Finding an alternative for capturing emissions.

PositionChemical Solvents

Burning elements from the earth has fueled society since the infancy of the Industrial Revolution. Without major breakthroughs in alternative energy production or storage, or an easing of concerns over nuclear power, this seems destined to continue, but with the developing national and international consensus that emissions--chiefly carbon dioxide or C[O.sub.2]--from power plants burning fossil fuels contribute to global climate change, electric companies are coming under public scrutiny, if not outright government mandates, to curb these emissions.

The trick will be scrubbing the emissions efficiently so the clean-up process does not syphon too much electricity from the plant. An efficient capture of the gas ideally would be as cheap as possible for power companies and their customers. However, current methods for scrubbing C[O.sub.2] and other greenhouse gases are too costly for most power plants to implement.

Jason E. Bara, professor of engineering at the University of Alabama, Tuscaloosa, is hoping efforts in his lab to find different chemicals from those now used to clean industrial emissions will lead to cheaper and more efficient methods. "We pursue this work with novel solvents to hopefully achieve the greatest energy efficiency for C[O.sub.2] capture. It's the magnitude of the problem and the impact on the global economy that makes it extremely important that capture processes be highly optimized when they are rolled out at full scale."

There are international efforts to reduce the man-made emission of greenhouse gasses, or GHGs, that likely contribute to global warming by trapping the sun's heat inside the atmosphere. These efforts include emission standards and financial penalties on excess emissions. Nearly all commercially-available efforts at scrubbing GHGs from emissions use a liquid solution of water and amine--derived from ammonia--that contacts the stream, removing the C[O.sub.2] or other unwanted gases.

The most common and most studied method is introducing monoethanolamine, or MEA, into natural gas or postcombustion emissions, a process that can capture at least 90% of C[O.sub.2] from flue gas.

The use of MEA to scrub flue gas is energy intensive since recycling the solution requires boiling it to desorb, or rid, the C[O.sub.2] before recycle of the MEA solution back into contact with the flue gas. The cost of the energy needed to use MEA in power plants, for example, likely would be passed onto consumers. Other issues...

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