Air Pura Hydroelectric Power Plant (PLTA) developed by PT. Dempo Mitra Internasional, located in Lubuk Betung Inderapura Nagari, Air Pura District, South Pesisir Regency, West Sumatra Province with an installed capacity of 13.1 MW. Energy production was sold at 79.01 GWh per year. The land needed for construction is 27.82 Ha. The time needed for development is needed for 36 months and the construction time is 24 months, with construction costs of Rp. 288,577,000,000. The assumption of the source of the loan is 70%, the source of the funds is 30%, the interest rate is 13.5%, the BCR is 1.33, the IRR is 16.10% while the NPV is Rp. 382,544,001,046, - and this project will Break Event Points (BEP) in 6.2 years.
Project Profile
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Project feature
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A. Technical Aspects

    a. Hydrology

       Conduct hydrological analysis through watershed data (DAS), Automatic Water Level Recorder (AWLR) and rainfall around the location to determine the planned discharge for the plant and flood discharge plans for planning civilian buildings in the river channel.

   b. Topography

       Conducting topographic survey and measurement activities to obtain conditions and situations as well as height differences from a location that will produce a situation map, long section and cross section.

   c. Geology

      Conduct geological studies to get an overview of the geological conditions of the study area by guiding geological maps, earthquake maps and conducting soil structure checks.

   d. Making basic layouts and designs.

B. Machine and Equipment Aspects

    Based on the review of technical aspects, the machinery and equipment used will be examined, starting from the machinery and equipment in the Power House to the point of transaction agreed with PT PLN (Persero), including the pole and distribution network, so that the energy produced connected optimally.

C. Environmental Aspects

     Environmental aspects include:

   a. Identifying field conditions both from the designation of the area / regional status as well as Economic, Social and Cultural.

   b. Identifying impacts that will arise both during pre-construction, construction and post-construction (operational).

D. Financial Aspects

     Financial aspects include:

  a. Make a calculation of estimated investment value needed from pre-construction activities, construction to the Commercial Operating Date (COD).

   b. Make calculations of estimated operational costs and estimated cash flows.

  c. Make financial analysis of several investment criteria including: Internal Rate of Return (IRR) project, IRR equity, payback period, Net Present Value (NPV), cost of goods manufactured, selling price of electrical energy, Benefit Cost Ratio (BCR) and ratio- other relevant financial ratios.

Location Area

   South Pesisir Regency is located between coordinates 01o 17 '13 "- 01o 46' 45" LS and 100o 53 '24 "- 101o 26' 27" BT. Administratively the area of ​​the South Coast is 3,346.20 km2 which is dominated by state forests, which is around 29.39%. South Pesisir Regency is a district located in the southeast part of the Province of West Sumatra with the following regional boundaries:

  - North: City of Padang

  - Southern side: Bengkulu Province

  - West side: Ocean Indonesia

  - East side: Solok Regency and Jambi Province

    The planned development of the Pura Air Hydroelectric Power Plant is located in the Batang Tabatang River Flow. Based on the studies that have been carried out, civil building facilities are planned on the right side of the river.

Government administration of Pesisir Selatan Regency, the location of hydropower is in the region:

  - Village: Rantau Besi

  - Nagari: Lubuk Betung Inderapura

  - District: Air Pura

  - Regency: South Coast

  - Province: West Sumatra

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Study Location of hydropower on Map Indonesia
Study Location of Air Pura hydropower on Sumatra map
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Study Location of Air Pura hydropower on Map of South Coastal District

   The weir is built on the riverbed elevation +255 m above sea level and the weir is made 10 m high, so the weir elevation becomes +265 m above sea level. Power House (PH) 1 is planned at an elevation of +216 m above sea level and PH 2 at an elevation of +131.70 m above sea level. While the elevation of the tail line is planned at an elevation of +127.40 m above sea level.
    For Run of River (RoR) type, the net fall height (hnet) is the water height difference in the weir (mercury height) with the water level at the beginning of the discharge channel reduced by the head loss, HL as shown in Figure 4.14.
If the water level before the MA intake is made equal to the elevation of the weir lighthouse, and the water level in the drainage channel MB and high loss press as follows:
 • At the intake door as big as HLa 
 • In the settling basin for HLb
 • Along the carrier channel as big as HLc
 • In a sedimentary bath for HLd
 • Throughout the rapid pipeline of HLe

