Ed Repa

On jan. 18, 2008, the U.S. Environmental Protection Agency (EPA) published final rules for spark ignition (SI) internal combustion engines (ICE), including those used to combust landfill gas (73 FR 3568). The final rule promulgates new source performance standards (NSPS) for SI-ICE and national emission standards for hazardous air pollutants for SI-ICE that are either located at an area source of hazardous air pollutants (HAPs) or have a site rating of less than or equal to 500 brake horsepower (hp) and located at major sources of HAPs. The final rule becomes effective on March 18, 2008.

The new source performance standards apply to all new, modified, and reconstructed SI-ICE, regardless of size. The standards require that these sources control emissions to the level achievable by the best-demonstrated technology, considering costs and any non-air quality health and environmental impacts and energy requirements. The NSPS requirements for new SI-ICE burning landfill gas are divided into two parts: 1) All landfill gas engines (except lean burn engines greater than or equal to 500 hp but less than 1,350 hp); and 2) Lean burn engines greater than or equal to 500 hp but less than 1,350 hp. The rules set emission limits for nitrogen oxides (NOx), carbon monoxide (CO), and volatile organic compounds (VOC) and are shown in the tables at left.

The final standards also apply to SI-ICE modified or reconstructed after June 12, 2006. SI-ICE overhauled as part of a maintenance program are not considered modified if emissions are not increased. Landfill gas-powered SI-ICE less than 500 hp manufactured prior July 1, 2008 or greater than or equal to 500 hp manufactured prior to July 1, 2007 and modified or reconstructed after June 12, 2006 must meet the following emissions standards: NOx=3.0 g/hp-hr; CO=5.0 g/hp-hr; and VOC=1.0 g/hp-hr. These engines must also meet the standards for NOx, CO, and VOC of 220, 610, and 80 parts per million, volumetric dry (ppmvd) at 15 percent oxygen (O₂) respectively.

The national emission standards for hazardous air pollutants apply to new or reconstructed SI-ICE rated at or less than 500 hp and located at a major source of HAP emissions. New and reconstructed SI-ICE at area sources must meet the standards listed in the tables at left. Many landfill gas-powered SI-ICE will fall into one or both of these categories.

In addition to emission requirements, the final rules establish the means for demonstrating compliance. They include:

Edward Repa is director, environmental programs, at NSWMA. E-mail him at [email protected].