dams are being upgraded to successfully pass Class One floods with increased spillway capacity. This upgrading of the present dams results in high investment costs, with a possibility that the increased capacity might never be used in the lifetime of the dam.

Fuse Plug is a viable spillway alternative, leading to an increase in the spillway capacity at a lower construction cost. Also the maintenance cost for a Fuse Plug is less compared to a traditional gated spillway.

2.1 Statement of Purpose The various purposes of this study are

1. To perform a Life Cycle Cost Analysis (LCCA) for the various types of Gated Spillways present at Fortum.

2. To perform a Life Cycle Cost Analysis of Fuse Plugs. 3. To compare the civil, mechanical, electrical and miscellaneous costs of the various Gated

Spillways.

An economic comparison of the Fuse Plugs and Gated Spillways will aid in future decision making with respect to the construction, refurbishment and upgrade of Dams. It will also aid in making a better decision as to whether a Gated Spillway or a Fuse Plug shall be built, when both are technically feasible. Moreover, it would help in deciding which spillway should be chosen among the various available options.

12

3 Literature Study and Interviews

3.1 Hydropower in Sweden In 2011, the number of hydropower plants in Sweden was approximately 2 050, with a total installed capacity of approximately 16 200 MW (World Energy Council, 2011). Around 80 % of the hydropower production is concentrated in the Northern part of Sweden, Norrland. A majority of the rivers in Sweden have been exploited for hydropower and only a few are unregulated. The following are the major rivers used for hydropower production in Sweden.

River Installed Capacity (MW) Yearly Production (TWh) Luleälven 4 366 14.6 Indalsälven 1 832 9.0 Umeälven 1 804 7.6 Ångermanälven 1 248 6.0 Dalälven 1 100 4.3 Skellefteälven 1 069 4.2 Faxälven 817 3.7 Ljusnan 786 3.7 Fjällsjöälven 560 2.0 Ljungan 479 2.0 Göta älv 326 1.6 Klarälven 351 1.3 Motala Ström 153 0.5 Other Rivers 1 741 5.7 Total 16 632 66.2

Table 1 Major Rivers used for Hydropower in Sweden (Kuhlin, Information about the Swedish hydropower, 2016)

The major unregulated rivers include Torneälven, Kalixälven, Piteälven and Vindelälven and are protected by the Swedish Environmental Code (Miljöbalken) of 1998. The unregulated rivers in Sweden have a total estimated potential of 27 TWh (Finnish Barents Group, 1998). Due to the strict environmental laws, constructing new hydropower plants are very difficult in the foreseeable future, and the major work is restricted to refurbishment and upgrading of the existing plants.

13

3.2 Rivers Fortum uses for hydropower Fortum has its Swedish hydropower plants located on the following rivers (red dots mark the plants):

Figure 1 Major Rivers Fortum uses for Power Generation

River (incl tributaries) No of Power Plants (Fortum) Ångermanälven 6

Indalsälven 10 Ljungan 4 Ljusnan 23 Dalälven 39 Klarälven 23 Norsälven 3

Byälven 11 Gullspångsälven 8

Total 127 Table 2 Major Rivers Fortum uses for Power Generation

14

3.3 Dams A dam is a barrier that stops water from moving along and increases the water level upstream. It is primarily used for diverting water for agricultural purposes, flood regulation and for electricity generation. In Sweden they are mostly used for electricity generation, thus diverting the water to the turbines for generation of electricity.

Dams can be classified into various types, depending on the design, usage, structure, materials used etc (Officials, 2016). On the basis of materials used, dams can be broadly classified as

1. Embankment Dams a. Earthfill Dams- For example Rongunsky Dam (Russia) b. Rockfill Dams-- For example Trängslet Dam (Sweden)

2. Concrete Dams a. Gravity Dams- For example Itaipu Dam (Brazil) which is a Concrete Face Rockfill Dam. b. Arch Dams- For example Hoover Dam (USA) which is a Concrete Arch Dam. c. Buttress Dams (Lamelldamm)- For example Ljusne Strömmar Dam.

Choice of dams vary according to the hydrological and hydraulic conditions present at a place. Earth Fill dams are the most common in Sweden. These dams contain more than 50 percent, by volume, earth fill materials. They are constructed in wide valleys having flat slopes at abutments (flanks).

3.4 Type of Gated Spillways To control the level of water in the reservoir, Gated Spillways are constructed to transfer water from the upstream to the downstream side in a controlled manner. Gated Spillways can be described on the basis of their civil engineering design, purpose and the type of gates used. The various types of Gated Spillways on the basis of the type of gates used are

1. Sector Gates (Sektorlucka)

Figure 2 Sector Gate

15

2. Segment, Radial or Tainter Gates (Segmentlucka)

Figure 3 Segment Gate (www.wikiwand.com, 2016)

3. Slide or Plane Gates (Planlucka) or Wheel Gates (Hjullucka)

Figure 4 Wheel Gate (Main Engineers, 2016)

16

4. Flap Gates (Klafflucka)

Figure 5 Flap Gate (CMCHydro, 2016)

5. Drum Gates (Valslucka)2

Figure 6 Drum Gate

2 Drum gates are present in old spillways and have not been installed in recent times. As such they have not been included in the study.

17

The majority of Gated Spillways in the Fortum power plants are equipped with Segment Gates. Also Sector Gates, Drum Gates and Plane Gates (incl. Wheel gates) are present at some power plants. Sector gates are not built now as they require heavy maintenance and thus are expensive. Plane gates are built at many dams, as they are easy to operate and maintain. However they cannot be used for spillways with high spillage capacities, as the rails supporting the gate cannot operate smoothly at high pressure. A Flap Gate is also being constructed at the Lima power plant. While the older spillway gates are operated mechanically, the ones constructed since seventies are operated using hydraulics. Many of the gates are refurbished and changed from being mechanically driven to being hydraulically driven. At many places upgrading is carried out to increase the discharge capacity of the Gated Spillways, in order to withstand an increased capacity of Design Flood. Usually Class 1 dams (dams with a higher consequence) are the ones that are prioritized for upgrade in spillway capacity.

Some of these gates are present in the Bottom Gated Spillways as Bottom Gates (Bottenlucka). Their primary objective in many of these cases is not spillage, but other tasks like lowering of reservoir height, clearing of debris and transfer of sediments downstream.

Figure 7 Bottom Gate (Kuhlin, 2016)

18

3.5 Fuse Plugs A Fuse Plug is an erodible section of a dam, designed to erode when the water level reaches a certain height, thus allowing for an increase in the spillage capacity. The design is such that the erosion takes place in a timely manner, lowering the water level and thereby preventing overtopping and collapse of the rest of the dam. The collapse of a Fuse Plug however results in a permanent decrease in the water level in the reservoir which, depending on the location and design of the fuse plug, and the time taken to rebuild it, can lead to monetary losses and a loss in energy production. The figure below shows the structure of a standard fuse plug.

Figure 8 Fuse Plug Structure

Figure 9 below shows the working of a Fuse Plug for a laboratory scale model. After the water reaches the trigger level, the erosion of the downstream surface of the dam begins. After some time the dam the core is exposed, which collapses soon to give way to the water upstream, thus realising the full spillage capacity of the fuse plug.

