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2.11 NAM NGIEU HYDROPOWER PROJECT

The Nam Ngieu Hydropower Project is located in Xiengkhouang Province on the Nam Ngieu, a tributary of the Nam Ngiep. The layout of the Project is shown in the attached plan. The Project involves the construction of a dam of about 30 m height and a headrace tunnel of 3.7 km to mobilize a total head of about 190 m. Transmission interconnection with the Central Grid would be effected through an 8 km line to Phonsavan. The Consultant has evaluated the Project using:

• Existing field data – no new field data was collected;

• Updated hydrology (1966 to 2002 streamflow series);

• EVALS hydropower dimensioning and evaluation software;

The technical and economic characteristics of the Project are summarized in the following table. The EVALS outputs are provided. Some environmental and social costs are accounted for in the EVALS evaluation and are reflected in the program outputs. No project interactions were assumed in determining these outputs. With a weighted generation cost of 5.9 ¢/kWh, the economics of the Project are marginal. IPP off-take from Nam Mo would provide a more attractive source of generation and system support for the Xiengkhouang area (provided Nam Mo proceeds).

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Technical and Economic Data (Source: EVALS Output):

Development: Installed Capacity Factor 1.75 Contractual status No mandate awarded Level of study InventoryAccess Roads: New road 8 km Rehabilitation kmHydrology: Name of river Nam Ngiep Av. annual precipitation (dam site) 1,729 mm/a Ave. Reservoir Inflow 11.0 m3/sReservoir: Full supply level (FSL) 1,059 m asl Minimum operating level (MOL) 1,059 m asl Max storage volume (FSL) 21.21 hm3

Maximum reservoir area (FSL) 2.6 km2

Reservoir filling time 0.5 monthsDam: Main dam type RCC Gravity Maximum height 30 m Crest length 160 mDiversion: Design discharge m3/s Tunnel Diameter 3.6 m Tunnel Length 3,700 mSpillway: Spillway type Gated Ogee Design discharge 1,890 m3/sPower Station: Type Surface Number of units 3 Turbine type Francis Turbine rated head 188 mTransmission: Line Length 8 km Voltage 115 kVOutput: Installed Capacity 31.08 MW Guaranteed capacity (95%) 30.99 MW Average generation 133 GWh p.a. Primary generation (95% firm) 28 GWh p.a. Secondary generation 104 GWh p.a. Average plant factor 48 %Economic: Basic project cost (no esc. or IDC) 40.20 mUS$ Capacity cost 1,358 US$/kW Average energy cost 3.5 ¢/kWh Weighted energy cost 10 5.9 ¢/kWh

10 The calculation of weighted generation cost values secondary energy at half the value of primary energy

based on a definition of primary energy as energy produced with 95% firmness.

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2.12 NAM NGUM 1 EXTENSION PROJECT

The existing Nam Ngum 1 power station is located in Vientiane Province and is the pivotal generation facility in the EdL system. The facility includes five units for a total installed capacity of 150 MW facility and was developed in three stages through the late sixties and early seventies. The Nam Ngum Extension Project proposes an augmentation of the facility’s generating capacity. In 1995, the Nam Song and Nam Leuk projects were moving towards implementation. Both projects diverted additional flows into the Nam Ngum reservoir and various options for increasing the installed capacity at the existing Nam Ngum 1 power station were therefore studied to determine how best to exploit the augmented generation flows (Nam Ngum 1 Hydropower Station Extension, Feasibility and Engineering Study, Lahmeyer/Worley, 1995). Under the pricing regime of the time for non-firm exports to EGAT, the addition of new capacity through upgrades of Units 1 and 2 was attractive but a new unit was marginal. The layout of the preferred augmentation option from that study is provided. Under the PSDP, augmentations to the capacity of Nam Ngum 1 were re-evaluated using:

• Existing field data – no new field data was collected;

• Updated hydrology (1966 to 2002 streamflow series);

• EVALS hydropower dimensioning and evaluation software;

• EVSYS module for evaluating coordinated operation of two or more projects to compare outputs of the existing facility with an augmented facility;

• SEXSI Power System Expansion software, to determine the incremental benefits of additional capacity at Nam Ngum 1 by simulating the operation of the Project within the interconnected EdL / EGAT system.

