Methane exploitation in Lake Kivu – a double benefit!

Lake Kivu is a large tropical lake situated in the Great African Rift Valley between the Republic of Rwanda and the Democratic Republic of Congo. This unique lake contains an enormous quantity of dissolved methane (~60 billions of m3) and carbon dioxide (CO2 ~300 billions of m3).

Lake Kivu is a large tropical lake situated in the Great African Rift Valley between the Republic of Rwanda and the Democratic Republic of Congo. This unique lake contains an enormous quantity of dissolved methane (~60 billions of m3) and carbon dioxide (CO2 ~300 billions of m3).

Worldwide, only two other lakes (lakes Monoon and Nyos) contain high concentration of CO2 in their deep water. In 1984 and 1986, landslides triggered spontaneous gas eruptions from the two just mentioned lakes, which asphyxiated at least 1740 inhabitants of the surrounding area. These unfortunate eruptions occurred because the CO2 concentrations in the lake were near 100% saturation.

Contrary to these two killer lakes, Lake Kivu has a maximum gas saturation of 55%. The water pressure is therefore ~2 times higher than the partial pressure of the gases. To trigger an eruption, water from 320 m would have to rise by 150 m, before gas bubbles start forming spontaneously. 

For the next decades, the 2 million inhabitants of Lake Kivu shores can be reassured - a gas eruption is unlikely to occur! Even if the methane is still increasing today, methane extraction from the lake will reduce this risk.

Methane exploitation in Lake Kivu is therefore a win-win opportunity. It will both supply energy and reduce the risk of gas eruption.  Depending on the efficiency of the process, the methane extraction could produce as much as 500 to 800 MWe during 40 years. Then, the exploitation will be reduced to the annual natural recharge of methane in the lake, transforming it into a veritable renewable source of energy.

Since October 2008, methane has been extracted by the KP pilot station generating 1.5-2MW. Two pilot stations of 3.5 MW from the Rwandan Investment Group and of 25 MW by KivuWatt are under construction. Concessions for a total of 200 MW have already been signed between the Government of Rwanda and the three above companies. The DRC and Rwanda are also starting a project for a common exploitation of 200 MW.

To assure a safe and environmental friendly exploitation, the Lake Kivu Monitoring Program has been set up under the Ministry of Infrastructure. The team is monitoring the main risks associated with the methane gas extraction: the alteration of the lake stability and the deterioration of the lake ecosystem due to an increase of the nutrients inputs.

To minimise these risks, international experts elaborated rules and guidelines for the extraction in the document “Management Prescriptions for the Development of the Lake Kivu Gas Resource” released in January 2010. To enforce these prescriptions and to conjointly manage the methane resource, the creation of a bilateral regulation authority has been initiated between Rwanda and DRC. An international workshop will be held in Gisenyi from 6 to 8 February 2011 to further discuss the challenges of the methane extraction with all stakeholders: gas operators, experts, researchers, investors, donors, governments and local partner institutions.

In conclusion, the local population can be assured to live safely on the idyllic shores of Lake Kivu. The methane in Lake Kivu is not a retarding bomb, as expressed too many times in the media. First, the gases are efficiently trapped below the depth of 250 m and their concentrations are currently too low to produce an eruption. Second, the methane extraction is currently removing the dangerous gas and will therefore deactivate the retarding bomb. To control the risks of this extraction, the governments of Rwanda and the DRC, with the help of the international community, are building up a regulating authority. At the same, the extracted methane is generating electricity. Methane extraction in Lake Kivu is therefore a real win-win solution!

MININFRA

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