Figure 9 Working of a Fuse Plug (Laboratory of Hydraulics, 2014)

19

The location of a Fuse Plug however is very site specific. Whether a Fuse Plug is used at a particular site or not, depends on the various factors like (Av Rajnikant, 2004)

a) Topography- Fuse Plugs are generally constructed on nearly flat channels (Tracy Vermeyen, 1992) and having a provision for discharging the excess flood water into the same river or a neighbourhood valley.

b) Geology- The foundation should be solid rock, in order to withstand erosion when the Fuse plug is washed out after being triggered.

c) Downstream Conditions- A tail channel should be present downstream to ensure the flow is diverted back to the main river after the triggering of the Fuse Plug.

d) Optimisation of Minimum Reservoir Operation Level- The triggering of a Fuse Plug will lead to a decrease in the reservoir level. This should be taken into consideration and the level of the Fuse Plug foundation must be chosen carefully.

3.5.1 Usage of Fuse Plugs in Sweden Till date only a few Fuse Plugs have been constructed in Sweden. One of them is at Vittjärv HPP, located in Luleälven river, at Boden Municipality in Northern Sweden, owned by Vattenfall. It was constructed between 2007 and 2010.

Figure 10 Vittjärv Fuse Plug (Google Maps, 2016)

Fortum is also planning to install Fuse Plugs at Lanforsen and Untra; and a full scale test on a downsized fuse plug has been carried out recently. The results from the test have been promising, as the fuse plug generally behaved as expected.

3.5.2 Usage of Fuse Plugs outside Sweden Globally the number of Fuse Plugs constructed is small. According to one estimate, less than 20 Fuse Plugs have been constructed worldwide until 2004. Although the number is small, they

20

have been constructed in all the major continents of the world. The following is a list of some of the Fuse Plug Dams outside Sweden:

• Oxbow, USA. • Gangapur and Muramsilli, India. • Mnjoli, Swaziland. • Mrica Dam, Indonesia. • New Waddell Dam, Bartlett Dam, and Horseshoe Dam in Arizona, USA. • Warragamba Dam, Chaffey Dam and Copeton Dam in New South Wales, Australia. • Otter Creek Dam in Utah, USA. • Guri Dam, Venezuela. • Burnt Fuse Plug, Canada. • Douglas dam, Colorado, USA. • Hagneck Channel, Switzerland.

3.6 Life Cycle Cost Analysis The Life Cycle Cost for a Spillway is a combination of a number of costs, some of which are recurring whereas some are one-time fixed costs. Life Cycle Cost Analysis (LCCA) on the other hand is a methodology for determining the total cost of ownership of an asset throughout its lifetime. For a project it includes the various costs starting from its inception and feasibility study, to its final dismantling cost at the end of its life time. The Life Cycle Cost for a Spillway is a combination of a number of costs, some of which are recurring whereas some are one-time fixed costs. LCCA is used to compare the various alternatives available to the user, offering a similar level of service, from an economic point of view. Often during the design phase of constructing/renovating a new/existing dam, multiple spillway design/type alternatives are available to the designer. LCCA will help in determining the most cost effective spillway design that may be used. The two most common ways of carrying out the LCCA are the deterministic and probabilistic approach (Kahraman, 2002).

1. In the deterministic approach, each input variable has a fixed cost as defined by the user on the basis of historical data, assumptions and experience. This is also the approach followed in the various estimates received from the consultants, by Fortum. As each input has a fixed cost, the final costs obtained also represent a fixed number. This approach does not take into account the accuracy of the value of each input variable, which leads to these inaccuracies being a part of the final result.

2. The probabilistic approach, assumes a variation (randomness) in the value of input variables, in the form of a probability distribution, and finally delivers the LCC in the form of a range, incorporating the variations. Thus it tells us what is the smallest value, the most likely value, and the largest values we can expect, and also the probability of the cost being below a certain value.

Deterministic approach is the traditional and most common approach for calculating LCC, whereas the probabilistic approach is being increasingly used to determine LCC (Wang, 2012). In

21

our analysis, deterministic approach of LCCA has been fundamentally used as this is the most common approach. However, the data collection for this model in itself in based on estimates and assumptions. A number of uncertainties are present in the data and the cumulative impact of these uncertainties can undermine the accuracy of the model. As such, to take into account these uncertainties, and their effect on the final results, a probabilistic approach based on Monte Carlo simulation is used. This gives a range of values as the final estimate, incorporating all the uncertainties and their various combinations that lead to a plurality of possibilities.

3.6.1 Construction Cost Index (Anläggningskostnadsindex) The Construction Cost Index (Anläggningskostnadsindex, Appendix 1) is an index providing a comparison of the construction prices over the years in Sweden. The index used in this thesis is the one provided by Energiforsk for use by the hydroelectricity industry. The Index is further divided into subsections of separate indexes for mechanical, electrical and civil sections.

3.6.2 Monte Carlo Simulation Monte Carlo Simulation is a technique used for probabilistic analysis in engineering. It obtains a statistical value of the output on the basis of statistical values of the various inputs. It illustrates how the uncertainties in the input values lead to an uncertainty in the values of outputs. It uses randomness to solve problems and is increasingly useful when the number of inputs with uncertainties increases. The following example illustrates how Monte Carlo simulation works.

Suppose we are constructing a wall for which a) The estimated material cost varies between 900 SEK and 1 100 SEK and the mean cost is

1 000 SEK. b) The estimated labour cost varies between 900 SEK and 1 100 SEK and the mean cost is

1 000 SEK. c) The labour cost and material cost are independent of each other.

Thus the total mean cost is 2 000 SEK. However the actual cost can vary anywhere between 1 800 SEK and 2 200 SEK. An infinite number of combinations of these costs can occur. For example 950 SEK for material cost and 1 020 SEK for labour cost, giving a total cost of 1 970 SEK. Monte Carlo simulation randomly takes a value from the first cost and adds it to a random value of the second cost to get a value of the total cost. The procedure is repeated 1 000’s of times and a histogram of the various values of total costs is generated. This histogram gives an estimate regarding the probabilistic distribution of the total costs. In most of the cases, between 5 000 – 10 000 repetitions result in convergence of the results.

This simulation technique can be employed for the determination of Life Cycle Cost (Wang et al, 2010). In the determination of Life Cycle Costs, in many cases all the necessary data is not available. As such many assumptions are made on the basis of expert opinions, experience, historical data etc. This is especially relevant when forecasting the Life Cycle Costs for the future, as most of the assumptions are guesses based on historical data and present trends.

During the Monte Carlo Simulation, the various input variables are represented in terms of probability distributions like normal distribution, triangular distribution, uniform distribution, PERT distribution etc. depending on the input variable. Random values are selected for the various input variables from within the distribution and the final output is generated. The

22

process is repeated a large number of times and results are obtained. The results obtained represent the range of most likely outcomes.

Figure 11 Monte Carlo Simulation for Multiple Input Variables (ADCATS, 2016)

Using Monte Carlo Simulation for LCCA, the results represent the most likely cost of the project over its lifetime and can be used to obtain the probability that the cost will be between two particular values.

