Nepal’s first hydropower from a glacial lake

From the edge of the terminal moraine of the Langtang Lirung Glacier, there is a 360 degree view of icy peaks, and below is the monastery town of Kyanjin blanketed in overnight snow.

Towering above is Langtang Lirung with snow being blown off its 7,227m summit, with the jagged peaks of Kimshun standing like bodyguards with Tserko Ri, Yala Peak and Gang Chhenpo. And to the south is the rampart of the Naya Kanga ridge.

“When I was a boy we brought the yaks up here to graze, and they could cross the ice from one side of the glacier to the other,” says Gyalbu Tamang. “This lake was formed only in the last 20 years.”

As climate change thaws the mountains, right across the eastern Himalaya in Nepal, Bhutan and southern Tibet, hundreds of new lakes have formed at the snouts of glaciers. Some have found outlets and emptied themselves, while others, like this one, swelled up dangerously.

In the past 40 years, there have been 26 glacial lake outburst floods on Nepal’s rivers, and with newer and bigger lakes forming, they pose a serious risk to new roads, settlements and hydropower plants downstream.

However, glacial lakes do not just need to be a threat, as has been shown by a unique project on the Langtang Lirung Glacier. This glacial lake at 4,100m is being drained to lower its level, and the water is used to generate electricity.

The Langtang Microhydro Electricity Project was built three years after the 2015 earthquake-avalanche that devastated the valley, with help from the Hong Kong-based Kadoorie Charitable Foundation. The $534,000 scheme has a weir and spillway at the moraine, and the water is taken through a fibre glass-insulated penstock pipe to a powerhouse that generates 100kW of electricity, providing 24 hours of electricity to 120 households and tourist lodges in Kyanjin and Langtang.

The project is a first-of-its-kind in Nepal to power a village, and holds promise for other remote Himalayan valleys where the risk posed by expanding glacial lakes can be mitigated, while at the same time providing electricity to tourism-dependent families.

“It can be a plus-plus, you need to simply drive a glacial lake to turn a turbine while simultaneously lowering the water level and reducing the pressure on the moraine dam,” says energy economist and former Water Resource Minister Dipak Gyawali.

The only downside would be that most glacial lakes are at very high elevations where there are few settlements, and also the greater cost of transporting equipment by helicopter. But if the risk-reduction from glacial lake outburst floods is factored in, these multi-purpose projects would be cost-effective.

There are other dangerous glacial lakes in Nepal like Imja in the Everest region and Tso Rolpa in Rolwaling Valley, where the water level has been lowered at enormous cost, but the schemes have not added the hydropower component. Tso Rolpa had a small power unit to supply electricity to the project, but it is not in use. Imja was financed by the UNDP with funding from the Global Environment Facility, while Tso Rolpa was funded by the Dutch government.

Glacial lakes have been used to generate power in the Peruvian Andes, and in the Swiss Alps existing reservoirs filled with glacial melt have been generating 4% more electricity because of accelerated melting. The Swiss are even mapping future hydropower plants on glaciers for a time when all the ice will be gone. In Bhutan, a pilot scheme on a glacial lake at 4,200m is trying to lower the water level using siphons, and plans to also see if it is feasible to generate electricity.

Experts say that with a little more investment, the moraine dams on glacial lakes can be strengthened for a fraction of a cost of building a new artificial dam for electricity generation. For this, the Langtang Microhydro Project presents a working model for other glacial lakes in Nepal where there are plans to lower the water level.

"In previous decades it used to be expensive to build power plants on glacial lakes because they were so remote, but now that roads have reached many valleys, they are more feasible," says glaciologist Pradeep Mool.

Gyalbu Tamang lost his parents and many relatives in the catastrophic earthquake-avalanche in 2015 that killed as many as 300 people in Langtang. But for him and other trekking lodge owners who used to depend on solar panels, the 24-hour electricity has transformed the quality of life.

He says: “We can charge our phones, use appliances, the children can read at night, it is like living in a city.”

Read also: DANGER: Nepal’s glacial lakes are filling up, Nepali Times