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 Ashwin Kumar Dec 3, 2012 01:03  |
Thanks for the proposal. Is there data from the ConocoPhilips trial that can be used to evaluate such a scheme?
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 Andrew Lockley Dec 3, 2012 06:37  | Proposal contributor
I'm unaware of this at present. However, the ConocoPhilips trial is not the only technology available. Heating or depressurizing (lifting) the clathrates are alternatives. There are several trials around the world of clathrate extraction technologies. The CP trial is however useful as it leaves strata intact, and sequesters CO2 during extraction.
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 Michael Maccracken May 3, 2013 03:43  |
The notion of extracting the clathrates (presumably to be combusted, turning the methane to carbon dioxide and reducing its potential influence on the climate by a large factor) would seem to be more about mitigation than geoengineering. While it would waste the potential energy value of the clathrate, might it be that a more geoengineering like option would be to find organisms that one could help spread or inject into the melting muds above the clathrates that would consume the methane? Introducing biological organisms is, of course, frought with potential complications, but in that clathrates are not right at the surface of the sediments, it would seem to be an interesting question about whether this is because clathrates in those layers have long ago melted and released their methane or there were/are organisms in the sediments just waiting to consume the methane as the temperature goes up about the clathrate freezing point? That bubbling is occurring might help to answer this if we can determine how much is methane and how much is CO2 (and in doing so accounting for any uptake of the gases on the way up as a result of solution in the waters).
As another possible alternative to extracting the clathrates, might it be possible to derive energy by combusting/oxidizing them in place? Presumably one could do this by introduction of oxygen and raising the temperature to a suitable level. Would not introduction of oxygen be far simpler than extraction of blocks of clathrates? Or perhaps do this in part in order to melt other clathrates and pipe that gas to the surface instead of trying to extract solid blocks?
It would seem that a bit more thought about this idea is needed.
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Andrew Lockley May 3, 2013 04:32 | Proposal contributor
I would argue that flaring of clathrates which would otherwise vent into the atmosphere is definitely geoengineering. It's not an anthropogenic emission (other than as a consequence of AGW), so it's not 'mitigation' per se.
There's no real need to alter the biology of the sediment/water column over the clathrates. Where there's methane and oxygen, methanotrophs will tend to follow. Generally, the water column does a better job than does the sediment column, as it's better oxygenated and better mixed.
It may reassure you to know that I've already considered many of the issues you've raised.
It would potentially be possible to combust the clathrates in situ, by pumping down oxygen. However, it's likely simpler just to heat the clathrates to get them to give up the methane, if it's not practical to lift the material. For clarity, there's no reason to raise it in 'large blocks'. It would be far simpler to grind the material and raise it in a suction hose.
Interestingly, CO2 can displace CH4 from the clathrate lattice, so it may be possible to recover the methane without disrupting the matrix. Whilst any CO2 injected would be just as vulnerable to the loss of the matrix as would the methane, the effect on the climate resulting from a later uncontrolled release would clearly be less significant.
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 2013geoengineeringjudges 2013geoengineeringjudges Jul 10, 2013 12:42 |
Thank you for sharing your ideas and for the work invested to create this proposal. Your proposal has been considered carefully by the judges, and while the proposal has interesting ideas, and we appreciate the response to questions that were raised, the scheme appears more closely related to mitigation than geoengineering. We do, however, acknowledge the point made by you in comments that flaring of clathrate that would otherwise vent into the atmosphere is geoengineering. Another important issue to be addressed before such a scheme is considered a viable approach to geoengineering is to be able to identify deposits that are sufficiently probable to release methane and thus where the expected consequences of leaving the deposits intact are significantly worse than consequences of mining and burning the methane to release CO2.
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