Room and pillar mining; Pillar and stall mining; Room and pillar mine
Room & Pillar is so named, because pillars of coal are left standing to help support the roof of the mine and is still common in underground coal mines
Installation time
An important factor in the total field installation cost, which can be minimized by the use of flexible composite pipe that does not have to be welded at the installation site
Net energy of an energy producing installation
One ton of gasoil; 1 gallon of gasoil
Gasoil or diesel fuel has a density of about 0.75 kg/liter, so 1000 kg will be 1333 liters which is 350 gallons. Thus to convert the price of gasoil in cents per gallon to dollars per ton one needs to multiply the price by 3.5