MECA is a non-profit association made up of the world's leading manufacturers of motor vehicle emission controls. MECA's member companies have over 30 years of experience and a proven track record in developing and commercializing exhaust control technologies for motor vehicles. A number of our members have extensive experience in the development, manufacture, and commercial application of emission control technologies for diesel heavy-duty engines. In the 1990s, MECA companies have spent several hundred million dollars on developing, optimizing, and commercializing advanced emission control technologies to help enable motor vehicles to meet increasingly more stringent emission control regulatory requirements. If the EPA's proposed highway heavy-duty engine and vehicle/diesel fuel sulfur control program is adopted, these companies are committed to make the necessary investments to insure that the emission control technology needed is available.
Today, I will briefly review the status of the exhaust emission control technologies that EPA has identified as the leading control technologies to meeting the stringent emission reductions called for in the Agency's proposal and then discuss the critical need for very low sulfur fuel to allow these technologies to be utilized effectively. Our comments today are based on work being performed by our members, their extensive experience in the field of motor vehicle catalysis, and a growing body of technical data that is beginning to emerge from such programs as the joint government/industry DECSE Program.
Technological Feasibility of Meeting the Proposed Diesel HDE Standard
We believe the emission standards of 0.2 g/bhp-hr NOx and 0.01 g/bhp-hr particulate (PM) proposed for highway diesel-powered heavy-duty engines standards can be achieved in a cost-effective manner within the lead-time provided, if very low sulfur diesel fuel is available. EPA, in its proposal, identified two candidate technologies for meeting the proposed emission limits catalyst-based diesel particulate filters for particulate (PM) control and NOx adsorber technology for oxides of nitrogen (NOx) control. EPA also cites SCR as a NOx control option.
Catalyst-Based Diesel Particulate Filters -- Diesel particulate filters are commercially available today; the only remaining engineering effort is to optimize the filter systems for the specific engine to which they will be applied. Worldwide, over 20,000 PM filters have been equipped on diesel engines. This year, Peugeot (PSA) introduced filter-equipped passenger cars that use a fuel-borne catalyst for regeneration of the filter system. The control efficiency performance and durability of filter systems has been demonstrated. Catalyst-based DPFs used on engines operated on low sulfur diesel fuel can achieve PM and toxic HC reductions well in excess of 90 percent. Indeed, when very low sulfur diesel fuel is utilized, the level of particulate emissions is almost undetectable. Where diesel fuel containing <10 ppm sulfur has been used, filter technology has demonstrated impressive durability. Indeed, in some applications, filters have continued to provide excellent particulate removal after over 350,000 miles of vehicle operation (see e.g., SAE Paper No. 2000-01-0480).
NOx Adsorber Technology -- Development and optimization work with NOx adsorber technology is progressing at a rapid rate, and our members believe that with the availability of very low sulfur diesel fuel, this technology will be commercialized in the 2007 timeframe for diesel engines. Indeed, the prospect that EPA will likely require very low sulfur diesel fuel in the 2006 timeframe has already stimulated an increased commitment to bring this technology forward in diesel engine applications. The design objective for NOx adsorber technology combined with advanced engine designs is to approach or exceed a 90 percent control level from 2004 emission requirements. These levels of control have been demonstrated for certain engine operating conditions (DECSE, Phase I Interim Draft Report No. 2: NOx Adsorber Catalysts, October 1999).
Our industry firmly believes that the main challenges for commercializing NOx adsorber technology are engineering in nature and that there are no fundamental technical barriers to final product development of this technology, provided that very low sulfur diesel fuel is available. Extensive R&D; work continues in the areas of optimizing the NOx adsorption/desorption and conversion functions, and defining and optimizing sulfur removal ("desulfurization") techniques and strategies, as well as examining the use of sulfur traps upstream of the catalyst. Our members are making the substantial investments in R&D; because they believe these are fertile areas for improvements in this technology.
