21st Century Truck Initiative/Partnership (21CTP)
Within the Engine Systems area, the main industry partners would be the engine manufacturers (Caterpillar, Cummins, Detroit Diesel, and Volvo/Mack Powertrain) and their suppliers, which would be working to achieve the efficiency and emissions goals of the Partnership. They would be assisted in this effort chiefly by the US Department of Energy (DoE), FreedomCAR and Vehicle Technologies Program, through the work in combustion and emission controls, materials, and combustion modeling that was ongoing within that office. DoE was also working with industry on advanced fuel formulations for future vehicles to enable these more efficient and cleaner engines. The US Department of Defense had an interest in this work to achieve its goals of more fuel efficient tactical and utility vehicles. The Environmental Protection Agency played a role in this area through establishment of emission standards and through studies of the fuel efficiency and cost impacts associated with meeting the established standards.
A highly integrated approach involving fuel formulations, engine technology, combustion, emissions controls, and materials was essential in meeting the 21CTP vision for this strategic element. "Engine system" in the goals referred to the combination of fuel, engine, and emissions aftertreatment equipment. Unlike the other major areas of the truck system, increasing the energy-efficiency of the engine system reduce fuel consumption by a corresponding amount. Specific technology goals as of 2006 were:
- Develop and demonstrate an emissions compliant engine system for Class 7-8 highway trucks that improves the engine system fuel efficiency by 20% (from approximately 42% thermal efficiency today to 50%) by 2010.
- Research and develop technologies that would achieve a stretch thermal efficiency goal of 55% in prototype engine systems by 2013, leading to a corresponding 10% gain in over-the-road fuel economy over the 2010 goal.
- By 2010, identify and validate fuel formulations optimized for use in advanced combustion engines exhibiting high efficiency and very low emissions, and facilitating at least 5% replacement of petroleum fuels.
For year 2010, a goal of 50% thermal efficiency was targeted over the most widely used operating points for class 7-8 highway trucks, which were the greatest fuel-consuming classes of all trucks. Considering that a fuel economy penalty was expected from additional emission controls, this represented close to a 20% improvement over 2002 technology. The technology improvements achieved for the large highway truck engines were expected to be mostly transferable to other truck classes for similar proportional gains. For 2013, an even more aggressive goal of 55% was planned for prototype engines in a dynamometer lab environment at the 2010 emissions levels.
Prior to December 2006, an intermediate goal was set to meet the EPA emissions regulations to be phased in between 2007 and 2010, while still improving engine efficiency. More specifically, there was a desire to demonstrate at least 45 percent peak thermal efficiency for heavy-duty diesel engines while meeting 2007 Federal (EPA) emissions levels [1.18 g/bhp-hr NOx (fleet average) and 0.01 g/bhp-hr PM]. This intermediate goal had been met by December 2006. The challenge for 2010 was said to then have been meeting the NOx+HC standard of 0.20 g/hp-hr and the particulate matter (PM) standard of 0.01 g/hp-hr. Carbon monoxide (CO) and hydrocarbons (HC) were also regulated, but they posed no significant challenge for the conventional diesel combustion process. Complying with the CO and HC emission regulations would primarily be challenging when LTC modes of combustion, such as HCCI, that were employed for NOx and PM control. Close attention would also be applied to ensure that alternative combustion regimes and aftertreatment systems do not increase "toxic" unregulated emissions.
The partnership also supported retrofit of emission control devices to in-use engines and the R&D necessary to develop and certify them. With the relatively slow turnover of trucks and engines, the retrofit programs had significant potential for impact on air quality. Quantitative goals here could not be determined as of 2006, because of the wide range of applications in the existing vehicle fleet and general lack of control over implementing retrofit systems.
Goals for fuels (and lubricants) satisfied two major objectives: (1) they are enabling technologies, integral with combustion and aftertreatment, to meet the emissions and efficiency goals, and (2) in a longer-range strategy, expanded use of non-petroleum fuels was a goal in itself. A major goal for the fuels area was completed in 2005 through the documentation of sulfur levels that would enhance the ability of engines to meet 2007-2010 emissions goals (requiring a systems approach), while maintaining or improving efficiency. (completed with the conclusion of APBF-DEC). In 2006, the fuel industry complied with the EPA 2001 sulfur rule, which was based in part on DOE-generated data.
Intermediate goals and additional milestones were stated in December 2006 as follows:
- By 2010 identify and exploit fuel properties that could increase efficiency and reduce overall tailpipe emissions through (1) lower engine-out emissions, including new low-temperature combustion regimes, and (2) enhancement of aftertreatment performance for 2010 emissions regulations.
- By 2013, identify non-petroleum fuel formulations (e.g., renewables, synthetics, hydrogen- carriers) for advanced engines and new combustion regimes for the post-2010 time frame that enable further fuel economy benefits and petroleum displacements while lowering emissions levels to near-zero, thus adding incentive for using non-petroleum fuels.
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