There are HUGE deposits of methane locked up in deposits known as Methyl-hydrates on the sea bed all around the world. To give you an idea of how much, just around the US it's estimated that there are between 110,000 trillion cubic feet and 680,000 trillion cubic feet. The entire worlds consumption of methane currently stands at about 90 trillion cubic feet a year.
This idea is to create an AUV (Autonomous Underwater Vehicle) that goes around 'hovering' the deposits up.
Methyl-hydrates are a 'bubbly' form of ice that can be made to release methane through heating, decompression or adding chemicals such as methanol.
Methane based fuel cells have been developed (see link) that run at 680°C, so as well as a power source, quite a convenient heat source maybe?
Therefore by combining a fuel cell with an AUV and a tank to store 'mined' methane, I reckon that it'd be possible to have a fleet of vehicles on the ocean floor sucking up methane with a single operations/maintenace surface vessel in control.
If the deposits were to become unstable by themselves through global warming, it'd result in a dump of methane directly into the atmosphere, considering methane is a greenhouse gas much worse than CO2 (how comes there's no subscript 2 on charmap?), even though burning it is unsustainable and bad for global warming it's better than waiting for global warming to dump it into the atmosphere - assess the deposits most likely to destabilise and mine them first.-- scubadooper, Aug 05 2004 Direct methane burning fuel cell http://www.nature.c...letype=&dynoptions=Doesn't use recombination. [scubadooper, Oct 04 2004, last modified Oct 05 2004] Not bad. Worth a bun at least. Though it does seem like it's safer to leave the methane where it is, otherwise we're adding CO2 and heat to the atmosphere which will cause more global warming, which will start pulling the rest of the methane out of the oceans.-- Worldgineer, Aug 05 2004 1) Gas-hydrates are usually not found directly on the seabed but under a couple of hundred meters of sediments.
2) Existing AUVs can only run for a day or so, due to ancient batery technology. So you need a ship out there anyway...
3) Where should an AUV store the now destabalised methane, which takes hugh amounds of volume?
4) If you want to collect this tiny fraction of gas-hydrates lying on the seafloor, I would suggest an ROV with a lot of horizontal spacing to the mother-ship and a tube sucking the stuff onboard.
Jack-- JackHide, Mar 27 2008 I assume Methane is cleaner than oil so it's a step in the right direction, and of course the US hates dependency on foreign oil.
It seems that a promising way of releasing the methane is to use CO2.
The main problem with current research on extraction is how spread out the fields are, so I assume this idea is meant to address that problem.-- marklar, Mar 27 2008 Yes, I forgot to mention that the idea of a self-sufficient AUV powering itself with the harvest methane is a very good idea.
But you will just never harvest gas-hydrates with an AUV, due to the volume issue...-- JackHide, Mar 28 2008 I'll harvest them. Where are they?
<holds breath>-- wagster, Mar 29 2008 random, halfbakery