in conclusionIn total fairness, I think 500 ton coal has the volume more or less 20,000 cubic foot.
If you have 150 square feet room (average room size in a house) with 8 feet ceiling, then we need 16 and half rooms to fill all the cool.
According NAG’s proposed production rate, each day, each auger need to dig out 16 and half rooms (total packed) of coal, especially we are talking that the coal seam average thickness is only 91 cm (3 feet). Huge auger can’t dig continuously deep down because seam is only 3 feet thick.
I think I have sealed this discussion. Z06 will be very mad about us having any extra words.