The problem is that water does not put out ethanol fires, and the foam that has been used since the 1960s to smother ordinary gasoline blazes does not work well against the grain-alcohol fuel.
Wrecks involving ordinary cars and trucks are not the major concern. They carry modest amounts of fuel, and it is typically a low-concentration, 10 percent blend of ethanol and gasoline. A large amount of conventional foam can usually extinguish such fires.
Instead, the real danger involves the many tanker trucks and railcars that roll out of the Corn Belt with huge quantities of 85 or 95 percent ethanol and carry it to parts of the country unaccustomed to dealing with it.
"Now, the most common hazardous material has a new twist to it," said Mike Schultz, a firefighter who manned a foam gun during a recent blaze in Missouri.
The risk is more than theoretical. Over the past several years, ethanol accidents on highways, along railroads, and in storehouses and refineries have triggered evacuations and fires from Texas to Minnesota, injuring several people and killing at least one person.
Water is not used against gasoline fires, because it can spread the blaze and cause the flames to run down into drains and sewers. Instead, foam is used to form a blanket on top of the burning gasoline and snuff out the flames. But ethanol, a type of grain alcohol often distilled from corn, eats through that foam and continues to burn.
Such fires require a special alcohol-resistant foam that relies on long-chain molecules known as polymers to smother the flames. Industry officials say the special foam costs about 30 percent more than the standard product, at around $90 to $115 for a five-gallon container.
Fighting ethanol fires also requires a change in tactics. Brent Gaspard, marketing director for Williams Fire & Hazard Control Inc., an industrial firefighting company in Texas, said firefighters cannot just charge ahead and attack an ethanol fire with foam.
"If you just plunge the foam into the fuel, it's going to be less effective. You have to let the foam gently run across the surface so you create a shield," he said.
