Energy and Environment Reporting for Texas

You May Want to Slow Your Coal Roll in Texas

The world is warming, and there’s heated debate over what to do about it, or if it’s even warming at all. (Hint: It is.) Amidst this debate, some opponents of government regulations and environmental policy have taken up protest by retrofitting their diesel trucks to spew billowing clouds of black, noxious smoke. When the soot gets blasted, it’s called “rolling coal.” Some save the move for those special moments when they’re in front of a Prius, then post the video online.

The practice is illegal under federal legislation, but apparently not so hard to get away with in Texas. The state’s transportation code prohibits excessive smoke from a vehicle, but that code includes a handful of exceptions for diesel engines, saysTom Vinger, spokesman for the Texas Department of Public Safety.

“[Diesel engines] will smoke during acceleration, gear changes, some travel conditions, vehicle loading, and those exceptions are covered under the law,” Vinger said.

There are several ways to make your truck “roll coal,” ranging from removing factory-installed emissions regulators to reprograming the small computer that coordinates fuel injection.

But according to the Environmental Protection Agency’s Clean Air Act, it is illegal “to manufacture, sell, or install a part for a motor vehicle that bypasses, defeats, or renders inoperative any emission control device.”

Reprogramming of emissions equipment is hard to detect in state inspections since Texas does not require emissions testing for diesel engines. There is a visual test that looks for a proper exhaust system. One mechanic told StateImpact Texas that an inspector would easily notice if required factory parts were removed from a truck.

On online diesel forums, some owners have reported that it can be easy to pass inspection with a truck customized to roll coal. One user on the Dodge diesel website CumminsForum.com claimed to have removed several emissions parts from his truck and said “I believe [my truck] is also supposed to pass a visual inspection [of emissions system] but as impressed with the sound of the truck as my inspector was, he let the visual slide.”

“Rolling coal” likely gets its namesake from the deep black color of the smoke from a diesel exhaust. According to Neil Carman Clean Air Program Director with the Sierra Club Lone Star Chapter, that’s troubling.

“When you see any kind of smoke, you’re going to find some level of carcinogens,” said Carman. “But the soot indicates that you’re also getting a high volume of unburned diesel fuel – unburned diesel vapor.”

Vaporized diesel in the air is “very bad,” said Carman, who also spent 12 years inspecting industrial plant emissions for the Texas Commission on Environmental Quality (TCEQ).

Fuel that burns completely will be reduced to pure carbon dioxide and water vapor, but when it doesn’t it’s components can reunite in the air to form large toxic molecular rings called PAHs, the topic of a recent Austin study. Carman calls them a “super carcinogen.”


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