3.7 Interviews A number of experts, both at Fortum and outside of Fortum, have been contacted and interviewed so as to gain insights and information which many times were not available in the data archives. Also suitable assumptions have been made at many points, on the basis of the information provided by the experts.

23

4 Methodology The methodology and the modelling framework is explained in the following sections

4.1 Modelling framework and structure Although the economic lifetime of a project is usually taken as 50 years and investment decisions are made considering it as a lifetime, it is common to observe the dams far exceeding this value. This is primarily due to proper and timely maintenance of the dams. Thus in this study, the Gated Spillway structure lifetime of 80 years is considered as the guiding Life Cycle Duration for the Gated Spillways.

4.2 Selection of Spillway Dams The dams to be considered for the analysis were selected in order to include a mix of various Gated Spillways and ease of data availability. A majority of the dams included in this study are on the Dalälven river located in Central Sweden. The analysis also includes dams on Ljungan, Ljusnan, Klarälven and Ångermanälven rivers.

After going through the power plants of Fortum, the following is the list of plants analysed for the Gated Spillway costs:

Dam Class Year of

Spillway Construction

Dam Dimensions

L/B/H [m]

Total No of gates

No of Segment

Gates /Total

Spillage capacity [m3/s]

No of Sector Gates /

Total Spillage capacity [m3/s]

No of Plan

Gates / Total


No of Flap

Gates / Total


Other Gates Remark

Åsen 1A 1963 85/4/20 2 2/1098 - - - - -

Avestaforsen 2 2008 12,5/2,2/9 4 4/2400 - - - - - Eldforsen 2 2001 NA 3 3/1212 - - - - -

Sveg 1A 1975 150/3,5/24 6 2/1220 - 4/885 - - 2 Bottom Gates

Parteboda 1A 1960 35/2/10 7 1/ NA - 4/253 - 2/ NA -

Järpströmmen 1A 1944 30/2/16 3 2/475 1/150 - - - - Forshaga 3 1950 NA 4 - 4/652 - - -

Tänger 1B 2009 30/2,2/7 3 2/186 - 1/29 - - 3 Bottom Gates

Lima 1A 2016 26/3,2/18 3 2/1020 - - 1/335 - - Avesta Lillfors NA 1981 333/NA/5,7 0 - - - - - Overflow

Weir Table 3 Various Gated Spillways and their Spillage Capacities

The dams of the above power plants include a mix of Sector Gates, Segment Gates, Plane Gates, Wheel Gates etc. Many of the Gates are equipped with heating for winter conditions. The old gates are cog wheel driven and the newer ones are driven by hydraulic cylinders. Also many of the old gates have been upgraded from being cog wheel driven to being driven by hydraulic cylinders.

24

Table 4 below presents the list of Fuse Plugs analyzed for the Life Cycle Cost.

Fuse Plug Year of Construction

Total Spillage Capacity (m3/s) of Fuse Plugs

Design Flood (years)/ Return Period

Vittjärv 2009 560 1 000 Lanforsen (Test Fuse Plug)

2015 150 1 000

Burnt Fuse Plug 1991 1 125 10 000 Bartlett Fuse Plug

1994 7 410 10 000

Table 4 Fuse Plugs Considered

4.3 Costs Considered The various costs considered for the Gated Spillways, have primarily been divided into the four subsections Civil, Mechanical, Electrical and Miscellaneous Costs. Similarly for the Fuse Plugs, the various costs have been divided into two subsections of Civil and Risk Costs. A Fuse Plug does not have any mechanical of electrical components, as such there are no costs associated with them. Also the Overhead Costs (O&M) associated with them is very small, as it generally involves removing of vegetation from the surface of the Fuse Plug.3 All the costs were tabulated in a model created in MS Excel. Detailed breakdown of the costs has been tabulated below.

SPILLWAY COSTS Gated Spillways Gates

Civil Costs Mechanical Costs Electrical Costs Miscellaneous Costs Initial Construction Cost (ICC)

Initial Construction Cost (ICC)

Initial Construction Cost (ICC)

Project Management Costs

Overhead Cost Overhead Cost Overhead Cost Overhead Cost Reinvestment Cost (Major Repair)

Reinvestment Cost (Major Repair)



Design Cost Design Cost Design Cost Inspection Cost (FDU + FDI Cost + PFMA Cost)

Electricity/Heating Cost Fuse Plugs

Civil Costs Risk Costs Initial Construction Cost (ICC)

Probabilistic Production Loss Cost = (Probability of Triggering)*(Production Loss Cost)

Overhead Cost (O&M) Probabilistic Reconstruction Cost = (Probability of Triggering) * (ICC) Table 5 Costs Considered

Initial Construction Cost: This refers to the costs incurred during the initial construction of the Gated Spillways. Overhead Cost: Overhead Cost refers to all the costs incurred in the routine operation and maintenance of the Gated Spillways. 3 In case of Vittjärv Fuse Plug, the Overhead Costs also include the maintenance cost of the road build over it.

25

Reinvestment Cost (Major Repair): A spillway undergoes a major refurbishment at least once during its lifetime. This incurs significant costs. Design Cost: Design costs refer to the costs incurred for consultants. Electricity/Heating Cost: These refer to the cost of the electricity consumed by the gates during winters. The gates are heated in the winters to keep them ice free in order to ensure a reliable operation. Project Management Cost: This refers to the costs of the various personnel involved in the management and execution of the project. Inspection Cost: This refers to the costs incurred during inspections of the whole dam structure. In-depth Safety Evaluation FDU is a major inspection done every 9/12/18 years depending on whether the dam belongs to Consequence Class 1, Class 2 or Class 3. Indepth Inspection FDI is a more frequent one, done every 3/6 years also depending on the Consequence Class of the dam. PFMA (Possible Failure Mode Analysis) is carried out at the same frequency as an FDU. Only a percentage of these costs are associated with the Gated Spillways. Probabilistic Production Loss Cost: This refers to the probabilistic monetary loss incurred if the production at the power plant needs to be reduced or stopped in case of triggering of the Fuse Plug. Probabilistic Reconstruction Cost: This refers to the probabilistic cost incurred in reconstruction of the Fuse Plug, in case it is triggered.

4.4 Assumptions The data has been obtained from a plurality of sources. The major source of data are the Fortum archives at Borlänge and Arbrå. The data has primarily been taken from the bids available and other official documents present. However, the data available at these archives has not been comprehensive, and various reports, files and estimates from several Fortum employees and external experts have been used. Wherever data was unavailable, reasonable assumptions have been made after consultations with experts. The various assumptions used throughout the analysis are

1. The time period of the life cycle has been assumed to be 80 years as this is also the lifetime of concrete assumed in construction projects. This has been done in consultation with the experts. (Löwén, 2016) (Svensson, 2016)

2. Wherever unavailable, the design costs for civil, mechanical and electrical works have been assumed as 8 %, 7 % and 9 % respectively (Löwén, 2016) . Also Project Management Costs are assumed as 4% (Bjerhag, 2016).

3. For the FDU and FDI costs, 40 % of the total of these costs were assigned to the Gated Spillways. Similarly for PFMA costs, 50 % the total costs were assigned to the Gated Spillways. (Eriksson, 2016).

