Protecting Your Stored Fuel Quality
Atlantic hurricane season typically lasts from about the beginning of June through the end of November. Many people think that the bulk of hurricanes happened early to middle part of the hurricane season. But the bulk of hurricanes, according to weather data, happen from August through the end of September.
For those in charge of buying, storing, and maintaining fuels, there’s a tremendous need to ensure that the quality of stored fuels to be used in an emergency is protected and maintained. This means the stored fuel combusts properly without black smoke and adverse emissions, the fuel does not leave deposits inside of the engine, and the engines themselves run as well as they should in burning that fuel.
This consideration is vital because if stored fuels for emergency purposes are not ready for use at the exact time that they're needed, then the consequences of such a problem are amplified due to the severity and the desperation of the situation at hand. When a hurricane hits in Florida or a tornado happens in the south of the Midwest, public and private sector entities assume the diesel biodiesel or ethanol fuels set aside for storage will perform their roles to power generators, emergency management equipment, and other vehicles that perform the duties called for in the relevant emergency management action plan.
Whatever kind of fuel you use in whatever capacity, there are certain things that you as a fuel manager can do to ensure that the stored fuel is going to continue to be ready to use when you need to put the longest.
Making Sure The Fuel Stays Together
No matter if you use fuel in an emergency vehicle, cleanup heavy duty equipment, or a backup generator, if the fuel quality is not within specification when it is needed, then the vehicle or engine is not going to run properly or it may not even run at all when it is needed most. This concept of poor fuel quality is really about what ends up in the fuel and, more importantly, what ends up in the fuel that does not burn as well as the fuel itself. When you hear about fuel oxidation, gums, varnishes, and fuel sludge, they’re talking about parts of the diesel fuel mixture that used to be soluble in solution with the fuel blend, but which have been attacked and undergone chemical reactions to be substances that are heavy enough to fall out as sludge and which don’t burn very well when the engine uses them. Fuel stability treatments aim to keep these substances from forming, instead keeping the fuel mix together so it burns as well as it should.
Of the common fuels in the marketplace – ethanol, diesel, biodiesel - these all have some common storage quality issues that can all be addressed with simple solutions. So we will take some time to examine some of the common issues inherent to the preservation of these fuels – to ensure they’re ready for action when you and your business or group are faced with important action. Understanding the root causes of the disruption of fuel quality in storage is the first step in setting up a fuel care protocol (or reexamining an existing one) that will ensure that you’re as prepared as possible for when you need to respond to an emergency in the quickest and best means possible.
Diesel fuel is still the most common backup fuel stored in the United States. The diesel fuel in use today is not exactly like the diesel fuel that was in use 10 or 15 or 20 or more years ago. The big difference between diesel fuels now and diesel fuels then is the level of sulfur allowed in the diesel fuel. This difference stems from requirements introduced to the Clean Air Act around the year 1990, which ushered in big changes on the removal of sulfur from the fuel. In the old days, diesel fuel could contain as much as 5000 ppm of sulfur. Recall that elemental sulfur is one of the components of petroleum when it is extracted and refined into diesel fuel. The Clean Air Act mandated a dramatic reduction in sulfur content from 5000 ppm to 500 ppm. That's about a 95% reduction. Later, the amount of sulfur was reduced even more drastically, from 500 ppm to just 15 ppm sulfur allowed in on-road diesel fuel. This new cleaner fuel is known as ultra-low sulfur diesel (ULSD) and it’s the only kind of diesel you can use for virtually all on-road vehicles and engines. This change was ushered in around the years 2006 and 2007. So, in the space of, at the most 15 to 20 years, you went from 5000 ppm sulfur content to just 15 ppm sulfur content.
What does this mean for fuel storage for emergency management? Most fleet operators are well-versed in the fact that the removal of sulfur changed the lubricity properties of the fuel. However many emergency management professionals are not aware that the removal of sulfur from diesel fuel makes diesel fuel far more likely to have bacteria, fungus, and microbial infestation problems emerge in storage. Sulfur is toxic to many kinds of microbes and the removal of the sulfur essentially removed a natural biocide from the diesel fuel. Less sulfur means less inhibiting of microbial growth. Fuels management professionals now find that they're far more likely to have a microbial infestation problem with these new ULSD diesel fuels.
