Gases, mainly CO₂, CH4 and H₂S, accumulate due to biogenesis in deep water up to 485 m. Gas in solution after hundreds of years is trending closer to saturation, contributing to Lake Kivu’s dangers. Lake saturation means the carrying capacity of dissolved gas is fully loaded. Any over-accumulation threatens an imminent limnic eruption.
The dissolved gas volume is almost as large as the 500 cubic km of the lake itself. This will mostly release like a giant geyser in less than a day. In Lake Kivu’s case this can be catastrophic to all life forms in the lake environment, where millions of people live today near the shores.
No. An eruption, occurring at Lake Nyos in Cameroon in 1986, caused 1746 casualties. Another happended in Lake Monoun. As Lake Kivu is 10,000 times larger, millions of deaths follow if we do not prevent it.
So Lake Kivu’s dangers relate to its huge inventory of gas, so the consequences can be over 1000 times larger. A dense cloud of gas will fill the valley to a depth of 100 m or more. Anyone caught inside the cloud will be asphyxiated by the lack of oxygen, or more quickly poisoned by the released hydrogen sulphide content of 2000 ppm.
Yes. The natural processes that create the biogas (methane) and co-products carbon dioxide and hydrogen sulphide have operated for thousands of years. It’s a near perfect environment for this to happen. So it’s not just about stopping gas generation, but about reversing any more accumulation to reduce the danger.
The “trigger” gas is methane as it’s much less soluble. Its 25 times higher partial pressure than CO₂ increases the eruption potential disproportionately. If one harvests methane, one can prevent an eruption. But the key to harvesting gas and preventing an eruption lies in how it’s done, in compliance with the rules. Doing extraction the wrong way can bring on a disaster even more quickly.
We now know that there are several wrong ways, and perhaps only one right way. The difference lies in two main areas; (1) Is enough of the methane removed from the lake in the extraction process? (2) Does the process destroy or preserve the natural safety mechanism of the lake that keeps the gas contained in deep water?
We need to do the right thing, harvesting methane for commercial reasons to make the lake safe, in a way ensuring continued safety. The alternate to commercial production would cost billions and would never get funded.
One can calculate when the lake would be certain to erupt simply, by following the trends. But the trend is changeable. We can even reverse the trend by our actions. Changes in nature can also vary the trend. Nature governs new gas formation; i.e. how fast or slow is like growing a crop.
Algal growth in the shallow waters depends on nutrients and oxygen. Wind and rain govern oxygen levels, with seasonal variation. But little -used agricultural fertilizers partly govern nutrient levels. Even more impactful is gas extraction bringing up deep water. It is N and P-rich, depositing it in the Biozone above 60m. Therefore algal growth rates can double or more.
There is five times more volume of CO₂ in the lake than methane. About four times as much comes into the raw gas from older, simpler extraction methods. More advanced extraction techniques produce less. But in both cases we must water-wash the gas to remove CO₂.
The whole balance is important. It’s not only important to retain CO₂ deep in the lake, where it is safest, but it has a role in driving the extraction process. CO₂ washed out of the produced gas into shallow water would be better to return to depth instead.
It can be a huge problem, but it has the potential to become a giant climate benefit. The big gas emission problem seems inevitable. The lake saturation is trending to cause a huge eruption in about 50 -70 years. An eruption can release as much GHG as the United States in a year, anywhere between 2-6 gigatons of carbon, on any single day.
How then can we benefit? It is prevention of what is otherwise going to happen, but with some great side benefits. Those benefits include providing cheaper, cleaner, carbon-negative energy to the region.
As it stands we seem destined to see it happen in plus/minus 50 years. But the known, unpredictably-timed potential for a new volcano or a seismic rift can pre-empt that scenario by decades. This scenario can trigger a major lake eruption any time from now. In one of the most active volcanic and seismic areas on the planet, this is an ever-present risk. However, the longer such an incident delays, the more severe an eruption could be as the gas inventory builds.
Over time, the reason for and importance of developing Lake Kivu has changed. At first it was about filling an urgent need for power.
Recently it has become more focused on reversing climate change.
But overshadowing all of that, and potentially far more newsworthy, will be the humanitarian impact of a lake eruption. Millions of people could lose there lives on that same day. If caught in a toxic cloud in the dead of night, people would be defenceless.
With the best of safety alarms, with sirens warning people to get to high ground above the gas cloud, many people will not make it. Prevention is far better than any cure.
The lake has become a special case in academia, dating back to the 1930s. It would not surprise if more PhDs and Masters degrees were awarded on this body of water than nearly every other one. It is a unique lake with uncommon characteristics. You will find many papers in the EAWAG faculty, in Kastanienbaum on Lake Lucerne in Switzerland.
Blog posts on this site describe and refer to more papers.
The expertise comes from academia, consulting and the engineering world contributed to the large body of knowledge and to the drafting of the rules for use of Lake Kivu. Eawag provided experts on the lake itself to the pro-bono Expert Group.
A recent paper published in Elsevier’s Science Direct was written by two members from COWI and Hydragas, in the Expert Advisory Group for Lake Kivu Development. It was published in January 2020. It speaks in great detail about Lake Kivu’s dangers and the solutions.
For the long lead time to developing a solution to Lake Kivu’s problems, that is a tough one. This is the province of scientists in the pursuit of knowledge, perhaps the publishing of one’s theory or invention. It can’t be for quick money. Most involved here earn little.
Now that’s where latecomers may have the advantage. They don’t have to spend millions of their own funds to pursue the ideas, experiment with solutions or to volunteer as an expert. In fact they clearly don’t have to commit the proverbial 10,000 hours to become an expert or the owner of a valid solution. They can wait, see who has it right, do some due diligence and then perhaps invest there in a fantastic opportunity. Lake Kivu’s dangers should not only be known by then, but their mitigation should be embedded in the solution
The best solution that comes out for the extraction process is, however, incredibly valuable. Beyond bragging rights of having resolved one of the world’s intractable problems, there are huge potential commercial rewards. Any company that gets to that position is therefore a candidate biotech unicorn.
The best solution can extract up to $60 billion in revenues from the lake, with >80% FCF and high returns. The efficiency of extraction and the recovery of available gas are vital in turning a non-profit into a super profits earner, through smart and world-leading technology.
No. At this time there are two methodologies for claiming carbon credits. First is the simple replacement of diesel with clean fuel, that counts for about 7.5 Mtpa carbon. The alternative biogas emits 1.19 Mtpa.
Secondly, but much more significant is the prevention of an eruption that would emit 1.9 Gigatons in a one-off event, calculated at 28 tons CO₂ per ton methane. Calculated at 87 t/t, the one-time carbon emission is 5.9 gigatons in a day. That number is close to the USA’s annual emissions of 6.9 gigatons in 2014. The value of these carbon emissions averted is huge; at just $30/ton, the value ranges from $60 – 175 Billion.