eMission to reach Tier 4
From January 1st 2011, the United States Environmental Protection Agency (EPA) will alter emission regulations that require engine manufacturers to meet Interim Tier 4 regulations for the off-highway market, including tractors and combines. With Tier 4 being the most significant regulation, this has numerous implications for agricultural machinery.
For over 10 years, the push to lower emissions has followed a tiered approach, with Tier 1 setting limits on particulate matter (PM) and oxides of nitrogen (NOx). Currently in Tier 3, the push to reach Tier 4 will be eased through Interim Tier 4 (IT4). These regulations call for a 90-percent reduction in PM and a 50-percent drop in NOx with final Tier 4 emissions regulations to further lower PM and NOx to near-zero levels by 2014.
Challenging engine manufacturers, there are two main ways to reduce PM and NOx. One method of reduction is with cool exhaust gas recirculation (EGR) and an exhaust filter. This method mixes measured amounts of exhaust gas with incoming fresh air to lower the engine’s peak combustion temperature, thereby reducing NOx to an acceptable level. However because of the lower combustion temperatures, this leads to an increase in PM. To bring this back to a reduced level, exhaust gases are routed through an exhaust filter containing a diesel oxidation catalyst and a diesel particulate filter. The PM is trapped in the filter and is oxidized into nitrogen gas and carbon dioxide and released through the exhaust pipe. This process should not impact the operation of the machine.
The second method is with Selective Catalytic Reduction (SCR).
Engines that utilize SCR for NOx reduction tend to operate at higher peak combustion temperatures, which reduce the engine’s PM output. However because of the higher combustion temperature, the engine creates more NOx. These levels of NOx are reduced through injecting Diesel Exhaust Fluid (DEF or urea) into the stream. When the exhaust gases combine with the DEF in the SCR catalyst, NOx is broken down into nitrogen gas and water vapor, allowing it to be released through the exhaust pipe.
John Deere will be building on from its field-proven Tier 3 PowerTech engine platform to meet Tier 4 regulations following the cooled EGR approach. A more operator-friendly technology, cooled EGR is easier to maintain compared to SCR systems. Read more about Interim Tier 4 here
eMission to reach Tier 4
From January 1st 2011, the United States Environmental Protection Agency (EPA) will alter emission regulations that require engine manufacturers to meet Interim Tier 4 regulations for the off-highway market, including tractors and combines. With Tier 4 being the most significant regulation, this has numerous implications for agricultural machinery.
For over 10 years, the push to lower emissions has followed a tiered approach, with Tier 1 setting limits on particulate matter (PM) and oxides of nitrogen (NOx). Currently in Tier 3, the push to reach Tier 4 will be eased through Interim Tier 4 (IT4). These regulations call for a 90-percent reduction in PM and a 50-percent drop in NOx with final Tier 4 emissions regulations to further lower PM and NOx to near-zero levels by 2014.
Challenging engine manufacturers, there are two main ways to reduce PM and NOx. One method of reduction is with cool exhaust gas recirculation (EGR) and an exhaust filter. This method mixes measured amounts of exhaust gas with incoming fresh air to lower the engine’s peak combustion temperature, thereby reducing NOx to an acceptable level. However because of the lower combustion temperatures, this leads to an increase in PM. To bring this back to a reduced level, exhaust gases are routed through an exhaust filter containing a diesel oxidation catalyst and a diesel particulate filter. The PM is trapped in the filter and is oxidized into nitrogen gas and carbon dioxide and released through the exhaust pipe. This process should not impact the operation of the machine.
The second method is with Selective Catalytic Reduction (SCR).
Engines that utilize SCR for NOx reduction tend to operate at higher peak combustion temperatures, which reduce the engine’s PM output. However because of the higher combustion temperature, the engine creates more NOx. These levels of NOx are reduced through injecting Diesel Exhaust Fluid (DEF or urea) into the stream. When the exhaust gases combine with the DEF in the SCR catalyst, NOx is broken down into nitrogen gas and water vapor, allowing it to be released through the exhaust pipe.
John Deere will be building on from its field-proven Tier 3 PowerTech engine platform to meet Tier 4 regulations following the cooled EGR approach. A more operator-friendly technology, cooled EGR is easier to maintain compared to SCR systems. Read more about Interim Tier 4 here
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