Rwanda told: Tap the killer gas

Monday August 31 2009

A study found a nearly 20 per cent increase in methane concentration in Lake Kivu between 1974 and 2004 while carbon dioxide levels had also increased by around 10 per cent in that 30-year period. Photo/FILE

A study found a nearly 20 per cent increase in methane concentration in Lake Kivu between 1974 and 2004 while carbon dioxide levels had also increased by around 10 per cent in that 30-year period. Photo/FILE 

Rwanda should start exploiting its huge methane deposits at the Lake Kivu right away, or cancel it altogether due to the high risks involved.

According to scientists drawn from the Swiss Federal Institute of Aquatic Science and Technology, there lurks a serious hazard in the depths of the lake as over 250 billion cubic metres of carbon dioxide and 55 billion cubic metres of methane are dissolved in the deep waters.

Research indicates that the methane gas concentrations have been increasing with a rise of over 20 per cent over the past 30 years. The appreciation is attributable to a huge increase in nutrient inputs associated with population growth around the lake.

“If the gas concentrations continue to increase or a severe disruption occurs, the situation could change rapidly. Large bubbles of gas could rise to the surface triggering a chain reaction that could lead to a massive gas eruption,” says Prof Alfred Wüest, head of the surface waters department at the Institute.

The scientists say the release of a mixture of carbon dioxide and methane gases could have catastrophic consequences for the heavily populated shores of Lake Kivu, where an estimated two million people live.

This could suffocate them leading to deaths. In 1986, a disaster of this kind occurred on Lake Nyos in Cameroon, with more 1800 people dying after a gas eruption.

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Lying between Rwanda and the Democratic Republic of Congo, the Lake Kivu is said to have huge potential for the country’s much needed energy supply.

To avert the imminent deaths and meet the current power shortage in the country, the Rwandan government now plans to exploit the gas reserves for electricity generation. According to the country’s Minister for Energy Dr Albert Butare, the grand energy project will generate over 250 million cubic metres of methane per year.

Dr Butare says Rwanda will be partnering with DRC on the exploitation of methane. This, he says, will help the two countries exploit the full potential of the deposit, which stands at 55 billion litres. The value of the gas reserves is currently estimated by experts at around $14.3 billion.

“Our negotiations with DRC are progressing well. Once we strike a deal, we will be able to generate more than 200MW in a year,” Dr Butare told the East African Community investment conference held in Nairobi recently.

He said that the government was in the process of signing a number of agreements with foreign and local investors to extract the gas. Currently, the country is carrying out two pilot projects expected to generate 50MW of power

In March, Rwanda entered into an agreement with a New York-based ContourGlobal to develop the lake’s gas project. The deal, worth $325 million, will add an additional 100MW of electricity to the country where only about five per cent of the population are connected to the national grid. Worse is the fact that the prices are twice as high as those of other East African nations because of the inadequate supply.

“Lake Kivu possesses a unique methane gas held in solution deep within the lake water. This gas can be harvested for power generation. Extracting the gas will greatly mitigate the environmental hazards associated with a natural release of the lake gases,” Joseph Brandt, president and chief executive officer of ContourGlobal said.

According to Mr Brandt, ContourGlobal will construct and operate a platform-based gas extraction system that will be moored off the Rwandan coast. The gas will be processed and transported by pipeline to the firm’s power plant being developed in Kibuye, Rwanda.

Analysts say the modern technology being used by ContourGlobal in the methane extraction will greatly reduce the dangers associated with it. They say that once a pipe extended into the depths of the lake is installed, water will rise spontaneously. At the surface, the water will evaporate, separating methane from carbon dioxide.

“ContourGlobal has been designing and developing the project for two years and has conducted extensive seabed surveys and methane gas sampling in the lower depths of the Lake. The project will be constructed in two phases with the first phase of 25MW becoming operational in 2010 and the second phase of 75MW going into operation in 2012,” he said.

Prof Wüest says it makes sense to use the gas for energy, especially if the risk of an eruption can be reduced at the same time.

But even as the Rwanda government plans for the epic energy source, poised to be the only one of its kind in the world, scientists are raising a number of issues which could be a controversy to the grand energy project.

One of them concerns the depth at which the degassed water should be returned to the lake so as to prevent disruption of the stratification.

Also under debate is whether at least some of the carbon dioxide can be piped back into the deep water, so that greenhouse gas emissions to the atmosphere from methane exploitation are kept to a minimum.

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