Selective Catalytic Reduction (SCR) Technology -- SCR technology is being developed for commercial application for motor vehicles in the very near future. The technology is achieving significant NOx reductions and is also capable of reducing HC emissions and PM. . On-road demonstration of SCR technology has established excellent NOx reduction performance after over 325,000 miles of vehicle operation with over six million miles of accumulated commercial fleet operation.
The Need for Very Low Sulfur Diesel Fuel
Meeting a 0.2 g/bhp-hr NOx standard and a 0.01 g/bhp-hr PM standard over the full useful life (435,000 miles) of an on-road HDDE as certified over combined transient and steady-state certification test procedures with not-to-exceed standards will be challenging. As previously stated, we believe these challenges can be met, and the ultimate goal of a truly clean diesel engine is possible, but again very low sulfur diesel fuel will be needed. Sulfur in fuel adversely affects the performance of all catalyst-based emission control technologies. The impacts range from reducing the effectiveness of these controls to rendering certain catalyst-based controls ineffective.
While we continue to recommend that EPA establish a sulfur cap of 5 ppm, our members believe that with a sulfur cap of 15 ppm emission control strategies can be developed to meet the proposed emission limits. Specifically, with a 15 ppm cap our members are extremely confident that all catalyst-based filter technologies can be designed to help meet levels of 0.01 g/bhp-hr PM over the full regulatory useful life of the engine and that NOx adsorber technology will be optimized to meet the 0.2 g/bhp-hr NOx standard.
Catalyst-Based Diesel Particulate Filters -- With a sulfur cap of 15 ppm, our members are extremely confident all catalyst-based filter technologies can be designed to meet levels of 0.01 g/bhp-hr PM control over the full regulatory useful life of the engine. As sulfur levels rise above a 15 ppm sulfur cap, it becomes increasingly difficult and then impossible to achieve the NTE limit requirements for the entire engine speed and load map. The recently completed DESCE program confirmed the direct impact between sulfur levels and the formation of sulfate (DECSE, Phase I Interim Data Report No. 4 -- Diesel Particulate Filter, Final Report, January 2000).
In addition to an increase in sulfate, the level of sulfur in diesel fuel adversely affects the temperature level at which regeneration of the filter occurs. Achieving the exhaust temperatures needed to bring about filter regeneration is an engineering challenge even for a fully optimized engine/filter system depending on the engine design, engine application, and ambient temperatures. Failure to achieve proper regeneration can adversely affect performance and the durability of the filter system. Therefore, the impact of sulfur in raising the regeneration temperature can be very problematic. Operating experience with filter technology in Europe with <10 ppm sulfur diesel fuel demonstrates that proper filter regeneration will occur, even when vehicles are operated in areas such as Sweden, where low seasonal ambient temperatures do occur.
NOx Adsorber Technology -- While sulfur levels above 5 ppm present additional design challenges for NOx adsorber technology, companies that are developing this technology believe that with the considerable R&D; efforts already underway, NOx adsorber technology will be optimized to operate with a cap of no higher than 15 ppm.
At sulfur levels above the proposed 15 ppm cap, companies developing NOx adsorber technology have serious reservations regarding the ability to commercialize NOx adsorber systems that can function effectively for the extended useful lives of HDDEs. At these higher sulfur levels, a NOx adsorber quickly becomes ineffective as the sulfur attaches to the sites meant to "trap" the nitrogen oxide emissions. The sulfur remains attached to these sites until high temperature, rich conditions, which are not characteristic to normal diesel engine operation, are met.
SCR Technology -- SCR technology, which utilizes an oxidation catalyst to facilitate NOx reduction to achieve high control efficiencies, requires the same low sulfur levels as the NOx adsorber technology. Other SCR technology designs are less sensitive to sulfur, but even for these technologies, very low sulfur fuel allows these technologies to achieve the highest NOx reductions and allows for the full optimization of the engine/exhaust control technology system.
CONCLUSION
We recognize that reaching the objective of the truly clean diesel engine is not an easy task and it will require a substantial commitment of resources on the part of the engine manufacturers, the exhaust emission control industry and the oil industry. We believe that, working together, we can meet this objective. Our industry is prepared to make the necessary investments to help insure that the desired emission reductions are achieved.
Thank you.