So take the removal of a natural biocide of sulfur, add water accumulation in storage, and you have a perfect recipe for the destruction of stored fuel quality. Water plays several roles in the destruction of stored fuel quality. The accumulated water builds up in fuel storage tanks that are vented to the outside. Temperature changes from day to night cause condensation to develop on the inside of the storage tanks; this condensed water rolls down the sides of the tank and sinks to the bottom of the diesel fuel because water is of course heavier than diesel fuel. Every fuel management professional knows it is common practice to have at least some water sitting at the bottom of every storage tank. This water allows for the possibility of microbial growth in that stored fuel. Bacteria, fungi, and microbes need a layer of water interfacing with a layer of diesel fuel to get all the things that they need to grow and thrive inside of a fuel storage tank. Any time you have a layer of water in a storage tank, you have at least a good potential for current or subsequent microbe growth and problems.
Most fuel storage professionals have a protocol to control water in tanks. There are water coalescers, filters, and centrifuges that can allow for the removal of significant amounts of water from tanks. There are also highly effective fuel treatment options, such as those manufactured by Bell Performance, that will absorb significant amounts of water and cause it to be locked into the diesel fuel for combustion.
Another factor water plays concerning stored fuel quality is its role in the chemical breakdown of diesel fuel. Diesel fuel can undergo chemical breakdown over time by a number of avenues. Microbes that infest storage tanks produce acids and corrosive substances as a result of their biological processes. These biological byproducts accelerate the breakdown of the quality of the diesel fuel just as you would expect an acid to do. They also promote corrosion of the inside of the storage tank.
Biodiesel blends such as 2% or 5% biodiesel are more and more common in municipalities and organizations who face state, local and federal mandates to increase the volume of biofuels that they use in public vehicles. Higher levels of government are always happy to issue requirements dictating the behaviors of the entities below them.
Not only this, but biodiesel fuel users are also taking advantage of its natural lubricating properties, which can restore all of the lubricity properties of the diesel fuel that were lost when the sulfur was reduced by over 98%. A blend of as little as 2% biodiesel methyl ester into an in-spec diesel fuel base will restore all of the lost lubricity from the removal of the sulfur. This keeps these principalities from having to purchase additional lubricity additives from their fuel suppliers. So it is a win–win situation for these fuel usage. They get a high-lubricating diesel fuel blend, and they get to claim a certain number of gallons of renewable biofuels used towards the mandate that they are seeping from further up the political food chain.
But for all of its great qualities, some caveats come with biodiesel, even when the percentage of biodiesel in the blend is less than 5%. Biodiesel has proven to be an excellent food for microbes to feast upon. A B2 or a B5 biodiesel blend faces a greater possibility of these problematic infestations of microbes developing over time. This is coupled with the ongoing issue of water condensation buildup in the storage tank. When these factors come together at the same time, he proves to be a perfect breeding ground for microbial infestation. And when you have a microbial infestation, the only thing you can do about that is to use a biocide treatment (like Bell Performance’s Bellicide product).
When these causative factors come together, you have a perfect breeding ground for microbial infestations. Using a biocide treatment is the only thing that will kill and eliminate the problem. There are not many biocides commercially available because the regulations for bringing a biocide to market are very strict. That's why you can't find very many on the store shelves. Good biocides are concentrated to use a treatment rate of 1 ounce to between 40 to 80 gallons of fuel. A good biocide will also be active in both the fuel phase and the water phase of the stored liquids.
Oxidative and water breakdown in stored diesel and biodiesel fuels
Biodiesel and regular diesel fuels are prone to what is known as oxidative stability breakdown over time, as referenced earlier in this document. Certain things can be shown to chemically deteriorate and break apart diesel fuel and biodiesel blends. These factors are water, oxygen, light or heat, and bacterial byproducts. All of these factors contribute to either providing the fundamental ingredients for the chemical reactions that cause a fuel’s breakdown, or the acceleration of the oxidative breakdown of the fuel quality over time.
Exposure to water and oxygen in the air provides oxygen which is an essential ingredient of oxidation and hydrolysis chemical reactions. These are classifications of chemical reactions that break diesel fuel molecules apart and turn them from stable molecules to unstable molecules that want to form sludge and deposits in stored fuel. Biological byproducts of bacteria and fungus in fuel tanks lead to tank corrosion and the breakdown of stored fuel in the tank because of their acidic nature. Exposure to heat provides the energy catalyst needed to make sure that these harmful chemical reactions happen at a faster rate in the fuel.
