Lake Kivu's deadly secret


Tea and coffee, Rwanda's primary exports, have been the main drivers of an average increase of 5 per cent GDP growth in recent years. But the country, dependent on grants, possesses little of the lucrative finite natural resources that have traditionally attracted investment in neighbouring countries. Over 70 per cent of the nation's 10 million citizens live on the poverty line, with an average life expectancy of 45 years.

One reason why Rwanda is confined to primary agricultural initiatives is the acute shortage of electricity. National power plants generate just 60MW, while the country – dependent on imported oil and hydroelectric power – regularly experiences frequent blackouts. Power is accessed by 6 per cent of the population, chiefly residents of urban areas, but four out of five citizens live in rural areas.

Ironically, one solution to Rwanda's energy deficiency – its vast deposits of methane gas beneath the waters of Lake Kivu – could cause far more lethal problems than its current power shortage.

The Lake Kivu basin, shared with neighbouring DR Congo, is seated in the groove forming the volcanically – and technically – active East African Rift Valley. The lake, with a surface area of 2,400 [km.sup.2] and a maximum depth of 485 metres, holds an estimated 55 [km.sup.3] STP of methane gas, with 120 million cubic metres (STP) generated per annum. Thus far, the government of Rwanda has established one methane extraction plant, with another 50MW pilot project initiated by the Rwanda Energy Company, a 99 per cent subsidiary of the Rwandan Investment Group (RIG), already in operation.

In March 2009, international firm Contour-Global also announced a 25-year agreement signed with the Rwandan government to develop Lake Kivu's methane deposits, towards the goal of generating 100MW in two phases: 25MW to be realised by 2010, and 75MW going operational in 2012. Methane, extracted from below 280m – where high concentrations of dissolved gasses migrating upward from the earth's 'rifting' fractures are trapped by 'lids' of fresh water – will be processed and transported to Contour-Global's Kibuye-based power plant, thereafter to be domestically utilised, or exported to neighbouring regions. The deal, heralding Rwanda's largest foreign investment yet – at US$325m – signifies not only an increase in available energy, but also the recognition of a potentially deadly situation.


Just like gunpowder

Methane is not the only lethal chemical locked in place by the layers of dense fresh water in Kivu, one of Africa's largest and deepest lakes – there is also 300-500bn cubic metres of carbon dioxide (co. sub.2). The natural risk associated with such 'killer lakes' can be triggered by lava flows, earthquakes, landslides, storms, even dumped industrial waste, resulting in mixed and sinking solutions, disrupting stratification, and causing gases such as carbon to parachute to the surface.

This nightmare scenario was brought to life at Cameroon's Laye Nyos in 1986, when a landslide shifted tonnes of rocks into the lakebed, resulting in the penetration of gases, including previously trapped carbon. Like bubbles spilling from the neck of a bottle, 1.7 million tonnes of carbon dioxide gas in waves, travelling at over 60 km/h, rolled through villages, quietly suffocating over 1,750 people. The lake 'overturn' concluded with a jet of water exploding from beneath the lake, where gas concentration remained at its highest, catalysing a 25 meter 'tsunami' that stripped surrounding regions of vegetation, and the lake itself of life.


Though every 'killer lake' maintains its own unique chemical fingerprint, Kivu remains particularly sensitive due to the historical frequency of earthquakes and eruptions such as recently occurred in Goma; unregulated extraction triggering 'champagne' gas bursts destabilising gas layers, and dumped waste generating methane that is not trapped within Kivu's stratified 'stair-like' structure. Kivu's methane – explosive when exposed to air, in conjunction with the carbon – has considerably increased in recent years, saturating 40 per cent of the lake. However, in contrast to Nyos, which holds 300 million cubic metres of carbon dioxide, with a saturation of 71.5 per cent (10 litres of gas per litre of water from 210 metres), Kivu's saturation begins creeping upward from 250 metres, ie: 8 per cent at 280 metres, increasing to 57 per cent at 290 metres.


