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Technical Summary
Related Information
The following table lists information collected by EPA staff showing the potential capabilities of a variety of both currently available and future emissions reduction technologies. This list may not be used to provide formal emission reduction claims for SIP purposes, compliance programs, or consent decree projects. This list is intended to provide guidance in selecting appropriate technology for air quality program needs and to provide a general estimate of the emissions reduction capabilities of the various technologies. Actual emissions reductions, cost, fuel economy penalty will be a function of the individual applications and situations. EPA has created a verification program that will officially evaluate the emission performance of technology as individual manufacturers submit their products to the verification program. EPA will list the official performance data and associated information on our Diesel Retrofit Program's Verified Technology List.
| Technology | Emission Reduction | Price ($) | Sulfur Tolerance (ppm) | Fuel Penalty (%) | Performance Penalty | Availability/Maturity | Issues/Comments | |||
|---|---|---|---|---|---|---|---|---|---|---|
| NOx | PM | HC | CO | |||||||
| Base Metal Oxidation Catalyst |
-- | 10-30 | 50 | 50 | 1-2K | <500 | 0-2 | -- | commercial; proven |
designed to minimize oxidation of sulfur |
| Precious Metal Oxidation Catalyst |
-- | 20-40 | 90 | 90 | 1-3K | <15 | 0-2 | -- | commercial; demo |
designed for maximum reductions |
| Base Metal Oxidizing PM Filter |
-- | 80 | 50 | 50 | 6.5-10K | <500 | 2-4 | -- | commercial; demo | reliable regeneration without supplemental addition of heat limits application based on duty-cycle, ambient condition considerations |
| Highly Oxidizing Precious Metal PM Filter |
0-5 | >90 | 90 | 90 | 6.5-10K | <15 | 1-3 | -- | commercial; demo | with care can be applied to all applications |
| Active Lean NOx Catalyst (requires supplemental fuel injection) | 20 | -- | -- | -- | 6.5-10K | <250 | 4-7 | -- | commercial; demo | possible N2O generation; 10k hr durability data exists |
| 4-Way Catalyst (ActiveLean NOxCat + PM Filter) | 20 | 80 | 70 | 70 | 8-10K | <500 | 4-7 | -- | commercial; demo | currently undergoing durability testing |
| NOx Adsorber | >90 | 10-30 | 90 | 90 | -- | <15 | -- | -- | 2007; R&D | requires engine integration, means for supplemental fuel injection |
| Diesel Emulsion | 5-30 | 20-50 | -- | -- | 0.01/gal | above 500 | none | requires engine re-calibration to maintain power, PM benefit due to engine de-rate calibration changes may mean no PM benefit | commercial; demo | undergoing health effects testing, injection system durability issues, cold start PM/HC/CO emissions can increase, additives used to prevent emulsion freezing can make aldehydes/ formaldehyde |
| Selective Catalytic Reduction | 60 | 0-30 | 50 | 50 | 10-20k Urea 0.80/gal | <500 | urea consumption ~4% of fuel use | -- | commercial; demo; proven for stationary | infrastructure; requires engine integration: NOx sensor or engine NOx-map; ammonia slip possible vanadium emissions |
| Compact Selective Catalytic Reduction | 90 | 10-30 | 90 | 90 | 10-20k Urea 0.80/gal | <50 | urea consumption ~6% of fuel use | -- | -- | uses precious metal oxidation catalysts to improve NOx control and to limit Ammonia slip; issues same as above |
| Fuel Borne Catalyst | <10 | <33 | <50 | <50 | .05-.06/gal. | <350 | (8) | -- | commercial; demo | not much known; undergoing health effects testing, potential for fine metallic emissions, some providers now only sell product when operated with a PM filter |
| FBC w/lightly catalyzed oxidation catalyst | <10 | 30-60 | <50 | <50 | 1-1.5K .05-.06/gal. |
<350 | (4-6) | -- | commercial; demo | potential for fine metallic emissions, some providers now only sell product when operated with PM filter |
| FBC w/lightly catalyzed PM filter | <10 | 85 | 80 | 80 | 3.5-4.5K .05-.06/gal. |
<50 | 2-(2) | -- | commercial; demo | designed to meet CARB target of 0.01g/bhp-hr. exhaust temperature needed for regeneration limits applications based on duty cycle, ambient condition considerations . |
| Cooled-EGR | 50 | see issues | -- | -- | -- | <500 | 0-5 | -- | commercial demo from engine manufacturers; R&D as a retrofit | requires major engine integration: fuel and air management system upgrades needed to counteract increased PM from EGR; condensation concerns; packaging constraints |
See the publications page of the National Clean Diesel Campaign for fact sheets and reports on various aspects of retrofit technology operation and application.