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 Ashwin Kumar Mar 4, 2013 02:35  |
Thank you for the proposal!
1) You write that: "In some cases, the plant may have a net energy output." How would you characterize when such cases are likely to occur?
2) Does the proposal envision plants at locations where methane is captured? What would be done with the energy produced? How would you compare with the alternative of transporting methane?
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 Andrew Lockley Mar 5, 2013 01:05  | Proposal contributor
The 'net energy output' depends on the concentration of methane, but the usability will depend also on the local environment. Self sustaining combustion can exist in gas streams at surprisingly low concentrations, but the output is low-grade heat. Without a use for this heat, it's not a productive output. The production of steam for electricity generation requires higher-concentrations streams, giving hotter combustion, or the use of a support fuel. Furthermore, the investment in generation plant and transmission infrastructure may not be recouped, even with concentrated streams, due to location constraints and limited power output. So the economics and physics of the definition of energy output differ substantially.
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 Michael Maccracken May 2, 2013 06:36  |
Would it make the effort more efficient to add wind vanes to the shaft of the diesel to help give a bit of extra torque?
As I understand the state of technology, there is a high enough methane concentration in cattle feed lots to make it economical to use as a fuel for a diesel/turbine engine (except that combustion can generate unwanted nitrogen oxides) or to even decompose it using a fuel cell (the problem for the fuel cell being the other contaminants in cattle feed lots). In high latitudes, the methane might be quite pure, and the concentration is at least slightly elevated on average, so in the region of a source, might the concentration be high enough to use a fuel cell to decompose the methane while generating enough power to earn the income for the effort?
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Andrew Lockley May 3, 2013 03:49 | Proposal contributor
Originally, I did look at using wind energy to power such devices. This is useful in remote areas. However, a mechanical link may not be viable - as wind speeds are higher well above the ground than they are in the turbulent layer where emissions are highest. (If mechanical transmission to the ground was practical, I assume wind turbines would use a belt or shaft transmission to a ground-level gearbox or generator.)
As regards a fuel cell, it's potentially possible - but there's unlikely to be any market for the energy in remote permafrost regions.
In general, these techniques need to cope with very dilute streams - so energy recovery may be impractical generally. I'm unsure as to the efficacy of fuel cells in treating dilute streams. However, were it an attractive method, it might have been tried for coal mine ventilation air already.
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 2013geoengineeringjudges 2013geoengineeringjudges Jul 10, 2013 12:02 |
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 responses to questions that were raised, it is unclear how much of methane release from natural sources this scheme would address and whether it can be developed to oxidize a significant fraction of the methane that is released in this way.
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