Methane generation in Lac Kivu

1. LAKE KIVU METHANE GAS EXTRACTION FOR
POWER GENERATION
METHANE RESERVES

2. TABLE OF CONTENT
1. OVERVIEW
2. ORIGIN OF GAS IN KIVU LAKE
3. METHANE REGENERATION IN THE LAKE
4. METHANE EXPLOITATION
METHANE RESERVES

3. 1- OVERVIEW
Kivu Power project intends to exploit the Lake Kivu’s methane resources in
order to produce and supply electricity for commercial benefits. The main
objectives of this project are the following:
 Extraction and treatment of methane gas to produce 30 to 40 MW of
electricity.
 The conversion of gas methane to electricity to compensate the scarcity in
energy for the concerned districts.
 Reduce the risk of an environmental disaster.
METHANE RESERVES

4. Various research groups have advanced vastly different hypotheses to explain the
origin of these dissolved gases and specially the methane/
 Schmitz and Kufferath suggested a bacterial origin for the methane.
 K. Burke and Miiller proposed a magmatic origin.
 Deuser et al. advanced a model where bacteria use simultaneously organic and
inorganic carbon to produce methane.
 A detailed study of the physical and chemical properties of the water and the
dissolved gases by Tietze and Tietze et al. revealed that one-third of the methane
was formed in the upper sediment and two-thirds in the deeper sections of the
sediments.
2- ORIGIN OF GAS IN KIVU LAKE
METHANE RESERVES

5. The formation of Kivu methane appears to be the result of two simultaneous
mechanisms:
 One due to the fermentation of biogenic sediments.
 The other is due to the reduction of magmatic CO2 by bacteria.
Whereas CO2 is of geogenic origin (subaquatic springs), CH4 is most probably
formed by biogenic processes (Deuser et al,; Tietze; Tietze et al.; Schoell et al.;
Pasche et al.).
2- ORIGIN OF GAS IN KIVU LAKE
METHANE RESERVES

6. 3- METHANE REGENERATION IN THE LAKE
The measurements by Schmid et al. indicated that CH4 concentrations had
increased by up to ~15% since the measurements of Tietze 1978,
corresponding to a rate of increase of ~0.5% year−1.
Based on this CH4 formation excess, we can expect an increase of the lake
CH4 content from currently 65 to 72 km3 over the next 50 years as indicated in
the table below:.
Unit BZ IZ PRZ RZ Total
Depth m 0-60 60-200 200-260 260-485 0-485
CH4 Formation Rate km3 /year 0 0.067 0.021 0.18 0.27
CH4 Formation during 50 years km3 0 3.4 1 9.1 13.5
CH4 Net Storage during 50 years km3 0 0.6 0.2 6.2 7
METHANE RESERVES

7. 3- METHANE REGENERATION IN THE LAKE
Simulations conducted by Eawag 2009 demonstrated the accumulation of
CH4 over the years as shown in the following figure:
Observed (2004) and simulated CH4 profiles Eawg, 2009.
METHANE RESERVES

8. 3- METHANE EXPLOITATION
Gas extraction from Kivu Lake is expected to be further developed in the near
future. The second phase of the KivuWatt project may reach a total capacity of
100 MW. Another concession agreements have been signed between the
Government of Rwanda and SPLK (Sheema Power Kivu Lake - former
Symbion) for a capacity of 56 MW and GasMeth for a capacity of 50 MW. In
the other side of the lake, concession agreement has been signed between
the Government of Democratic Republic of the Congo and Kivu Power for a
capacity of 40 MW.
METHANE RESERVES

9. 3- Methane Exploitation
Over 50 years, the methane content in the resources zone would be increased
by 7 km3.
Figure below shows the full power available for both hypothesis:
 Methane regeneration in the lake.
 No methane regeneration in the lake.
METHANE RESERVES

10. 3- METHANE EXPLOITATION
As shown in the figure, for 50 years of exploitation and even with considering
that no methane regeneration occurred, 313 MW is available which is greater
than the total of projected power production for all Kivu lake projects (246 MW)
from both sides.
It is concluded that the exploitation of the CH4 for the next 30 years with full
production from all projects will not harvest the half of CH4 reserve in the Kivu
Lake.
METHANE RESERVES