The Best Practices in Underground Coal Gasification

UCG Features

• UCG processes involve igniting an underground coal deposit. The ignition produces gas, which is harvested at the Earth's surface. Turbines use this gas as clean power for movement, generating electricity. As a result, cleaner energy, with less harmful emissions, produces many production items, such as chemicals.

Air-In Borehole

• One of the best practices for UCG is a properly designed air-in borehole. This borehole must extend down into one side of the underground coal deposit. Workers ignite the coal deposit. A mixture of oxygen and water are continually forced down this borehole and into the heated coal. This mixture ensures that the coal stays ignited, producing the needed gas by-product.

Gas Out Borehole

• The second borehole must be located at the far end of the coal deposit, away from the air in borehole. The coal-produced gas exits the deposit through the gas out borehole, terminating at a collection device at ground level. Typically, a manufacturing or power plant uses the emitted gas at the Earth's surface for powering machinery.

Gas By-Product

• In the past, hydrogen gas by-products from the coal gasification were discarded as a best practice. However, current industry needs stipulate that the best practice is to store the hydrogen gas. This gas aids in chemical manufacturing, as well as powering alternative fuel vehicles.

Surrounding Rock Structures

• Another concern for achieving best practices is choosing the coal deposit. The surrounding rock strata must be strong enough to prevent any cave ins of the coal deposit. As the deposit ignites, and remains ignited, the coal deposit will slowly shrink. Rocks supporting the ground above the deposit must be strong enough to retain the shape of the land.