The U.S. has come a long way on its 17-year trek to cleaner air and has less than two years to go.
The 1996 implementation of EPA’s Tier 1 standards launched a schedule of progressively lower targets that ends with near-zero nitrous oxides (NOx) and particulate matter (PM) emissions for 2015 off-road diesel engines. This category, called nonroad mobile equipment engines, includes excavators and other construction equipment, airport ground service equipment, and utility equipment like generators, pumps, and compressors.
In other words, most of your rolling stock.
The final set of emissions targets is split into two parts:
- Tier 4A (Tier 4 Interim, Interim Tier 4, and iT4)
- 90% less PM and 50% less NOx than 2006 Tier 3 levels
- applies to 2013 and 2014 model-year engines
- Tier 4B (Final Tier 4)
- 90% less NOx than Tier 3
- 2015-and-after model years
Manufacturers have developed a host of technologies—direct-flow air cleaners, cooled-exhaust gas recirculation (CEGR), variable geometry turbochargers (VGT), diesel oxidation catalysts (DOC), and diesel particulate filters (DPF)—to meet these goals. That innovation has a price. iT4 engines are 5% to 15% more fuel-efficient but 10% to 40% more expensive than Tier 3 models; Tier 4B 10% to 20% more expensive than iT4.
Upgrade, replace, or wait it out?
Federal law allows Tier 3 owners to use the equipment until the end of its expected service life. Therefore, it’s possible, but not necessary, to upgrade pre-iT4 engines unless your state requires it.
EPA’s Engine Flexibility Program allows equipment manufacturers to transition into producing iT4-compliant products but restricts the number of each “flex engine” backhoe, skid-steer loader, and excavator model they can manufacture annually. Non-government owners buying used equipment should be aware that future construction projects and bids might consider the ages and/or emission levels of their mixed fleet. So, prospective buyers should consider emissions performance of both new and existing equipment in trade and resale options.