About two million people live in the valley surrounding beautiful Lake Kivu in east central Africa, and some of them – or all of them – could be killed
by it almost instantly. That is the concern of some scientists who have studied Lake Kivu as well as two other lakes that have already experienced a
gas eruption. Ironically, it is Lake Kivu's deep-water reservoir of dissolved methane gas that will soon be the catalyst for positive change, as the
big news in Rwanda now is that an American company, ContourGlobal, will soon be extracting 6.4 million
standard cubic feet of methane per day from the lake to fuel an electrical plant it will build in the picturesque lakeshore town of Kibuye.
Lake Kivu (pronounced kee'voo) has a surface area of 1,040 square miles, and is located on the border between Rwanda and its war-torn neighbor to
the west, the Democratic Republic of Congo (DRC). Kivu's maximum depth of 480 meters ranks it as the 15th deepest in the world. However, at the bottom
of this beautiful lake – beginning at a depth of about 300 meters – lies a formidable potential for disaster: the lowest layer of water contains 55
billion cubic meters of methane and 250 billion cubic meters of carbon dioxide (CO2).
Lake Kivu is the largest of Africa's three "exploding" lakes. Although they may not think about it much of the time, all two million people in the
Lake Kivu basin live with the possibility of sudden death by asphyxiation if the lake experiences a seismic disturbance great enough for it to
"overturn" with a lake-sized burp or explosion, an event scientists call a limnic eruption. If the lake releases its reservoir of deadly CO2, this
heavier-than-air gas will spread outward and displace the normal oxygen-containing atmosphere. After a few minutes, people and animals engulfed by the
CO2 would die of asphyxiation.
Two million is a lot of people: it is roughly the population of Kansas City and its suburbs or the entire Orlando metropolitan area.
Theoretically, if even half of the lake basin's current population were to perish after a limnic erruption – one million people in the Lake Kivu basin
instead of two million – it would rank in the top three most deadly naturally disasters in all of recorded history, the other two being floods in
China.
This is not without precedent in modern times. In fact, it's a phenomena that captured scientists' attention only in recent decades. In 1986, in
the west African nation of Cameroon, LakeNyos, a crater lake, had a limnic eruption believed to have been precipitated by a landslide. An estimated 80
million cubic meters of CO2 rolled down the mountain, quickly and quietly suffocating 1,746 local inhabitants. Dr. George Kling of the University of
Michigan, an expert on the exploding lakes, described the deadly CO2 rising out of this lake like beer foaming out of a shaken bottle. Since the Nyos
eruption, Dr. Kling and other scientists have focused their attention on Lake Kivu, which is 3,000 times the size of Nyos and contains 350 times the
amount of gas. Scientists have estimated that the volume of gases has increased as much as 30 percent in just the past 30 years.
Fossil evidence has revealed several incidences of massive biological extinctions in the course of thousands of years, leading scientists to
believe that this has happened before and will happen again...unless, of course, mankind intercedes.
That's where New York-based ContourGlobal, its investment partner Reservoir Capital Group, and its engineering partner Antares Offshore come into the picture. ContourGlobal, through its new subsidiary, Kivuwatt
Ltd., secured a 25-year agreement with the government of Rwanda to extract methane from Lake Kivu and to then sell the electricity it makes back to
Rwanda's power agency, Electrogaz. Phase one of the project – a floating barge, gas separation equipment, and a power plant – are now in the process of
being assembled and scheduled to be completed by this time next year. After approximately six months, ContourGlobal KivuWatt would most likely proceed
with Phase two, the addition of three more gas extraction platforms to bring the electric power plant to its full capacity of 100 megawatts.
Bill Fox, P.E., who is the project manager for KivuWatt, notes that it is the methane gas dissolved in the depths of the lake that is considered
to be more unstable and therefore most troublesome with respect to preventing a lake turnover. The gas separation technology they will use is not new
by any means – it is very similar to the process used in the oil and gas industry. However, it has been uniquely adapted for the proportions of methane
and carbon dioxide that are dissolved in the depths of Lake Kivu.
Mr. Fox describes ContourGlobal as an energy company that operates in niche markets, preferring projects with a favorable impact on the
environment. The company looks to adapt technology for its own purposes, as it has done in working closely with engineers at Houston-based Antares
Offshore, the company it hired to design the platform-based gas separation equipment for the Kivuwatt project.
According to Mr. Fox, the barge and separation vessel will be moored 13 kilometers from shore, and, like an energy company that taps an underwater
oil reservoir from a platform, what travels up the vertical pipe (called a riser) is a mixture of oil, natural gas, water, etc. The KivuWatt barge will
have four risers produced of rigid, high density polyethylene (HDPE) that will reach a depth in the lake of 355 meters. Mr. Fox explains that the huge
water pressure that deep in the lake will help propel the gas-laden water upward in the riser, and as the water travels upward, it will experience what
he calls "gas lift" as the methane and CO2 begin to be released from solution and will rush upward as a mixture of water and gas bubbles.
