Does Low-Sulfur Diesel Affect Generator Performance Negatively?

Introduction

Diesel generators are essential for backup power in industries, hospitals, data centers, and homes. 

Their performance largely depends on the quality of the fuel used. Over the years, environmental regulations have led to significant changes in diesel fuel composition, particularly the reduction of sulfur content. 

While low-sulfur diesel fuels are beneficial for reducing emissions, many generator owners and operators wonder whether they negatively impact performance.

In this article, we will look at the effects of low-sulfur diesel (LSD) and ultra-low-sulfur diesel (ULSD) on diesel generators. 

We will analyze how sulfur reduction affects lubricity, power output, fuel system components, cold-weather operation, and long-term maintenance. 

Additionally, we’ll discuss ways to mitigate potential issues and ensure optimal generator performance.

Understanding Low-Sulfur Diesel (LSD) and Ultra-Low-Sulfur Diesel (ULSD)

What Is Low-Sulfur Diesel?

Low-sulfur diesel (LSD) is a refined fuel with a significantly lower sulfur content than traditional diesel. 

In the past, diesel fuels contained high levels of sulfur, which contributed to air pollution. 

To reduce harmful emissions, environmental regulations mandated the transition to LSD and, later, ultra-low-sulfur diesel (ULSD).

Ultra-Low-Sulfur Diesel (ULSD) and Global Regulations

ULSD contains a maximum of 15 parts per million (ppm) sulfur, making it much cleaner than older diesel formulations. 

The Environmental Protection Agency (EPA) in the United States and similar regulatory bodies in Europe and Asia have implemented strict sulfur content regulations to curb pollution.

While ULSD helps reduce sulfur dioxide emissions, its altered chemical composition can pose challenges for older diesel generators, especially those designed for high-sulfur fuel.

How Diesel Generators Rely on Fuel Composition

Diesel generators convert chemical energy in fuel into mechanical energy, which then powers electrical generators. The quality and composition of the diesel fuel directly impact:

• Combustion efficiency – Proper fuel combustion is essential for maintaining stable generator operation.

• Lubrication of fuel system components – Fuel injectors, pumps, and seals rely on fuel lubricity to reduce friction.

• Power output – A decrease in fuel energy content can reduce overall generator efficiency.

• Maintenance requirements – Certain fuel properties influence the longevity of engine components.

Since low-sulfur diesel differs from traditional high-sulfur fuel, it can introduce several performance concerns.

Potential Negative Effects of Low-Sulfur Diesel on Generators

Reduced Lubricity and Increased Wear

One of the biggest concerns with low-sulfur diesel is the loss of natural lubrication. 

Sulfur compounds in diesel fuel previously provided lubrication for critical engine components. 

The removal of sulfur results in lower lubricity, which can lead to:

• Excessive wear on fuel injectors and high-pressure fuel pumps.

• Premature failure of fuel system seals.

• Increased friction, causing heat buildup and potential damage.

Older diesel generators that were not designed for ULSD are particularly vulnerable to these effects. 

Without proper lubrication, these systems may experience accelerated wear and require more frequent repairs.

Impact on Fuel System Components

The transition to low-sulfur diesel affects various fuel system parts, including:

• Fuel injectors: Reduced lubricity can cause nozzle deposits, affecting fuel atomization and combustion efficiency.

• Seals and gaskets: Older generators with natural rubber seals may experience hardening and cracking due to chemical differences in ULSD.

• Fuel pumps: Increased internal wear can lead to performance issues and reduced fuel delivery rates.

Replacing fuel system components prematurely can significantly increase maintenance costs for generator owners.

Increased Risk of Corrosion and Deposits

Sulfur in diesel fuel played a secondary role in preventing certain types of corrosion within the fuel system. With the removal of sulfur, the following problems may arise:

• Corrosion of fuel tanks and lines: ULSD is more prone to attracting water, leading to rust and microbial growth.

• Increased risk of injector clogging: Water contamination and oxidation byproducts can form deposits inside the fuel system.

• Formation of fuel sludge: ULSD oxidizes more easily, leading to the accumulation of sludge in storage tanks.

If not properly managed, these issues can cause fuel system failures and unexpected generator shutdowns.

Potential Power Output Reduction

ULSD has slightly lower energy content compared to high-sulfur diesel, which can result in:

• Reduced fuel economy: Generators may consume more ULSD to produce the same power output.

• Lower efficiency: Older engines may struggle to maintain optimal combustion, leading to decreased performance.

While the power loss is not extreme, it can become noticeable in high-load applications.

Cold Weather Performance Issues

In cold climates, low-sulfur diesel has a higher tendency to gel due to:

• Reduced sulfur content: Alters the fuel’s natural resistance to freezing.

• Higher paraffin levels: Increases the risk of fuel thickening in low temperatures.

Generators operating in freezing conditions may experience difficulty starting or maintaining consistent power output.

Do Newer Diesel Generators Handle Low-Sulfur Diesel Better?

Modern diesel generators are designed to handle ULSD more effectively. Manufacturers have introduced:

• Advanced fuel injection systems to compensate for lubricity loss.

• Hardened fuel system components that resist wear and tear.

• Emission control technologies to improve efficiency with ULSD.

While newer models are better adapted, older generators still face significant challenges when running on low-sulfur diesel.

How to Mitigate the Negative Effects of Low-Sulfur Diesel

Using Fuel Additives for Lubricity

To counteract reduced lubricity, diesel generator owners should consider:

• Lubricity-enhancing fuel additives that reduce wear on injectors and pumps.

• Anti-corrosion agents to protect fuel tanks and lines.

• Fuel stabilizers that prevent oxidation and sludge formation.

Regular use of high-quality fuel additives can extend the lifespan of generator components.

Regular Fuel System Maintenance

Proper maintenance is essential when using ULSD, including:

• Frequent fuel filter changes to prevent clogging.

• Cleaning fuel injectors to remove deposits.

• Inspecting seals and gaskets for wear and replacement.

A proactive maintenance schedule helps prevent fuel-related performance issues.

Proper Fuel Storage and Handling

Storing low-sulfur diesel properly can prevent degradation and contamination:

• Use moisture-resistant storage tanks to reduce water accumulation.

• Regularly drain water separators to prevent microbial growth.

• Monitor fuel quality over time to avoid oxidation-related problems.

Ensuring proper storage conditions minimizes the risk of generator performance issues.

Conclusion

The shift to low-sulfur diesel has undeniable benefits for reducing emissions, but it also presents challenges for diesel generators. 

Reduced lubricity, potential component wear, and fuel degradation are key concerns for generator operators, particularly for older models. 

However, with proper maintenance, fuel additives, and storage practices, these issues can be mitigated.

For those relying on diesel generators for backup power, understanding the impact of low-sulfur diesel is crucial. 

By adopting best practices and staying informed about fuel quality, generator owners can maintain optimal performance and ensure long-term reliability.

If you operate a diesel generator, consider implementing fuel management strategies to prevent performance loss and costly repairs. 

Whether through lubricity-enhancing additives or improved maintenance routines, proactive measures will help your generator function efficiently despite the challenges posed by low-sulfur diesel.