• 220 kV line to the south faces delays

 Southern Sri Lanka faces a risk of losing nearly 120 MW of power supply early next month with the rapid depletion of water levels at the Samanalawewa hydropower reservoir, The Sunday Morning learns.

It is learnt that the water levels are reducing due to the draining of water in order to sustain the continuous supply of drinking water to the Udawalawe area, which is at present experiencing extremely dry weather.

It is reliably learnt that the Ceylon Electricity Board (CEB) has been compelled to produce additional hydro to release more water so as to provide a continuous supply for drinking and other purposes as requested by the Mahaweli Authority.

The water capacity currently available at the Samanalawewa Reservoir (as of 15 July) is likely to be sufficient to produce hydropower for another 15-20 days if it continues to be drained out at present capacity, it is learnt. 

As per CEB generation statistics, the nighttime peak generation of the Samanalawewa hydro complex on 14 July at 7 p.m. was 196.3 MW and the water level of the Samanalawewa Reservoir below spill as of 14 July at 7 p.m. was 20.34 m, whereas the spill at the reservoir was 31 m.

The hydropower storage in Samanalawewa was 32.1 GWh and it is 24.1% of the total hydropower reservoir capacity, according to CEB statistics. Further, the Samanalawewa hydropower reservoir catchment area had not received rains in the recent weeks, as per statistics available on Friday (14).

The Sunday Morning learns that the depletion of more hydro-capacity threatens the continuous supply of electricity to the Southern Province due to the unavailability of optional power plants in the area. The only available alternatives are the CEB-owned 50 MW, diesel-powered generators.

The transmission of electricity from the Central to the Southern Province has several constraints due to issues with transmission lines. To solve this, a new 220 kV line was proposed from Polpitiya to Hambantota and another 220 kV line from Kotmale to Polpitiya. 

A total of around 80% of the construction of the transmission line from Polpitiya to Hambantota has already been completed, but the rest has been delayed for years. It is also learnt that the construction of the new 220 kV line from Kotmale to Polpitiya has only had the foundation laid.

When contacted by The Sunday Morning, CEB Spokesman Additional General Manager (Generation) Dhammika Navaratne said there was a dire shortage of water in Udawalawa area due to the extreme dry weather conditions.

“The Mahaweli Authority has requested the CEB to increase the flow release at Samanalawewa through turbines after generating power. Two weeks ago, the CEB increased the hydropower generation. 

“Earlier, we used only 0.5 million cubic metres per day, but now we have increased it to 2 million cubic metres per day because of the water issue. It has caused a severe depletion of water levels at Samanalawewa. If it continues at the current capacity, we will only have enough water at the reservoir to generate electricity for 15-20 days,” he explained.

“If we drain water levels at this capacity and the rain doesn’t return during this period, there will be a serious issue when supplying electricity to the Southern Province,” Navaratne opined.

He acknowledged that the construction of the transmission line had been delayed due to several issues. 

Without rain for Samanalawewa, the CEB may have to purchase supplementary power at a higher cost from private power suppliers, it is learnt.

Speaking to The Sunday Morning, a senior engineer attached to the CEB who wished to remain anonymous said that the total cost for the completion of the construction of the 220 kV line would be around Rs. 1.2 billion, which would be an investment in critical energy infrastructure as it would solve the energy shortage in the Southern Province.

According to the source, the construction of the line had commenced four years ago and had been delayed due to Covid-19 in 2020 and later due to the economic crisis faced by the country.

As per the ‘Initial Environmental Examination: Transmission Subprojects on Clean Energy and Network Efficiency Improvement’ prepared by the CEB for the Asian Development Bank (ADB), the development of the new Polpitiya GSS will facilitate extension of the 220 kV transmission system to the Southern Province at a future date, which resolves most of the under-voltage and line overloading problems in the southern transmission network.

The ‘Long-term Transmission Development Plan 2013-2022’ has identified the 220 kV transmission connection to Hambantota from New Polpitiya. This will operate as a transmission highway to flow hydropower generated at the Mahaweli and Laxapana complexes to the southern load centre, and hence facilitate reliable power supply to the Southern Province.