Sulfur Compounded in Ethanol Regulations

by Susanne Retka Schill (Ethanol Producer Magazine) As the Tier 3 deadline approaches, it's important to understand the difference between EPA and ASTM treatments of the element. -- The U.S. EPA’s Tier 3 rules are not new—they were finalized two years ago—but a compliance deadline is approaching that may catch a few ethanol producers unprepared. Come Jan. 1, ethanol must prove it meets the lower 10 parts per million (ppm) standard for sulfur content.

Sulfur levels are important for air quality measures, primarily because sulfur compounds kill the catalyst used to clean up automobile exhaust.

It’s a more difficult rule for the oil refiners to meet, Kelly Davis, Renewable Fuels Association director of regulatory affairs, explains. “They have to remove the sulfur during processing.” Pure ethanol is not a known source of sulfur, she adds. “We typically do not see sulfur above 10 ppm in our ethanol, but as part of the fuel supply chain, we have to prove that we comply, so it’s more of bureaucratic issue—paperwork.”

The industry actually has been meeting the standard for years. It first was adopted in California in 2003 and, due to the fungibility of the ethanol supply, the RFA has encouraged all ethanol be under 10 ppm ever since. What’s different, Davis says, is that it is now an EPA rule with reporting requirements.

Most of the sulfur comes from the denaturant used to make sure the fuel ethanol won’t end up in a glass, in which case it should be taxed. Natural gasoline is the most economical denaturant, and thus the most commonly used. Also called wellhead gas, drip gas or casing head gas, it is a coproduct of natural gas production. Petroleum-based gasoline can also be used, but generally isn’t due to price.

There may be some changes coming with ASTM standards, McCoy (Monty McCoy, director of technology in the ethanol process group at U.S. Water Services) says, and it’s important the ethanol industry gets involved, as some suggestions would make the sulfate specifications even tighter in higher blends. “I would like to see more people join,” he says. “It’s $75 a year and you can get in the queue to become an official voting member. Then these plants can start having some impact on the way these standards are written.” Right now, he adds, the members from the auto and oil industries heavily influence the process. READ MORE