Wärtsilä Takes On A “Killer”

KivuWatt, a 25 MW power plant fueled by methane gas trapped in “killer lake” Lake Kivu, Rwanda, will be adding a fourth Wärtsilä 34SG engine.

The plant in Kibuye, Rwanda is currently powered by three Wärtsilä 34SG engines running on methane gas lifted from the depths of Lake Kivu, which is known as the “killer lake” because of the large amount of methane trapped under a layer of heavy water washed out of nearby volcanoes.

When the gas concentration gets too high, or the lake is hit by one of the region’s regular earthquakes, the gas can be set free. This poses a threat to the people living in the vicinity.

“By tapping into these gas resources, the project makes Lake Kivu a safer place, while supplying much-needed electricity to the national grid,” said Atte Palomäki, executive vice president, Communications & Branding, Wärtsilä Corp.

The methane is lifted from a depth of 300 m by a special barge anchored 13 km off-shore. The gas is purified on the barge and transported to the shore through an underwater pipeline. The gas is then used in the engines of the power plant, providing low-cost renewable energy to the local community and to the country, the company said.

“This project will significantly enhance the energy supply of the country, while improving the safety of the millions of people living on the shores of Lake Kivu,” said Joseph C. Brandt, CEO of ContourGlobal, the owner of the power plant.

Wärtsilä was contracted to supply the Smart Power Generation plant with a full engineering, procurement and construction (EPC) delivery in 2011. The plant has been operational and running on the extracted methane since December 2015. Currently ContourGlobal is preparing to extend the plant with the next Wärtsilä 34SG engine.

Wärtsilä said the 34SG engine offers the highest simple cycle efficiency in the market, showing no derating at the altitude of 1500 m. The engines are optimised to run on Lake Kivu’s gases that have a lower heating value than normal natural gas. This has helped to downsize the size of the extracting barge and optimise the costs of producing electricity, the company said. Wärtsilä has previously delivered two other EPC projects to ContourGlobal in Africa: a 100 MW plant in Togo, and a 53 MW plant in Senegal. The Senegal project currently has a 32 MW extension under construction.

Wärtsilä’s installed capacity in Rwanda is now 46 MW, which is approximately 50% of the country’s available power generation capacity. In Africa, Wärtsilä’s installed base is 6500 MW in 46 countries. The majority of the projects are based on EPC and include full operations and maintenance contract.