A geology professor from West Virginia University, Tim Carr, met with the citizenry in the top of the state last week to discuss the on-going developments along the gas-rich Marcellus Shale. Carr focused part of his talk on natural gas liquids (NGLs) — the propane, ethane, and butane — which have been coming up along with the natural gas, says The Intelligencer & Wheeling News Register.
“Natural gas liquids are worth money, and you have a lot of them,” the professor said, perhaps as a reminder to property owners who may be thinking of leasing out their mineral rights. (In fact, the NGLs are worth more than the NG right now.) And with new processing and fractionation plants going up to accommodate the gas harvest, Carr offered this pithy summary of how the gases are split using cryogenic recovery:
You refrigerate the gas and the liquids fall out.
Well said. Now how does that work exactly? Methane, the main ingredient in natural gas, has a super-low boiling point. Meanwhile, its sidekick NGLs all boil at higher temperatures. So drop the temperature, and the larger hydrocarbon gases turn to liquid and “fall out” — leaving purer methane behind. As a point of reference, propane boils at minus-44° F, methane at minus-259° F.
The model for cryogenic processing is a bit like the distillation of alcohol, just a few hundred degrees colder. So a memo to energy companies trying to staff their new processing plants in West Virginia: Hire the local moonshiners.