Under Pressure

  John Eichberger |  June 1, 2018

The strongest pressure washer you can buy at Home Depot delivers water at 4,500 pounds per square inch. Now, imagine fuel being injected into an engine piston chamber at 40,000 pounds per square inch! That is the reality of modern diesel engines – cranking out more miles per gallon by leveraging high pressure common rail (HPCR) injector systems. But nothing comes without complications and the Fuels Institute is leading a collaborative effort to study opportunities and challenges in the market.

Which brings us to this month’s musical reference. Remember a few months ago, I wrote about the melody-stealing “artist” Vanilla Ice. Now, I think it is time to get real about pressure and resurrect for the benefit of all society the immortal Bowie and Mercury:

“Mm ba ba de
Um bum ba de
Um bu bu bum da de
Pressure.”

If you say those words out loud, you might be able to imitate the sound of a big rig rolling down the road. (Try it.)

In an era when all the media is focused on the potential disruption represented by electric vehicles and on-demand ride hailing services, we must not forget the message we see on bumper stickers - “Without trucks, America stops.”

According to the American Trucking Associations, 71% of freight tonnage in the U.S. is moved by trucks. This means that nearly everything we buy has spent some time in the back of a truck. And in 2015, these trucks traveled 450.4 billion miles. It is a pretty big deal – and these trucks will not be replaced by electric engines or technology service providers, at least not anytime soon.

So we must pay attention to the fuel that powers these trucks. In 2017, the U.S. consumed 57.5 billion gallons of ultra-low sulfur diesel (ULSD) fuel, a fuel that was introduced in 2006 to enable advanced emissions control technologies to be installed on trucks starting in 2007.

Matching fuel with engine needs is critically important to enhance efficiency and reduce emissions, not just in passenger cars but also in these big rigs. Like Forrest said, “Fuels and engines go together like peas and carrots.” (Or something like that.) So let’s take a look at what seems to be happening in the market.

The Engines
The heavy duty vehicle market is facing its own challenges to satisfy federal regulations demanding improved efficiency. By 2027, these vehicles must improve their efficiency by an average of 27% vs 2017, with some vehicle types having to improve by more than 35% – this is a steep hill for these big rigs to climb. (For more details, download the Fuels Institute’s report, “Tomorrow’s Vehicles – A Projection of Medium and Heavy Duty Vehicle Fleet Through 2025.”)

As a result, engine manufacturers are delivering better engines, leveraging a variety of strategies to boost efficiency. One of the most significant changes has been the deployment of the high pressure common rail (HPCR) injection systems referenced in the opening paragraph. These units have contributed to much more efficient engine operations, but have also introduced new sensitivities.

Today’s HPCRs can inject fuel into the piston chamber at pressures of about 40,000 psi, compared with units that injected fuel at 5,000 psi just a few years ago. And there are indications that future designs may boost pressure to 60,000 psi. In addition, clearances and tolerances within these systems can be as small as 1 micron, which raises the importance of fuel cleanliness.

There are multiple things that can happen if fuels used in these systems contain particles. For one thing, a fuel particle can contribute to injector clogging and failure, which has been reported quite often. In addition, any particle that does pass through the system is injected into the piston chamber at 40,000 psi and can lead to pitting, scoring and erosion of the engine’s metal parts.

The desire on the part of engine manufacturers and fleet operators to improve fuel quality to enable these higher efficiency devices led to the formation of the Fuels Institute’s Fuel Quality Council – a collaborative effort among engine manufactures, fleet operators, fuel producers, distributors and retailers. The Council is engaging in research to quantify the scope and cost of fuel system-related problems and to evaluate options for improving overall fuel quality. (An initial literature review identified some of the issues of concern and is available on the Fuel Quality Council site.)

The Fuel
On the fuel side of the equation, there was a major change to diesel fuel composition in 2006 with a 97% reduction in sulfur content, resulting in ULSD with not more than 15 ppm sulfur. This was mandated by the U.S. Environmental Protection Agency to enable vehicle emissions control technology. Today, all on-road diesel fuel meets this sulfur cap.

