Diesel Tractor Fuel Efficiency and Exhaust Emissions Standards
Diesel engine performance and costs represent crucial factors for agricultural producers while pollutants from the exhaust are largely a social concern but also important to producers. Beginning in 1970, Congress authorized the Environmental Protection Agency to regulate emissions with amendments in subsequent years (U.S. EPA, 2023). In 1996 the EPA issued strict Exhaust Emission Standards for Nonroad Compression-Ignition Engines, causing a major paradigm shift in acceptable emission levels. A primary concern coming from many manufacturers was the difficulty of designing an engine to meet these standards without compromising the engines’ power output and efficient fuel consumption (Lloyd and Cackette 2001; EPA Final Rule 2004). In this article, we examine the impact of fuel efficiencies as exhaust emission standards evolved in stringency from their beginning in 1996 to today’s standard.
In part one of a two-part article series, we begin by describing health concerns, the EPA exhaust emission policy and the data from the Nebraska Tractor Test Lab (UNL-NTTL) database, we then discuss the introduction of technologies enhancing fuel efficiency, and we describe the approach we take to understand how tractor fuel efficiencies have evolved since the introduction of EPA tiers from our data. We end with a discussion between tiers and tractor fuel efficiency. In the second part of the series, we identify the impact of EPA tiers on fuel efficiency through an econometric analysis.
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