The long, tubular separation vessel beneath the barge will work like a propane tank, he says, and the engineers who designed the setup have
calculated that the de-gassification "sweet spot" for the depth of the separation vessel is 20 meters below the barge and water surface. At that
particular depth and pressure, there will be an optimization of the separation of methane and CO2 from the water. Between 75 and 85 percent of the
methane will be released from the water and it will continue to rise up to where it will travel across to the power plant in one flexible reinforced
thermoplastic pipeline (RTP). This horizontal pipeline will be suspended 10 meters below the water's surface, tethered to the lakebed by concrete
anchors and marked by buoys. The de-gassed water, carbon dioxide, and the significantly smaller amount of methane will be piped back downward to a
depth of 240 meters and safely discharged in a stratum of the lake that sits above the deep, gas-laden resource zone.
According to Mr. Fox, Lake Kivu is a "slower-responding lake" compared to the two lakes in Cameroon that experienced limnic eruptions in the
1980s. While KivaWatt's phase one operation does not vent or disperse the accumulation of CO2 from Lake Kivu, he would not rule out the possibility
that it could be a component of the second phase installation. Ideally, Mr. Fox would like to see the CO2 captured and put to some use.
Logistically, the barge itself is now being built at the shore by a prominent Kenyan civil engineering and transportation firm and is expected to
be completed in April 2011. It will then be towed out from shore 13 kilometers to be outfitted with the risers, separation vessel, and coiled pipeline.
The flexible gas pipeline would otherwise float on the water surface, but suspending it 10 meters below will prevent interferance with fishing boats
and other craft. When the three phase two barges are deployed, they will be moored about five kilometers apart and each have their own pipeline to the
shore.
KivuWatt is also carefully timing the completion of the electric power plant to coincide with the first gas arriving on shore to avoid
unnecessary, duplicate plant startup costs.
All together, this venture is projected to require an investment of up to $325 million. By some estimates, the methane resources could supply
Rwanda's energy needs for 400 years. Lake Kivu is, to a significant degree, a renewable resource. The carbon dioxide collects at the bottom of the lake
as it bubbles up from molten rock deposits below the lake bed. Bacteria in the water convert the CO2 to methane. The entire region is known as Africa's
Great Rift Valley, and it is a center of volcanic activity, including Mt.Nyiragongo near Goma, the capital of the North Kivu province (DRC). One
British newspaper, in a feature story on Lake Kivu's deadly gases,
reported that a Swiss study found that the CO2 concentration in Lake Kivu rose 10 percent between 1974 and 2004, while the methane concentration rose
15 to 20 percent. Experts believe the methane created each year would fuel a 100-megawatt electrical plant.
The capital investment in developing Lake Kivu as an energy source represents very good news for Rwanda, which has long been starved for energy.
Even though only five percent of the population has electricity at this time, the country's power provider, Electrogaz, can't supply the full demand of
55 megawatts and must import about 13 percent of its electricity. When the full 100-megawatt capacity of the methane-fueled generators of KivuWatt are
online, Rwanda expects to have a surplus of electrical power that it could export to neighboring Uganda. Plentiful, economical electricity is expected
to not only fuel business and industry as well as raise the standard of living, it should prevent further deforestation of the land as people refrain
from gathering wood to be used for fuel.
Unlike some of its neighbors, Rwanda's top government officials seem focused on progress to some degree. In fact, the World Bank named Rwanda as
the top reformer of business regulation for 2010, and it is the first sub-Saharan African nation to be thus cited for creating more positive business
conditions.
Geographically, Rwanda is a nation that is slightly smaller than Massachusetts, and is dwarfed by its neighbor, the Democratic Republic of Congo
(DRC), whose area is 35 percent larger than Alaska. The most populous city in the Kivu region, Goma, is in the DRC. Goma could be devastated by a
sizable limnic eruption of Lake Kivu, especially since the DRC is the second-poorest nation in the world.
Sub-Saharan Africa is, in general, an economically challenged part of the world. With the influx of investments of technology such as what has
been developed by Antares Offshore on behalf of ContourGlobal, Rwanda may be just a couple of years away from beginning a societal transformation that
access to affordable electrical power could produce. A venture like this is not without risks, however. Several projects have been initiated, but only
one was operating last year. In 2008, another company's platform sank just as it was ready to start production. Some scientists warn that tampering
with the lake's gases might in itself trigger a disaster. Mr. Fox notes that there have been volcanic eruptions with no adverse effects, and the
engineering team worked diligently to meet all guidelines and to address any concerns. As for the opinion of the public of the construction of the
methane equipment and the power plant, "they seem to be looking forward to it," says Mr. Fox. Indeed. Even the tourist reviews depict beautiful Rwanda
in upbeat tones, calling it "brimming with optimism."