4. Electricity and control equipment has been assumed to have a lifetime of 20-30 years and thus changed twice over the period of 80 years. (Egnell, 2016).

5. Electricity costs for heating the gates during winter have been derived using the values available for the gates at Forshaga, and then extended to other gates proportional to their dimensions (if available) or spillage capacity. A linear relationship has been assumed between the electricity costs and gate area or spillage capacity. The heating has been assumed to being carried out for five months per year for 70 % of the time. (Eklund, 2016).

6. Wherever costs for Electric and Control equipment are unavailable, costs have been entered on the basis of estimates by expertise. (Egnell, 2016).

26

7. The Construction Cost Index (Anläggningskostnadsindex) (Energiforsk, 2016) published by Energiforsk is used for converting the historic costs to their present values. Concrete Work Index (Betongarbeten) is used for the Civil costs. Rock Work Index (Bergarbeten) has not been used as in majority of cases, the percentage of Rock work in the total works was unavailable. In the cases where this detail was available, it was small compared to concrete work and as such using Concrete Work Index is a fair approximation. Mechanical Work Index (Mekanisk utrustning) and Electrical Work Index (Elektrisk utrustning) have been used for Mechanical and Electrical Costs respectively. For other Miscellaneous Costs, Above Ground Index (Totalindex, ovanjordsanl) has been used.

8. The Construction Cost Index has two values for a year, from January-June and July-December. An average of these two values has been taken as the Index value for the whole year.

9. The Overhead Costs have been calculated by multiplying the present costs with the number of years remaining in the lifetime of the spillway.

10. Major Repair Costs, wherever unavailable, have been assumed to be 50 % of the Initial Construction costs for the Civil Costs and 45 % of the Initial Construction costs for the Mechanical Costs.4

11. If two or more different types of Gated Spillways were present in a dam, and total costs were available instead of individual costs, the costs were divided among the various Gated Spillways, firstly on the basis of expert opinion wherever possible. In other cases the costs were divided proportional to the spillage capacities of the various Gated Spillways.

12. For the Monte Carlo Simulation, the input data is represented in terms of the Triangular Probability Distribution. The Triangular Probability distribution is assumed as a closer representation of the input data. The 3 vertices of the triangle from left to right represent the Lower Cost, Most Likely Cost (red arrow) and Upper Cost respectively.

Figure 12 Triangular Probability Distribution (Structured Data LLC, 2016)

4.5 Calculations The following calculations have been carried out

1. In case of the deterministic analysis, the Total Cost is the sum of Civil, Mechanical, Electrical and Miscellaneous Costs.

2. For the Monte Carlo Simulation on the other hand, costs from the deterministic analysis are considered as the Most Likely Cost. The costs of the lower and upper points are selected as a percentage of the Most Likely Costs and are shown in the tables below.

4 For Major Repair Costs, the Data available has been limited and the assumptions above are based on the data available for some of the recent Refurbishments. The range varies largely with some projects having refurbishments costs of just 10% to some having as high as 80 % of the initial costs.

27

10 000 random data points are generated for each of the different costs and the total sum is calculated by adding these costs. Thus a cost distribution of 10 000 points is obtained at the end of the simulation.

Gated Spillways Lower Cost Most Likely Cost Upper Cost Civil Costs 95% 100% 120% Mech Costs 95% 100% 115% Elec Costs 95% 100% 105% Misc Costs 95% 100% 120%

Table 6 Cost Distribution for Gated Spillways

Fuse Plug Lower Cost Most Likely Cost Upper Cost Construction Costs 95% 100% 120% Overhead Costs 95% 100% 120% Risk Costs 95% 100% 120%

Table 7 Cost Distribution for Fuse Plugs

3. The probabilistic costs in case of triggering of a Fuse Plug are calculated by multiplying

the Probability of Fuse Plug Triggering during the given period of 80 years with the respective total costs associated with it. The Probability of Fuse Plug Triggering is calculated according to the Binomial Distribution Equation (P)

𝑃𝑃 = 1 − �1 − �1𝑇𝑇��𝑛𝑛

(1) where, P is the Probability of Fuse Plug Triggering T=Threshold Return Period (100 or 1 000 or 10 000 year flood) n= number of years considered (80 years in our case)

28

5 Results and Discussions

5.1 Costs of Gated Spillways with respect to Spillage Capacity Figure 13 below shows the costs of the various Gated Spillways in relation to their spillage capacity. It is seen that for spillage capacities of less than 100 m3/s, the LCC per unit of spillage is very high compared to other Gated Spillways. Also, as the size of the Gated Spillways increases, the LCC per unit of spillage decreases. Thus it can be concluded that wherever possible, a bigger spillway is better than a plurality of Gated Spillways. However, the type and size of Gated Spillways is also dependent on various engineering considerations and not only on the economic aspects.

The LCC per unit of spillage of Plan Gates is lower than that of Segment Gates for similar spillage capacities, as can be seen from the trend lines of the graphs below. LCC per unit of spillage for a Plan Gate (Sveg) with a spillage capacity of 225 m3/s is 60 000 SEK /m3/s whereas that for a Segment Gate (Järpströmmen) with a spillage capacity of 237 m3/s is 175 000 SEK /m3/s.

However it must also be considered that the Plan Gate construction at Sveg was part of a larger construction project with refurbishment for a total of 885 m3/s of spillage capacity for Plan Gates and 1220 m3/s Spillage capacity for Segment Gates. Thus Economies of scale were also in favour of lower Plan Gate costs at Sveg. On the other hand Tänger has undergone a major expansion in its spillage capacity, which is a primary reason for its high costs.

For the Flap Gate (Lima), the costs are much higher than Plan or Segment Gates with similar spillage capacity.

Figure 13 LCC for various Gated Spillways

Parteboda

Tanger

Järpströmmen

Eldforsen

Lima

Åsen

Avesta

Tänger

Parteboda Parteboda

Förshaga

Sveg

Lima

Järpströmmen Sveg

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

0 100 200 300 400 500 600 700

SEK/

M3 /

S

SPILLAGE CAPACITY m3/s

L C C A C C O R D I N G T O I N C R E A S I N G S P I L L A G E C A P A C I T Y Segment Plan Flap Sector

29

5.2 Costs of Fuse Plugs with respect to Spillage Capacity Figure 14 below shows the ICC (Initial Construction Cost) of the various Fuse plugs. It is seen that the ICC decreases sharply with an increase in the spillage capacity of the fuse plugs. Figure 15 shows the LCC of the various Fuse Plugs, which also follows the same trend. There is a Probabilistic Production Loss Cost associated with Lanforsen and Vittjärv while calculating the LCC. However no such cost is associated with Burnt Fuse Plug (Canada), as it is located some 100 km upstream of the regulating dam, and its triggering does not affect the operation of the power plant downstream. This shows that an optimal placement of a Fuse Plug (in cases where it is permitted by design) leads to decreased cost. The Bartlett dam (USA) is not used for hydropower generation and is mainly used for agricultural purposes. Thus no Probabilistic Production Loss Cost is associated with it.

