Division of Air Quality Air Non-Point and Mobile Sources

Questions & Answers: Ultra Low Sulfur Diesel (ULSD)

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What is ultra-low sulfur diesel?

Ultra-low sulfur diesel (ULSD) is diesel fuel containing a maximum of 15 parts per million (ppm) of sulfur. Previous sulfur levels were up to 3,000 ppm for Alaska's on-highway diesel.

Will the newest diesel engines require this fuel?

Serious damage will occur without it. Sulfur in diesel fuel must be lowered to become compatible with modern pollution-control technology being installed on later model diesel engines. This equipment will reduce fine particles (soot) and pollutants in diesel exhaust by over 90%.

What happens if I fuel my new truck with the old high sulfur fuel?

Incorrectly fueling a 2007 model year or later engine with high sulfur fuel will damage the emission controls. The catalyst will be rendered useless and the emissions will not be controlled. Excess sulfur will plug the particulate trap which may cause a back pressure and possibly damage the engine. Fueling a 2007 and newer model year engine with high sulfur fuel will void the engine warranty and is against federal law.

Why is EPA doing this?

Over the last few decades, health scientists have demonstrated negative health impacts from exposure to diesel exhaust and soot. Exposure to diesel exhaust is widespread and there is increasing evidence that diesel exhaust or soot may cause lung cancer and aggravate health conditions.

Will my old diesel engines run on ultra-low sulfur diesel?

Older vehicles and equipment will run on ultra-low sulfur diesel and will experience a small reduction in particulate matter. Operators of old diesel engines may want to replace gaskets and seals as very old gaskets shrink and leak when running on low sulfur fuels. However, EPA and the Engine Manufacturers Association do not anticipate problems burning ultra-low sulfur diesel in old engines. On the other hand, vehicles and equipment outfitted with new emission control technology ( e.g. diesel vehicles with 2007 model year and later engines can fail if run on the high sulfur diesel fuel).

What about construction equipment like graders or back hoes? Do they have to use ULSD?

Eventually. This group of engines includes farm equipment and portable diesel generators. They will need to transition to low sulfur diesel (500 ppm sulfur) after summer 2007, followed by a transition to ultra-low sulfur diesel in 2010.

What about my community's power generator?

Stationary engines, like those used in power generation, will likely follow the same timeline as non-road mobile engines. That timeline includes a transition to low sulfur diesel in 2007, followed by a transition to ultra-low sulfur diesel in 2010. There is no 2007 transition to low sulfur diesel if your community lies off the road system or lacks state ferry service.

At retail locations, will the diesel dispenser have a different size nozzle to prevent a customer from misfueling?

No. EPA did not require unique dispenser nozzles for 15 ppm diesel fuel. Misfueling was not determined to be a significant problem to justify the increased cost on fuel pump charges.

How does ULSD fuel affect air quality?

ULSD fuel enables the use of cleaner technology diesel engines and vehicles with advanced emissions control devices, resulting in significantly improved air quality. Annual emission reductions will be equivalent to removing the pollution from more than 90 percent of today's trucks and buses, when the current heavy-duty vehicle fleet has been completely replaced in 2030.

What other cold weather-gelling strategies are available to the end user?

Historically, diesel engines have had problems starting in cold weather. To prevent similar problems with ULSD, the industry has developed a number of fuel-additive products for use in the cold-weather operation of diesel-powered vehicles and equipment. Both fuel refinieries and terminals blend additives into ULSD supplies in anticipation of cold temperatures, and other additive products are available that drivers can add themselves into their fuel tanks in anticipation of extremely low temperatures.

Is the end user responsible for fueling with diesel in excess of 15 ppm?

The end user is at fault where that individual knowingly fueled a MY2007 with clearly labeled 500 ppm diesel when 15 ppm diesel fuel is required.

Why is heating oil exempt from the sulfur content regulations?

These Ultra Low Sulfur Diesel regulations are only applicable to on-road mobile sources, therefore heating oil is not an affected source.

What does a diesel retrofit refer to?

Diesel retrofits are a type of control device that can be installed on diesel powered engines in order to reduce exhaust emissions. Diesel retrofit control technologies include particulate filters (DPF), oxidation catalysts (DOC), closed crank ventilation system (CCV), exhaust gas recirculation (EGR), selective catalytic reduction (SCR) devices, and lean NOx catalysts (LNCs).

What are the benefits of using diesel retrofit devices?

Diesel Particulate Filters (DPFs) reduce emissions of particulate matter 2.5 (PM_2.5), hydrocarbons (HCs), and carbon monoxide (CO) by 60-90%. DPFs require the use of ultra-low sulfur diesel fuel (ULSD). Diesel Oxygen Catalysts (DOCs) reduce PM_2.5 emissions by about 30% as well as reduce emissions of HCs by 50% and CO by 40%. DOCs do not require the use of ULSD. Closed Crank Ventilation systems (CCVs) reduce PM_2.5 by 10-15%, HCs by 30-40%, and CO by 50-90%.

Does ULSD affect the power and fuel economy of diesel equipment?

Under typical operating conditions there should be no noticeable impact on the overall power of the vehicle. The reduction in energy content in ULSD could result in reduced fuel economy by some estimates of about 1%, which is within normal variability of diesel fuel.

Contact Adeyemi Alimi or phone: 907-269-6953 if you have questions regarding ultra-low sulfur diesel and DEC's role.