Poyndexter,Let's consider a coal with 20 m3/t gas content. The...

Poyndexter,

Let's consider a coal with 20 m3/t gas content. The Heating Value of pure methane is 40 MJ/m3, hence 800 MJ for the CBM gas.

The HV of a bituminous coal is 35 MJ/kg, that is 35000 MJ/t
The energetic ratio HV CBM gas/HV coal is 800/35000 = 2.3%.

UCG process will increase this ratio but not much. In situ testings have proved that the sweeping is comparable to longwall mining, that is 70% to 90% of coal in-place being used.
Due consideration being given to that remote controlling of underground gaseification can not be so tight as at surface installations, the UCG still delivers much more energy than CBM.

Depth is not a problem for UCG, I would even say it's a bonus.
Please read the following review of the british Department of Industry and Trade. It's a little bit long, but my opinion is that you could find it informative. The section of interest is chapter 2.2.

http://www.berr.gov.uk/files/file19154.pdf

You read correctly my "lateral thinking". The idea is to destress the shallower and deeper seams to recover permeability and to produce CBM.

But one can go further.

CO2 sequestration, (that could be the last life of a CBM reservoir after ECBM), requires supercritical conditions. The pressure has to be kept over 74 bars of confining hydraulic pressure (1000 psi). This can only be achieved below 740 m.

The economics of these operations still have to be established.
Estimates by estimated persons are that UGC + Gas To Liquid can be profitable with crude oil price at 85 $/bbl only if the coal costs less that 20$/t.
If the oil rises back over 110 $/bbl UGC+GTL is profitable with coal price lower than 100 $/t.
EGL, doesn't need to pay for the coal but the access to it has a cost. In the case of EPG, if would be sufficient that UGC pays back the wells and GTL plant, the reward is the CBM.

For the CO2.
The cost of CCS varies from 60 to 90 euros/t, depending on the process. 2/3 of the cost are due to the capture process, this means that the cost of transports and sequestration are still higher than the current trade price of the CO2 (17 euros/t).

It currently is cheaper to pay than to depollute but the costs of CO2 capture are expected to decrease by 50% and the emission allowances should be decreased (CO2 trading at 100 €/t in 2020?). There will be some possible profit for CO2 sequestrators, and EGL, as greenhouse gas emitter will need to compensate for it's emissions.

Cheers
Z.