Figure 14 ICC of Fuse Plugs

Figure 15 LCC of Fuse Plugs

Lanforsen

Vittjärv

Burnt

Bartlett

0

5000

10000

15000

20000

25000

30000

35000

0 1000 2000 3000 4000 5000 6000 7000 8000

SEK/

m3 /

s


ICC of Fuse Plugs

Lanforsen

Vittjärv

Burnt

Bartlett

0

5000

10000

15000

20000

25000

30000

35000

0 1000 2000 3000 4000 5000 6000 7000 8000

SEK/

m3 /

s


LCC of Fuse Plugs

30

5.3 Comparison between Fuse Plugs and Gated Spillways Figure 16 below shows the Life Cycle Cost (LCC) per unit of spillage of Fuse Plugs and Gated Spillways. It is observed that LCC of Fuse Plugs is less than most of the Gated Spillways. The Fuse Plug cost varies anywhere between half to one-tenth of the price of Gated Spillways. The cost difference ratio is particularly large for smaller spillage capacities. It can be seen that the price of Fuse Plugs is one-fourth or less, for spillage capacity of less than 400 m3/s. Between 400 m3/s and 600 m3/s of spillage, the ratio increases. However as the spillage capacity increases, the Total Cost increases for both Fuse Plugs and Gated Spillways. Thus even though the ratio decreases, the difference in absolute amount of monetary difference between them will increase.

Figure 16 LCC comparison between Gated Spillways and Fuse Plugs

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

0 200 400 600 800 1000 1200

SEK/

M3 /

S


LCC ACCORDING TO INCREASING SPILLAGE CAPACITY

Spillways Fuse Plugs

31

5.4 Comparison of cost breakdown for Gated Spillways and Fuse Plugs Figure 17 below shows the Life Cycle Cost breakdown of the Gated Spillways into its various categories. It is seen that the Civil Costs are the major costs involved in spillway construction. These costs however vary depending on spillway size. Civil Costs are followed by Mechanical Costs. Mechanical Costs involve the costs of the steel gates as well as the hydraulic or mechanical systems used in operating them. Electrical Costs on the other hand are lower, as is the case with Miscellaneous Costs.

Figure 17 LCC Breakdown for various Gated Spillways

Figure 18 below shows the Life Cycle Cost breakdown according to the service life of the Spillway. We see that the Initial Construction Cost is the major cost involved. The Major Refurbishment Cost, which involves a major upgrade of the Gated Spillways, are mostly carried out after 20- 40 years of their initial construction. This refurbishment includes costs for two major processes. First is for making repairs in the gate structure, replacement of seals, changing to a hydraulic mechanism, paint, repairing of concrete etc. The second is in case of upgrading of the discharge capacity of Gated Spillways to a higher capacity, as has been done in projects like Eldforsen5. As limited data is available for Major Refurbishment Cost, reasonable assumptions have been made. This cost largely varies between various Gated Spillways depending on the extent of repairs/upgrade needed. Also several major repairs may be carried out during the lifetime of the spillway leading to significantly high costs. A sensitivity analysis for the Major Refurbishment Cost has been done in section 5.6

5 In Eldforsen, over the period of 10 years, the spillway gates have been refurbished twice in order to increase the discharge capacity by increasing the height of the gates. This has been done in stages, as Fortum was waiting for required permits from the concerned authorities.

0

20000

40000

60000

80000

100000

120000

140000

Segment(Avestaforsen)

Plan (Sveg) Sector (Sveg) Flap (Lima)

SEK/

m3 /

s

Various Costs Involved

Civil Mech El Misc

32

Figure 18 LCC breakdown for various Gated Spillways

Figure 19 below shows the Life Cycle Cost breakdown for Vittjärv Fuse Plug per m3 of spillage. The Initial Construction Cost is the highest, whereas the other costs are comparatively small. The Overhead Cost usually involves the expenditure incurred for the prevention of growth of vegetation on the Fuse Plug surface. The Probability of Fuse Plug Triggering (designed for flood with a return period of 1000 years) over the period of 80 years is equal to 0.077. Thus the Probabilistic Reconstruction Cost and Probabilistic Production Loss Cost are very small in comparison to the above costs.

Figure 19 LCC breakdown for Vittjärv Fuse Plug

0

35000

70000

105000

140000

Segm

ent

(Ave

staf

orse

n)

Plan

(Sve

g)

Sect

or (S

veg)

Flap

(Lim

a)

Segm

ent(

Jarp

strö

mm

en)

SEK/

m3 /

s Various Costs Involved

InitialConstructionMajorRefurbishmentTotal OperationalCosts

0

4000

8000

12000

16000

20000

Vittjärv

SEK/

m3 /

s

Costs involved in Vittjärv (SEK/m3/s)

Initial Construction Overhead Costs

Probabilistic Reconstruction Cost Probabilistic Production Loss Cost

33

5.5 Electricity Costs and comparison with Total Operational Costs The Total Operational Costs for the Gated Spillways can be divided as

1. Electricity Costs 2. Other Costs

a. Inspection Costs b. Overhead Cost (Civil/Mech/Elec/Misc)

Figure 20 below shows the cost breakdown of the Overhead costs in four Gated Spillways. We see that although the percentage of Electricity Costs for the various Gated Spillways varies, it is significant for many of the Gated Spillways. The electricity price used in the calculation for the Gated Spillways labelled “1” is 250 SEK/MWh, as the electricity prices in Sweden have been quite low over the past few years (Nord Pool, 2016). If the prices increase over the next few years, the percentage share of the Electricity costs will increase significantly. In Figure 20, the Gated Spillways labelled “2” represent the increase in electricity costs, if the electricity prices increase by 30 % i.e. 325 SEK/MWh.

Figure 20 Electricity Costs vs Other Costs (kSEK)

0

3000

6000

9000

12000

15000

18000

SEK/

m3 /

s

Total Operational Costs Other

Electricity

34

5.6 Monte Carlo Analysis for Cost of Gated Spillways Figure 21 below shows the Probability Distribution Factor for the LCC of Segment Gates at Avestaforsen. The results are obtained by carrying out a Monte Carlo Simulation for the various available costs. (The simulation code is available in Appendix 2). The Y-axis represents the Frequency that how many times a particular value has been obtained during the simulation that was carried out for 10 000 data points. The X-axis represents the LCC for the spillway. Although the Median value is 58 256 SEK/m3 /s (red arrow), there is a high probability that the costs will be higher.

Figure 21 Avestaforsen LCC Probability Distribution

The table below shows the probability of the cost between various ranges. It can be seen that there is a 96.9 % probability that the costs will be lower than 1.1 times the median value i.e. lower than 64 081 SEK/m3 /s. Also the mean value is somewhere around 60 581 SEK/m3 /s with a standard deviation of 1 714 SEK/m3 /s.

Percentage of Median cost

95-100% 100-105% 105-110% 110-115%

100* (Probability of occurrence)

8 57.1 31.8 3.1

Table 8 Probability of LCC of Avestaforsen between various values

Figure 22 below shows the Probability Distribution Factor for Vittjärv Fuse Plug. Although the Median value is 28 761 SEK/m3 /s (red arrow), there is a high probability that the costs will be higher.

