Tiny Ceramic Tubes Could Cut Greenhouse Gas Emissions

by VR Sreeraman on Aug 4 2007 4:10 PM

Tiny tubes made from an advance ceramic material could cut greenhouse gas emissions from power stations to almost zero, scientists have discovered.

The material Lanthanum-Strontium-Cobalt-Ferric Oxide, also known as LSCF, has the remarkable property of being able to filter oxygen out of the air. 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, scientists said.

LSCF is not a brand new material. It was originally developed for fuel cell technology, but engineers at Newcastle University in northern England, in collaboration with Imperial College London, have developed it for potential use in reducing emissions from gas-fired power stations.

Scientists say it can possibly also be used in coal and oil-fired electricity generation plants.

Conventional gas-fired power stations burn methane 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, which look like small, stiff, drinking straws, are permeable only to oxygen ions - individual atoms carrying an electrical charge.

When air is blown around the outside of the tubes, only the oxygen component of air reaches 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 oxygen-depleted air, which consists mainly of nitrogen, can be returned to the atmosphere with no harmful effects on the environment, while the resulting stream of carbon dioxide can be piped to a processing plant for conversion into chemicals such as methanol, a useful industrial fuel and solvent.

Alternatively, the flow of air and methane around the tube can be controlled so that only partial combustion takes 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.

Crucially, LSCF is also resistant to corrosion or decomposition at typical power station operating temperatures of around 800C.

The new combustion process has been tested in the laboratory and found to be successful.

The details of the research and development project appear in the August 3, 2007 issue of the journals, Materials World and The Chemical Engineer.