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 2013geoengineeringjudges 2013geoengineeringjudges Jul 6, 2013 02:58  |
Thank you for sharing your ideas and for the work invested to create this proposal. We have considered this proposal carefully, but there are important issues relating to the feasibility of what is being proposed that have not been addressed. The main issues to consider in any further development of this proposal are how much of an impact the proposed solutions will have on the cost of air capture of CO2 and whether this will make a difference to its viability, and whether the proposed solutions will have a larger effect if they are deployed to instead offset CO2 emissions. To think about this latter point, consider how much the energy needed to scrub a unit of CO2 from the air compares with the energy from, for e.g., the amount of coal that produced this CO2.
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 Jimmy Johnston Jul 6, 2013 07:16  | Proposal contributor
Hello,
The original question posed concerned the extraction of methane from air. The suggestion was that CO2 scrubbing would require scaling which would never be sufficient. From your reply I can only assume that a certain level of CO2 extraction is already in operation. This I hadn’t realised.
The practicality of the application of a methane / CO2 / air / other split is maybe the most important area so I’ll start with that.
It must be possible (I don’t know) to determine the geographical areas of maximum methane concentrations. That being the case, mobile extraction sets do not appear infeasible consisting of either one or two turbines such that either hydrogen or methane can be the input energy source running compensated generators. The cycle would start with hydrogen firing, requiring no sequestration. The pump/filter/compression operation would accumulate methane; at a set point the stored methane would be switched to be a replacement for the hydrogen at which stage sequestration would be required.
During the above, CO2 would be drawn down and sequestrated separately. Sustainability is the key i.e. re-using part of the extraction to power further extraction.
Several years ago I was looking at energy storage and stumbled upon the flywheel energy storage system, developed at NASA. The interest was not necessarily energy storage but more the component parts. It appears that the majority of the mechanical friction within that device has been eradicated. Counter torque compensation eradicates the majority of the electrical induction braking. Put the components together and you are getting towards a very efficient machine, efficient enough to warrant minimal energy input to operate.
You ask if the offset of present fossil fuel emissions would be more appropriate than CO2 drawdown. In my opinion, both are essential and complimentary.
I can only assume that, currently, CO2 scrubbing is driven electrically which presumably is costly with the added knowledge that the power has already contributed to the CO2 that is being drawn down. Even if the power source has a sequestration mechanism (in the UK that is certainly not the case) you will know that the sequestration process itself consumes power so although the operation is cleaner it is actually more inefficient such that you have to produce more power etc. etc.
The only way to decrease the costs is to decrease the input energy required to produce the power. You can then sequestrate at a cost that is covered by the increase in efficiency.
I hope this reply covers the points included in your message.
Regards
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