Comments on: Rwanda Lake Poses Gas Danger, Energy Promise

By: Alain Harelimana

Alain Harelimana — Thu, 16 Feb 2012 09:57:00 +0000

I am happy to see that Lake Kivu is of big interest to
many people, and I appreciate precisions given by experts (Finn, Martin,..) on
the scientific point of views on lake Kivu. I would like to ensure Shannon that
Lake Kivu is at a very stable state now (it is only at 55% of saturation).
Swimmers in Lake Kivu do not need to worry about gas explosion in Lake Kivu now
(2012). If methane gas was not extracted until 2100, then swimmers would fear
for an explosion!! However, we are working on preserving the safety of the lake by extracting methane gas (which
is the trigger element of gas explosion in Lake Kivu because of its high
partial pressure). On the other hand, our
monitoring team is there to ensure that methane gas extraction will be done in
a safe and sustainable way. The Management Prescriptions (MPs) are there to
give guidance on good practices to ensure safety and sustainability of methane
gas extraction and we are committed to find a way of enforcing them. On the
other hand, the monitoring team is there to monitor if there are any impacts of
methane gas extraction on the public and on the environment. From this year
2012, we will be capable of monitoring the physico chemical properties, the
biological states of the lake and we will have an inspection system on
extraction facilities. Concerning the
cooperation with DRC, I wish to inform Genty that the Ministry of
Infrastructure in Rwanda and the Ministry of Hydrocarbons in DRC are working
hands in hands and plan to harmonize their views on the MPs. The 2 governments
are aware that failure of one of the operators (on Rwanda’s site or on DR
Congo’s site) will inevitably affect the common resource.

By: Anonymous

Anonymous — Tue, 14 Feb 2012 11:19:00 +0000

Hello Steve and Anna,
When Augusta Umutoni says the lake is relatively stable, and Martin Schmid that it takes a major event (major input of energy) to cause a limnic eruption, then it is true – for the time being.
And by the way, Steve is right. The danger in case of an eruption has got nothing to do with an explosion. The gas that would emerge from Lake Kivu is not ignitable, but it is heavy, asphyxiating and toxic. If ever happening, such a cloud would be extremely deadly, given that its volume would suffice to cover the entire lake with a cloud more than 100 m (300 ft) thick.
The main question is however what we do to the lake while extracting the gas. It is extremely important to maintain the known density structure in the lake so that also the future generations have the possibility to protect themselves against the ever accumulating gases in the lake. Harvesting the present stock of methane is not enough. Otherwise we would only have postponed but not hindered a future eruption. If gas extraction schemes are allowed to destroy the present density structure, it is most likely impossible for the future generations to protect themselves against the risks of a limnic eruption through commercial gas extraction.
This very short description may open the eyes of the reader to the fact that there are very significant depths in this matter, not covered by Anna’s story. On the level it is at, however it provides a quite good coverage, but it tends to leave behind a little too easy feeling among the readers. There are still significant challenges to be solved.
Finn Hirslund(one of the experts having drafted the rules for safe gas extraction from Lake Kivu also referred to as the Management Prescriptions)

By: Anonymous

Anonymous — Mon, 13 Feb 2012 18:54:00 +0000

Again, possibly another big missed opportunity for the Congo. Did the Congolese government try to get involved (through the Office of the Governor of North-Kivu)?

By: Anna Boiko-Weyrauch

Anna Boiko-Weyrauch — Tue, 31 Jan 2012 13:46:00 +0000

Hello Francisco,
Great question. Actually the CO2 WILL be pumped back into the lake (“redissolved” is the word they use) although at a shallower depth in order to maintain the density gradient.

There has been a conversation among scientists about whether it is better to release the CO2 or re-dissolve it, and until recently it was considered necessary to vent the gas. However, a group of experts finalized guidelines in 2009 to ensure the safe removal of gas and continued lake stability. The 2009 Management Prescriptions say, “More recent and precise analysis of the density control and gas-lift requirements of the lake leads to a policy of more balanced and precise measures to control lake stability and production (page 17).”

Redissolving the CO2 into Lake Kivu won’t pose a hazard, because CO2 contributes “only about 25% to total gas pressure,” according to Lake Kivu expert, Martin Schmid.

Thanks,
Anna Boiko-Weyrauch

By: Anna Boiko-Weyrauch

Anna Boiko-Weyrauch — Mon, 30 Jan 2012 13:41:00 +0000

Hello Steve,
Right now, Augusta Umutoni in charge of monitoring Lake Kivu for Rwanda said that the lake is stable because the layers of water in the lake are of such different densities (like oil and water) that it would take quite a bit of additional pressure for the gas to escape the water pressing down on it.
An earthquake by itself could not trigger an explosion, according to Lake Kivu expert, Martin Schmid at Eawag. He wrote me in an email, “A large landslide within the lake may do so, but only if the lake is much nearer saturation than today, the most possible trigger would be a magma eruption within the lake.”
Mazukus relate to isolated releases of CO2, and are more commonly found in Congo than Rwanda.
Thanks,
Anna Boiko-Weyrauch

By: Francisco Leotte

Francisco Leotte — Thu, 12 Jan 2012 13:56:00 +0000

I suppose the idea would be to release CO2 into the atmosphere rather than pumping it back into the lake after the extraction of the methane?! I know partial pressure of the dissolved gases would change and the lower layer would become slightly more stable yet trying to extract most of the CO2 and releasing it into the atmosphere would be by all means more advisable and constitute an effective solution to improve the lake’s stability. Isn’t this so?

By: hugo sarmento

hugo sarmento — Mon, 09 Jan 2012 14:23:00 +0000

very good piece, scientifically correct. That is rare in our days…

By: Steve Stephenson

Steve Stephenson — Sun, 08 Jan 2012 13:15:00 +0000

Article ignores major issue: without an “explosion” the CO2 in the lake could be released by natural or man-made disturbances similar to Lake Nyos, http://en.wikipedia.org/wiki/Lake_Nyos. The resulting CO2 cloud would blanket the valley and suffocate millions of people and livestock. See http://en.wikipedia.org/wiki/Lake_Kivu.

By: Shannon Fitzgerald

Shannon Fitzgerald — Sat, 07 Jan 2012 22:14:00 +0000

Great reporting about Lake Kivu – I swam there last year – now slightly nervous about possible exposures – fascinating science.