NSF PR 95-65 - October 2, 1995
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Plasma Progress Presents Possibilities for Pummeling Pollution
Imagine a small magic box which, attached to the bottom
of every bus, truck and automobile, could take in
toxic gas and convert all that blue and brown smoke
to clean air.
Scientists and engineers are advancing toward this
goal with studies of how to use plasma physics to
eliminate some of the worst sources of sickening smog
and corrosive acid rain. Years of basic research have
provided progressively more understanding of the physics
and chemistry of plasmas, a kind of free-for-all cloud
of electrons, ions, neutral atoms and molecules all
slamming into each other and interacting with other
atomic particles in the environment. Glowing neon
lights, bursts of lightning, crackling static electricity
and the flash from an engine's spark plugs are all
plasmas in action.
Plasma remediation was identified as a promising technology
for treating contaminated gas streams and air at the
First International Symposium on Advanced Oxidation
Techniques in 1993, sponsored by the National Science
Foundation (NSF) and the Electric Power Research Institute.
This is because plasmas do more than sparkle; they
cause a blizzard of chemical reactions. Many university
researchers are now investigating whether plasma-powered
chemical reactions can help cut belching diesel fumes.
"The challenge is to develop plasma generators that
will convert toxic emissions into benign or more treatable
products quickly, safely and economically," says NSF-funded
engineering professor Mark J. Kushner of the University
of Illinois UrbanaChampaign, who is developing computer
models to determine how well plasma generators can
do the job. He is collaborating with researchers at
Los Alamos National Laboratory and the University
of Southern California to validate the models which
industry could adopt to design practical manufacturing
systems.
"Advances in computer modeling of plasmas have saved
some industries such as lighting and microelectronics
months and possibly years of trial-and-error manufacturing
design," Kushner says. "We hope to transfer that technology
to using plasmas for solving environmental problems."
Catalytic converters for automobile gasoline engines
process toxic compounds such as nitrous oxides into
harmless gases. In diesel engines the conversion isn't
complete because particles and unburned hydrocarbons
in diesel engine exhaust can dirty the surfaces of
conventional catalytic converters. Kushner's work
aims to finish the task by processing the toxic gases
using a plasma directly in the exhaust.
In a plasma generator, high voltage from a vehicle's
generator passes into a metal cylinder by way of an
electrode. Kushner is using his computer models to
find the right combination of factors - variables
such as voltage, electron acceleration and electrode
dimensions -- to create a burst of free electrons
that can lock and unlock chemical bonds and disarm
emissions.
Plasmas for truck exhaust must be economical, Kushner
says, because calculations indicate that if more than
10 percent of a truck's engine power is needed to
run a plasma generator, engineers are better off redesigning
the engine.
Other industries are already generating plasmas to
reduce toxic emissions and recycle captured compounds.
In coal burning power plants, for example, nitrogen
oxides can be split up and reformed as nitrogen, oxygen
and nitric acid. The nitrogen and oxygen can be released
safely into the atmosphere while the nitric acid can
be combined with ammonia to make fertilizer. A more
difficult challenge is how to safely convert large
volumes of fumes emitted by chemicals used by, for
example, dry cleaners and auto body shops. Here the
chemical conversions within the plasma are more complex
and volatile. Improvements in plasma research also
are important to the semiconductor chip industry,
which uses plasma generators in manufacturing. Better
computer simulations of plasma technology could lower
the cost of producing computers, microwave ovens,
cellular phones, fax machines and hundreds of other
products that depend on computer chips to operate.
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