Ultra Low Sulfur Diesel (ULSD): Cleaner motor fuel and lower sulphur emissions

Introduction

Ultra low sulfur diesel (ULSD), the fuel that is transforming the energy industry and reducing polluting emissions. In a world where sustainability is a priority, ULSD has become a key part of improving air quality and optimizing the performance of diesel engines. Its low sulfur content not only complies with strict environmental regulations, but also enables the use of advanced emission control technologies. But what makes this fuel so efficient and what impact does it have on industry and the environment?

In this article, we will discuss what ultra low sulfur diesel (ULSD) is, how it is produced, what regulations prompted its use and what are its main applications.

What is Ultra Low Sulfur Diesel (ULSD)?

Ultra low sulfur diesel is a type of fuel that contains significantly lower sulfur concentration compared to traditional diesel. The reduction of sulfur content in this fuel allows to reduce the emission of sulfur dioxide (SO₂), a compound harmful to health and the environment.

ULSD has become the standard in many countries due to its role in reducing air pollutants. Today, ULSD contains a maximum of 15 parts per million (ppm) of sulfur, compared to the previous low-sulfur diesel that could contain up to 500 ppm.

What regulations drove the adoption of ULSD?

The adoption of ultra low sulfur diesel was driven by various environmental regulations around the world. In the United States, the Environmental Protection Agency (EPA) established stringent standards starting in 2006 to reduce the sulfur content in diesel, which resulted in making ULSD mandatory in the market.

These regulations were part of an effort to reduce pollutant gas emissions from diesel vehicles and improve air quality in urban areas. In Europe, European Directive 2009/30/EC also introduced stricter limits for sulfur content in diesel fuel, obliging European Union member countries to adopt the ULSD by 2009. These efforts were complemented by additional regulations aimed at reducing emissions of fine particulate matter and gaseous pollutants through the adoption of cleaner diesel engine technologies.

Globally, many developing countries have also begun to implement similar regulations to reduce the environmental impact of the diesel engine. The trend towards clean fuel has been supported by the World Health Organization (WHO), which has warned about the risks of air pollution, especially in densely populated urban areas.

How is ultra low sulfur diesel produced by hydrodesulfurization?

ULSD is produced by an advanced process known as hydrodesulfurization (HDS), which allows the removal of sulfur from the fuel. This process is carried out in oil refineries and involves the following stages:

1. Hydrotreating: The crude diesel is subjected to a reaction with hydrogen at high pressure and temperature in the presence of a catalyst.
2. Sulfur removal: During the reaction, sulfur compounds are converted to hydrogen sulfide (H₂S), which is then removed by absorption and separation processes.
3. Final refining: Treated diesel passes through a series of filters and processes to ensure that it meets minimum sulfur content regulations.

This process ensures that ULSD is compatible with modern diesel engine injection and after-treatment systems, allowing for more efficient and cleaner combustion.

Ultraclean Technology has developed a solution for the separation of sulfur from hydrocarbons, consisting of a proprietary chemical process (Ultrex®) and a patented liquid phase transfer catalyst (PTC). The Ultrex® solution is an oxidative desulfurization process at scale.

Benefits and challenges of ULSD

Environmental and technological benefits of ULSD

The positive environmental impact of ULSD is evident on several fronts:

• Reduced sulfur emissions: ULSD drastically reduces sulfur dioxide (SO₂) emissions, which is a precursor to acid rain. This benefit is crucial, as acid rain can damage ecosystems, water bodies and the infrastructure of buildings and monuments.
• Less air pollution: Thanks to the reduction of sulfur dioxide (SO₂), the use of ULSD decreases the formation of particulate matter, which is directly related to respiratory health problems, such as asthma and heart disease. In addition, fine particulate matter generated by the diesel engine contributes to air pollution and smog formation, especially in urban areas.
• Compatibility with emission reduction technologies: The low sulfur content in ULSD is necessary for the efficient operation of advanced technologies such as diesel particulate filters (DPFs) and selective reduction catalysts (SCR), which remove remaining pollutants in the exhaust gas, such as nitrogen oxides (NOₓ). Without the adoption of ULSD, these technologies would not be able to operate efficiently, making it difficult to comply with EPA and European Union emissions regulations.
• Improved engine efficiency: ULSD is compatible with newer diesel engines that have been specifically designed to operate on low-sulfur fuels. This diesel engine is more efficient, performs better and emits fewer pollutants. As a result, newer diesel vehicles have a lower carbon footprint compared to older models using higher sulfur fuels.

