LSCF tubes, tiny tubes made from an advanced ceramic material, have the remarkable property of being able to filter oxygen out of the air. If air were to be blown around the outside of an assembly of a large number of the tubes located in a gas fired power station, oxygen would pass through the wall of the tube to the inside, where it would combusts with methane gas that is being pumped through the of the tubes. By burning fuel in pure oxygen, it is possible to produce a stream of almost pure carbon dioxide, which has commercial potential for reprocessing into useful chemicals.
Engineers at Newcastle University in northern England, in collaboration with Imperial College London, have developed LSCF for potential use in reducing emissions for gas-fired power stations and possibly coal and oil-fired electricity generation as well. Conventional gas-fired power stations burn methane, the primary component of natural gas, in a stream of air, producing a mixture of nitrogen and greenhouse gases including carbon dioxide and nitrogen oxides, which are emitted into the atmosphere. Separating the gases is not practical because of the high cost and large amount of energy needed to do so.
However, the LSCF tubes would allow only the oxygen component of air to reach the methane gas, resulting in the production of almost pure carbon dioxide and steam, which can easily be separated by condensing out the steam as water.
The LSCF, which stands for Lanthanum-Strontium-Cobalt-Ferric Oxide, tubes look like small, stiff, drinking straws and are permeable to oxygen ions — individual atoms carrying an electrical charge. Crucially, LSCF is also resistant to corrosion or decomposition at typical power station operating temperatures of around 800C.
The oxygen-depleted air, which consists mainly of nitrogen, can be returned to the atmosphere with no harmful effects on the environment, while the carbon dioxide can be collected separately from the inside of the tubes after combustion.
An alternative would be to control the flow of air and methane so that only partial combustion took place. This would result in a flow of 'synthesis gas', a mixture of carbon monoxide and hydrogen, which can easily be converted into a variety of useful hydrocarbon chemicals.
The new combustion process has been developed and tested in the laboratory by Professor Ian Metcalfe, Dr Alan Thursfield and colleagues in the School of Chemical Engineering and Advanced Materials at Newcastle University, in collaboration with Dr Kang Li in the Chemical Engineering Department at Imperial College London. The research has been funded by the Engineering and Physical Sciences Research Council (EPSRC).
Note: This story has been adapted from a news release issued by University of Newcastle upon Tyne
This technology, even if practical, does not address the larger question of what to do with the CO2!