Water and E10: Trouble by the Tank Full

Water contamination in E10 gasoline-ethanol blends presents a new paradigm to filling station operators.

Straight gasoline is hydrophobic; that is, it won’t mix with water, so any water that got into the tank sank harmlessly (relatively speaking) to the bottom. Ethanol is hydrophilic so water that enters storage tanks is immediately absorbed and contaminates the fuel. Understanding and controlling the effects of this contamination on your fuel and your tanks is critical in assuring you and your customers don’t end up having bad fuel ruin a good day.

The American Petroleum Institute* cites three significant consequences of water contamination in gasoline-ethanol blends:

  • Phase separation
  • Micro-organisms
  • Accelerated Corrosion and Conductivity

Phase separation

Small quantities of water can be dissolved in a gasoline-ethanol blend, but beyond a certain concentration (.5‰ @ 60 degrees F), saturation will be achieved. Any additional water beyond this point, even a small amount, will cause the ethanol to separate from the gasoline and form a separate solution with the water. This phenomenon in gasoline-ethanol storage tanks is known as phase separation. When phase separation occurs, the water/ethanol solution sinks and forms a layer on the bottom of the tank, leaving gasoline in the upper level with a lower ethanol content and a reduced octane level. In tanks where phase separation has occurred, the remaining gasoline-ethanol blend in the upper level is out of compliance for ethanol content and the posted octane rating on the dispenser.

Micro Organisms

Microbes can flourish in tanks containing gasoline-ethanol blends and cause corrosion of internal tank surfaces. Microbial induced corrosion (MIC) can occur under aerobic and anaerobic conditions. Micro-organisms survive by feeding on the hydrocarbons at the interface between the water layer and the gasoline layer. Wastes and fermentation products secreted by the microbes produce water, sludge and acidic byproducts that can cause material degradation. The acidic residues of sulfate reducing bacteria can cause metal corrosion and may, if left unmanaged, cause a tank failure. There is also recent evidence of MIC in un-phase separated product. The primary cause of microbial growth is the presence of water. Minimizing and managing water intrusion into the tank system from all sources are effective measures to discourage the growth of microbial colonies.

Accelerated Corrosion and Conductivity: Compared to gasoline and hydrocarbon fuels, ethanol has a high electrical conductivity and oxygen content. The chemical properties of ethanol also contribute to its ability to readily absorb water. The suspension of water within gasoline-ethanol blends enhances galvanic corrosion and rusting by providing an oxygen-rich environment that is also a good conductor of electricity. These conditions present in ethanol blend service can lead to corrosion and ultimately metal loss in various components that are not normally adversely affected by gasoline.

Preventing water contamination is the key to managing all three of these issues. The problem is that it is virtually impossible to prevent contamination, so a strategy of managing the water that does get into your tank system must be considered. K100G fuel treatment from Kinetic Fuel Technology Inc. is the only product proven to fully remediate water contamination in gasoline-ethanol blends. K100G is many times more hydrophilic than ethanol, and chemically bonds with water molecules in such a way as to prevent them from going into solution with ethanol. It is specifically formulated to keep the water/K100 molecule in full suspension, thereby preventing phase separation. Likewise, microbes cannot flourish in K100 treated fuels because there is no longer a gasoline/water interface in which to survive. The enhanced conductivity problem is also controlled because the water is no longer chemically available to catalyze the process.

As long as there are no obvious signs of gross water contamination in a storage tank system, regular additions of K100G should be sufficient to totally control incipient water issues. If the tank turns over several times a month, adding 5 gallons of K100G every third fuel drop should be enough. If the tank turnover is significantly slower than that, add 5 gallons of K100G every second drop.

*API Recommended Practice 1626