Friday, March 1, 2013

NETL Updates Membrane CO2 Capture Research

Membranes offer a potential low-maintenance and economical method for gas separations from power plant flue gas streams. Polymer membranes and supported liquid membranes show great promise to solve problems in the area of clean energy production. Carbon dioxide, a greenhouse gas, is a principal by-product of energy production from fossil fuels. Capturing CO2 from power plant flue gas streams is critical to the goal of reducing the nation’s carbon footprint and preserving the environment. Currently, there is no technology that can meet the goals for carbon capture as set forth by the U.S. Department of Energy. These goals are 90% capture of the CO2with a less than 35% increase in the cost of energy.

The National Energy Technology Laboratory (NETL) is pursuing the development of both polymeric and supported ionic liquid membranes for CO2 capture. Development of adequate membrane technology requires equipment capable of rapidly measuring membrane performance. Typical membrane testing equipment operates under either constant pressure or constant volume conditions. Constant pressure instruments pass feed gas over one side of the membrane and a sweep gas over the other side of the membrane.

The feed gas is comprised of the gases which are to be separated while the sweep gas is inert and serves the purpose of carrying away the gas that passes through the membrane (i.e. , the separated gas). By carrying away the separated gas, the sweep gas allows for increased efficiency of the separation. Constant volume instruments are set up with a membrane separating a pressurized vessel and an evacuated vessel. The pressurized vessel contains the gases which are being separated. As the gases permeate through the membrane, the pressure in the evacuated vessel will increase. The rate of pressure increase permits a determination of the ability of the membrane to separate the gases.

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