As a service to our customers, dealers and friends, Bell Performance hosts quarterly webinars on fuel topics of interest to their friends and their customers. This is Part 3 of a transcript of one of these recent webinars held on Fuel Changes & The Impact They Have On Your And Your Business. If you would like to watch the archived presentation, please click here. If you would like to read part 2, please click here.
Continued from Part 2
Sulfur is a natural component of oil, because crude oil is a natural product. When you refine that oil, that sulfur ends up in the different components that you take out of it. All fuels except for the really light ones like the natural gas, all of the distillate and the residual fuels have some kind of sulfur content in them.
Reducing Sulphur Content
For most of the 20th century, regular on road #2 diesel had a sulfur content of 5,000 parts per million, but around 1990, Congress decided that it was time to start looking at some laws to impact some of the environmental concerns that the public was concerned about. The pollution of the ozone layer, toxic urban air pollution in smog and acid rain was a big one. The pictures of those forests, all those dead trees. The public wanted something done about that and so what Congress did was they said, "Well, sulfur content, sulfur emissions from things like diesel fuel are the primary driver of acid rain, so what they did is they cut the amount of sulfur that you were allowed to have had in diesel fuel and this was done at the refinery level.
What we ended up with now is, instead of diesel fuel from before the 90s which had 5,000 parts per million in it of sulfur, the diesel fuel now has 15 parts per million. That's a 99.7% reduction.
Did that accomplish the goal of what they needed it to do? If you're reducing sulfur by 99%, that's definitely going to have a very prominent positive effect on the environment. How do they remove the sulfur? Well, it's done at the refinery level and they use hydro desulfurization processes. They basically take it out as H2S gas. They use that sulfur to make things like sulfuric acid, and what they end up with is a diesel fuel that has between 4 and 7 parts per million of sulfur. That gives them a little bit of wiggle room for in case somebody adds something down the line that raises the sulfur content.
Effects of Low Sulphur on Fuel Quality
Now, what affect did this have on the fuel itself? There's about 5 main affects that we're going to talk about. The first affect is the effect on the fuel lubrication, what they call the lubricity value of the fuel.
Generally, sulfur content in fuel has been associated with the ability of that fuel to lubricate things like injectors and fuel pumps. Injectors and fuel pumps have relied on the fuel lubricity value in order to lubricate them and make them not wear out prematurely. Now, when you remove sulfur, then you lower the fuel's ability to do this. What this does for the user is it increases wear on these parts. It increases wear on fuel injectors, on fuel pumps and specifically premature wear on parts, shortened part life and of course it stands to reason that you're going to get higher maintenance costs as part of that.
First problem, reduced fuel lubrication because they took the sulfur out. Consequence of that, increased maintenance costs and wearing out of injectors things like that.
Second main problem is lower energy content. When they process the fuel, they not only remove the sulfur, but they also remove other things like aromatics which are a type of molecule that makeup a significant portion of the diesel fuel, they remove those.
What that does is, that changes the energy value of the fuel, lowers the energy value and any time you have lower energy value, which is it's a 1% reduction, anytime you have a lower energy value, then that lowers the MPGs for the consumer, for the user and it also basically makes it more expensive. How much more expensive? Well, 1% energy reduction, or reduction in energy value doesn't sound like a whole lot, and when they were running the numbers, they were estimating that for every 100,000 miles that you drive, your cost is going to go up by $500. For the average, for the consumer that has a diesel pickup truck, that's pocket change. They can find that change in their sofa, but for a fleet that has hundreds of vehicles running on diesel, that cost adds up and that is an extra cost that could be used in another area. It's significant to them. Also, back to that place in the cost of ultra-low sulfur is that it's more expensive to produce. They estimated that it's going to add between 5-25 cents per gallon to that diesel fuel. You're getting a little bit less mileage, but it's also a built in cost on the front end that is costing users more.
Second effect of ultra-low sulfur diesel, it's more expensive basically. Third effect, contamination or possible contamination with high sulfur diesel fuel. If you think about it, think about all the storage tanks around the country. A lot of their storage tanks are older ones that used to have high sulfur and low sulfur diesel in them. When they started transitioning into ultra-low sulfur diesel, some of those might have been drained and filled with ultra-low sulfur diesel, but if you were to go and test all of those tanks, then what you would likely find is that a significant number of them have sulfur content that is too high, that's out of compliance. The reason this is, is because it doesn't take very much leftover fuel, high sulfur fuel in the bottom of that tank to bring the whole mix out of compliance. To a certain extent, it's a mathematical issue. Let's say you have a thousand-gallon tank and the thousand-gallon tank used to be filled with low sulfur diesel 500 part per million diesel. They want to switch it over to ultra-low sulfur, so they drained it, but let's say it had some sludge that was left in the bottom.
They drained it and they got it down there, but they may have left some of that sludge down there and they filled it up with ultra-low sulfur diesel. Sludge tends to act a little bit like a sponge. There was trace residuals of this higher sulfur diesel fuel left in there. In a thousand-gallon tank, all you need is 15, 20 gallons of just leftover trace low sulfur diesel in order to throw the whole thing out of compliance. There's a lot of tanks that are out of compliance out there.
The Impact of Non-Compliance
In and of itself, basically who cares? Why are we even talking about this? To a certain extent, contamination with high sulfur diesel, this is not a performance issue. It's not going to destroy equipment by and large; it's not going to cause engine problems. What this becomes is a compliance issue and a legal issue because when they switched over to ultra-low sulfur diesel, the Department of Transportation which are the people who tend to enforce this, they announced penalties if you were a truck driver and you had your fuel tested and it was found to be out of compliance, then you were faced with penalties of $32,500 per tank per day. They would back date that and they would assume that you had been using this fuel for 21 days, 28 days.
