news soon, page-108

Firstly, apologies to the forum for the tet de tet with Dic this morning ... I was ... er ... a little strident ... gotta practice turning the other cheek it seems 8)).

Now to latter queries on this thread.

I understand UCG to recover up to about 75% of the in-seam energy content of a gassy coal seam ... in the gasification process, UCG picks up the 5% or so of in-seam methane the crude, hunter gatherer CSG companies (lol) would otherwise extract.

If the hunter gatherers clean the forrest out first, I guess the clever UCG gas farmers (lol) would only get to extract a further 70% or so of the remaining in-seam energy.

I hear what Seamfiend says re the 15-20 x factor of UCG in relation to insitu coal I would imagine might need to remain in place to reduce subsidence ... perhaps at depths like 300-400m it doesn't matter ... I'll look into it this week.

All this begs the question of why bother extracting the 5% of in-seam energy as CSG doesn't it? Particularly when it gets extracted in the UCG process anyway and as it also looks to be feasible to manufacture CSG via UCG and the methanation process ... what happens if this can be done cheaper than extracting CSG conventionally?

In reality, there are practical difficulties in considering UCG as a second energy extraction stage after initial CSG extraction, including:

# Not all seams/sites suited to CSG are also suited to UCG

# CSG requires complete draining of groundwater from the gassy coal seam so that gas desorbs from the coal and flows towards extraction wells in a gaseous state.

# UCG takes place within the saturated coal seam by creating a "bubble", which can be collapsed in a controlled manner at any time to stop the process.

# If UCG was to be a second stage after initial CSG extraction, it would be necessary to wait for groundwater hydrostatic pressures to return to a pre-CSG state before commencing UCG operations ... I dont have a good feel for time scales, but this could be 0.5-2 yrs or so I think (similar to the dewatering period).

# Fraccing, the creation of extra in-seam fractures to improve permeability for CSG extraction, may alter the suitability of the seam for subsequent UCG (not really sure on this)

# Interestingly, if only 1/15 to 1/16 the area from which CSG was extracted was suited to a second stage UCG operation you have just doubled the energy reserves that were just extracted as CSG.

The 1/15 to 1/16 factor in itself makes a farce of the CSG industry's concern over overlapping UCG tenements ... they just look so damn greedy imo ... the Qld Govt wants to quarantine about 10% of CSG land (or reserves) for domestic energy security ... per the recent CXY submission to the Qld Govt, UCG could easily supply the domestic market for decades, allowing the CSG companies to export 100% of their output as LNG ... its a win win imo.

Cheers
Dex

PS to Seamfiend ... the hoary issue of overlapping CSG/UCG tenements was most definitely resolved in the short term in favour of the CSG industry by the politically expedient but convenient furphy of UCG groundwater contamination imo ... begs the question as to why the Qld Govy missed the opportunity to put a moratorium on CSG extraction for the same period or until that industry could gets its own particular contaminated groundwater issues in order?