Preparing stored fuels for emergency readiness tries to take these factors into account. There’s nothing that can be done for exposure to heat, and light exposure is a non-factor most of the time. The remediation of water exposure and prevention of bacterial infestation are the most common steps to produce tangible results.
Ethanol blends, in the grand history of fuel storage use for emergency management, are a relatively new player on the horizon. Ethanol addition into gasoline became much more common around 2005 and 2006 when a previous fuel additive called MTBE was phased out of the national gasoline supply because of fears of it contaminating groundwater. Ethanol became the substitute for fulfilling the role of being an oxygenate. Oxygenates add more oxygen to a gasoline mixture, and that causes the gasoline to burn with fewer harmful emissions that affect urban air quality. The addition of oxygenates to the gasoline supply is mandated by the EPA through the Clean Air Act.
Cities and municipalities find that they can do the same thing with ethanol fuels that they can do with biodiesel - that is, use their ethanol fuel usage as a credit towards the number of gallons they are required to use annually of renewable fuels.
The problems associated with ethanol fuels are more controversial and more “in the news”, so to speak, than diesel fuel problems are. That may be because ethanol blends are in widespread use by everyday consumers and everyone else in this country who burn gasoline.
Ethanol blends are more sensitive to storage problems than diesel fuels are. That may be because gasoline itself is more highly refined and more sensitive than diesel fuels are. Ethanol blends attract water much more easily than diesel fuel blends do. The ethanol molecule is a natural chemical attractor of water. And this can be a big problem for stored ethanol fuel blends. This water accelerates oxidative and breakdown of ethanol fuels contributes to the same type of microbial infestation problems in ethanol blends, and can initiate phase separation. Phase separation happens when an ethanol blend, such as a 5% or a 10% or 15% blend, absorbs water from the atmosphere. When the amount of absorbed water exceeds the water tolerance of the fuel blend, the water absorbed will pull the ethanol out of the solution with the gasoline. What ends up in the tank is a mixture of water and ethanol at the bottom with the remaining gasoline on top.
This is bad news for a couple of reasons. One, when the ethanol undergoes space separation and falls out, it strips many of the important components that contribute to that gasoline having a high octane rating. This loss of octane rating is related to the practice of fuel blenders and refineries using ethanol to increase the octane rating of the gasoline blend. Ethanol has a very high octane rating, something that racing drivers notice very well. Refineries know that they can take low-octane gasoline and add high-octane ethanol to end up with an 87-octane mixture. Or an 89, 91, or 93 octane-rated gasoline. Ethanol is, per unit, cheaper than gasoline, which means they save money doing this.
But if the blend undergoes phase separation, and the ethanol drops out of the gasoline mixture, what’s behind is, at best, the same low octane and poor quality rated gasoline they started with. At worst it's even lower octane fuel than they started with because the ethanol had carried away some of the vital organic components that were already in the gasoline and which were making up a portion of the fuel’s octane rating.
Important Solutions for Protecting Fuel Quality
For many of the problems described above, fuel management professionals choose to use one of the quality fuel additives in the marketplace that are available to solve or lessen these problems cost-effectively.
Diesel fuel stabilizers are typically antioxidant products that prevent the chemical reactions from starting that cause fuel quality to break down over time. Oxidative chemical reactions in diesel fuel are a chain reaction; this means that the process starts with a few chemical reactions that lead to more chemical reactions, eventually leading to widespread breakdown of that diesel fuel. Oxidative fuel stability ingredients function by stopping these first chemical reactions in the process. If you stop the first chemical reactions in the chain reaction, you stop the rest of the chain reaction and, in this case, this means preserving the fuel quality of the stored diesel fuel.
Water control ingredients are essential to helping to control the buildup of water that happens in stored diesel fuel and stored ethanol fuels. Bell Performance manufactures several single-function and multifunction fuel treatment products (DFS Plus and Ethanol Defense) that absorb water buildup in ethanol and diesel fuels. Bell Performance multi-function treatments, such as Dee-Zol, also provide combustion improvement and detergency functions in addition to their water control features.
Biocides are essential weapons in the fuel manager’s arsenal for making sure that stored fuels stay free from bacterial infestation and the headaches that these infestations cause. Ideally, you want a dual-phase biocide that works in both the petroleum and the water phases of stored fuel, including gasoline, ethanol, diesel, and biodiesel.