Keeping the Gasoline Tank Cool (And protected from UV)

By law, above-ground gasoline tanks are ALWAYS painted white or silver. This minimizes solar heating and thus minimizes day/night breathing emissions. I'm a tank inspector from way back. I had a consulting business, and I've been around, over and in thousands of tanks, from 500-10,000,000 gallons. E10 loves to absorb water from the atmosphere. If the water content reaches about 0.5% (more in summer, less in winter), the water will separate, taking the alcohol with it and creating a 15%-by-volume layer that won't burn. Phase separation, as this is called, is very unusual because absorption from the air is a very slow process, taking months. The usual cause, in fact, is a leaking filler cap or vent, not absorption. It's a slow process, taking months to become important. But prudence requires closing the vent whenever the engine is not in use. Spray can sneak in through the vent.Water absorption does NOT need to reach phase-separating levels to cause problems. At just a few hundred ppm,…