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Explaining Ethanol: What You Need to Know About RVP, E15, and More

For decades, ethanol has been a combustible topic in Washington, D.C. Interests representing farmers and ethanol producers often clash with the petroleum industry.

The latest involves President Donald Trump’s commitment to a campaign promise backing ethanol. Trump is caught between the desire of petroleum refiners to weaken ethanol blending mandates, which Environmental Protection Agency Administrator Scott Pruitt has already started, and the ethanol industry’s goal of allowing year-round sales of E15. That blend of gasoline with 15% ethanol could dramatically boost U.S. ethanol demand since the fuel is mostly sold as E10, or a 10% ethanol blend.

But paving the way to more E15 pumps at gas stations, like most things governmental, is complicated.

You can see the current battleground the next time you put gasoline into your pickup on a hot day. It’s those gasoline vapors shimmering into the air around the fuel nozzle. That volatility can be measured as:

Reid Vapor Pressure

It’s the amount of pressure coming from vapors from 100°F. gasoline, measured in pounds per square inch (psi). For most of the country, the EPA mandates RVP of 9 pounds or less during hot summer months.

Clean burning?

Most of us think of ethanol as greener than gasoline, and it is in many ways. It has a smaller carbon footprint than petroleum-based fuels. Ethanol by itself isn’t a highly volatile fuel, either. In a mixture with gasoline, however, that changes. “When you add the two, the volatility goes up a little bit,” says Chris Bliley, vice president of regulatory affairs for Growth Energy, an ethanol trade group. Without getting too technical, ethanol molecules become less attracted to each other in the presence of some of the stuff in gasoline (a complex mixture containing everything from paraffin to cancer-causing benzene). This effect varies with the type of gasoline, but it makes the ethanol more volatile. A blend of E10 has an RVP of about 10 pounds, a pound more than gasoline alone.

Effects on Smog

In the 1990s, as EPA and cities fought smog, volatile compounds in gasoline, sometimes helped by ethanol, were evaporating and reacting with sunlight to form ground-level ozone, an irritant in smog. “This was at a time when we were told not to fill up until after dark,” Bliley says. Partly because ethanol has other environmental benefits, like reducing carbon monoxide, EPA at first granted what became known as the “1-pound waiver.” That allowed the sale of E10 with its higher RVP.  In a 1990 amendment to the Clean Air Act, Congress made the waiver for E10 part of the law. Today, according to EPA, mobile source air pollutants are about half the levels of 1990.

Unwelcome E15

This higher blend of 15% ethanol in gasoline didn’t exist during the early days of fighting smog. EPA finally approved the sale of E15 for most cars in 2011, followed by more struggles over how E15 should be labeled at the pump. Some independent chains now sell it. Many owned by refiners don’t. Most importantly, EPA hasn’t granted the 1-pound waiver to E15. So gas stations can’t sell it in summer months (except to flex-fuel vehicles that can burn any level of ethanol blends). An attempt to grant the waiver to E15 by changing the Clean Air Act failed in Congress last year. “E15 actually has less volatility than regular E10 gasoline has today,” says Bliley.

That’s true, although the difference is small, about .10 pound in some tests, and a lot depends on the type of gasoline used in the tests. When gasoline has more than 20% to 30% ethanol, the vapor pressure backs off more. Levels above 50% have less RVP than gasoline.

Like many in the ethanol industry, Bliley views the summer ban in E15 sales as an unneeded anachronism from an earlier, more polluted era. A lot has changed since then.

“The irony is that you can sell E15 year-round in Chicago, Dallas, and Washington, D.C., but not in Des Moines,” he says. Those big cities already sell reformulated gasoline that’s less volatile. When it’s blended with E15, the RVP is still below EPA’s limits.

An E15 boom?

E15, with 50% more ethanol than E10, holds potential to boost demand for the fuel and for corn used to make it – if EPA or Congress ever approve the RVP waiver (also called the E15 waiver). For that to happen, ethanol production capacity in the U.S. would need to expand. So would installation of retail gas pumps to dispense E15. Jeff Broin, CEO of POET, one of the largest ethanol producers, concedes that this would take years.

Yet, greater sales of E15 would eventually expand the market for ethanol by 7 billion gallons, Broin said during a visit to Des Moines, Iowa, in March. That would create demand for more than 2 billion bushels of corn in the U.S. Broin is also co-chair of Growth Energy.

Some analysts have offered more conservative, but still bullish estimates.

“If we can get the E15 waiver, I see consumption rising to 19 billion gallons,” Mike Blackford, an analyst with INTL FC Stone told the Iowa Renewable Fuels Summit in January. That would be well above the current level of about 14 billion gallons sold in the U.S., as well as the 15-billion-gallon mandate for corn ethanol blending under the federal Renewable Fuel Standard. The RFS sets goals for biofuel use under the 2007 Energy Independence and Security Act.

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