T-R PHOTO BY ADAM SODDERS
The Casey’s General Store on Iowa Avenue in Marshalltown is one of a large number of gas stations in Iowa that sells biodiesel and ethanol-blended fuels. At this gas pump, a customer could choose biodiesel blended fuel, green, or an ethanol-blended gasoline, white.

Gas stations dot Iowa’s countryside and cities, and words like “biodiesel” and “ethanol” can be seen on gas pumps as travelers fill up their tanks — both are examples of biofuels.

Unlike gasoline, which is derived from oil found largely underground which dates back millions of years, biofuels originate from plant and animal materials produced in the present.

“Basically, ethanol is made from the corn starch inside the corn kernel,” said Cassidy Walter of the Iowa Renewable Fuels Association.

The starch is separate from the kernel’s protein, which goes into products like animal feed, and from the corn oil produced when the kernel is processed. That oil can then be used in biodiesel fuel.

“We make biodiesel from oils or fats. Biodiesel is made from fatty acids,” said Dave Slade, executive director of Biofuel and Technology services at Renewable Energy Group Inc.

Along with corn oil, products like animal fats, canola oil and soybean oil are useful for making biodiesel fuel. Soybean oil is one of the more common sources of the fuel, and Iowa is among the country’s top producers of that crop.

Slade said before the biodiesel industry became mainstream, soybean farmers often couldn’t get rid of all of the leftover soybean oil produced by processing the beans for their protein. Biodiesel provided a market for that oil and is a source of income for producers nowadays, he said.

Pig and cow fats can also be used to make biodiesels, and those species of livestock are also common in Iowa. The biodiesel industry has provided a new market for such oils and fats, which previously were largely underused, Slade said.

“It really has added a lot of value to these products,” he said.

The oils and fats used in biodiesel production go through chemical processing, so Slade said it is not a good idea to just pour oil into a diesel engine.

Walter said ethanol production allows for more complete use of corn kernels.

“Ethanol production is huge for Iowa farmers. It adds a lot to their bottom line,” she said. “Ethanol production in Iowa adds billions to our economy.”

Slade and Walter said one of the major benefits ethanol and biodiesel provide is not only added income to the farmers who produce the raw materials needed to create the fuels, but also to consumers pumping the fuels into their cars.

“Ethanol is the cheapest source of fuel octane in the world,” Walter said.

In regular gasoline, she said aromatic hydrocarbons, or aromatics, are added to the fuel to produce octane. Octane is a measurement of how much pressure a fuel can take before it combusts, and Walter said aromatics are bad for human health.

Adding ethanol to gasoline provides good fuel octane without such health impacts, she said.

The environment is also helped by the use of ethanol, Walter said.

“The more ethanol you have in your fuel, the cleaner it is,” Walter said. “In addition to those environmental and health benefits … it is cheaper, you have a lower price at the pump.”

Slade had similar conclusions about biodiesel.

“Biodiesel is made from agricultural products ultimately, so they are taking that carbon, it comes out of the atmosphere to go into the plants,” he said. “It’s called biogenic carbon.”

For example, Slade said the carbon stored in modern day plants, like soybeans, comes from Earth’s modern day atmosphere. He said burning biodiesels recycles that same amount of carbon back into the air.

“We’re not adding more, we’re just cycling it,” Slade said.

In contrast, he said the carbon trapped in gasoline made from crude oil has been out of Earth’s atmosphere for a much longer time. According to National Geographic, crude oil takes millions of years to form from ancient organic materials and other sediments buried deep underground.

Carbon dioxide produced by burning crude oil products is new to Earth’s modern day atmosphere and adds the greenhouse gas to the air. Slade said biodiesels are 50 to 90 percent less carbon intense than fossil fuels.

Both biodiesel and ethanol are widely available at gas pumps across Iowa, though usually mixed with crude oil-based gasoline and diesel. Slade said B10 to B20, or diesel mixed with 10 to 20 percent biodiesel, is common.

Walter said the most widely-available ethanol mix is E10, which is gasoline mixed with 10 percent ethanol fuel. Other blends, like E15 and E85 are available, and Walter praised the recent decision by the Environmental Protection Agency to lift a ban on selling E15 fuel during the summer months, making it available year-round.

For more information on biofuels, visit https://www.epa.gov/agriculture/agriculture-and-biofuels