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Understanding Ultra Low Sulfur Diesel Fuel

Monday, May 4th, 2020
what is diesel fuel

Opinions about ultra low sulfur diesel fuel (ULSD) vary. Some think it is great for the environment while others think it causes more problems than it is worth. Here we will cover the benefits, drawbacks, and history of ULSD fuel.

The history of ULSD fuel

The Clean Air Act was established by Congress in 1970 in an effort to reduce harmful emissions from vehicles. In 1990, an amendment to this was enacted to enforce stricter rules regarding hydrocarbons, carbon monoxide, sulfur oxides, particulate matter, and nitrogen oxides. Specific to sulfur, the EPA also enacted stricter rules to reduce sulfur oxide emissions from diesel fuel.

The EPA finished a federally mandated program called the 2007 Heavy-Duty Highway Diesel Program to limit emissions from high diesel vehicles even more. In 2006, this mandate decreased the max sulfur limit from 500 to 15 parts per million (ppm). This is when Ultra Low Sulfur Diesel came to be.

Soon after the highway diesel program was enacted, the EPA also issued the Clean Air Non-Road Diesel – Tier 4 Final Rule.This regulated sulfur emissions for off-road vehicles in 2007. This reduced sulfur content in off road diesel from 3,000 to 500 ppm in 2007 and from 500 to 15 ppm in 2010.

Why was reducing sulfur content in diesel fuel important?

Since 1990, the EPA has been responsible for mandating a 99.7% reduction in sulfur content in fuels. This was necessary because of the harmful emissions of sulfur oxides, specifically SO2. These emissions can cause lung damage and respiratory issues. The oxides can also damage trees, plants, and stones and even cause acid rain.

The downsides of reducing sulfur in diesel fuel

Reducing the sulfur content in diesel fuel helps the environment, but doing so also means that the composition of the fuel had to change. Refineries removed large amounts of sulfur from diesel using hydrotreating methods, which also resulted in the following.

  • Reduced natural lubricity compounds
  • Lower conductivity
  • Lower aromatic content
  • Increased costs in production (by an estimated 5 to 7 cents per gallon)
  • Increased cetane levels
  • Decreased fuel economy (by about 1%)
  • Lower energy density

Another downside to reducing the sulfur content in diesel and creating different fuels is tank corrosion. This problem has hit an all time high since the 2007 changes. When fuel tankers transport fuels (both gasoline and diesel), they sometimes participate in switch loading. On one day, a tanker could be delivering ethanol-based fuel and the next a load of ULSD.

The corrosion is caused by the ULSD having a higher affinity for water. When water is vital for microbial growth and microbes can result in corrosion. This problem can also be caused when small amounts of biofuel come into contact with ULSD.

Solving issues with ULSD

To help prevent issues that result from using ultra low sulfur diesel fuel, it is recommended that you use fuel additives. Using a range of these products can help reduce problems and keep your fuel doing its job properly. To prevent tank corrosion, you must be sure not to mix your ULSD with water. You can do this by making sure the fuel does not have water or microbes before or after your deliveries are made.

If you have your own fuel storage tanks, you should have some sort of maintenance system. This will help you keep up with testing more easily by removing water and contaminates, as well as letting you catch fuel leaks.

High-quality fuel products and services

If you would like to learn more about different types of fuels or need Bulk Fuel and Related Services, give Kendrick Oil Company a call. We provide a variety of services throughout Texas, New Mexico, Oklahoma, Kansas, Colorado, and Louisiana. You can reach us at (800) 299-3991 to find our more.