by Frank Bohanan
There’s a new way to reduce smog in town, and you can get it now. And no, it’s not called a scooter, although we’re partial to any zero-emission vehicle that keeps our kids from asking for the keys to the Lexus. The smog-eater in questions is the PremAir Catalyst System, a product of the Engelhard Corporation, a leading supplier of precious metals and catalytic converters to the world’s automakers.
Unlike traditional approaches to minimizing air pollution -- efforts that try to reduce those chemicals emitted from tailpipes, fuel tanks or smoke stacks which combine to form pollution (known as “precursors”) -- the PremAir system reduces pollution directly by converting undesirable ground-level ozone into oxygen. It is actually based on a technology that’s been used for years to provide oxygen in commercial airliners by taking some of the air ingested by the jet’s engines and using it to generate an oxygen supply for the passengers and crew.
The design of the system is totally passive to the end user, meaning that it has no moving parts to fail. All it needs is a steady stream of air that contains ozone, the hotter and more polluted the better. Maintenance, if any, is minimal and is essentially limited to keeping the catalyst surface area clean.
The PremAir system is elegant in its simplicity. It consists of a special catalytic coating, which is easily applied to a heat exchanger. As air flows over the coating, it chemically converts ozone into oxygen in direct proportion to the amount of ozone it is exposed to.
Its versatility means PremAir can be used in other applications as well. The PremAir coating can also be used on stationary heat exchangers like the A/C units on the roofs of commercial or residential buildings. The only real prerequisites are that the air contains ozone and that a little heat is present to get the reaction going.
Potential problems related to the use of PremAir appear to be few. The most common concerns are damage to the coating due to exposure to road salt and “debris” such as bugs and road tar, etc. These effects are reversible by a proper cleaning and they have minimal effect on the conversion efficiency; since they tend to only affect the front surface of the heat exchanger, the majority of the coating’s surface area is unaffected.
Expense, originally an issue, is becoming less so. The cost has come down steadily to the point where a typical automotive application only results in a cost increase of about $50 per vehicle. In light of the potential emission credits available this can be a very cost-effective means of achieving emission compliance. In fact, the PremAir system could potentially eliminate the need to install more expensive emission control equipment on some vehicles.
Where it’s at
The PremAir system currently is installed as standard equipment on the Nissan Sentra CA and Volvo S80 and V70 models, in addition to having been used by several municipalities on transit buses. Volvo has stated they intend to make it standard on all of their car models while several other carmakers have expressed interest as well.
Both the California Air Resources Board and EPA both have ruled “ozone-eating” technologies such as PremAir can qualify for emission credit, and thus contribute to meeting tailpipe emission requirements. Data show the available emission benefit due to PremAir can equal California’s tough SULEV hydrocarbon standard of 0.01 gm/mile, since up to 80 percent of the ozone passing through a PremAir coated heat exchanger is converted to pure oxygen.
Drivers can expect to see more widespread usage of PremAir as the price drops and the technology improves. While its premise might sound complex, PremAir works simply – and best when it’s needed most, on hot days in slow-moving traffic where the ground level ozone concentrations are highest. Eventually, PremAir may even reduce the need for other conventional catalyst equipment – ironic for the Engelhard engineers that invented it, since their company makes a lot of money from the status quo, but a boon for environmentally concerned car owners.