KivuWatt: exploitation of the lake methane (ContourGlobal)

[moinsdewatt]

Gas, very special!

Kigali uses ContourGlobal to convert methane from Lake Kivu into electricity

Ecofin Agency 28 May 2014

The Rwanda ContourGlobal will rely on to produce electricity from methane mixing and CO2 that contains Lake Kivu, on the border between Rwanda and DR Congo, reports AFP.

The American company, in this context, signed a concession 25 years with the Rwandan state and EWSA, public company for production and distribution of electricity in Rwanda.

It will operate some km60 3 methane and about 300 km3 carbon dioxide contained in this lake 2370 km2 is "the only one in the world where this gas can be commercially exploited," we learn.

"There is no drilling, the gas is pumped into the lower layers of the lake that are saturated with methane" explained Yann Beutler, head of KivuWatt pilot project that already provided 2MW electricity from the methane lake. "From the moment the water rises to the surface, it releases gas and the gas is collected," added Mr. Beutler, stressing that the methane is extracted from the mixture and sent to a plant on the shore, while the CO2 be dissolved in water and returned to the depths of the lake.



The KivuWatt pilot project required an investment of nearly 200 million, financed by about 45% by loans from international institutions for official development assistance, reports AFP.

http://www.agenceecofin.com/gaz/2805-20 ... lectricite

[Christophe]

original project but I'm not sure at all that this is only possible in the world!

But I prefer that these methane hydrates are exploited in this way rather they are released naturally in the atmosphere!

By cons, Lake Kivu is 240m average depth, cf.
http://fr.wikipedia.org/wiki/Lac_Kivu

I did not think that the hydrates formed at shallow depth if: http://fr.wikipedia.org/wiki/Hydrate_de_m%C3%A9thane

Methane hydrates are stable at high pressure and low temperature (see "stable conditions" curve magnitude: 35 0 to bars ° C) 4.

However, the methane hydrate form is solid at temperature and pressure conditions much less drastic than those required to liquefy the same gas; thus, pure methane in pure water form hydrates from about 380 m in fresh water 4 ° C (maximum density of water), about 440m in salt water to 35 g / the 5; for comparison, methane is liquefied at -161,5 ° C (111,6 K). Water ice fills for methane the function of a kind of molecular sponge, thereby stabilizing the methane in solid form. Thus, methane hydrates may form at temperature and pressure conditions encountered naturally on Earth, specifically, in the basement of the land surface in cold regions on the one hand, under the ocean side share.

So:

Edit: the max depth is 485m therefore compatible with gas hydrates

[chatelot16]

exactly! when there is gas in the water it is better to take it before it is lost!

and it is easy in the case of this lake, it is kept in water with a pressure depth: just pump the water for gas: no risk of pollution

in the case of methane hydrate in cold countries is more complicated but I'm sure there are some who seek!

[Christophe]

Yes, but in what form is methane in the Kivu then?

Reply :

http://fr.wikipedia.org/wiki/Lac_Kivu#M.C3.A9thane

[chatelot16]

So:

therefore could make or open pit in some cold countries: dig for loading isothermal truck ... and dump truck in a rechauffge system which recovers the gas

Mine only operate in winter and in summer to reseal not make the sun from the gas

[Christophe]

Yes we could!

We could also combine that ratisseraient invent the ocean floor ... (this will certainly one day)

So if I understand, even if it is physically possible that hydrates in Lake Kivu methane is trapped in layers:

Unlike known double natural diffusion or studied laboratory systems here the CO2 and dissolved CH4 contribute significantly to the stratification layers, with Uncommon balances between the stabilizing effect of dissolved salts and the destabilizing effect of temperature. Thick layers of mixed 0,48 m on average appear to still be in a state of active convection, "the average thickness of interfaces (0,18 m) is surprisingly constant and independent of the stratification scale. The vertical heat flux correlate well with temperature measurements across interfaces "13.

[Christophe]

This reminds me of a documentary I saw it years ago on the Bermuda Triangle: some mysteries (boat disappearance but also aircraft) could be explained by sudden release of large pockets of gas (methane, CO2 ...)

[chatelot16]

strata in the water are still more convenient than in the ground: just plunge a pipe has good depth and pump, and the surface separate gas and water

the majority of the gas is naturally separated when there is more pressure: it can bring out what little is left by putting water in depression

it is not only methane but also CO2

must it be redissolved CO2 before rejecting the water? CO2 is it favorable to the conservation of methane? in this case it would be important to put the CO2 back in order to avoid that the methane goes out en masse because of the modification due to the exploitation

interressante other info on the origin of this gas: it says that the bacterium converts CO2 and hydrogen into methane

it confirms me hope of ameloirer digester efficiency by adding the CO2

[dirk pitt]

but, potential 60km3. we do not know the recovery rate. but even if it was 100%, it would never make that about 1 week of global gas cons ..... (if my table corner calculation is accurate)
it is really scraping the bottom of the barrel to satisfy our energetic addiction.
well, it's true that for Rwanda, it's probably a much bigger share of their cons, but it was to put things in perspective.

[chatelot16]

of course, this is just a lake, a drop of water has the global scale, but for those who are next to what is currently a danger: the possibility of a catastrophe if a geological phenomenon wagging the bottom

exploit this gas will be a good local resource, and the exhaustion of this resource will remove the danger