They could flush enough built-up sediment from the many streams feeding into the lake to cause the layers to mix, MacIntyre says. Typically, when water at the surface of a lake is cooled – by winter air temperatures or rivers carrying spring snowmelt, for example – that cold, dense water sinks, and warmer, less dense water rises up from deeper in the lake. Partly in an effort to avert the threat of an eruption, the Rwandan government has a plan to suck up the water from the lower reaches of the lake and extract the dissolved gases. Katsev says that the lake is monitored regularly for signs of upticks in gas concentration, so a sudden upwelling “will not catch us by surprise”. By Anna Boiko-Weyrauch and Rob Hugh-Jones PRI's The World. And if enough methane were released into the air at Kivu, there is the additional risk that it could ignite. For Lake Kivu the gas content is still below saturation, and the risk of an eru p-tion is not imminent. If Kivu were to erupt, says limnologist Sally MacIntyre of the University of California, Santa Barbara, “it would be completely catastrophic”. The murder that drove America to the brink, Time: A love story coloured by incarceration, JD Vance: Trump whisperer turned Senate hopeful, Why second Covid wave is devastating India, Relief and tears: 'Finally we can breathe' VideoRelief and tears: 'Finally we can breathe', Five electric car brands to look out for in China. Kivu is in a seismically active area, so an earthquake could generate waves in the lake that would mix the layers enough to release the trapped gases. The country has very few energy resources of its own, which has helped make it one of the most expensive countries in east Africa to power a home or business. Lake Kivu is a meromictic lake, which means that it has a second, lower layer of high-pressure water that contains dissolved methane and CO2. This isn’t just a theoretical concern. Kivu is in a seismically active area, so an earthquake could generate waves in the lake that would mix the layers enough to release the trapped gases. If the water becomes completely saturated with dissolved gases, any additional CO2 or methane injected into the lake will be forced to bubble out of solution, rise and be released into the air. The dissolved gases are kept in the water by the high pressure at such depths. Almost half of its electricity is generated using diesel fuel, which has to be trucked into the country. The deeper water is also saltier due to sediment raining down from the upper layers of the lake and from minerals in the hot springs, which further increases the density. But there's something else below the surface of the water besides fish. These gases have accumulated over 800 to 1000 years. A much larger methane extraction programme, called KivuWatt, came online in 2015. They use three vessels tied together, and petrol lights at night, to attract the fish and then catch them in the nets suspended below their boats. KivuWatt’s 3000-ton extraction barge, moored 13 km from Lake Kivu’s shoreline, draws the gas-laden waters from a depth of 350 meters. “They take this gas, ship it via pipeline onshore and burn it the way you would burn fossil fuels to generate electricity,” Katsev says. Lake Kivu contains exceptionally large amounts of dissolved carbon dioxide and methane in its deep waters. But at Lake Kivu, circumstances have conspired to block this mixing, giving the lake unexpected qualities – and surprising consequences. Other lakes in the western Rift Valley are rich in fish species. Environmental consultants Sinclair Knight Merz, who reviewed the KivuWatt plans, warned that if it was not carefully operated, it could itself cause an explosion or gas release from the lake. Still, for a lake with that much danger lurking below, any reduction in risk is a valuable step. Something fraught with both risk and promise. If they can continue catching fish, and have electricity in their homes for the first time, that would be a big step forward - and hopefully the risk of a lake eruption will be reduced too. Engineer Augusta Umutoni, who leads the Rwandan government team monitoring the project, rejects this idea, but does worry that the extraction process could change the lake's chemistry. Scientists have found what may be evidence of at least one previous limnic eruption at Kivu that likely occurred between 3,500 and 5,000 years ago, and possibly several more recent ones. Whatever the cause of an eruption, the effect would be the same. The high levels of carbon dioxide and methane in the deep waters of Lake Kivu could cause a devastating limnic eruption if disturbed (Credit: Richard Gray). At least one past eruption discovered in the sediment record appears to have been caused by drought that evaporated enough water from the top of the lake to reduce the pressure at the lower levels and release the dissolved gases. About 1,400 miles (2,250km) north-west of Kivu, a crater lake in Cameroon known as Lake Nyos similarly accumulates and traps large amounts of dissolved gas – in this case CO2 – from a volcanic vent at the bottom of the lake. Experimental stations, seen in the distance, have been set up in an attempt to safely tap the gases in the depths of Lake Kivu (Credit: Richard Gray). Lake Kivu fishermen use different methods of fishing, like for small fish, the method is called isambaza. Mr Barry says the gases will be largely separated from the water, and from each other. This methane gas mining from the bottom of Lake Kivu is an interesting, unusual source of renewable electricity. A methane gas facility on Lake Kivu. "The methane would not spontaneously cause an explosion on the surface. Microorganisms use some of the CO2, as well as organic matter sinking from above, to create energy, producing additional methane