From 230MW to 25MW: Kaptai hydel's climate fate

The rainy season is the time for a hydropower plant to run at full capacity as water fills up its reservoir to generate electricity, and the capacity utilisation can be as high as 95%.

But this is not the case for Bangladesh's lone hydropower project at Kaptai.

The 230MW Karnaphuli Hydropower Station is failing to boost its production in the ongoing rainy season when the country is facing frequent production cuts at other fuel-based power plants hindering business.

The data from Bangladesh Power Development Board suggests the hydropower station now runs at 13% to 26% capacity while the plant officials say irregular rain and ancient machinery have cut its capacity.

From March to April this year, its electricity generation went down to 25MW. It is, however, producing 60-70MW this month, added the officials.

According to information from the station's control room, only one unit was operational with occasional closures from March to mid-June due to low water level.

However, the authorities have been running one unit full time since June 17 with water flow rising and two units during peak hours (6pm to 10pm) from July 1.

Engineer ATM Abduzzaher, manager of Karnaphuli Hydropower Station, told The Business Standard, "During the countrywide power crisis last year, our power production was relatively good. After that, the rainfall has decreased a lot."

He added, "All our units are functional. But we could not run more than one unit at a time for four consecutive months due to water shortage. Sometimes that too was kept shut … Rainfall is decreasing every year."

If water flow increases in the dam, the power plant has a record of producing as much as 200MW, according to the control room data.

Six decades ago, the artificial lake was formed in the Kaptai upazila of Rangamati, around 50km from Chattogram city, flooding around 655 square kilometres of area and displacing around one lakh people. Spanning a catchment area of 4,250 square miles, this lake serves as the water reservoir for power generation for the plant. In addition to rainfall, water flows into the lake from India and the Lushai hills.

Climate experts and plant officials say the decreasing rainfall is a consequence of climate change, and irregular rainfall has reduced water flow for the lake.

According to data from the Bangladesh Meteorological Department and the power plant authorities, in 1988, the plant area received 2,708mm of rainfall, and over 1.66 crore acre-foot of water flowed into its reservoir.

This led to the production of 100.20 crore units of electricity.

In 2022, the rainfall dropped below 2,125mm and water flow fell to 75.98 lakh acre-feet, causing a decline in electricity production to 76.60 lakh units.

Dr Ainun Nishat, a water resources and climate change specialist, said, "Because of climate change, rainfall is decreasing in some places in the world while it is increasing elsewhere. The timing of rainfall has changed in our country."

He added, "Accumulation of silt has also reduced the Kaptai Lake's capacity to hold water though there is no study on this. The depth can be increased. It is also possible to increase the capacity of the power plant by renewing old technology."

Ageing equipment

The planning for the Karnaphuli power station dates back to 1906. A survey was conducted in 1923, and in 1946, the dam was proposed to be built in the Barkal area, 65km upstream from the current dam location.

Construction of the project started in 1957, with Utah International Inc, a construction company from the US, as the project contractor.

Since its establishment till 2022, the power station has generated a total of 39,606 million units of electricity.

The first two units were initially set up with a capacity of 40MW but they have the potential to produce a maximum of 46MW.

The subsequent three units have a capacity of 50MW each, but their utilisation is hampered by technical issues. The capacity of the third unit has decreased to 39MW from 50MW, while the capacity of the fourth and fifth units have dropped to 35MW.

According to the power plant engineers, the turbine of each unit has an operational lifespan of 10 years, after which it requires thorough overhauls.

Unit-2 was overhauled in December 2021 and Unit-1 was overhauled in December 2022 . Both the units can be run at full capacity.

Unit-4 was overhauled in June 2010 and unit-5 in April 2011. Unit-3 was overhauled in December 2012. So, these three units have exceeded their intended lifespan leading to a gradual reduction in their capacity over time.

As per the mechanical wing of the power plant, the ageing of equipment, particularly the turbine of unit-3, has hindered its ability to efficiently save energy during operation.

Additionally, cracks have been noticed in the generator compartments of unit-4 and 5, preventing these units from running continuously.

Officials have indicated that delays in conducting timely repairs primarily stem from bureaucratic complications.

Despite floating tenders, the Bangladesh Power Development Board (BPDB) has faced difficulties in securing a qualified contractor, resulting in the withdrawal of tenders on at least three occasions.

ATM Abduzzaher stated that it has been a decade since the renovation of unit-3, and with the available spare parts, it can continue running for an additional two years.

However, despite inviting tenders three times in the last four years, a contractor has not been appointed for the renovation of unit-4 and -5, he said.

Capacity enhancing uncertain

According to the Bangladesh Power Development Board, the production cost per unit of electricity is Tk22 for diesel-powered plants, Tk10 for LNG gas, Tk4 for the Barapukuria coal power plant, Tk6 for imports, Tk12 for solar power, and Tk12 for furnace oil-powered plants.

However, when all units of the Karnaphuli Station are operational, the production cost per unit significantly decreases to approximately 30-40 paisa. Operating only one or two units also keeps the cost to less than Tk1.

Despite the cost-effective power generation, the enhancement of electricity generation capacity at the hydropower plant is uncertain.

In 2000, the Japan External Trade Organisation conducted a survey with the intention of commissioning two additional units with 50MW capacity each.

However, the implementation of the project faced objections from the local communities residing in the hills, leading to its cancellation.

According to official documents, the creation of Kaptai Lake resulted in the flooding of 22,000 hectares of arable land and 18,000 residential houses.

The displacement caused by the dam affected around 100,000 people, 70% of them Chakma people.

During the dam's construction, it was proposed that the reservoir would be managed by a body called the Reservoir Operation Committee (ROC), which was intended to include representatives from the tribal communities. However, this committee has never been made effective.

Due to concerns about both the previous displacement and the potential for further flooding in the hilly regions, local communities took a stance against the expansion of the power plant. As a result, units 6 and 7 were not constructed.

Officials say if two additional units are constructed, they would only be operational for three months in a year, as the rest of the time they would need to be shut because of the water shortage.

"The water shortage is severe, and even if there were two more units, they would have to be suspended due to the scarcity of water," said ATM Abduzzaher.

The drop in the lake's water level also significantly impacts the water transportation system of six upazilas in Rangamati.

Of them, Jurachhari, Bilaichhari, and Barkal upazilas rely solely on waterways for communication. As the water in the lake recedes, launches cease to operate, forcing people to rely on small boats like dinghies for transportation.

Consequently, transportation costs for businesses in these three upazilas increase, affecting public life as a whole.

Kaptai / hydropower / Bangladesh / Karnaphuli