what's the go?, page-36

Poyndexter,

I just wished to point out that when you create a void in the rocks, you destress below because the overburden is reduced and you destress above but this time because the roof of the cavity collapses and this as far as the surface.

And this phenomenon is, imo, the main reason why the UCG will not be used extensively in lorraine despite the energetic advantage. From the mining past it has been proved that 80% of the voids created by the mine, if not compensated by filling, resulted in surface subsidence within 2 years.

Lorraine isn't the australian outback. There are buildings, roads, motorways, buried lines and even the european gas pipeline crossing through. Convenient locations would be scarce... and I am not even talking of gazonor, NPC is among the most populated "departments" of France.

The collapse of the roof is integral part in the design of UCG process, it spreads lateraly the combustion zone and optimizes the recovery.

From the energetic point of vue, recover only CBM and leave the coal in place is a scandal, economically it may make sense.
The results of the testing at El tremendal (SP,1997, 570 m) show that the cavity ratio Width/Height was 5.
A 500 m long system would cost minimum 3 millions euros with Coiled Tubing. For a 10 m thick coal seam it would give access to 10 x 50 x 500 = 25000 m3, 32500 tons. Cost by ton in place: 92 euros, this is without energy generation.
1 ton coal delivers 11 000 KWh. The only energy recovery factor I know of is chinchilla, they boast 75%.
Then 32 500 t x 11 MWh x 0.75 * 300 euros/MWh = 8 millions euros sales (with specific buy rates). I estimate the processing equipement at 15 millions euro minimum...

In 2001 the DTI had estimated a similar project in UK at 28 millions euro with conventional drilling and several scenarii gave the best output of 1.1 euro/kWh.

UGC is currently not viable by itself. I will have a closer look at chinchilla but conditions are totally different from Lorraine.

No progress on the electrification of gazonor... basically doing the same calculations than we do here :)

cheers

Zadig