Arizona officials want waivers for summer gas blend. Expert says that would worsen air quality

Gas prices are always on our minds here in the Valley, where many people are dependent on their cars to get around.

But with gas prices skyrocketing as a result of President Donald Trump’s attack on Iran, officials are scrambling for ideas to control costs. That’s particularly urgent with summer approaching — or, as it’s felt like recently in Phoenix, already here.

Gas stations in many states — including Arizona — are required to switch to a different blend of gas in hotter months, which is more expensive to produce.

Sen. Ruben Gallego and Gov. Katie Hobbs have been lobbying the federal government for waivers on that requirement this summer.

To explain what this summer blend is, and why it exists, Robert Rapier, a chemical engineer who also writes about energy issues, and covered summer blends in a recent piece for Forbes, joined The Show.

Full conversation

SAM DINGMAN: Robert, good morning.

ROBERT RAPIER: Good morning. How are you doing?

DINGMAN: Well, thank you for being here. To start, Robert, tell us why summer blend gas exists in the first place.

RAPIER: OK, so this goes back to the 1990 Clean Air Act amendments, and it was a result of smog in a lot of different densely packed cities. And gasoline blenders from then had to meet two specific requirements. They've got to meet the octane. Everybody's familiar with octane. You put it in your car, depending on what your car needs, and that stays constant all year round.

But the other very important specification is called Reid Vapor Pressure, RVP. And basically what that means in layman's terms, it is the tendency to evaporate. It's how easily it evaporates. And so in winter, when it's cooler, we can have a blend, a gasoline blend with a higher RVP, so would evaporate faster in summer, but in winter it evaporates more slowly because it's cold.

And the reason this is important is butane is a major component of this blend. Butane is abundant, it's cheap. And so that makes the winter blends a lot cheaper to produce. And it's also off-season, so it's off-demand season. So we got all these three factors contributing to generally make winter gasoline less expensive.

And then the inverse happens in the spring. As summer driving season is starting to starting to heat up and the temperature starting to heat up, the, the RVP specification goes down. And so that means that gasoline blenders have to get that butane out. And that means supplies have now been cut because you can't put the butane in there. A cheap ingredient is coming out, and it's all coming when high demand season is about to kick off.

So that's why we have it, and that's why the gasoline prices spike as we head to summer every year.

DINGMAN: OK, OK. So very quickly, Robert, listeners may have heard that the EPA announced a fuel waiver recently, which will allow gas stations to sell fuel blended with ethanol.

Is that the same thing as these cleaner burning blends that you're describing?

RAPIER: So it has a — it's related. So ethanol is a component that is blended into gasoline. And one of the things ethanol does when you blend it in is raises the vapor pressure. And so it's a consideration as well. As you're moving into the summer months and that vapor pressure requirement drops, you have to reduce the amount of ethanol that goes in.

And so what they've said, and it's probably a little too late to have an impact this year because gasoline blenders are already reducing the inventory in their tanks from the winter blends. This turnover takes a little bit of time, and so they have to get ahead of it. They have to be completely — all high, high vapor pressure gasoline has to be out of the system by the turnover date.

And so they probably don't have enough time for it to make a major impact at this point. But there is no free lunch. I mean, what happens is this contributes to smog. I mean, that's the reason it was done.

And if you want to know the impact, just look at Los Angeles. I mean, this is a major contributor to Los Angeles air quality being so much different between the 1970s and today. I mean, 1970s Los Angeles air was brown. And because of these new requirements, these seasonal requirements, that's helped clean up the air. And it's the case with any densely populated city with that, has warm summer temperatures.

DINGMAN: Yeah, well, I know one of those. It's called Phoenix. Let me ask you this. We have just about 30 seconds left here, Robert.

Sen. Gallego, as I mentioned, has been advocating for a waiver on these blends for Arizonans this summer. He claims it could save drivers 40 to 50 cents a gallon. Is that accurate?

RAPIER: That's probably an overestimate, but it could definitely save money. But again, there's no free lunch. I mean, our air quality here is generally not that great. And that will worsen air quality. There's no question about that.