35

Figure 22 Vittjärv LCC Probability Distribution Collected

The table below shows the probability of the cost between various ranges. It can be seen that there is an 85% probability that the costs will be lower than 1.1 times the median value i.e. lower than 31 637 SEK/m3 /s. Also the mean value is somewhere around 30 193 SEK/m3 /s with a standard deviation of 1 177 SEK/m3 /s.

Percentage of Median Cost

95-100% 100-105% 105-110% 110-120%

100* (Probability of occurrence)

10 44.7 31.3 13.9

Table 9 Probability of LCC of Vittjärv between various values

The above analysis has been done on the basis of dividing the cost into Civil, Mechanical, Electrical and Miscellaneous sections. However if the cost is divided on the basis of timeline, it is be divided into 3 sections of Initial Construction, Major Refurbishment and Overhead Costs.

Figure 23 and Figure 24 below shows the Probability Distribution Factor for the LCC of Segment Gates at Avestaforsen dividing costs on the basis of timeline. In these two cases, the probability of Major Refurbishment Cost has been varied. In case of Figure 23, it ranges from 80% - 120% of the deterministic cost, whereas in case of Figure 24 it ranges from 60% - 120% of the deterministic cost. The major refurbishment costs vary greatly between projects and as such it is interesting to see how it effects the LCC of the Gated Spillways. The mean has shifted from 60 090 SEK/m3 /s to 58 948 SEK/m3 /s and the standard deviation has increased from 2 325 SEK/m3

/s to 2 827 SEK/m3 /s. From Table 10 below, we can also see that the probability of LCC being lower than the median value has increased from 22.7 % to 40.1 % as area of graph to the left of the median has increased. Thus the analysis can also be used to see how LCC will vary if one or more of the input distributions are changed.

36

Figure 23 Avestaforsen LCC Probability Distribution (80%-120%)

Figure 24 Avestaforsen LCC Probability Distribution (60%-120%)

Percentage of Median Cost

95-100% 100-105% 105-110% 110-120%

100* (Probability of occurrence 80-120)

22.7 46.5 25.4 5.4

100* (Probability of occurrence 60-120)

40.1 38 18.1 3.79

Table 10 Probability of LCC variation for Avestaforsen, while changing Major Refurbishment Cost

The above analysis for selected Gated Spillways and fuse plugs is representative and can be carried out for other Gated Spillways similarly, by changing the data values of the Matlab program available in Appendix 2.

37

5.7 Fuse Plug triggering Figure 25 below shows how the LCC cost varies in scenarios where the Fuse Plug triggers once or twice over a period of 80 years, as compared to its normal functioning. The costs increase significantly as the Production Loss Cost and Reconstruction Costs are added to the initial Life Cycle Costs. The blue line represents the LCC of normally functioning Fuse Plugs. The red and green lines represent the LCC if the Fuse Plug is triggered once or twice respectively.

Mathematically in case of normal functioning of the Fuse Plug, we have

LCC = Civil Costs + Risk Costs

In case of triggering once in 80 years, we have

LCC = Civil Costs + Risk Costs + Production Loss Cost + Initial Construction Cost

In case of triggering twice in 80 years, we have

LCC = Civil Costs + Risk Costs + 2*(Production Loss Cost + Initial Construction Cost)

Figure 25 LCC comparison of Fuse Plugs for different scenarios

There is however a very less probability (less than 8%) that a Fuse Plug will be triggered in that given time period.

Lanforsen

Vittjärv

Burnt

Bartlett

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

0 1000 2000 3000 4000 5000 6000 7000 8000

SEK/

m3 /

s

SPILLAGE CAPACITY (m3/s)

LCC of Fuse Plugs Normal Function

Triggering Once

Triggering Twice

38

6 Conclusions Although the selection of a Spillway is not entirely based on costs, and involves various technical considerations, a number of conclusions can be drawn from the above analysis

1. A large Gated Spillway is more economical than a plurality of small Gated Spillways. Thus wherever possible, from an economical perspective it is more feasible to install a large spillway, instead of a number of small ones. However, having a plurality of Gated Spillways provides more flexibility and if one of the Gated Spillways stops functioning due to a fault, the others still continue to work.

2. Plan Gated Spillways are the cheapest among the available Gated Spillways and should be the first choice from an economical perspective.

3. Fuse Plugs have a lower LCC than any Gated Spillway when constructed for floods with a return period of 1 000 years or greater. Thus, from an economic perspective it would be preferable to build a Fuse Plug when upgrading a facility for Class 1 floods.

4. The Initial Construction Cost is the largest cost incurred in the Life Time of a spillway. As such this phase presents the largest opportunity for cost saving via proper planning and optimization of Construction. Moreover costs of major refurbishments vary widely and can be reduced by proper maintenance.

5. Civil Costs are the largest among the Civil, Mechanical and Electrical Costs. 6. The Electrical Cost forms a significant part of the Total Operational Costs. 7. Probabilistic LCCA is a better tool for predicting the total costs, as it incorporates the

effect of various uncertainties. It can be used to determine, how a change in one or more input variables effects the total costs. Also this technique can be used in various cost calculations other than LCCA.

8. Fuse Plugs form a cheap viable option. However if a number of Fuse Plugs are constructed on a river scheme, it might be an economic disaster. Consider the scenario that if a Fuse Plug triggers upstream, it might bring excess water to the reservoirs downstream, leading to triggering of the Fuse plugs downstream, one after the other. This triggering of multiple fuse plugs at the same time might cause huge financial losses to the company, particularly finances required for reconstruction of all the Fuse Plugs. It might also lead to losses in production. This might also strain the man-power resources of the company.

39

7 Recommendation for Future Work On the basis of the experiences and learnings from this project, the author can make the following recommendation for future projects

1. Based on the reservoir network and dependency, a study of the reservoirs where Fuse Plug may be installed should be carried out, taking into consideration the domino effect of Fuse Plug triggering.

2. Develop a criteria or a framework to identify as to where Fuse Plugs are suitable to be installed, from Civil, Economic and Hydrological perspectives.

40

References ADCATS. (2016). Association for the Development of Computer-Aided Tolerancing Systems. Retrieved from http://adcats.et.byu.edu/

Av Rajnikant, M. K. (2004). Hydraulics of Spillways and Energy Dissipators. CRC Press.

Bjerhag, H. (2016). (T. Parray, Interviewer)

Bragg, S. (2016, 03 10). Accounting Tools. Retrieved from www.accountingtools.com/discount-rate-definition

CMCHydro. (2016). Retrieved August 2016, from http://www.cmchydro.es/en/repair-gates.php

Egnell, P. (2016, Feb). (T. Parray, Interviewer)

Eklund, P. (2016). (T. Parray, Interviewer)

Energiforsk. (2016). Retrieved August 2016, from https://energiforskmedia.blob.core.windows.net/media/20126/anlaggningskostnadsindex-2015_2.pdf

Eriksson, M. (2016). (T. Parray, Interviewer)

Finnish Barents Group. (1998). Energy Report on the Nordic Parts of the Barents Region. Copenhagen.

Google Maps. (2016).

Kahraman. (2002). Capital budgeting techniques using discounted fuzzy versus probabilistic cash flows. Information Sciences—Informatics and Computer Science: An International Journal - Special issue: Intelligent information systems and applications, 57-76.

