Every summer, drivers across the U.S. experience a familiar frustration: rising gas prices. What many don’t realize is that part of this seasonal price increase stems from the switch to summer gasoline blends. This transition, mandated by the Environmental Protection Agency (EPA), is designed to reduce air pollution—but it also comes with economic and logistical challenges.
As someone who has both written extensively on this topic and literally produced these gasoline blends myself, I can tell you firsthand why they exist, how they work, and why they’re essential to fuel regulations. With policymakers currently proposing waivers to allow winter gasoline to be sold in the summer, let me explain why these regulations exist in the first place.
The Science Behind Summer Gasoline Blends
The primary reason for switching to summer gasoline is volatility control—specifically, controlling a measure known as Reid Vapor Pressure (RVP). RVP is a gauge of how easily gasoline evaporates at high temperatures. In the summer heat, high volatility fuels evaporate more quickly, increasing emissions of volatile organic compounds (VOCs). These VOCs contribute to ground-level ozone and smog, which can cause respiratory issues and environmental damage. Think Los Angeles air quality in the 1970s, and that’s what we are talking about.
To combat this, summer gasoline blends are formulated with lower RVP to reduce evaporation. Refiners achieve this by removing the more volatile components—particularly butane, which is inexpensive and plentiful but evaporates easily. Winter gasoline, by contrast, contains more butane to enhance volatility for easier cold-weather starting.
Why Summer Gasoline Is More Expensive
Switching to summer gasoline blends isn’t just a simple matter of adjusting refinery settings. The changeover requires refineries to alter their production processes, drawing on a different mix of hydrocarbons to produce lower-volatility fuel. This typically results in:
• Higher refining costs due to the removal of cheap, high-volatility components like butane
• Reduced supply, as refineries must produce a more constrained blend
• Logistical challenges, since different regions require different summer formulations based on local air quality standards
The result? A price increase of 10 to 15 cents per gallon on average during the summer months, with greater spikes possible in areas with strict regulations, such as California.
Why We Don’t Just Stick With One Blend Year-Round
Some might argue that switching gasoline blends every year is an unnecessary burden and that we should standardize fuel formulas. However, using winter blends in summer would lead to higher emissions and worse air quality, particularly in urban areas already struggling with pollution.
On the other hand, using summer gasoline year-round isn’t practical either. Winter gasoline blends are designed for cold-weather performance, ensuring that engines start easily and run efficiently in low temperatures. A lower-volatility summer blend could make it harder to start a car in freezing conditions.
The Debate Over Gasoline Waivers
Occasionally, policymakers propose temporary waivers to allow winter gasoline to be sold in the summer—usually in response to spiking fuel prices or supply disruptions. While this might provide short-term relief at the pump, it comes with environmental trade-offs.
For example, during Hurricane Harvey in 2017, the EPA temporarily lifted RVP restrictions to prevent supply shortages. However, such waivers can lead to increased smog formation and air quality concerns, especially in metropolitan areas where pollution levels are already high.
Final Thoughts
Summer gasoline blends exist for a reason. While they do contribute to seasonal price increases, they play a crucial role in reducing pollution and improving air quality during the hottest months of the year. The seasonal transition may frustrate drivers, but it reflects a careful balance between environmental concerns and fuel performance.
At the end of the day, it comes down to a simple trade-off: Do we want slightly cheaper gas, or do we want cleaner air? The choice isn’t just about economics—it’s about the quality of the air we breathe.
Note: There are a lot of questions and misinformation around refining. To address this, I just recorded a two-part series on refining for The Energy Mixx Radio show. You can listen to the first episode here on iHeart Radio.
By Robert Rapier