Dechen Dolkar

The 1,020 MW Punatshangchu-II Hydroelectric Project (PHPA-II) is projected to incur a revenue loss of around Nu 3.18 billion over the next three months due to water seepage issues at its powerhouse.

This estimated loss is based on the proposed tariff for PHPA-II, which is still under negotiation.

The Minister for Energy and Natural Resources, Gem Tshering, said that the government has proposed a tariff of Nu 5.8 per unit of electricity generated by the project while the Indian government has offered Nu 5.1 to Nu 5.2 per unit.

Lyonpo said that the final tariff rate is still under discussion and is expected to be finalised within this month.

PHPA-II consists of six generating units, each with a capacity of 170 MW. The project management initially aimed to commission two units by September and test an additional two units during the same month, with full commissioning of all six units targeted for December.

If the two units had been commissioned on schedule and based on the lower proposed tariff of Nu 5.2 per unit, the government could have earned around Nu 2.55 billion from electricity exports in October and November. For December, due to reduced water levels, revenue from one unit was projected at Nu 636.48 million, bringing the total expected revenue for the three months to Nu 3.18 billion.

However, the water seepage problem has delayed the full commissioning of PHPA-II by several months. The project management has not provided a precise timeline for the delay, as the water-conducting system is still being dewatered.

Lyonpo Gem Tshering said that the dewatering and refilling process may take about three months.

“The management plans to commission two units by December, despite the low water levels during that period,” he said.

Currently, the project team is dewatering the tunnel and installing false ceilings. The dam’s water level has been lowered by a few metres to empty the headrace tunnel, surge shaft, and pressure shaft. This process is expected to take over a month, with an additional similar timeframe required to refill the water conductor system.

Installation of electro-mechanical equipment will resume once the false ceilings are in place, a process that is expected to take approximately three months.

Water seepage in the machine hall of the powerhouse was first detected on August 13, with a flow rate of about four litres per second.

A technical group convened on September 5 and recommended immediate remedial actions, including the installation of false ceilings in the powerhouse cavern and service bay, alongside dewatering the water-conducting system.

The total cost of the PHPA-II project is estimated at Nu 94.45 billion.