More detail on the project can be found in the project’s CDM document here.
The civil engineering and electro-mechanical equipment of the Salido Kecil MHP, although built ~100 years ago, is an engineering masterpiece and a benchmark for high-quality hydropower projects even for today. The system is equipped with Siemens & Schuckert generators, Pelton turbines, and first-generation Hansen & MAN mechanical jet deflectors, all from Germany.
- Civil work infrastructure. A 2.2 km long power channel -- partially in an earth-covered tunnel, with 4 long aqueducts and a pair of parallel gravel sedimentation basins near the intake, and a pair of parallel de-sanders near the forebay -- provide the perfect water quality for the operation of the electro-mechanical system. With a head of 110 m, the cast iron penstock is 342 m long and 600/700 m in diameter, with lead-sealed joints.
- Electro-mechanical system. The system has 3 generators direct-coupled at 750 RPM to 3 different Pelton turbines, each of 400 kVa capacity. Each turbine has 2 runners on the shaft, with 4 nozzles. In total, there are 6 runners and 12 nozzles. Eight nozzles are on/off type and 4 nozzles are adjustable, in order to fine tune the water level at the forebay tank during the dry season. The system is equipped with synchronizing jet defector control at each nozzle. The design output of the system was 600 kW.
- Early 1900s: The project was constructed by Dutch engineers to provide electricity to a nearby gold mine.
- 1940s: Japanese military occupied the plant for its own use.
- 1950s: The Indonesian civil war resulted in the abandoning of the project, during which the penstock was extensively damaged from extreme floods in West Sumatra.
- Early 1960s: PT. Anggrek Mekar Sari (AMS) repaired the system and obtained government permission to operate and sell electricity to the local grid of the utility, PLN.
- 1960s - 1990s: AMS’ attempt to sell electricity to the neighboring city of Painan and later to a local cement factory failed due to PLN connecting the area to the West Sumatra grid.
- 1995: During a period of large government subsidy for diesel, PLN connected a diesel-powered plant to the same local grid, and AMS was forced to disconnect the Selido-Kecil Mini Hydro from the local grid.
- 1995 - 2005: To survive financially, AMS sold electricity to its own ice factory, utilizing the one last functional turbine. entec AG from Switzerland conducts field assessments and an investor search to rehabilitate the entire system of 3 turbines.
- 2006: After much difficulty in finding investors due to the policy situation, entec AG decided to invest on its own and secured a loan from the Triodos Development Bank in the Netherlands.
- 2006 - 2007: PT entec Indonesia (a subsidiary of entec AG) jointly with AMS, on a Build-Operate-Transfer (BOT) basis, started the rehabilitation of the “Unit 2” turbine, resulting in an output of 315 kW.
- 2008 - 2009: The “Unit 1” turbine is rehabilitated. The project obtains the Gold Standard Verified Emission Reductions (GS-VER).
- 2011 - 2012: The “Unit 3” turbine is rehabilitated, requiring the ice factory to close.
- 2013: All 3 units are rehabilitation and operational, generating 780 kW, instead of the expected design output of 1000 kW, due to losses in the penstock.
Source for timeline: Rehabilitation of the Mini Hydro Power Plant PLTA Salido Kecil, Feasibility Study, Entec AG Switzerland, 1999
There are two schemes of power purchase agreement in Indonesia’s energy administration: excess power and independent power. Unfortunately it was not possible until now to change the Excess Power Purchase Agreement (EPPA) applied during the operation of the ice factory to an Independent Power Producer Agreement (IPPA), and the tariff is still very low. From 2005 until 2018, it was IDR 441 (USD 0.45 / kWh in 2005). From 2018 until today, it has been IDR 470 IDR (USD 0.32 / kWh ), which is a fraction of the IPPA tariff in the region (about USD 0.61 / kWh).
Considering the inflation, the USD 0.45 in 2005 is equivalent to USD 0.60 today and not USD 0.32 US. So the actual tariff paid is again being lowered every year. Without an increase of utility tariff, history may repeat, and the operation in some years will again not be profitable. Moreover, in the last 3 years the power plant has been disconnected for some months due to administrative issues and it has been causing a huge income loss.
