U.S. EPA'S clean-diesel retrofit technology 'verification" protocols now final

Diesel Fuel News, Oct 27, 2003 by Jack Peckham

The U.S. EPA-supervised "Environmental Technology Verification" (ETV) test protocol schemes for clean-diesel fuels, additives and selective catalytic reduction (SCR) are now final, following nearly two years of development.

The final protocols (see: http://etv.rti.orWapct/pdf/GVP_MS_Fuels.pdf and htto://etv.rti.org/apct/pdf/GVP_MS_SCR Rev6-2.pdf) require engine tests in a laboratory, rather than in-use field data or chassis measurements.

For highway engine fuels and additives tests, the protocol implies default use of up to 15-ppm sulfur ultra-low sulfur diesel (ULSD) rather than today's conventional 500-ppm sulfur fuel. Non-road engine applications could be tested with today's non-road fuels (up to 3,500 ppm except in California, where the limit is up to 160 ppm). However, EPA's office of transportation air quality (OTAQ) would allow use of today's highway diesel fuel for "verification" tests if the additive still achieves real emissions reductions, under the standard test requirements.

"Refinery diesel product streams must be used to produce the base fuels for tests," according to the new ETV protocol. "Because oxygenates are rarely used in diesel, neither the California nor the national average fuel may contain oxygenates.

"Although additives are not used consistently in diesel, it is permissible for the California and/or the national average fuel [used in tests] to contain a registered additive or additives designed to maintain fuel quality during transport and storage, such as an antioxidant and/or corrosion inhibitor."

Some clean-fuels and clean-additives proponents had complained that EPA's test protocol language could block the use of ordinary highway diesel fuel for "verification" tests, limiting market opportunities (see Diesel Fuel News 2/3/03, p4; 11/11/02, p4; 6/10/02, p2).

However, EPA diesel retrofit program official Jim Blubaugh told us that EPA will issue a "guidance document" fairly soon clarifying that today's highway diesel fuel could indeed be used to verify "clean" fuel/additive retrofits.

"The desire is not to preclude a fuel additive based on today's diesel fuel," Blubaugh told us. EPA's office of transportation air quality (OTAQ) "does recognize that you can put an additive in today's fuel and evaluate [its emissions effect] according to that."

Some technology proponents likely would want to test their additive with ULSD anyway, to show emissions benefits when ULSD becomes the standard fuel in 2006. But "our side of this is not to preclude any additive or emulsion" even if retrofit "verification" testing is with today's 500-ppm sulfur highway fuel, Blubaugh told us.

EPA/ETV does specifically allow the use of today's 500-ppm sulfur diesel fuel blended with a "clean" fuel-borne catalyst (FBC) additive technology if combined with an exhaust catalyst/filter device (see related story, p9).

Meantime, for SCR retrofit "verification," maximum sulfur content in diesel fuel isn't limited by ETV. Rather, if the SCR is for highway engines, then fuel sulfur content must meet current or future EPA regulations--and the same goes for non-road engines.

"For stationary source engines, the [local] permitting authority may dictate fuel requirements," the ETV protocol points out.

In any case, "because the performance and durability of many types of diesel retrofit technologies are affected by the sulfur content of the diesel fuel, applicants should specify the maximum sulfur level of the fuel for which their technologies are designed," the protocol says.

Table 3. Properties of Base Fuel for ETV of Diesel FMs

                                  Nationwide
Property                         Average Fuel      California Fuel

Accepted by EPA-OTAQ                 Yes                 Yes
Cetane number                      43 to 46            51 to 54
Aromatics, volume %                32 to 36            20 to 24
Specific gravity                 0.84 to 0.86        0.83 to 0.85
Additives                        minimal (b)         minimal (b)
Sulfur, ppm
                   Highway         0 to 15             0 to 15
                   Nonroad      2500 to 3500 (c)      100 to 160
Distillation range
10% point, [degrees]F             410 to 430          410 to 430
50% point, [degrees]F             490 to 520          490 to 520
90% point, [degrees]F             585 to 620          595 to 630

                               Applicant-Choice       ASTM Test
Property                        Base fuel (a)

Accepted by EPA-OTAQ                No (a)
Cetane number                                           D 613
Aromatics, volume %                                     D 5186
Specific gravity                                        D 1298
Additives
Sulfur, ppm
                   Highway                              D 6428
                   Nonroad                              D 2622
Distillation range
10% point, [degrees]F                                    D 86
50% point, [degrees]F                                    D 86
90% point, [degrees]F                                    D 86

(a) Testing of FMs using a base fuel chosen by the applicant is
possible within this protocol.

(b) Cetane improvers and some other additives cannot be avoided in
refinery products. However, these are to be minimized, and no
additional additives are to be used.

(c) Use of highway diesel sulfur levels allowed in accordance with 40
CFR part 89.330.