Carb, Cec Unveil Programs For Cleaner Diesel Fuels

Diesel Fuel News, Dec 11, 2000 by Jack Peckham

California Air Resources Board (CARB) and California Energy Commission (CEC) both unveiled new programs to help cleaner diesel fuels qualify for state emissions-reduction programs.

The new CARB program spells out how "alternative diesel fuels" including Fischer-Tropsch diesel, diesel-water emulsions, biodiesel and ethanol-diesel blends can become CARB-certified.

(Web: www.arb.ca.gov/diesel/diesel.htm).

To qualify, the "alternative" diesels must reduce nitrogen oxides (NOx) and particulate matter (PM) emissions below that of conventional CARB diesel fuel (10% aromatics limit) on CARB's standard test.

A fuel won't qualify if it merely cuts PM but increases NOx in exchange (or vice-versa), CARB manager Gary Yee explains. The emissions testing will be engine-out rather than post-aftertreatment, with no engine modifications allowed.

The "alternatives" also must not cause any increase in "toxics" and must cut hydrocarbon emissions "at least 25% lower than any applicable diesel vehicle emission standard."

Any metallic compounds in the fuel, such as copper, iron, cerium, lead, cadmium, chromium and phosphorus must be revealed. CARB wants to know if such compounds might cause an increase in toxic emissions, or potentially damage exhaust catalysts or other aftertreatment systems.

Applicants must show the fuel's impact on emissions of formaldehyde, acetaldehyde, benzene, toluene, ethyl benzene, xylenes, butadiene, and polycyclic aromatic hydrocarbons.

Applicants also must reveal the fuel's viscosity, volatility, ignition quality, operating temperatures, engine wear tendencies, corrosion, lubricity and flash point.

All the alternatives have limitations. Water-diesel emulsions normally aren't freely interchanged with ordinary diesel fuel. Lubricity is well-known problem for FT diesel, although additives can fix this problem. Ethanol-diesel blends can't meet ASTM standards for flash point, and therefore require special handling requirements. Biodiesel blends have been shown to reduce the solid fraction of PM, but often cause an increase in nitrogen oxides (NOx) and hydrocarbons.

So, because of potential operational problems, CARB will require the "alternative" candidates to show their fuel "does not adversely affect the performance and operation of diesel engines or cause premature wear or cause damage to diesel engines."

As examples, the agency cites "lubricity, corrosion and damage to engine parts such as fuel injector tips."

CARB also will require applicants td "provide data showing under what temperature and conditions does the candidate alternative diesel fuel remain stable and usable in California."

*CEC Launches NOx Tech Program

Assuming the "alternatives" will jump CARB hurdles, then they also might qualify for a piece of $2.2 million in new CEC NOx reduction funds to advance retrofit technologies that can cut diesel NOx emissions by a least 15% while not increasing PM. (More info, see: www.energy.ca.gov/contracts/index.html#ttfo).

The technologies developed under the CEC program also can be applied to any new on-road diesel engines that can meet or beat a 1.0 grams/brake horsepower-hour NOx limit, or, for off-road diesels, at least 30% lower than existing NOx limits.

Applicants must put up 50% in matching funds for these grants.