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Cutting pollution boosts power

Altering traditional engine parts like changing a piston's combustion bowl has helped cut pollution emissions.

Diesel advances to meet the EPA's stages, or tiers, for reducing diesel pollution in recent years has primarily centered on improvements in combustion performance. This explains the increasing use of electronic controls, aftercooling, and higher fuel pressures in current engines, particularly those in large horsepower tractors and combines.

"It has been a technology race to meet the EPA's Tier 3 requirements, which are being phased in on certain engine sizes this year," points out Tim Meyer of Cummins Inc. "Farmers benefit from that race with engines that are not only more efficient but also deliver longer torque curves."

The increased use of electronic controls or programmable power has given deisel engines the ability to deliver more horsepower at a specific time, Meyer adds. "For example, this power boost is seen in combines that don't lag down when the unloading auger is engaged."

EPA plans don't stop at Tier 3 standards and mandate further reductions in particulate matter (PM) and oxides of nitrogen (NOx) in diesel exhausts. Regulations call for the levels of these pollutants to be 98% below unregulated levels starting in 2011.

These requirements are pushing the limits traditional engine technology can provide to clean up combustion. This situation is requiring manufacturers to begin installing PM filters and after-treatment (after combustion) devices on engines later this decade.

"These after-treatment devices operate similar to catalytic converters by absorbing NOx from the exhaust, for example," Meyer says. "The device is designed to regenerate or burn off the NOx when the pollutant reaches a certain level of accumulation."

The drawback to after-treatment technology is that it's expensive as it uses precious metals to operate. This will put pressure on engine prices. The technology will also force a reduction in the sulfur content of fuel "as sulfuric acid buildup destroys such devices," Meyer adds.

The EPA is requiring refiners to reduce fuel sulfur levels to 500 parts per million (ppm) beginning in 2007. By 2010, sulfur levels must drop to 15 ppm. Finally, federal law will prohibit the use of higher sulfur fuels in model year 2011 and later engines. This situation will require farmers to store both low and ultra-low sulfur diesel fuel in the future.

Altering traditional engine parts like changing a piston's combustion bowl has helped cut pollution emissions.

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