Rules of the Road - Looking Back
A common question is, “Why do we have to control the emissions from our engines?” The answer lies in the history of the environmental movement and public outcry over pollution that culminated in the creation of the EPA in 1970 by Congress at the request of President Nixon. Despite the noise coming from both sides of the political debate, EPA’s mission is best summarized by this excerpt from the memo that recommended its formation to the president:
The enormous future needs for land, minerals, and energy require that the protection of our environment receive a powerful new impetus. In this, the nation will be on the “horns of a dilemma.” The economic progress which we have come to expect, or even demand, has almost invariably been at some cost to the environment. Pesticides have increased the yield of our crops and made it possible for less land to produce more food. They have also polluted the streams and lakes. Automobiles have broadened our economic and social opportunities, even as they have dirtied the air and jammed our highways. Some means must be found by which our economic and social aspirations are balanced against the finite capacity of the environment to absorb society’s wastes.
Where We Are Today
Over the intervening years, EPA, in conjunction with the states and sometimes even smaller local administrative districts, have enacted rules aiming to reduce the emissions of pollutants that have demonstrated human health or other adverse environmental effects. Currently the sections of the Code of Federal Register (CFR) known as Quad J (40 CFR Part 60, Subpart JJJJ) and Quad Z (40 CFR Part 63, Subpart ZZZZ) set the maximum amounts that can be emitted from an engine.
The Quad J rules cover what are called Criteria Pollutants: NOx, CO and VOCs (nitrogen oxide, carbon monoxide, volatile organic compounds). The limits on engine emissions are determined based on the engines combustion type (rich or lean burn), horsepower, date of manufacture, fuel source and operating hours. Quad Z regulations derive from the Clean Air Acts requirement to control the emissions of Hazardous Air Pollutants (HAPs), such as formaldehyde, which are known or suspected to be carcinogens.
Likewise the Quad Z regulations have different emission limits depending upon the engines combustion type and horsepower, but additionally have different limits depending upon whether the site where the engine is located is classified as a Major Source of HAPs or an Area Source. A Major Source is defined as a location that has the potential to emit more than 10 tons/year of any single HAP or more than 25 tons/year of any combination of HAPs. In order to address ozone levels that contribute to smog formation, certain states and other local administrative districts have enacted even stricter regulations. Southern California and the corridor from Dallas-Fort Worth (DFW) to Houston are two examples of this. For instance, while the Quad J limit for NOx emissions on a new rich burn engine is 1 g/bhp-hr, in the DFW region is 0.5 g/bhp-hr. For spark ignited, 4 stroke, Lean Burn engines located at a Major Source, EPA has given you the choice of demonstrating control of CO instead of formaldehyde. However, your state may have requirements to control formaldehyde to higher levels than required for CO. It is up to you to stay informed with what your emissions limits are and how frequently you need to test your emissions to demonstrate compliance.
What Will Happen Tomorrow
The societal discussion or argument, rather, on the merits of pollution control vs. economic growth will continue. Overall, the trend in emissions limits since the 1970s has been for continual tightening of regulations no matter which party is in power in Washington. It is likely that this trend will continue and that everyone involved with industrial engines will have to keep working to meet the challenges that will come. q
About the Author
John W. Robinson, Jr.
Catalytic Combustion Corporation, Vice President, Catalyst Group
John has more than 20 years of experience in the catalyst industry including formulation development, substrate design, process modeling for sizing calculations, and deactivation studies for both traditional and new catalyst applications.