An extension comprising a single 40 MW unit was investigated. The EVSYS outputs are provided for the existing Nam Ngum 1 power station (150 MW) and for the Nam Ngum 1 Extension (150 MW + 40 MW). The incremental performance of the extension works is calculated as the difference between these outputs. Interactions with the Nam Ngum 2, Nam Ngum 3 and Nam Ngum 5 projects were investigated. Simulations demonstrate that the Nam Ngum Extension scenario was not the least-cost development path for the system because IPP off-take from the Nam Theun 2 and Theun Hinboun Expansion projects provides sufficient power for the system and results in the Nam Ngum output being exported. Exports to EGAT are priced as non-firm energy, well under the specific weighted cost of generation. This situation prevails for a period of about 5 years by which time demand in the grid has grown enough to accommodate Nam Ngiep 1, a project preferred to Nam Ngum Extension because of its lower weighted generation cost.

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A more detailed appraisal of the Project may be justified for two reasons:

1. An extension of the existing Nam Ngum power station would have a shorter construction time than an equivalent greenfield project (provided plant procurement could be fast-tracked) and could be brought on-line relatively quickly;

2. The project has characteristics that make it attractive to multilateral and bilateral agencies and may therefore be more readily financeable under concessional terms.

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2.13 NAM NGUM 2B HYDROPOWER PROJECT

The Nam Ngum 2B Hydropower Project is located on the Nam Ngum immediately upstream of the existing Nam Ngum 1 reservoir in the Xaysomboun Special Zone. The location of the Project is shown in the attached plan. Due to its size, location and economics, the Nam Ngum 2 project is envisaged primarily as an export project selling to Thailand as its principal market. A concession has been awarded to the Shlapak Group to develop the site. The Project comprises a dam with a power station at its base generating from the head created by the dam. The developer prepared a feasibility study of the site using a FSL of 375 masl. At this level the reservoir would inundate 122 km2, creating a large dendritic reservoir and requiring the resettlement of large numbers of local inhabitants. Land suitable for resettlement in the area is not abundant. Other difficult social and environmental problems also attend a reservoir of this size and location and have been an obstacle in financing the Project. As part of a general optimization of the Nam Ngum basin, Electrowatt-Ekono (Power Sector Strategy Study, 2002) proposed a variant, Nam Ngum 2B, with a FSL of around 285 masl (refer Section 2.14). The lower FSL avoids many of the Project’s impacts but it also reduces seasonal regulation of the river and undermines the economics of Nam Ngum 2B as a standalone project. With Nam Ngum 3 providing upstream regulation, it is attractive. The Consultant evaluated the Nam Ngum 2B Project using:

• Existing field data – no new field data was collected;

• Updated hydrology (1966 to 2002 streamflow series);

• EVALS hydropower dimensioning and evaluation software;

• SESAMEE environmental and social impact assessment.

The technical and economic characteristics of the Nam Ngum 2B Project are summarized in the following table. The tabulated results assume upstream regulation from Nam Ngum 3B. The EVALS outputs are provided. Some environmental and social costs are accounted for in the EVALS evaluation and are reflected in the program outputs. The project’s wider impacts have been assessed using SESAMEE and are internalized into the evaluations reported in Section 6 of Volume A, Main Report.