    Obtained by Hbrutto = MA - MB and Hnetto = Hbrutto - (HLa + HLb + HLc + HLd + HLe).
From the elevation data above, and the calculation of the loss of head (separate calculation) from the weir to the PH is obtained:
 a. Pura 1 Water Generator
     Gross fall height, Hbrutto = 265 m - 216 m = 49 m
     The net fall, Hnetto = 260 m - HL = = 49 m - 2.83 m = 46.17 m
 b. Temple Water Station 2
     Gross fall height, Hbrutto = 215.5 m - 131.7 m = 83.8 m
     Net fall height, Hnetto = 215.5 m - HL = = 83.8 m - 2.82 m = 80.98 m

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Picture of the Study Situation of Pura Air Hydroelectric Power Plant

A. Temple Water Plant 1

    The power installed in a generator is calculated using equation 3.1. The power generated in the Air Pura 1 Generator with Q design (Q50) is 12.33 m3 / s and the net fall height is 46.17 m. By using formula 3.1, the Installed Power P = 1000 x 9.8 x 12.33 x 46.7 x 0.85 = 4.747 KW ≈ 4.8 MW.

B. Temple Water 2

   The power installed in a generator is calculated using equation 3.1. The power produced in the Pura 2 Power Plant with Q design (Q50) was 12.33 m3 / s and the net fall height was 80.98 m. By using formula 3.1, the Installed Power P = 1000 x 9.8 x 12.33 x 80.98 x 0.85 = 8.326 KW ≈ 8.3 MW.

Total Capacity of Hydroelectric Power Plant = 4.8 + 8.3 = 13.1 MW

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Determination of Net Fall Height

    The distance between the Air Pura Hydro Power House to the Kambang GI is 50.5 km. For a distribution network of 20 kV along 1.8 km through a water carrier channel that belongs to the company. Likewise for the connecting substation, an area of 100 m2 (10m x 10m) is needed.

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Layout of the Pura Air Hydroelectric Network

Electric Energy Production

   a. Pura 1 Water Generator

Generating energy production per year is calculated by multiplying power by operating time (hours) in one year.

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Energy Calculation and Air Pura 1 Capacity Factor (CF)

   b. Temple Water Station 2

Generating energy production per year is calculated by multiplying power by operating time (hours) in one year

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Energy Calculation and Air Pura 2 Capacity Factor (CF)

   The production of energy produced by PLTA Air Pura is as follows:

Hydropower Hydropower Hydropower = Energy Energy Hydropower Plant 1 + Air Pura 2

= 28,690,576 + 50,321,916

= 79,012,492 Kwh / year

= 79,012 GWh / year



  Social, economic and environmental surveys are intended to provide an overview of the effects that might occur with the construction of hydropower. The results of the survey and socialization showed that the community around the site responded positively to the PLTA development plan.

  To maintain the life of river biota, not all flow discharges are used for hydropower, but there is a discharge that is released downstream when the river discharge is in critical condition. The existence of the dam building also considers the stability of the cliffs, river valleys, such as building cliffs (revetments), and embankments on the low side of the river, so that the dam overflow does not damage the land on the left and right sides of the dam downstream. In the carrier channel and the settling basin will also be avoided excessive soil cutting, which is to make channel trases that tend to follow the contour line.

  From the results of environmental surveys conducted, the existence of hydropower buildings will have a positive and negative impact on the surrounding environment, both physical and flora and fauna. Comprehensive environmental impact assessment will be carried out by a team of experts in a separate study (UKL / UPL).

  From an economic standpoint, based on the economic data of South Solok district in general, the construction of hydropower will add value to the economy of the local community, both in the construction stage and in the operational phase. In the construction phase, it will absorb local workers and at the operational stage will open opportunities as employees according to the needs of the company.

Address :
Tim-Tim Street, Blok Y-2
Ulak Karang Padang City, West Sumatera
+62 751 442991