|110 Texas counties affected by TxLED|
The Texas Low Emissions Diesel (TxLED) requirements are designed to lower the emissions of NOx and other pollutants from diesel-powered vehicles and non-road equipment in 110 counties in the eastern half of Texas as part of the State Implementation Plan to address non-compliance with federal ozone standards.
Under the rule, diesel supplied in those 110 counties must comply with the more stringent California Air Resources Board specifications for diesel fuel (e.g., 10% or less total aromatic hydrocarbon content; a cetane number of at least 48, a maximum 15-ppm sulfur content).
Originally adopted in 2000, the rule was due for implementation in April 2005. That was changed to the current 1 October 2005 implementation date.
The law first applies to producers and importers; bulk plant distribution facilities have until November, and retail fuel dispensing outlets, wholesale bulk purchaser/consumer facilities, and all other affected persons until 1 January 2006.
Biodiesel is not by default an approved solution for TxLED, either as an additive or neat (B100).
The executive director of the TCEQ has determined that blending biodiesel into Texas Low Emission Diesel (TxLED) is not acceptable unless the blend has been approved by TCEQ as being equivalent to TxLED in reducing NOx emissions.
Pure biodiesel (B100) and other biodiesel blends such as B20 are known to be effective in reducing emissions of carbon monoxide, total hydrocarbons, and particulate. The U.S. Environmental Protection Agency (EPA) has verified the use of biodiesel as a retrofit technology to reduce these specific emissions.
However, the use of B100 in compression-ignition engines is also known to increase NOx emissions by at least 10 percent and by 2 percent or more with B20 blends.
This increase in NOx emissions is acknowledged by industry groups, the EPA, the California Air Resources Board (CARB), and the National Biodiesel Board. In fact, because of the known increase in NOx emissions, the Engine Manufacturers Association (EMA) does not recommend the use of B100 or biodiesel blends as a means to improve air quality in ozone non-attainment areas. (TxLED FAQ)
The TCEQ will accept the use of biodiesel on a case-by-case basis if the blend can demonstrate that is has been verified by EPA or CARB to reduce NOx emissions by a percentage that is equivalent to or greater than the NOx reduction of at least 5.7 percent attributed to TxLED when blended with regular EPA diesel; or it has been approved by the executive director as an TxLED alternative diesel formulation.
An alternative diesel formulation is one that either meets the emissions target without specifically meeting the fuel characteristics as specified by TxLED, or that is produced through blending with an approved additive.
So far, only two additives have been approved: Lubrizol PuriNOx and, most recently, Biofriendly Green Plus.
Green Plus is a fuel catalyst. Mixed into diesel in concentrations of 50 ppm or less, the additive promotes a more complete, and lower-temperature combustion, resulting in reduced emissions and an improvement in fuel economy, according to their testing results, of some 6%–9%.
Lubrizol takes a different approach, blending a diesel-water-PuriNOx emulsion. The water in the emulsion promotes a finer, more even spray and combustion at a lower temperature, and the PuriNOx additive keeps the diesel-water mixture stable.