Kuhlin, L. (2016). Retrieved August 2016, from https://vattenkraft.info/?id=498

Kuhlin, L. (2016, 02 25). Information about the Swedish hydropower. Retrieved 03 16, 2016, from https://vattenkraft.info/?page=5

Laboratory of Hydraulics, H. a.-E. (2014, 08 14). Fuse plug spillway at the Hagneck-Channel. Retrieved 03 14, 2016, from http://www.vaw.ethz.ch/people/fb/archive/fb_hagneck_channel

Löwén, K. E. (2016, April). (T. Parray, Interviewer)

Main Engineers. (2016). www.alibaba.com. Retrieved from http://www.alibaba.com/product-detail/FIXED-WHEEL-GATE_113545626/showimage.html

Nord Pool. (2016). http://www.nordpoolspot.com. Retrieved June 2016, from http://www.nordpoolspot.com/Market-data1/Elspot/Area-Prices/SE/Yearly/?view=table

Officials, A. o. (2016). Retrieved 08 2016, from http://www.damsafety.org/news/?p=e4cda171-b510-4a91-aa30-067140346bb2

41

Structured Data LLC. (2016). Riskamp. Retrieved 08 2016, from https://www.riskamp.com/beta-pert

Svensk Energi. (2012). RIDAS- Power Companies' guidelines for dam safety. Stockholm.

Svensk Energi, Svenska Kraftnät och SveMin. (2007). Guidelines for determining the design flows for dams. Stockholm.

Svensson, M. (2016). (T. Parray, Interviewer)

Tracy Vermeyen, D. M. (1992). Alternatives for enhancing spillway capacity currently being pursued by the U.S. Bureau of Reclamation. U.S. Bureau of Reclamation.

Wang et al, N. (2010). Monte Carlo simulation approach to life cycle cost management. Taylor and Francis, 739-746.

Wang, C.-S. (2012). Monte Carlo simulation approach to life cycle cost management. Taylor and Francis, 739-746.

World Energy Council. (2011). HYDROPOWER IN SWEDEN. Retrieved 2016, from https://www.worldenergy.org/data/resources/country/sweden/hydropower/

www.wikiwand.com. (2016). Retrieved August 2016, from http://www.wikiwand.com/en/Tainter_gate

42

Appendix 1: Construction Cost Index (Anläggningskostnadsindex 1989 - 2015/1)

5000

4500

4000

3500

3000

2500

Rock Work

Earth Work

Concrete Work

Mechanical Equipment

Electrical Equipment

Total Index (Above ground)

Total Index (Underground).

2000

1500

1000

500

0

1989

19

89

1990

19

90

1991

19

91

1992

19

92

1993

19

93

1994

19

94

1995

19

95

1996

19

96

1997

19

97

1998

19

98

1999

19

99

2000

20

00

2001

20

01

2002

20

02

2003

20

03

2004

20

04

2005

20

05

2006

20

06

2007

20

07

2008

20

08

2009

20

09

2010

20

10

2011

20

11

2012

20

12

2013

20

13

2014

43

Appendix 1: Construction Cost Index (Anläggningskostnadsindex 1989 - 2015/1)

Year (ÅR) 1948 1948 1949 1949 1950 1950 1951 1951 1952 1952 1953 1953 1954 1954 1955 1955

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2

Rock Work 99 99 100 100 100 100 107 112 119 121 120 120 120 120 122 122 Earth Work 100 100 100 100 100 100 106 110 116 117 117 117 116 116 117 116

Concrete Work 101 101 101 101 100 100 110 121 131 134 134 131 132 131 134 138 Mechanical Equipment 99 99 100 100 100 100 116 116 129 129 125 125 123 123 131 131 Electrical Equipment 98 98 100 100 100 100 114 114 123 123 120 120 119 119 125 125 Total Index (Above ground) 100 100 100 100 100 100 111 117 126 128 126 125 125 124 129 130 Total Index (Underground) 100 100 100 100 100 100 110 115 124 125 124 123 123 122 126 127

Year (ÅR) 1956 1956 1957 1957 1958 1958 1959 1959 1960 1960 1961 1961 1962 1962 1963 1963

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 1964 1964 1965 1965 1966 1966 1967 1967 1968 1968 1969 1969 1970 1970 1971 1971

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 1972 1972 1973 1973 1974 1974 1975 1975 1976 1976 1977 1977 1978 1978 1979 1979

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 1980 1980 1981 1981 1982 1982 1983 1983 1984 1984 1985 1985 1986 1986 1987 1987

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 1988 1988 1989 1989 1990 1990 1991 1991 1992 1992 1993 1993 1994 1994 1995 1995

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 1996 1996 1997 1997 1998 1998 1999 1999 2000 2000 2001 2001 2002 2002 2003 2003

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 2004 2004 2005 2005 2006 2006 2007 2007 2008 2008 2009 2009 2010 2010 2011 2011

Half year (HALVÅR) 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2



Year (ÅR) 2012 2012 2013 2013 2014 2014 2015 2015 0 0 0 0 0 0 0 0

Half year (HALVÅR) 1 2 1 2 1 2 1 2 0 0 0 0 0 0 0 0



44

Appendix 2: Matlab Programs

The following programs represent the code written to carry out the Monte Carlo Analysis

Program 1 and 2 represent the Monte Carlo Analysis for Avestaforsen and Vittjarv. Program 3 and 4 represent how the outputs will vary in case of change in the distribution of Refurbishment Costs. If a similar analysis is to be done for other spillways, it can be done by changing the corresponding data in the program.

We use “N” iterations in these programs. Here N = 10000 “Spill” is the Spillway capacity “ProbMinus5to0” is the probabilty between 95 % to 100 % “Prob0to5” is the probabilty between 100 % to 105 % “Prob5to10” is the probabilty between 105 % to 110 % “Prob10to15” is the probabilty between 110 % to 115 %, “Meany” is the Mean “Devi” is the Standard Deviation

45

Appendix 2: Matlab Programs Program 1: Avestaforsen Spillway

function [Estimate, ProbMinus5to0, Prob0to5, Prob5to10, Prob10to15, Meany, Devi] = ThesisTRI(N, Spill) % TRIANGULAR DISTRIBUTION/ AVESTAFORSEN SPILLWAY rng(0); pd1 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20) %generates triangular range between 0.95 and 1.20 pd2 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.15) pd3 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.05) pd4 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20) r1= random(pd1, 1, N); % generates N data points inside the Triangular Distribution r2= random(pd2, 1, N); r3= random(pd3, 1, N); r4= random(pd4, 1, N); CivilCost = 62216626; %From Data MechCost = 53941021; ElecCost = 10122880; MiscCost = 13534910; TotalCost = CivilCost + MechCost + ElecCost + MiscCost; CivilMat = (CivilCost * r1); %Gives N cost points inside the Triangular Distribution MechMat = (MechCost * r2); ElecMat = (ElecCost * r3); MiscMat = (MiscCost * r4); TotalMat = CivilMat + MechMat + ElecMat + MiscMat; Minus5to0 = TotalMat < TotalCost; ProbMinus5to0 = ((nnz(Minus5to0))*100)/(N); %nnz gives non zero elements Estimate = sum(TotalMat)/N; Meany = mean(TotalMat/Spill); Devi = std(TotalMat/Spill); hist(TotalMat/Spill, 50) % histogram generation From10to15 = TotalMat > (1.1*TotalCost); Prob10to15 = ((nnz(From10to15))*100)/(N); From5to10 = (TotalMat < (1.1*TotalCost)) & (TotalMat > (1.05*TotalCost)); Prob5to10 = ((nnz(From5to10))*100)/(N); Prob0to5 = 100 - Prob5to10 - Prob10to15 - ProbMinus5to0; end

