Emulsions, fuel additives moving up in clear-air plans for major cities

Diesel Fuel News, July 22, 2002 by Jack Peckham

Add the Washington, D.C., metro area to the growing list of major cities considering diesel-water emulsions or clean-diesel additives in order to meet tough U.S. EPA emissions "conformity" deadlines.

This month, Metropolitan Washington Council of Governments (MWCOG) aims to propose to its Transportation Planning Board (TPB) a pilot evaluation program of diesel-water emulsions and fuel additives.

Diesel school buses would be a major focus of this pilot test, because a new MWCOG study of heavy-duty traffic on local (residential) streets shows that school buses account for most of the heavy-duty street vehicle-miles traveled. That prompted local press coverage citing school buses as "major polluters" (Washington Times) and another claiming that "school buses account for 75% of the heavy diesel engines on local roads" (Washington Post).

Problem with these accounts: School bus emissions are relatively tiny compared to the millions of cars and trucks roaming metro D.C.'s highways, as MWCOG's own study shows. However, these local bus fleets are a bigger contributor to the total emissions inventory than previously thought, the MWCOG study shows.

Other types of public heavy-duty vehicles are likely to join in the emulsions/additives evaluation, MWCOG public affairs director Jeanne Saddler explains.

"We think the test might help speed up the federal EPA's approval process of the additives," she said. "If so, we could use them in this area as one of the effective measures to be used to clean up the air. At the moment, we can't propose using these additives as part of a plan to meet federal air quality standards because the additives haven't been verified as effective by EPA."

In a recent MWCOG transportation planning branch report, four products have been identified for potential pilot tests: Lubrizol's "PuriNOx" diesel-water emulsion, Wynn Oil's "W15-590" diesel fuel additive, "Molybdenum Lubricant" for lube oil, and a novel "Viscon" polymer fuel additive under development by Virginia-based GTA Technologies.

"PuriNox" has already been verified (see Diesel Fuel News 2/5/01, p2) by California Air Resources Board (CARB) as delivering a 14% reduction in nitrogen oxides (NOx) and a 63% reduction in particulate matter (PM). According to the MWCOG report, Lubrizol hopes to complete its required U.S. EPA fuels/additives "Tier 2" registration/health effects evaluation process this summer. Registration/Tier 2 evaluation is one of the requirements for EPA's upcoming diesel fuels/additives "environmental technology verification" (ETV) process (see Diesel Fuel News 6/10/02, p2).

Meantime, GTA's "Viscon" is being tested at West Virginia University's renowned diesel emissions research & development laboratories in a program that initially aims to win California Air Resources Board (CARB) "alternative diesel fuels" emissions reduction verification.

In evaluations on several buses in California so far, GTA claims that "results from these tests indicate a greater-than-15% reduction in NOx/PM," GTA spokesman John Warden told us: The earlier MWCOG report on Viscon however quotes a more modest 10% NOx reduction, along with an estimated 4 cent/gallon extra cost, offset by a 14% fuel economy boost.

According to Viscon's Warden, optimal polymer dosage rate in diesel fuel is 7 parts per million, with a lower retail cost than that foreseen by MWCOG (about 2.3 cents/gallon). The additive improves fuel droplet size uniformity to enhance combustion. Viscon calculates that resulting fuel savings (8 to 17%) will more than pay for the additive cost.