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Technical and Economic Data (Source: EVALS Output):

Development: Installed Capacity Factor 1.75 Contractual status Concession Level of study Nam Ngum 2B - InventoryAccess Roads: New road 25 km Rehabilitation 0 kmHydrology: Name of river Nam Ngum Av. annual precipitation (dam site) 2,166 mm/a Ave. Reservoir Inflow 193.5 m3/sReservoir: Full supply level (FSL) 280 m asl Minimum operating level (MOL) 248 m asl Max storage volume (FSL) 201 hm3

Active storage volume 150 hm3

Maximum reservoir area (FSL) 7.5 km2

Reservoir filling time 0.5 monthsDam: Main dam type RCC Gravity Maximum height 88 m Crest length 190 mDiversion: Design discharge 1,970 m3/s Tunnel Diameter 12.4 m Tunnel Length 300 mSpillway: Spillway type Gated Ogee Design discharge 7,600 m3/sPower Station: Type Surface Number of units 3 Turbine type Francis Turbine rated head 59 mTransmission: Line Length 88 km Voltage 115 kVOutput: Installed Capacity 196 MW Guaranteed capacity (95%) 195 MW Average generation 757 GWh p.a. Primary generation (95% firm) 128 GWh p.a. Secondary generation 628 GWh p.a. Average plant factor 43 %Economic: Basic project cost (no esc. or IDC) 180 mUS$ Capacity cost 1,063 US$/kW Average energy cost 3.0 ¢/kWh Weighted energy cost 11 5.2 ¢/kWh

11 The calculation of weighted generation cost values secondary energy at half the value of primary energy

based on a definition of primary energy as energy produced with 95% firmness.

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2.14 NAM NGUM 3B HYDROPOWER PROJECT

The Nam Ngum 3B Hydropower Project is located on the Nam Ngum immediately upstream of the proposed Nam Ngum 2B reservoir in the Xaysomboun Special Zone. Due to its size, location and economics, the Project is envisaged primarily as an export project selling to Thailand as its principal market. The location of the Project is shown in the attached plan. An exclusive mandate to develop the site has been awarded to GMS of Thailand and a feasibility study of the Nam Ngum 3 Project has been completed. The Nam Ngum 3 dam creates a reservoir extending approximately 80 km upstream through the steep and narrow valley. The Project involves extensive and expensive civil works (210 m high dam and 11 km headrace tunnel) and as a consequence the economics of the Project are marginal. In addressing this and the problems of the Nam Ngum 2 Project (refer Section 2.13), Electrowatt-Ekono (Power Sector Strategy Study, 2002) proposed an optimization of the Nam Ngum above the existing Nam Ngum 1 reservoir. This involved the reconfiguration of both projects (Nam Ngum 2B and Nam Ngum 3B) to improve the viability of both projects. The Nam Ngum 3 configuration prepared by the developer involves a powerhouse located on the right bank of the Nam Ngum just above the confluence with the Nam Phay. In this location the gross head developed by the dam and waterways is around 335 masl. As part of the optimization carried out by Electrowatt-Ekono, the Nam Ngum 3B variant was proposed, which took advantage of the steep river gradient by relocating the powerhouse further downstream to capture an additional 60 m of head. The installed capacity of Nam Ngum 3B was increased to about 690 MW. The Consultant evaluated the Nam Ngum 3B Project using:

• Existing field data – no new field data was collected;

• Updated hydrology (1966 to 2002 streamflow series);

• EVALS hydropower dimensioning and evaluation software;

• SESAMEE environmental and social impact assessment.

The technical and economic characteristics of the Nam Ngum 3B Project are summarized in the following table. No project interactions were assumed in the tabulated results. The EVALS outputs are provided. Some environmental and social costs are accounted for in the EVALS evaluation and are reflected in the program outputs. The project’s wider impacts have been assessed using SESAMEE and are internalized into the evaluations reported in Section 6 of Volume A, Main Report.

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Technical and Economic Data (Source: EVALS Output):

Development: Installed Capacity Factor 1.75 Contractual status Concession Level of study Nam Ngum 3B - inventoryAccess Roads: New road 68 km Rehabilitation 46 kmHydrology: Name of river Nam Ngum Av. annual precipitation (dam site) 2,166 mm/a Ave. Reservoir Inflow 110.8 m3/sReservoir: Full supply level (FSL) 720 m asl Minimum operating level (MOL) 660 m asl Max storage volume (FSL) 1,320 hm3