Challenges and considerations in the implementation of ULSD

Despite the benefits of ULSD, there are certain challenges in its implementation:

• Production costs: Refining ULSD is a costly process, which may cause the price of this fuel to be higher than traditional diesel; representing a barrier in markets where operating costs are sensitive, such as in transportation and logistics.
• Distribution infrastructure: In some countries, the fuel distribution infrastructure is not fully adapted to handle ULSD, generating difficulties in its availability and in the complete transition to a cleaner fuel.
• Impact on sectors with older vehicles: While modern diesel engines are designed to run on ULSD, older vehicles may require adaptations to use this type of fuel without damage. In addition, some after-treatment systems in older diesel engines may not be compatible with the new regulations, requiring additional investments in fleet renewal.

Comparison of ULSD and other diesel fuels

ULSD (Ultra Low Sulfur Diesel) differs from conventional diesel in its low sulfur content (15 ppm vs. 500 ppm), which allows for cleaner combustion and lower emissions.

• Price: More expensive due to advanced refining, with an additional cost of $0.05 to $0.25 per gallon.
• Demand: Growing in the USA, Europe and the maritime industry, being mandatory in modern engines and heavy machinery.
• Efficiency: Less deposits in motors, but with a slight loss of energy efficiency (1-2%).
• Environmental impact: Reduces sulfur emissions by 97%, complying with regulations such as EPA, Euro 6 and IMO 2020.
• Alternatives:
  • Biodiesel: More environmentally friendly, but less efficient and with compatibility problems.
  • Renewable diesel: Cleaner and more efficient, but less affordable.

ULSD is the standard choice because of its lower environmental impact and compatibility with modern engines, despite its higher cost. Its use will continue to increase due to strict regulations and the transition to cleaner fuels.

The future of diesel and energy alternatives

ULSD represents a significant transition to clean fuels, but it is not the only solution. Emerging technologies such as advanced biofuels, renewable diesel and electrification of heavy transport are gaining prominence in the quest for more sustainable mobility. Clean fuels such as ultra low sulfur diesel are paving the way for a future with a smaller carbon footprint.

Success Stories: Implementation of ULSD

• In Mexico, the Energy Regulatory Commission (CRE) established that, as of January 1, 2019, ultra low sulfur diesel must be supplied throughout the country, with some temporary exceptions in certain regions.
• In 2023, Pemex was able to produce close to 30% of the diesel required in the country, with a significant portion of this production coming from the Deer Park refinery in Texas.
• Ultraclean Technology has developed the Ultrex® solution for the separation of sulfur from hydrocarbons, consisting of a patented chemical process (Ultrex®) and a patented liquid phase transfer catalyst (PTC). In the following video, Ultraclean Fuels’ desulfurization experts explain how the Ultrex process works at their operating facility in New Mexico (USA).

Recent data and statistics

• Consumption in Mexico: In 2022, Mexico consumed approximately 1,772 million barrels per day of petroleum products, mainly used in cargo and passenger transportation.
• Market Prices: The price of ULSD varies by region and the global market. In the FOB spot market in the port of New York, the price has shown fluctuations in recent years, influenced by factors such as supply and demand, as well as geopolitical events.

Conclusion

Ultralow sulfur diesel is a key player in the transition to a more sustainable energy sector. It contributes to the clean fuels industry by providing a cleaner and more efficient option for diesel engines in a variety of applications. Thanks to environmental regulations and technological advances, ULSD has made it possible to reduce sulfur dioxide emissions, improve air quality and optimize the performance of modern diesel engines. As the world moves towards the adoption of clean fuels, ULSD will continue to play an important role in the transition to a more sustainable energy industry.

Discover at Inspenet how ULSD drives efficiency and sustainability – optimize your engine with us today!

References

1. American Petroleum Company Inc.: “Biocombustibles y ULSD: el futuro del diésel sostenible”
2. America Economia: “México perdió terreno ganado en 2022 en el suministro nacional de combustibles