Abby L. Harvey
GHG Monitor
1/16/2015
Researchers at Rice University, expanding on research conducted last year, have developed low-cost asphalt with the potential to capture carbon at natural gas wellheads. Last year’s research resulted in the development of a new material, a nanoporous solid of carbon with nitrogen or sulfur, and building on that research, the team, led by James Tour, discovered a way to replicate the carbon capturing ability of that material in the new, lower-cost asphalt. Key to the capture process is the inherent pressure at the well, Tour explained to GHG Monitor this week. “CO2 comes out with natural gas, generally a few percent CO2 but often it can be as high as 10 percent and then there are regions of the world it can hit even 70 percent, and that is generally vented to the air. What these polymers are very good at doing is using the inherent pressure,” he said.
The new asphalt material, when used at wellheads, would have an increased uptake performance when compared to the material developed in the last year’s research, Tour said. “The original work used commercial polymers and you got up to as high as 82 percent by weight capture, which means that for 1 kilogram of adsorbent material, we could capture 0.82 kilograms of CO2. The newer work, we’ve really reduced the cost by making this from asphalt, which is very cheap, and we’re up to … something like 114 weight percent, so if you start out with a material that is 1 kilogram, you’re going to capture 1.14 kilograms of CO2, which is very high,” Tour said.
However, because the process relies on the pressure of the well, for now the usefulness of the material is limited to wellheads. “Many people ask, ‘Can this be used in flue gas from coal fired power plants, all the CO2 that’s emitted from those?’ Not economically at this point,” Tour said. “The reason for that is that this was designed to work under pressure. It works on a pressure swing adsorption process and flue gases do not come out under pressure, they come out at about 1 atmosphere. It wasn’t designed for that. There’s no high pressure to take advantage of,” he said. “If you pressurize flue gas, which you can certainly do, then the economic value is no longer there so it costs too much to pressurize flue gas.”