Stated Rwanda's Minister for Environment, Vincent Karega, ‘One thing you should highlight about the Kivu gas is that the biggest concentration of methane is very much in the lake not at the shore.’ ‘So by the time the lava goes to the lake, before it hits the methane deposits at the centre, the waters of the lake have the natural effect of cooling it off and the end result is that nature has a way of bringing in an equilibrium to some of these events.’ But the lake bed itself is slowly being pried apart via the rift phenomenon, which is slowly eroding the lake's natural defence system – such as internal waves dissipating 'influxes of energy' – including that of moderate lava flows.


The lake's internal mechanism is estimated to reach a critical tipping point in 100-200 years, while a 2002 study by an international scientific team investigating the impact of sub-water lava inflow emanating from the eruption in 2002 of Mount Nyamuragira, a volcano in DR Congo just 32 km north of Kivu, revealed that, although the ‘possibility of a huge gas outburst from Lake Kivu where all or most of the gas dissolved in it would reach the atmosphere is very low ... the impact of such an event on the whole Lake Kivu region of about 10,000 [km.sup.2] could be very strong.’ The report's authors found that, although the lava inflow ‘into the lake was limited by lake internal mechanisms ... if the lava had reached deeper parts of the lake, a hazardous situation would have been built up.’


The Champagne effect

According to the report's authors – including Professor Michel Halbwachs, the French physicist previously charged with constructing RIG's pilot plant at a price of US$6m, and Dr Klaus Tietze, a German geophysicist, and the first to penetrate Kivu's chemical fingerprint as a young doctoral student, controlled degassing is the only solution. But while Halbwachs maintains that reinjection of [CO.sub.2] separated from methane at a depth of 270 metres upwards, is the solution, Tietze disagrees, stating that lakes with high concentrations of gas are unsuitable as an energy source, that both carbon and methane must be permanently extracted and that reinjected [CO.sub.2] would disrupt stratification, destabilising gas layers.

However, Eva Paul, Rwanda's minister of infrastructure revealed that the government's plants would not be bound by social and environmental legislation, and few regulations have been put in place. Meanwhile, the managing director of RIG has indicated to the media that although the project can be classified as a financial risk, the long-term potential of a new power source ‘generating 100MW for 400 years’ was worthy of exploration. Already, extracted methane has been used to power up boilers at the Bralirwa Brewery in Gisenyi, and transported via three-kilometre pipelines, established in 1963 by the Belgian Chemical Union.


But the conflicted area of the Kivu basin and the hostility between Rwanda and the DR Congo, with Kivu as a natural border, does not bode well for Kivu's estimated one dozen extraction platforms, vulnerable to armed attacks with potentially deadly consequences. Though Keraga claims that Rwanda would utilise the gas ‘in such a way that we do not encroach on the other country's share’, Rwanda is still being accused by the Congolese government of deliberately fermenting the looting of the Congo's mineral resources, such as coltan.

According to Rwanda's state minister for energy, Dr Alfred Butare, a US$1.5m-$2m feasibility study exploring joint exploitation of Kivu's methane will be financed by the European Commission. The study investigates three crucial components: Financing, technology and the social and ecological impacts, to be presented to potential donors for implementation, including the AfDB, World Bank and the EU. The project marks Rwanda's first carbon finance project under Kyoto's Clean Development Mechanism (CDM), leading to a signed agreement between Rwanda and the World Bank. ‘These gas deposits have been existent for generations with no actions taken. We are proud as government that we are taking the calculated risks of tapping it,’ stated Karega recently. ‘By so doing, we are proving to the world that we can turn this potent gas into a valuable resource, into an asset.’


Despite differences on the methodology characterising the ecological and political elements involved in Kivu's methane between scientists and the Rwandan and Congolese governments, one thing is certain: Kivu must be degassed in a controlled and regulated manner. Failure to do so may result in yet another tragedy; this time it may be the exhausted ecosystem going to war.


*This article first appeared in African Business.

*Khadija Sharife is a journalist and a visiting scholar at the Centre for Civil Society in South Africa.


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