Corn growers and ethanol producers want to expand their market by selling a new, higher-blend ethanol fuel that’s safe to use in most vehicles.

But the timeline for introducing E15 remains uncertain as industry and government officials continue to sort out the final details for the fuel’s sale.

The American Coalition for Ethanol and the Renewable Fuels Association held a webinar Tuesday to review the remaining obstacles for E15, which contains 15 percent ethanol.

Ron Lamberty, senior vice president of the American Coalition for Ethanol, said we’re unlikely to see E15 showing up at the nation’s gas pumps any sooner than September.

Among the hurdles that still need to be cleared:

Keeping E15 out of the wrong cars: The U.S. Environmental Protection Agency has said E15 is safe for all 2001 and newer cars and light-duty trucks. Before gas stations can start selling it, though, the industry needs to get final approval from the EPA for its “misfueling mitigation plan” to prevent drivers from mistakenly putting it in older vehicles, which could cause engine damage.

The plan includes mandatory labeling on E15 pumps, as well as regular, industry-funded testing of E15 pumps to ensure the contents match what the label says. Just under 100 ethanol producers have committed to paying for the testing program. In March, the EPA said the industry’s plan “would generally be sufficient,” but Lamberty said they are still awaiting final approval.

Prevent drivers from getting hosed: In response to a stakeholder comment, the EPA recently raised a question about “hose residual” at pumps where a single hose dispenses multiple fuels, said Lamberty. Most hoses hold about a quarter of a gallon of fuel. If the driver of an older vehicle were to fill up immediately after an E15 customer and only bought a small amount of gas, would they be at risk for engine damage?

To hold E15 sellers accountable for this would be a “very, very ticky-tack regulation,” said Lamberty. He suspects the petroleum industry or another opponent pressured the EPA to raise the issue.

Revising state regulations: Once the federal issues are worked out, E15 is ready for sale in Iowa and Illinois, said Kristy Moore, vice president of technical services for the Renewable Fuels Association. Both those states have updated rules to allow E15 sales, and Kansas is in the final stages of its revisions.

Lamberty said most of the changes are relatively minor. “In most cases, it’s a regulation that just doesn’t refer to E15 because there was no such thing” when the rule was written, he said.

Convincing gas station to sell it: Gas stations don’t have a mandate to sell E15, and some have concerns about infrastructure and liability. Some gas stations may need to upgrade to new pumps before they can sell E15. Some stations, particularly larger chains, Lamberty said, have concerns about liability if customers used the fuel in an unapproved vehicle. Iowa and Kansas have been working on legislation to protect gas station owners.

Find solution for summertime restrictions: The EPA places special pollution restrictions on gasoline during the summer. Gas that is more volatile produces more pollution. Volatility is measured in RVP, or “Reid vapor pressure.” Adding ethanol to gasoline increases volatility, but Congress gave E10 ethanol a waiver in 1990 because the fuel reduces VOC pollution enough to compensate for the higher volatility.

The law, however, is specific to E10 and doesn’t apply to E15. In order to legally sell E15 during the summer, it will have to be made from a blend with reformulated gasoline, which isn’t available in all states and also costs more. That added cost dampens the economic case for station owners to sell E15. That’s why Lamberty thinks many station owners will wait until after September 15 to start offering the fuel.