Retrofitting Emission Controls On Diesel-Powered Vehicles March 2002 Manufacturers of Emission Controls Association 1660 L Street, NW * Suite 1100 * Washington, DC 20036 www.meca.org Table of Contents Executive Summary.....................................................................................................................1 Available Control Technologies......................................................................................1 Diesel Retrofit Programs.................................................................................................3 Conclusion ........................................................................................................................3 1.0 Introduction............................................................................................................................4 2.0 Available Retrofit Controls...................................................................................................6 2.1 Diesel Oxidation Catalysts ........................................................................................6 2.1.1 Operating Characteristics and Control Capabilities .....................................7 2.1.2. Impact of Sulfur in Diesel Fuel on Catalyst Technologies..........................8 2.1.3 Operating Experience ...................................................................................8 2.1.4 Costs..............................................................................................................9 2.2 Diesel Particulate Filters ...........................................................................................9 2.2.1 Operating Characteristics and Performance .................................................9 2.2.2 The Impact of Sulfur in Diesel Fuel on Diesel Particulate Filters..............12 2.2.3 Operating Experience .................................................................................12 2.2.4 Costs............................................................................................................13 2.3 Exhaust Gas Recirculation (EGR) .........................................................................13 2.3.1 Operating Characteristics and Control Capabilities ...................................14 2.3.2 Operating Experience .................................................................................14 2.3.3 Costs............................................................................................................14 2.4 Selective Catalytic Reduction (SCR)......................................................................14 2.4.1 Operating Characteristics and Control Capabilities ...................................14 2.4.2 Operating Experience .................................................................................15 2.4.3 Costs............................................................................................................15 2.5 Lean NOx Catalysts .................................................................................................15 2.6 Crankcase Emission Control ..................................................................................16 3.0 Operating a Diesel Emission Retrofit Control Program..................................................17 3.1 Vehicle Selection ......................................................................................................18 3.2 Retrofit Control Technology Options ....................................................................19 3.3 Education and Training ..........................................................................................19 3.4 Incentives and Regulations .....................................................................................20 4.0 Technical Issues to be Considered When Retrofitting Emission Controls.....................21 4.1 Fuel Quality..............................................................................................................21 4.2 The Importance of Vehicle Maintenance...............................................................21 4.3 Matching a Retrofit Technology to an Engine Application .................................21 5.0 Conclusions...........................................................................................................................23 6.0 Case Studies..........................................................................................................................24 The New York City Metropolitan Transit Authority (MTA), New York City, NY 24 The Hong Kong Retrofit Program ...............................................................................24 The NYC Department of Sanitation Retrofit Project, New York City, NY .............24 The Central Artery/Tunnel (CA/T) Project, Boston, MA..........................................25 Washington Metropolitan Area Transit Authority Bus Retrofit Project, Washington, DC .............................................................................................................25 Diesel Solutions, Seattle, WA........................................................................................25 March 2002 i Figures Figure 1 Diesel Oxidation Catalyst Functional Diagram...........................................................7 Figure 2 Diesel Particulate Filter Schematic...............................................................................9 March 2002 ii Executive Summary Diesel engines are important power systems for onroad and offroad vehicles. These reliable, fuel-efficient, high torque engines power many of the world’s heavy-duty trucks, buses, and nonroad vehicles. While diesel engines have many advantages, they have the disadvantage of emitting significant amounts of particulate matter (PM) and the oxides of nitrogen (NOx) into the atmosphere. Diesel engines also emit toxic air pollutants. Health experts have concluded that pollutants emitted by diesel engines adversely affect human health and contribute to acid rain, ground-level ozone and reduced visibility. Studies have shown that exposure to diesel exhaust causes lung damage and respiratory problems and there is increasing evidence that diesel emissions may cause cancer in humans. Companies that manufacture emission controls have responded to the challenge of reducing the air pollution from diesel engines. Through their efforts, cost-effective retrofit technologies have been developed to reduce harmful emissions. In the mining, materials handling and trucking industries and in urban bus fleets, diesel retrofit technologies have demonstrated their ability to significantly reduce unwanted emissions at reasonable costs without jeopardizing vehicle performance. The Manufacturers of Emission Controls Association (MECA) has received many inquiries regarding the installation of emission controls on diesel engines. Inquiries have included requests for technical information, information on past retrofit experiences, the types of retrofit control technologies available, the suitability of a given technology to a particular application and emission reductions that can be achieved. This document has been prepared to supplement information already made available by MECA on emission control technologies. Periodically, as new information becomes available, this document will be updated. Available Control Technologies Today, viable emission control technologies exist to reduce diesel exhaust emissions. The major retrofit technologies are listed below. Retrofit technologies to control PM, hydrocarbons (HC), carbon monoxide (CO) and toxics air pollutants include: • Diesel oxidation catalysts • Diesel particulate filters • Enhanced combustion modifications • Crankcase emission controls Retrofit technologies to control NOx include: • Exhaust gas recirculation (EGR) • Selective catalytic reduction (SCR) • Lean NOx catalysts • Engine modifications plus PM controls March 2002 1 The retrofit of oxidation catalysts on diesel engines has been taking place for well over twenty years in the nonroad vehicle sector. Over 250,000 oxidation catalysts have been installed in underground mining and materials handling equipment. More recently, over 15,000 oxidation catalysts have been installed on urban bus engines as part of the U.S. Environmental Protection Agency's urban bus rebuild/retrofit program. Since 1995, over 40,000 systems have been installed on highway trucks, buses and other on road heavy-duty vehicles around the world. Oxidation catalysts installed on engines running 0.05 percent or less sulfur fuel have achieved particulate matter reductions of 20 to 50 percent, hydrocarbon reductions of 60 to 90 percent (including those HC species considered toxic), and significant reductions of carbon monoxide, smoke, and odor. Over 1,000 buses have been retrofitted with oxidation catalysts in London, England and over 1,500 oxidation catalysts have been installed on trucks and buses in Sweden. In April 2001, the Hong Kong Department of Environmental Protection completed a pilot program involving the retrofit of 59 diesel vehicles with diesel oxidation catalysts. Based on this pilot program, Hong Kong plans retrofit about 40,000 trucks with diesel oxidation catalysts in the near future. Development and commercialization of a number of second-generation diesel particulate filter systems have occurred. Second generation systems are capable of achieving 80 percent to greater than 90 percent PM reductions. Current filter designs are also capable of reducing toxic hydrocarbons by greater than 80%. In Europe,