Underwater methane to power Rwanda and Congo

RUHENGERI, Rwanda — Looming above this northern Rwandan town, the jagged peaks of the Virunga Mountains are emblems of both this country’s tragic history and its ongoing rebirth.

Here on these forested volcanic slopes, Gen. Paul Kagame secretly rebuilt his routed Rwandan Patriotic Army, a rebel force that would eventually seize power in the wake of the 1994 genocide.

Here, 16 years after those horrors, thousands of tourists come annually for a glimpse of Rwanda’s famed mountain gorillas.

And here, scientists are working to harness heat inside the earth, as well as methane gas in Lake Kivu 30 miles away, to generate power for Rwanda.

“From surface studies, we believe Rwanda has big potential for the development of geothermal power,” said geophysicist Stephen Onacha, a consultant with the Rwandan Ministry of Infrastructure. “We’re excited, because geothermal has many benefits in terms of operating costs and the environment.”

Rwanda is now starved of power and determined to use green technology to tap the volcanic resources of the Albertine Rift, the western branch of Africa’s Great Rift Valley.

Rwanda’s available electricity capacity is a scant 69 megawatts, a fraction of the power produced by a single coal-fired plant in the United States, according to data from the Ministry of Infrastructure. While Kigali, the capital, is well-lit, Rwanda's rural areas are left in the dark at sunset. Overall, just 6 percent of Rwandan homes and 10 percent of primary schools are connected to the electricity grid.

This limited supply of power means high costs to consumers and business — a drawback to investors the government hopes to lure into the country. In addition, nearly half of Rwanda’s grid capacity is now generated from diesel fuel — which is dirty and expensive in a landlocked nation.

Based on existing studies, Onacha said Rwanda might eventually generate 300 megawatts of geothermal power, which could significantly reduce the country's reliance on diesel.

Geothermal power — produced by turbines driven with steam extracted from the earth’s interior — emits just 1 percent of the carbon dioxide released from burning fossil fuels and if properly maintained is a fully renewable resource. In nearby Kenya, where geothermal energy is well developed, there is even a plant inside Hells Gate National Park, an arrangement Onacha suggests might be replicated in the Virungas park.

“It could be a nice complement to existing tourism,” he said. “People could visit both the plant and the park — as long as you take care that the gorillas don’t play in the hot water.”

Though harnessing geothermal power will take time, mainly because of the high costs of exploration, another large-scale project linked to Rift Valley geology is significantly further in development.

Dissolved at the bottom of Lake Kivu, located between Rwanda and the Democratic Republic of Congo, are an estimated 14 trillion gallons of methane gas and 60 trillion gallons of carbon dioxide, chemical byproducts of the region’s ongoing volcanic activity.

As early as 1962, methane — the principle component of natural gas — was extracted from Kivu and used to power the lakeside Bralirwa brewery, maker of Rwanda’s ubiquitous Primus lager. In recent years two pilot projects have attempted to harness the gas — less harmful to the environment than coal or oil — including a government-run scheme that is now producing 2 megawatts of power.

This is nowhere near the 700 megawatts Rwanda estimates it can generate from methane over a period of 60 years. Yet a parallel venture, launched through a concession agreement with New York-based developer Contour Global, promises to inch closer. Beginning with an initial phase of 25 megawatts, the project, known as KivuWatt, plans to deliver 100 megawatts of power though 12 gas generators — driven by methane extracted more than 800 feet below the Lake Kivu's surface. At present, Contour Global is building a platform and barge for extraction — the initial step in a first of its kind endeavor the company estimates will cost more than $500 million.

“This is unique in the world,” said Augusta Umutoni, head of project monitoring in the Ministry of Infrastructure. “We’ve long been aware of the lake’s potential, but since there is no precedent, it’s taken a long time to get off the ground.”

Though some worry about the environmental repercussions of altering Lake Kivu's chemistry, many familiar with the project, including Contour Global Country Manager Jarmo Gummerus, say the venture will help Rwanda and neighboring Congo avert disaster. According to Gummerus, if nothing is done, a growing concentration of carbon dioxide would eventually trigger what’s known as a limnic eruption: a deadly pocket of invisible gas that could rise above the surface and asphyxiate more than 2 million residents of the lake area.

This would not be a first: In the 1980s, two smaller “exploding lakes” in Cameroon overturned in such a manner, killing more than 1,800 people. Though the threat in Lake Kivu is not imminent — experts predict the carbon dioxide could reach saturation levels within 200 years — but it could erupt earlier if activity from one of the Virungas’ two active volcanoes were to stir up the lakebed.

As methane is extracted, Gummerus said, KivuWatt will also remove carbon dioxide, which will be re-injected into the lake at depths shallower than it is currently dissolved, lowering gas pressure to a degree where eruption would be impossible.

It’s a process that promises to neutralize the Albertine Rift’s greatest liability while reaping one of its many assets.

“We believe we have a robust design,” Gummerus said. “Both for power generation and for the safety of those living around the lake.”