Eawag has been conducting research in the vicinity of Lake Kivu in Africa for years. In the depths of this lake, danger is lurking in the form of billions of cubic metres of dissolved gases. Now, controlled use of methane could kill two birds with one stone, securing the region’s supply of electricity and reducing the risk of a lethal gas eruption.

Lake Kivu, between Rwanda and the Democratic Republic of the Congo, is around one-and-a-half times the size of the canton Zurich and almost 500 metres deep. Virtually idyllic, yet danger lurks in the depths of this unique waterbody. The water contains around 250bn cubic metres of dissolved carbon dioxide and 55bn cubic metres of dissolved methane. In recent years, Eawag researchers have proved that the concentrations are rising.

Earthquakes would be dangerous

The gas in the deep water remains solute because of the extremely stable stratification of the lake above it. However, if the concentrations continue to rise, or if a major disturbance occurs, such as a volcanic eruption or large earthquake for example, this could change abruptly. There would then be a risk that large numbers of gas bubbles would rise up, with disastrous consequences for the very densely populated shores of the lake. This is exactly what happened in 1986 at Lake Nyos in Cameroon, when a gas eruption caused the deaths of 1,800 people.

Rwanda’s government is currently striving to enable utilisation of the gas reserves in Lake Kivu for electricity generation. The principle is simple: if a pipe is laid in the depths of the lake, the gas bubbles forming in the pipe cause the water to flow upwards by itself. The methane must then be separated from the carbon dioxide, before it can be utilised.

Eawag oversees planning and pilot projects

Eawag research teams under Professor Alfred Wüest, head of the Surface Waters department, are overseeing the planning and the pilot projects for methane extraction at Lake Kivu on behalf of the Rwandan government and the Dutch Commission for Environmental Impact Assessment. The Swiss researchers’ long-standing expertise is in great demand, as nobody knows how the lake will react to the gas extraction. A planning mistake could be disastrous for the lake’s sensitive ecosystem and for the people who live off it.

The core tasks of the Eawag teams include development of a computer model that simulates the lake’s behaviour and a concept for permanent monitoring of this behaviour. In 2010, Eawag researcher Natacha Pasche received the 2010 Swiss Hydrobiology-Limnology Prize for her thesis on the nutrient cycle and methane production in Lake Kivu.