RUTSIRO, Rwanda (AlertNet) - The deep waters of Lake Kivu harbour a silent and invisible threat. Vast and growing quantities of methane and carbon dioxide, generated by volcanic activity, are trapped at the bottom of the lake. If they were to escape, the results could be deadly for the millions who live and work around Kivu’s shores.
Now the Rwandan government is pushing forward with a plan to extract the methane, hoping to reduce the risk of an uncontrolled release of the gas, and to use it to generate electricity for a country desperately short of power.
But the scheme is raising concerns among environmental safety experts who fear it may not do enough to lower the risk of a disaster, and among residents who worry that a mistake in the process could bring catastrophe upon them.
Lake Kivu, which straddles the border between Rwanda and the Democratic Republic of Congo, covers an area of about 2,700 square kilometres (1,040 square miles), divided roughly equally between the two countries. According to a 2010 Rwandan government study, the lake contains some 55 billion cubic metres of methane gas, trapped at the bottom of the lake by the pressure of the water above.
That volume of gas, if burned, could produce enough energy to power much of Rwanda for close to 70 years, experts predict.
The lake also harbours even greater quantities of carbon dioxide, generated by the same volcanic activity.
While trapped deep underwater, the gases cause no immediate problem. But an undetected leak of methane or of carbon dioxide could result in an explosion or asphyxiation.
GHOSTS OF LAKE NYOS
In an infamous 1986 incident, carbon dioxide bubbled up spontaneously from deep within much smaller Lake Nyos in Cameroon, forming an invisible cloud that moved across the land, killing more than 1,700 people.
Both carbon dioxide and methane constantly seep into Lake Kivu and other smaller lakes in the region through underground vents linked to two active volcanoes, Nyiragongo and Nyamuragira.
Officials say that extracting methane could reduce the overall amount of the gas in the water, improving safety, while the methane itself could be burned to generate as much as 400 megawatts of electricity for 70 years, which would allow this Central African nation of about 11 million people to reduce its reliance on costly and polluting diesel-powered generators.
Just 14 percent of Rwandans currently have access to electricity, according to the government, which aims to connect half of all schools, health facilities and administration offices to the national grid by the end of this year.
Exploitation of Lake Kivu’s gas reserves is viewed in Rwanda as key to catalysing economic growth. Hydroelectric power generation, which until the last decade provided most of Rwanda’s electricity, has been affected by falling water levels in the country’s lakes.
Many of the three million Rwandans who returned to the country after the 1994 genocide settled around the lake to farm the land, moving into and draining wetlands that once fed the lakes. The government has since 2007 moved to relocate some of them and try to rehabilitate the wetlands, but with limited effect.
The first phase of methane gas exploitation began in 2004 as a joint venture between Rwanda and the Democratic Republic of Congo. In March 2009, the Rwandan government signed an agreement with U.S. energy company Contour Global for an investment of $325 million to expand the project.
The KivuWatts project uses two barges moored in the middle of Lake Kivu to extract methane from 300 metres below the surface. The gas is then piped onshore to two plants, where electricity is produced.
Although only 3.6 megawatts of power is so far being generated, Rwanda’s minister for energy and water, Emma Francoise Isumbingabo, estimates that extracting a million cubic metres of methane could increase the country’s power output to more than 100 megawatts by the end of 2012, about one-and-a-half times the current capacity of 68 megawatts.
“In the past 17 years, Rwanda was left behind in the exploitation of renewable. But now something is moving, maybe at a slow pace but investors have learned to be patient,” Isumbingabo said.
Some experts have expressed concerns that the project is not proceeding fast enough to reduce the overall levels of methane in the water, and say that the technology being used may not be sophisticated enough to guarantee against an unintended release of methane or carbon dioxide.
“It is amazing that seven years on, with the installation of two plants in the middle of Lake Kivu, the risk remains high with the toxic gas which could spark the worst environmental disaster,” said an environmental researcher from the Kigali Institute of Science and Technology.
Rwandan authorities have now initiated discussions with donors including the World Bank and the African Development Bank to sponsor an expansion of the project. Rwanda and the DRC hope to extract enough methane in a joint project to generate a further 200 megawatts a year of power by 2015, most of it for export to other countries.
Companies from Canada, South Africa, the United States, China and Sweden have also been consulted about possible large-scale exploitation of the gas.
Some lakeside residents, meanwhile, complain that the project has not yet given them the benefit of improved electricity supplies. They also worry about the potential for the gas extraction to cause methane or carbon dioxide contamination of the water that they drink or water where they catch fish.
“These waters look pretty clean, but when tapping the hazardous gas to generate energy, these experts will also need to make sure that water samples are tested every time to control any possible risk of contamination,” said Emile Mungarurire, who owns a small business in Rutsiro, a district in western Rwanda bordering the lake.
The potential health effects of methane contamination of drinking water remain unknown, but are a growing concern in countries including the United States, where “fracking” – a method of extracting shale gas – is leading to methane contamination of some drinking water wells.
In Rwanda, some analysts view the methane extraction expansion plans and the participation of foreign investors as indications that the worst fears of project critics have been misplaced.
“Methane gas power is usually among the most warmly welcomed green options in Rwanda,” said Alex Kabuto, director general of the KivuWatt project.
“The purpose of the project is not only to combat power problems in the country but also to address dreadful things that could result from the killer lake,” he added, referring to the potential for a spontaneous release of hazardous gas.
Apart from improved access to power, some Rwandans say they are looking forward to the project’s potential economic benefits.
In Rutsiro, Emile Mungarurire said he hoped that methane gas plants would be built nearby, providing a much-needed boost to the impoverished remote areas on the shore of Lake Kivu, where some homes stand abandoned by villagers who have left looking for work elsewhere.
“Residents and neighbours were largely happy when we learned about the launching of methane gas extraction,” he said. “Electricity is still a precious commodity here.”
Aimable Twahirwa is a science journalist based in Kigali with a special interest in climate-related issues and agriculture. This story is part of a series supported by the Climate and Development Knowledge Network.