46

Appendix 2: Matlab Programs Program 2: Vittjärv Fise Plug

function [Estimate, ProbMinus5to0, Prob0to5, Prob5to10, Prob10to20, Meany, Devi] = ThesisTRI2(N, Spill) % TRIANGULAR DISTRIBUTION/ VITTJARV Fuse Plug rng(0); pd1 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20); %generates triangular range between 0.95 and 1.20 pd2 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20); pd3 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20); r1= random(pd1, 1, N);% generates N points r2= random(pd2, 1, N); r3= random(pd3, 1, N); CivilCost = 11935152; %From Data OandMCost = 2800000; RiskCost = 918059+453062; TotalCost = CivilCost + OandMCost + RiskCost; CivilMat = (CivilCost * r1); OandMMat = (OandMCost * r2); RiskMat = (RiskCost * r3); TotalMat = CivilMat + OandMMat + RiskMat; %Gives N cost points inside the Triangular Distribution Minus5to0 = TotalMat < TotalCost; ProbMinus5to0 = ((nnz(Minus5to0))*100)/(N); Estimate = sum(TotalMat)/N; Meany = mean(TotalMat/Spill); Devi = std(TotalMat/Spill); hist(TotalMat/Spill, 50) % histogram generation From10to20 = TotalMat > (1.1*TotalCost); Prob10to20 = ((nnz(From10to20))*100)/(N); From5to10 = (TotalMat < (1.1*TotalCost)) & (TotalMat > (1.05*TotalCost)); Prob5to10 = ((nnz(From5to10))*100)/(N); Prob0to5 = 100 - Prob5to10 - Prob10to20 - ProbMinus5to0; end

47

Appendix 2: Matlab Programs Program 3: Avestaforsen Spillway (80-120 %) function [Estimate, ProbMinus5to0, Prob0to5, Prob5to10, Prob10to20, Meany, Devi] = ThesisTRI4(N, Spill) % TRIANGULAR DISTRIBUTION/ Avestaforsen SPILLWAY % Refurbishment Costs varied between 80%-120% rng(0); pd1 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20); %generates triangular range between 0.95 and 1.20 pd2 = makedist ('Triangular', 'a', 0.80, 'b',1, 'c', 1.20); pd3 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.1); r1= random(pd1, 1, N); % generates N points r2= random(pd2, 1, N); r3= random(pd3, 1, N); CivilCost = 83354575; %From Data RefurCost = 41080375; OverheadCost = 15380488; TotalCost = CivilCost + RefurCost + OverheadCost; CivilMat = (CivilCost * r1); RefurMat = (RefurCost * r2); OverheadMat = (OverheadCost * r3); TotalMat = CivilMat + RefurMat + OverheadMat; Minus5to0 = TotalMat < TotalCost; ProbMinus5to0 = ((nnz(Minus5to0))*100)/(N); %nnz gives non zero elements Estimate = sum(TotalMat)/N; Meany = mean(TotalMat/Spill); Devi = std(TotalMat/Spill); hist(TotalMat/Spill, 50) % histogram generation From10to20 = TotalMat > (1.1*TotalCost); Prob10to20 = ((nnz(From10to20))*100)/(N); From5to10 = (TotalMat < (1.1*TotalCost)) & (TotalMat > (1.05*TotalCost)); Prob5to10 = ((nnz(From5to10))*100)/(N); Prob0to5 = 100 - Prob5to10 - Prob10to20 - ProbMinus5to0; end

48

Program 4: Avestaforsen Spillway (60-120 %) function [Estimate, ProbMinus5to0, Prob0to5, Prob5to10, Prob10to20, Meany, Devi] = ThesisTRI5(N, Spill) % TRIANGULAR DISTRIBUTION/ Avestaforsen SPILLWAY V2 % Refurbishment Costs varied between 60%-120% rng(0); pd1 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.20); % generates triangular range between 0.95 and 1.20 pd2 = makedist ('Triangular', 'a', 0.60, 'b',1, 'c', 1.20); pd3 = makedist ('Triangular', 'a', 0.95, 'b',1, 'c', 1.1); r1= random(pd1, 1, N); r2= random(pd2, 1, N); r3= random(pd3, 1, N); CivilCost = 83354575; %From Data RepairCost = 41080375; OverheadCost = 15380488; TotalCost = CivilCost + RepairCost + OverheadCost; CivilMat = (CivilCost * r1); RepairMat = (RepairCost * r2); OverheadMat = (OverheadCost * r3); TotalMat = CivilMat + RepairMat + OverheadMat; Minus5to0 = TotalMat < TotalCost; ProbMinus5to0 = ((nnz(Minus5to0))*100)/(N); %nnz gives non zero elements Estimate = sum(TotalMat)/N; Meany = mean(TotalMat/Spill); Devi = std(TotalMat/Spill); hist(TotalMat/Spill, 50) % histogram generation From10to20 = TotalMat > (1.1*TotalCost); Prob10to20 = ((nnz(From10to20))*100)/(N); From5to10 = (TotalMat < (1.1*TotalCost)) & (TotalMat > (1.05*TotalCost)); Prob5to10 = ((nnz(From5to10))*100)/(N); Prob0to5 = 100 - Prob5to10 - Prob10to20 - ProbMinus5to0; end

49

Appendix 3: Avesta Lilfors

An overflow weir is present at the Avesta Lilfors which was constructed in 1979. It raises the head to a height of 5,7 meters for the 22 MW Avesta Lilfors power plant and has a crest length of about 333 metres. The initial construction cost of the weir in 1979 was SEK 5,1 million which translates to a Net Present Value of 24,24 million. No maintenance cost are associated with it, till date no major repair has occurred. Considering that a major repair might occur in future, and assuming an additional cost of 50 % (12,12 million), the costs total to SEK 36,36 million.

The average water flow is about 350 m3/s. The lower reservoir limit is around +72 m with the crest level at +73 m in the RH00 height system. The dam can withstand water till a level of +76,5 meters, at which point the water flow is around 3 700 m3/s. At this maximum spillage capacity, the LCC per m3 of Spillage is around 9 827 SEK.

However, theoretically an overflow weir will pass all the water above its crest height. Thus in the authors opinion, it would be more realistic to make a comparison of an overflow weir with a dam. In that case various dimensions like the dam height, reservoir volume etc. can be used a source of comparison.

Documents

Life Cycle Cost Analysis of Gated Spillways and Fuse Plugs1068751/FULLTEXT01.pdf · Gated Spillways are usually constructed in Sweden. The Gated Spillways operate using civil, mechanical