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Much discussion has focused on the diesel truck engines being developed for 2010. They must meet the US Environmental Protection Agency's more stringent 2010 emission emissions standards. The regulations will cut emission levels from diesel-powered trucks by more than 90%, and sharply reduce allowable emissions of nitrogen oxides (NOx) from 1.2 grams/brake horsepower to 0.2 grams per brake horsepower hour.

To achieve cleaner burning engines, engine manufacturers are taking different technology approaches. This will bring about changes to all engines, but they will be less dramatic than the alterations made for the 2007 emission-complaint engines, which were less dramatic than modifications to 2004 emissions engines. The 2010 engines “are just a continued step to improving air quality.”

That was the consensus of representatives from engine manufacturers, convened at the meeting to discuss the 2010 engines and emissions. Making up the panel were Louis Wenzler, Cummins' director of on-highway products; Miguel Soetaert, group leader of Powertain Operations for Detroit Diesel; Tim Shick, director of business and product strategy for Navistar Engine Groups' Big Bore Engine Business; and Ed Saxman, manager of product marketing-powertrain for Volvo Trucks North America.

“The new engines put out very clean exhaust,” noted Saxman. “There's no reason why a natural gas engine should be considered cleaner than a 2010 diesel engine.”

Technology

Regarding solutions to 2010 compliance for on-highway heavy-duty products, Cummins “will remain with our X platform, which is what we call an in-cylinder solution, Wenzler said. “It takes our EGR (exhaust gas recirculation) product that we have today and makes advances to the fuel and the air handling systems, and uses the Cummins particulate filter.”

On mid-range engine products, Cummins will be using selective catalytic reduction (SCR) solution.

Detroit Diesel “will meet and exceed the 2010 emissions” with the BlueTec System from Daimler (Detroit Diesel is a Daimler company), Soetaert said. “BlueTec is a urea-based SCR system that works by injecting a diesel exhaust fluid into the exhaust stream. The heat of the stream converts NOx emissions into harmless levels of pure nitrogen and water vapor - two natural components of the air we breathe.”

“At Navistar we're going with advanced EGR, which is a proven and mature technology for us,” said Shick. “We're taking this technology to the next level for 2010.”

Volvo has selected exhaust gas aftertreatment in the form of SCR and will be injecting urea into the exhaust stream, Saxman said, but will be handling the reduction of NOx outside the engine. “This allows us to get a higher level of NOx out of the engine, which helps to achieve a fuel economy improvement.”

The four panelists said their companies have been preparing for the 2010 engines for a number of years, and all have test vehicles on the road. All four of the manufacturers “are on time and on schedule” to have their 2010 diesels ready.

Being global companies, Volvo and Daimler have had SCR diesels operating in Europe to meet emissions Euro 4 and Euro 5 emissions standards. While these aren't the same as 2010 emissions standards, said Saxman, the elements of the SCR are there, and that has provided a lot of experience.

More than 550,000 SCR trucks are on the road today in Europe, and SCR technology been used in coal-burning power generation industries and for stationary diesel engines “for quite a while,” Soetaert added. “It is a well proven technology for reducing emissions without reducing fuel efficiency and maintaining reliability.”

Operation

On the matter of fuel economy for the 2010 engines, all of the engine manufacturer representatives said there should be little impact on mpg. What's more, the engines should have improved reliability and durability.

BlueTec is expected to give Detroit Diesel's 2010 diesels better fuel efficiency - from 3% to 5% - because of the system's higher combustion temperatures, said Soetaert.

Shick said Navistar's 2010 engines will use high-pressure common-rail fuel systems for more complete combustion and fuel efficiency. “There should be no fuel economy decrease in any of our 2010 engines, and on some models there will be an increase.”

“Unlike EGR, SCR has elements that improve fuel economy,” said Saxman.

Typically in the past, engine designers faced the challenge that as they tried to improve fuel economy, NOx went up while some other emissions went down, he explained. “The benefit of SCR is that it will tolerate some of that increase in NOx because it will be handled in the aftertreatment.”

He said Volvo's EPA 2007 engines had “a fuel improvement of 3%, and we expect the 2010 engines to provide a further benefit in fuel mileage.”

Cummins 2010 engines “will be comparable in fuel economy,” said Wenzler.

“Engine selection needs to based on more than just fuel economy,” he said. “Other elements just as important are reliability, durability, and total cost of ownership through the lifecycle.”

The panelists concurred that maintenance intervals for heavy-duty engines should remain constant. With SCR systems, drivers will have to add diesel exhaust fluid. DPF systems will require some maintenance.