Since September 2019 the power plant has been interconnected again. However, the following observations were made:
- The power plant is on the end of a transmission line branch. More and more consumers are connecting, and the voltage is often dropping in the peak power times below 200V. This causes an overheating of the generator and transformer, and the generator must be disconnected in the peak hour. This triggers another voltage drop to 190V of the grid and reconnection is technically only possible at around 11pm or when the voltage is above 215V.
- The operation of Salido MHP reduces the transmission loss of the utility in our power line to the distribution transformer for about 10% of our production. This is not considered in the paid tariff- the opposite is the case– we need to switch off during peak hours because the voltage is too low.
Since 2006 Salido Kecil has produced more than 29 million kWh. What does this number mean? Well, producing this energy with diesel fuel would be the equivalent of about 9,700,000 L diesel fuel or 1,200 tank lorries, 8,000 L each. Lining up those lorries would result in a 12 km long traffic jam!
As per definition of the VER standard, more than 20,000 tons of CO₂ have been avoided, which is an equivalent of 11,000,000 m3 CO₂ gas. This is the volume equivalent of a balloon filled with CO₂ gas with 280 m in diameter, or the CO₂ gas that 20,000 trees would absorb in 40 years.
The water flow is reducing from year to year. The catchment area is mostly an extremely healthy tropical forest in the Kerinci Seblat National Park. Unfortunately, the buffer zone area near the 2.2 km long channel structures is village-owned and less protected. Until two years ago the access to this area was naturally blocked by vegetation and a narrow pathway. The limited access made it difficult to transport wood and agricultural products out of the forest, and therefore prevented uncontrolled and unwise logging.
Now there is infrastructure that widens the pathway and makes this area accessible for the public. In fact, the intake area of the MHP has been opened as a recreation area. During the recent COVID-19 lock down, the untouched area and steep long channel was cleared, which unfortunately exposed the civil structures to erosion and landslides. In addition, many old trees along the channel have been logged to clear land for agriculture.
In September 2020, PT entec had to repair a part of the power channel that severely cracked due to shifting terrain resulting from the erosion. Before this, the geology of the project site had been stable for 100 years -- thanks to healthy forests.
The water for the public water supply of Painan (10 km away) is taken out of the river below the MHP weir at the intake. Up to now this water is coming from a side river – if demand for water supply is rising and river flow is decreasing in the dry season, due to deforestation or climate, the available flow may reduce possible electricity production especially during the dry season. In addition to this, the water at the powerhouse tailrace is diverted to an irrigation scheme for rice fields, which has had significant economic benefit.
At the start of 2020, PT entec came to know that the channel had leakages, due to the channel crack that had formed because of erosion from deforestation, as explained above. The channel structure had started to sink down. Last month the leakage became severe, decreasing the output to 200 kW due to a loss of 100 L/s.
Despite COVID-19 travel restrictions, PT entec decided to repair and conduct a technical inspection of the entire power plant. Immediate shutdown and repair were conducted to avoid a potential landslide.
Not caring for such a problem can cause extremely high repair costs, not to mention long periods of shut down. A similar situation occurred at the 250 kW mini hydro project at the Tea Plantation Dewata on Java Island, causing a shut down of 5 months and damage costing far above 100,000 USD. Fortunately, the Salido power plant is back to full operation now. PT entec will continue to monitor.
The Salido Kecil MHP is one of many examples that show small-scale hydro power is still in many places a very sustainable renewable energy source. However the feed-in-tariff is still low for renewable energy and in particular for mini hydro power. The reason for this is that fossil fuel is still cheap, and there are many administrative obstacles to developing projects.
However, land use in rural communities often changes dramatically due to an increasing population pressure and the increasing income requirements for the rural population, in order to catch up with technological development and increasing wish to participate in the lifestyle shown by the internet and social media.
Cash crop production without any care for soil erosion protection and maintaining the biodiversity of the entire region is a pragmatic approach taken by the locals. It is a big task to raise awareness for the consequences of soil erosion and the urgent need of investing now into a clean and permanently flowing river supplying water for irrigation and public water supply.
It will be not easy but worthwhile to combine all factors of energy protection, economic, ecological, and environmental aspects; and protect the Salido Kecil’s historical asset and the beautiful forest along the waterway and the catchment area for future generations.
There is a big potential for eco-tourism and recreation in nature. It is therefore crucial to conduct an assessment to measure the economic values of the natural capital in this area and to develop environmental regulation that protects biodiversity, as well as local communities.