Naturally, when you're looking at 6 figure fines potentially, the industry said, "Whoa, whoa, whoa, whoa, whoa, whoa. That's a problem." The EPA kind of worked with them and allowed a slower implementation of the ultra-low sulfur diesel, but that implementation period, which was designed to try and get this higher sulfur fuel out of the system, that is over with. This effect of possible contamination with high sulfur diesel, this is a legal liability issue that people who manage fuel have to be concerned with.
Fourth effect, cold flow properties. Bell Performance is located in Florida. We do not tend to have cold flow problems down here, but we have a lot of people we deal with, a lot of customers, a lot of fleets up north. If you're up north in Michigan, Illinois, New York, anywhere above the Mason-Dixon line, you know that diesel fuel has cold flow issues in the winter. Diesel fuel naturally contains what they call paraffin wax components. Those are normally dissolved and burned seamlessly as part of the fuel, but when the fuel starts cooling down, some of those start to drop out of solution. They form crystals in the fuel. Those crystals bump into each other.
They get bigger over time as the fuel continues to cool. More and more are coming out and eventually what happens is that the fuel thickens and you get enough of this wax in there that it will do what's in that picture. It plugs the filter, and when the fuel filter's plugged the engine shuts down because there's no fuel flow anymore.
Now, ultra-low sulfur fuel has issues with this because of the processing. When they remove the sulfur, they also removed and destroyed some of the compounds like the aromatic compounds that in the old fuel, these molecules would act as dispersants and they would keep, if the wax crystals came out of solution, they would keep those wax crystals apart. Now, they're not in there anymore. There's nothing to keep the fuel from gelling at a higher temperature and that is exactly what happens.
What problems does this cause? The fuel gels at a higher temperature which means you have a greater, not a greater amount, but you have more gelling problems in a given winter period, so you get increased filter blocking, you get operability issues and if you are a business and you're running trucks out there, then anytime you have the potential for operability issues, you have the potential for lost business and big time headaches.
Big difference between how ultra-low sulfur diesel behaves in the field and the old fuel is that ultra-low sulfur diesel fuel is much more sensitive to cold weather problems than before.
Resistance to Microbes
The fifth, and last one that we're going to talk about, lack of resistance to microbes. This is probably the biggest one. This is the one that has the potential to affect the most number of people in the most serious way.
Regardless of what kind of fuel you're putting in a storage tank, microbial presence in those storage tanks is a universal problem faced by every person that has a fuel tank, everyone. That's because microbes are ubiquitous in the environment around us. We already know that. They get into the tank by any number of ways. It's not like somebody's taking a pea tree dish and dumping the contents into a tank. No, all that needs to happen is you get dust that comes in. You can have hundreds of millions of microbes on one single particle of dust. Water gets in whether it's by a tank leak, or by just water vapor on the air. If you get fuel drop, somebody drops some fuel, they've got microbes in their tank, it spreads very easily from tank to tank.
They get into the tank and what they're looking for is, they're looking for some kind of water layer. Anytime you have water in the tank, you have a layer of water on the bottom, you have fuel on top and those microbes are going to go down and they're going to settle into the interface where the two layers meet and they're going to draw what they need from both sides and they're going to grow and they're going to thrive and they're going to multiply and they're going to produce biomass and all sorts of stuff that's going to cause problems.
Microbial Growth: When. Not If
We mention water because as this point says, microbial growth, anyone that has a free water layer in their fuel storage tank has the very real possibility of having a microbial growth problem. It is not a matter of if, it is a matter of when. Seriously, it's not a matter of if, it's a matter of when for those types of situations. Most people don't seek to have a water layer. How does water build up in a tank? It can happen just by natural processes. Even just simple condensation, fuel, you get a 7-degree temperature difference between daytime and then when it cools down, temperature drops.
Any water vapor that's in the tank from air that has exchanged through air flow, that's going to condense on the sides of the tank. It's going to roll down to the bottom because water is heavier than fuel and it's going to build up a water layer over time. This is probably elementary stuff to those of you out there who have dealt with tanks in any significant capacity. That's just the way it is.
Even beyond condensation, you could have, when you get a fuel drop, somebody could transfer water in the fuel drop. If you've seen the gas stations where they have the underground tanks and they have the openings and they have spill buckets designed to catch water, and those can hold 2, 3, 4, 5 gallons of water. Somebody goes to do a fuel drop or something. They're not paying attention, some of that water goes into the tank. There are enough ways for water to get into tanks that it is virtually inevitable that a storage tank is going to build up water. Microbial problems are a potentially big issue. What problems do they cause? This is kind of the, “so what” part? What problems do they cause?
First thing is that fuel microbes are associated with filter plugging and they're very easy to spread to other areas. They produce biomass, they produce slime because of the natural processes that they undergo, the byproducts of their natural processes. The biomass, it clings to the sides of the tank, it gets into the filters, it plugs them and that's why if you manage any amount of tanks, you tend to know how often you have to change those tank filters.
When you start to notice that frequency is shortening or changing suddenly, that is a surefire sign that something is going on in that tank that you need to check out, and just like infections in the human body, infections in fuel tanks can be very easily spread anywhere that fuel goes. That's just the way it is.
Second problem is that microbes tend to destroy fuel stability. If you add microbes to fuels that have cracked stocks, you get a double effect. Microbes, when they grow, they produce acids, they produce biological byproducts and those will attack the fuel and they will break down the fuel quality. What problems does this cause? You get the exact same problem as you do when we were talking about fuel instability, all of those, deposits in the engine, black smoke and emissions, rough inefficient engine operation, all of the problems that are associated with unstable fuel, they're going to be associated here as well.
This post was published on May 27, 2016 and was updated on December 19, 2022.