Rice University scientists have devised a way to separate carbon dioxide from natural gas at wellheads that is cheaper and more energy efficient than current industry practices.
A porous material invented by the laboratory of Rice chemist James Tour (pictured) sequesters carbon dioxide at ambient temperature with pressure provided by the wellhead and lets it go once the pressure is released. The material shows promise to replace more costly and energy-intensive processes, according to Nature Communications.
Natural gas is the cleanest fossil fuel. Development of cost-effective means to separate carbon dioxide during the production process will improve this advantage over other fossil fuels and enable the economic production of gas resources with higher carbon dioxide content that would be too costly to recover using current carbon capture technologies, Tour said. Traditionally, carbon dioxide has been removed from natural gas to meet pipelines’ specifications.
The Rice material, a nano-porous solid of carbon with nitrogen or sulfur, is inexpensive and simple to produce compared with the liquid amine-based scrubbers used now.
The Tour lab, with assistance from the National Institute of Standards and Technology, produced the patented material that pulls only carbon dioxide molecules from flowing natural gas and polymerizes them while under pressure naturally provided by the well.
When the pressure is released, the carbon dioxide spontaneously depolymerizes and frees the sorbent material to collect more.
All of this works in ambient temperatures, unlike current high-temperature capture technologies that use up a significant portion of the energy being produced.
The technique allows operators to specifically remove carbon dioxide at the source. It doesn’t have to be transported to a collection station to do the separation, according to Tour. This could be especially effective offshore, where the footprint of traditional methods that involve scrubbing towers or membranes are too cumbersome.
It enables companies to pump carbon dioxide directly back downhole, where it’s been for millions of years, to use it for enhanced oil recovery to further the release of oil and natural gas, or to package and sell it for other industrial applications, according to Tour.