Environmental Protection Agency (EPA) Tier 4 emissions requirements have already had an impact on highway vehicles. New engine designs burn cleaner and more efficiently as they seek to meet EPA’s goal of reducing particulate and nitrogen oxide (NOx) emissions by more than 90 percent by 2014. Tier 4 will soon apply to application and other off-road equipment as well, with interim requirements of 50 percent reductions in NOx in 2011 and 2012 (by engine size).

Industry suppliers will rely on enhanced filtration and combustion to remove most particulates; however, two very different technologies are in play for removal of NOx. Case IH with Fiat Powertrain Technologies engines and AGCO with AGCO Sisu Power engines both use Selective Catalytic Reduction (SCR) technology. In both cases, the technology was introduced several years ago to meet earlier European emission reduction deadlines.

SCR relies on injection of urea as a diesel exhaust fluid (DEF) in the exhaust stream ahead of the catalytic chamber. As the heat turns the DEF to ammonia, the ammonia reacts with the NOx emissions, turning them into harmless nitrogen gas, water and some CO2. The process has been adopted as preferred Tier 4 technology by most major on-highway engine manufacturers.

John Deere is putting its money on cooled exhaust gas recirculation (EGR) and variable geometry turbochargers to reach Interim Tier 4 (IT4) NOx emissions goals. IT4 engines, like their Tier 3 predecessors, do not require a urea solution to meet the new standards. Final Tier 4 emissions technologies to be introduced in January 2014 are still under development and testing, but will likely build on current EGR systems. 

AGCO introduced its SCR technology for Interim Tier 4 (Tier 4i), e3 Clean Air Technology, in high horsepower tractors in North America two years ago. Case IH and John Deere just introduced its Interim Tier 4 units at recent Midwest farm shows. Introduction of the new technologies to self-propelled sprayers and other applicators will follow over the next few years.

Converting to Tier 4 Engines

Hagie, which secures its engines from Cummins, maker of Interim Tier 4 engines for over-the-road use, will be first to bring engines that meet the standards to application equipment. Like John Deere, Cummins has gone the cooled-EGR route.

“All our STS-class machines will be converting to the Interim Tier 4 engines as soon as our pre-2011 orders have been filled and excess existing engines are used up,” said Jim Williams, Hagie Equipment.

“We will be moving to Tier 4i engines in most TerraGator models mid-year 2011 and RoGators will be the latter half of 2011,” said Dave Lovell, AGCO Application Equipment. “Spra-Coupe is tentatively scheduled to move to Tier 4i engines in January 2012.”

“We recently introduced Interim Tier 4 engines in our 2011 Magnum and Steiger tractor lines and plan to introduce similar SCR technology in our Patriot sprayers and Titan Floaters,” said Ken Lehmann, Case IH.

“When we roll out IT4 on other self-propelled units, we will fully inform everyone,” said Barry Nelson, John Deere. “Currently, the 8R Series Tractors are the first machines with the IT4 engines and will be shipped in January 2011.”

Testing Still Underway

Getting high-horsepower tractor experience or, in the case of Hagie, on-highway experience with new technology before introducing it to field application equipment has its advantages. Already identified benefits should rapidly recover any increased costs.

“Testing is still underway, but expectations are for similar operating cost advantages as seen with our high-horsepower tractors,” said Lehmann. With its SCR-equipped tractors, Case IH has reported overall operating costs being reduced by approximately 10 percent, compared to similar Tier 3 engines. 

“SCR is all up-side for the customer when we look at what benefits are being seen on the tractor side,” said Lovell. “AGCO initially claimed up to 15 percent improved fuel economy over competitive EGR-equipped tractors. Nebraska Test Lab results in 2009 showed up to 20 percent improvements over competitive tractors.”

As application equipment and other off-road equipment move toward Interim and final Tier 4 emission levels, EGR and SCR technology-related efficiencies will be another element to compare. Although both meet today’s Interim Tier 4 levels, final levels required in 2014 may require even more fine-tuning of engine systems. If improvements registered to date are any indication, that could be a good thing.