However, in 2007 tank owners began reporting incidents of “rapid and severe corrosion of metal components in underground storage tanks (USTs) storing diesel fuel,” as characterized in EPA’s 2016 report, “Investigation of Corrosion-Influencing Factors in Underground Storage Tanks with Diesel Service.” This study found that 83% of the tanks they sampled were affected by moderate or severe corrosion, that corrosion is geographically widespread and that many tank owners may not be aware of corrosion in their systems.

The Coordinating Research Council (CRC) is overseeing a research project attempting to determine the primary causal factor resulting in such corrosion. This is the latest in a series of projects over the past decade that have sought to better understand what is happening in diesel USTs. But corrosion is just one potential challenge to fuel-engine harmony.

Some engine manufacturers claim that the diesel specification set by ASTM is inadequate to facilitate efficient operation of these modern engines. They point to tolerance within the standard for particulate and water content which is incompatible with engine designs and have expressed a desire to add additional standards that are not currently addressed in the specification.

Others note that the distribution system can introduce problems ranging from the fuel picking up contaminants throughout the system, absorbing water and lubricity agents at different stages, the introduction of various additives designed to address different issues, the interaction of the fuel with added biodiesel, practices of using tanker trucks for different fuel products and the aforementioned corrosion issue.

Meanwhile, there have been efforts at the National Conference on Weights and Measures to require the installation of tighter fuel filters on diesel dispensers to prevent particulate contaminates from entering vehicles.

But where within the supply chain diesel fuel is becoming problematic and when and how to implement changes that will result in higher and more consistent fuel quality remains unclear. There is no silver bullet. Even if ASTM were to change their specifications to match the needs of modern engines, without improvements to the distribution system fuel quality would still be suspect. Further, if current ASTM specifications are inadequate, no amount of improved product handling or filtration will make up for deficiency in the fuel.

Collaboration Can Relieve the Pressure 
How do you begin to tackle the myriad issues that could be contributing to problems with fuel and engine operations? How do you avoid vilification of any stakeholders and facilitate a constructive approach to improve the market? The Fuel Quality Council formed to facilitate just such a collaborative approach to improving the market and has determined that a multi-pronged strategy is required. It has set forth a path that will do the following:

  1. Problem Scoping. By surveying engine manufacturers, fleet operators and fuel providers, the Council seeks to quantify the frequency of fuel-related issues and the associated cost of repair/warranty/downtime to better understand the magnitude of the issue.
  2. Fuel Quality Survey. By reviewing currently available fuel quality sampling data and obtaining analyses of new fuel samples, the Council can better understand the quality of diesel fuel (with a focus on key characteristics) being introduced into engines and compare this with reported issues in the vehicle sector to focus attention on the most relevant issues.
  3. Distribution System Practices. By collecting and distributing best practices in diesel fuel product handling and distribution and demonstrate the financial benefits of adhering to such practices, the Council seeks to reduce incidents of contamination or product degradation throughout the system.
  4. Fuel Specification Amendments. The Council will interview stakeholders within the fuels and engines markets to understand what changes in fuel specification they might think are or are not necessary. The process will seek to identify commonalities across market sectors and identify opportunities for additional collaboration to yield better fuel quality.
  5. Cost-Benefit Analysis. Once options for improving fuel quality are identified, the Council will attempt to provide an analysis of what such options might cost the market and how those options might mitigate vehicle operating costs.

End Game
We know that the economy rolls on the backs of trucks. Therefore, it makes sense to take a holistic approach to evaluating market conditions and considering all options that could improve performance. Whether this ultimately includes an effort by industry to change diesel fuel specifications or to implement more aggressive product handling practices and requirements will depend largely on an analysis of the costs verse benefits, but such an analysis cannot even begin without more information. The simple fact that a very diverse set of stakeholders have come together to tackle this issue is a great indication of both the importance of fuel quality for modern diesel engines and the potential for a collaborative resolution.

“It's the terror of knowing
What the world is about
Watching some good friends
Screaming 'Let me out'”

Bowie and Mercury got it wrong – the danger is not knowing what is going on and not coming together for the benefit of the market. Ultimately, the goal is to make sure that diesel fuel is not like a box of chocolates – we should always know what we are going to get.

Latest Updates

On the Road Again
February 2021
Life is a Highway
January 2021
When It’s Love
November 5, 2020
Walking on the Moon
October 5, 2020