as a by-product. RWANDA - Shema Power Lake Kivu (SPLK) of Rwanda is set to produce 15 megawatts of electricity by June this year in its first phase of methane gas extraction from Lake Kivu, the company engineers have said. However, the downside of not producing its gas inventory responsibly can lead to a catastrophe. The harmful gases are expected to saturate the lake in 50 to 200 years, which poses a gas eruption threat … "Underneath the barge you've got what are called risers, and those are basically big straws," says Bill Barry, of ContourGlobal, the New York-based company developing the project. Lake Kivu has been known as the “killer lake” due to huge amounts of biogas trapped under a layer of heavy water containing minerals washed out of the nearby volcanos. However, if nothing is done the accumulating gas will cause a catastrophic eruption in all likelihood within the time span of 100-200 years. Kivu is 55 miles (89km) long, 30 miles (48km) across at its widest point and more than twice as deep as Nyos. About 1,400 miles (2,250km) north-west of Kivu, a crater lake in Cameroon known as Lake Nyos similarly accumulates and traps large amounts of dissolved gas – in this case CO2 – from a … For the people living in the lake’s vicinity, this could become an important source of energy. On 21 August 1986, the lethal potential of that gas reservoir was made tragically evident. Lake Kivu is one of Africa’s strangest bodies of water. The layers can be separated roughly into two regions: one of less-dense surface water above a depth of about 60m (200ft) and, below that, a region of dense saline water that is itself further stratified, says Alfred Wüest, an aquatic physicist at the Swiss Federal Institute of Technology in Lausanne. Dies ist nur durch den hohen Dru… Its unusual stratification and the CO2 and methane trapped in its deeper layers have researchers worried that it could be a disaster waiting to happen. Another possible trigger is volcanic activity under the lake or from surrounding volcanoes, but scientists think the risk of that is low. But we don't yet know how strong, or how frequent they were.". Eruptions can also be caused when something forces the deep water with its dissolved gases to mix with the layers above, reducing the pressure on the gases and allowing them to quickly come out of solution and escape, similar to the effect of shaking a can of soda and then opening it. The higher the pressure, the more gas can be dissolved in the water. As long as it's under pressure, it doesn't bubble. Dissolved within Kivu, which straddles the border of Rwanda and the Democratic Republic of Congo (DRC), are approximately 60 billion cubic meters … KivuWatt, a 26.2-MW power plant in Kibuye, Rwanda, was conceived to help reduce risk of an overpressure gas outburst at Lake Kivu. The lake contains an estimated 256 cubic kilometres of carbon dioxide (CO2) and 65 cubic kilometres of methane. The lake has a length along the dividing border of 98km and at its widest it’s 48km. More than 1,000 people died in 1986 when a lake in Cameroon released a cloud of CO2 that suffocated entire villages. Wüest and colleagues found that from 1974 to 2004 the concentration of CO2 increased by 10%. 3 Lake Kivu is a fresh water lake and, along with Cameroonian Lake Nyos and Lake Monoun, is one of three that are known to undergo limnic eruptions. Video, Surferâs âshockâ reunion with long-lost board, The beauty ideal fuelling an illicit drugs trade. VideoSurferâs âshockâ reunion with long-lost board, The beauty ideal fuelling an illicit drugs trade. © 2021 BBC. The methane it contains is enough to power the region with renewable natural gas (RNG) for 50 years. Durch den hohen Wasserdruck vermischen sich die Schichten in großen Tiefen nur sehr wenig, ab einer Tiefe von 180 m haben die Schichten hohe Verweildauern von bis zu 1000 Jahren. Deep at the bottom of the lake, about 1,000 feet (300m) down, Kivu's water is heavy with dissolved gas. As gas concentrations rise in Kivu’s depths, so does the risk. Climate is also a potential culprit. The chances of such a sequence of events may go up as the planet warms, MacIntyre says. Kivu doesn’t behave like most deep lakes. About 1,400 miles northwest of Kivu, a crater lake in Cameroon known as Lake Nyos similarly accumulates and traps large amounts of dissolved gas — … On 21 August 1986, the lethal potential of … Scientists estimate Lake Kivu contains around 1,000 times more gas than the two Cameroonian lakes, Lake Monoun and Lake Nyos, which both erupted in the 1980s. But the bigger concern at Kivu is the methane concentration, which rose 15-20% during the same period. We have clues it probably has had serious disruptions in the past. Read about our approach to external linking. While a landslide of the scale suspected in the Nyos eruption might not cause enough mixing at Kivu, due to the lake’s size and depth, there are several other possible triggers. Overall Lake Kivu’s renewable gas inventoryis over 12 tcf and growing. Read about our approach to external linking. That would be bad news for Kivu's fish and the human communities that depend on them. Because of its size, Katsev says, Kivu “has the potential for a major, catastrophic limnic eruption where many cubic miles of gas would be released”. More than a dozen seismic stations measure the activity near the lake in real time as well. “Extracting valuable methane from the lake’s depths might trigger an outburst of gas that could wash a deadly, suffocating blanket over the 2 million people who live around Kivu’s shores,” explains geologist Ole H Nielsen on his environmental blog What On Earth. Limnic eruptions can occur for two reasons. Recent data shows the methane concentrations in the lake are increasing. "Right now, we're taking