Active storage volume 983 hm3

Maximum reservoir area (FSL) 25.6 km2

Reservoir filling time 2.5 monthsDam: Main dam type Concrete Faced Maximum height 210 m Crest length 410 mDiversion: Design discharge 1,110 m3/s Tunnel Diameter 11.7 m Tunnel Length 900 mSpillway: Spillway type Gated Chute Design discharge 5990 m3/sPower Station: Type Surface Number of units 4 Turbine type Francis Turbine rated head 390 mTransmission: Line Length 198 km Voltage 220 kVOutput: Installed Capacity 690 MW Guaranteed capacity (95%) 553 MW Average generation 2,858 GWh p.a. Primary generation (95% firm) 2,256 GWh p.a. Secondary generation 602 GWh p.a. Average plant factor 47 %Economic: Basic project cost (no esc. or IDC) 773 mUS$ Capacity cost 1,366 US$/kW Average energy cost 3.5 ¢/kWh Weighted energy cost 12 3.9 ¢/kWh

12 The calculation of weighted generation cost values secondary energy at half the value of primary energy

based on a definition of primary energy as energy produced with 95% firmness.

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2.15 NAM NGUM 5 HYDROPOWER PROJECT

The Nam Ngum 5 Hydropower Project is located in Xiengkhuang Province. The dam is situated on the Nam Ting, a right bank tributary of the Nam Ngum in the upper reaches of the basin. The headrace tunnel cuts off a loop of the Nam Ting and delivers generation flows to a powerhouse located on the right bank of the Nam Ngum downstream of the Nam Ting confluence. The layout of the Project is shown in the attached plan. Other layouts using lower or intermediate dam sites and other powerhouse sites should be investigated. The Nam Ngum 5 site could support hydropower development up to about 100 MW and at this size the Project is best suited as a domestic project selling to EdL unless a joint operation arrangement is reached with a downstream export IPP. The Project was studied to pre-feasibility level in 1997. The Consultant evaluated the Project using:

• Existing field data – no new field data was collected;

• Updated hydrology (1966 to 2002 streamflow series);

• EVALS hydropower dimensioning and evaluation software;

• SESAMEE environmental and social impact assessment.

The technical and economic characteristics of the Project are summarized in the following table. No project interactions were assumed in determining these outputs. The EVALS outputs are provided. Some environmental and social costs are accounted for in the EVALS evaluation and are reflected in the program outputs. The project’s wider impacts have been assessed using SESAMEE and are internalized into the evaluations reported in Section 6 of Volume A, Main Report.

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Technical and Economic Data (Source: EVALS Output):

Development: Installed Capacity Factor 1.75 Contractual status MOU Level of study PrefeasibilityAccess Roads: New road 22 km Rehabilitation 20 kmHydrology: Name of river Nam Ngum Av. annual precipitation (dam site) 1,944 mm/a Ave. Reservoir Inflow 17.0 m3/sReservoir: Full supply level (FSL) 1100 m asl Minimum operating level (MOL) 1060 m asl Max storage volume (FSL) 318 hm3

Active storage volume 252 hm3

Maximum reservoir area (FSL) 14.6 km2

Reservoir filling time 4.5 monthsDam: Main dam type Concrete Arch Maximum height 97 m Crest length 260 mDiversion: Design discharge 30 m3/s Tunnel Diameter 4.4 m Tunnel Length 6,200 mSpillway: Spillway type Ungated Ogee Design discharge 1,300 m3/sPower Station: Type Surface Number of units 2 Turbine type Francis Turbine rated head 271 mTransmission: Line Length 77 km Voltage 115 kVOutput: Installed Capacity 75 MW Guaranteed capacity (95%) 59 MW Average generation 317 GWh p.a. Primary generation (95% firm) 284 GWh p.a. Secondary generation 32 GWh p.a. Average plant factor 49 %Economic: Basic project cost (no esc. or IDC) 114 mUS$ Capacity cost 1,907 US$/kW Average energy cost 4.7 ¢/kWh Weighted energy cost 13 4.9 ¢/kWh

13 The calculation of weighted generation cost values secondary energy at half the value of primary energy

based on a definition of primary energy as energy produced with 95% firmness.