sediment samples," says Prof Hecky. Built out of thousands of concrete and stainless steel, the platform captures methane gas, a rare asset that is shared between Rwanda and the Democratic Republic of Congo. Der Kiwusee weist in seinem Tiefenwasser sehr hohe Konzentrationen an gelösten Gasen auf. Lake Kivu, however, has almost 1,000 times more concentrated dissolved gases than its Cameroonian counterparts, which both erupted in the 1980s. About 14,000 people lived near Nyos at the time of the eruption. The CO2, however, will be reinjected into the lake, partly to avoid releasing a greenhouse gas, and partly because even removing the methane alone makes the lake safer. These sediment bands are “very unusual, organic-rich layers”, Katsev says, that may be the result of eruptions. Join one million Future fans by liking us on Facebook, or follow us on Twitter or Instagram. Relief and tears: 'Finally we can breathe' Video, Relief and tears: 'Finally we can breathe', Five electric car brands to look out for in China. This article originally appeared in Knowable Magazine, and is republished here with permission. They're fishermen's lanterns hanging off wooden boats to attract herring. That's why the project will start small - with just a pilot phase expected to start producing energy from the methane later this year. Lake Kivu contains an important methane gas resource. Video, The beauty ideal fuelling an illicit drugs trade, US jury finds ex-officer guilty of Floyd murder, Bat Out Of Hell composer Jim Steinman dies, UN urges UAE to prove Princess Latifa is alive, Middle East states among world's top executioners, Plan for pills to treat Covid at home by autumn, US to advise against travel to 80% of countries. Climate change is expected to bring more rain to East Africa, and “it’s going to come in the form of more extreme rain events with bigger intervals of drought in between”. There is great interest in Rwanda about the power generation aspect of this project, known as KivuWatt. Nyos is a relatively small lake, measuring a little more than a mile long (1.6km), just under a mile wide and less than 210m (700ft) deep. In 2008, Rwanda launched a pilot programme taking methane from the lake to burn as a natural gas and last year signed a contract to export bottled methane. The 2,400 sq.km lake contains high concentrations of naturally occurring methane gas (CH 4) and carbon dioxide (CO 2), with the highest concentrations at depths ranging from 270m to 500m.The oxygenated upper layer of the lake from the surface to a depth of 60m supports the lake’s biology. Russia’s grand plan to clean its Arctic nuclear waste, How a tropical island recovered from black rats, The Indian megacity digging a million wells, convection in various lakes of the world, including weird outliers like Lake Kivu, enough material to disrupt Kivu’s bottom layers, Wüest and colleagues found that from 1974 to 2004 the concentration of CO2 increased by 10, pump water from the deep layers of the lake, only 35% of the population has access to electricity. Lake Kivu Gas Project - GasMeth - Renewable Energy Lake Kivu Gas Project November-2019: GasMeth Energy (“GasMeth”), the Kigali based Gas Development and CNG business, is pleased to announce the successful completion of a $3.5m Two Year Short Term Loan with the Bank of Kigali. For people who have to travel on the lake for their livelihoods, the danger of gas bubbling up from below is a serious hazard (Credit: Richard Gray). When the gas concentration gets too high, or the lake is hit by one of the regular earthquakes in the region, the gas can be released, posing a threat to the people living in the vicinity. VideoFive electric car brands to look out for in China, The lowdown on the international feature Oscar nominees, Surferâs âshockâ reunion with long-lost board. Lake Kivu's fish are a crucial source of food for the two million people who live around the perimeter. Straddling the border between Rwanda and the Democratic Republic of the Congo, Kivu is one of a string of lakes lining the East African Rift Valley where the African continent is being slowly pulled apart by tectonic forces. The BBC is not responsible for the content of external sites. Deep at the bottom of the lake, about 1,000 feet (300m) down, Kivu's water is heavy with dissolved gas. An unusual set of properties make it an intriguing subject for scientists, as well as a potential source of both peril and prosperity for the millions of people living nearby. Kivu is in a seismically active area, so an earthquake could generate waves in the lake that would mix the layers enough to release the trapped gases. KIGALI (Reuters) - Rwanda said on Tuesday it had signed a $400 million deal to produce bottled gas from Lake Kivu, which emits such dense clouds of methane it … The methane will be piped to the Rwandan shore, where it will be used to fuel a new power plant. Possibly due to a landslide, a large amount of water was suddenly displaced, causing the dissolved CO2 to mix rapidly with upper layers of the lake and release into the air. Video, Five electric car brands to look out for in China, Surferâs âshockâ reunion with long-lost board. Man schätzt, dass etwa 225 km³ Kohlenstoffdioxid (CO2) sowie zusammen etwa 75 km³ Methan (CH4) und Schwefelwasserstoff(H2S) im See gelöst sind (Volumenangaben der Gase in entspanntem Zustand). Bacteria in the lake then convert some of the CO2 into methane. A 2002 eruption of nearby Mount Nyiragongo didn’t bring in enough material to disrupt Kivu’s bottom layers. This process, known as convection, generally keeps the surfaces of deep lakes warmer than their depths. "And we're going to have four of those, and they're going to go 350m (1,148 ft) into the lake.". 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