Ethanol is a high-octane solution to the toxic gas question

Source: By Holly Jessen, Ethanol Producer Magazine • Posted: Tuesday, October 13, 2015

Have you ever heard anyone use the phrase high-octane to describe a person or an event? I have. And the connotation was always positive.

One part of my job is to respond to calls and emails from people asking questions about ethanol. I’ve gotten questions about duckweed as a feedstock, talked to people who were told ethanol ruined their boat motors and high school or college students looking for help in completing an assignment.

Sometimes analysts call, wanting to pick my brain as an “expert” on the subject. I’m always careful to tell them that I don’t consider myself an expert, I’m simply someone who talks to experts and translates what they say into stories. Typically, though, once they start asking questions I find I do have plenty to talk about. And there are times when the analysts do really need some help understanding the subject, like the time I was asked about blending ethanol and biodiesel. OK, then, let’s just start at the beginning.

A few weeks ago, a student commented on a story with a question. Here it is, as posted. “i need to know how toxic is octane for a school project do you know……”

I answered her question via email, but decided to expand on that for today’s blog post. First, I need to correct a misunderstanding in the question. Octane is a term that is used to rate the quality or power of a fuel. To understand what octane is, consumers can look at the stickers on any gas pump, which reveal the octane rating of the fuel offerings.

According to the Oxford dictionary, an octane number is “A figure indicating the antiknock properties of a fuel.” The higher the number, the higher quality, and higher performance, the fuel. According to the Merriam Webster dictionary, high octane is an engine fuel that is “of a good quality that allows an engine to run efficiently.”

Another source I found is the Exxon Mobil website. “Octane rating is a measure of a fuel’s ability to resist ‘knock’. The octane requirement of an engine varies with compression ratio, geometrical and mechanical considerations and operating conditions. The higher the octane number, the greater the fuel’s resistance to knocking or pinging during combustion.”

So, let’s look at the octane rating of ethanol vs. gasoline. Ethanol has an octane rating of 113. In general, the gasoline drivers fuel up with has octane ratings of 87, or regular gas, 89, known as mid-grade, or 91 to 93, premium fuel.

The better question then, is not how toxic octane is, but how toxic are compounds contained in gasoline? The answer is, pretty toxic. Check out this information from the Urban Air Initiative. I’m going to quote the next two paragraphs directly from that organization’s website, because they can say it better than I could.

“Harmful emissions from the toxic compounds in gasoline are a thousand times smaller than the width of one human hair. These ultra-fine particulates (UFPs) produced in the combustion process persist in the air, penetrating deep into the lungs and directly entering the bloodstream.”

“As our research efforts unfolded, we became extremely alarmed by the numerous scientific and research studies that reveal the harmful health effects of toxic emissions resulting from the use of high aromatic content gasoline. Contrary to what the term ‘aromatics’ would infer as something pleasantly fragrant, it’s just the opposite! Petroleum refiners synthesize toxic substances called ‘aromatics’ from crude oil in order to increase gasoline octane levels and profits. In fact, aromatics have been classified by the Environmental Protection Agency (EPA) as Hazardous Air Pollutants.  While this represents a risk to anyone near high traffic areas and freeways, it is particularly harmful to people living in urban communities.”


Here’s more information on the same subject from the same source.

Let’s take it a step further. As managing editor of Ethanol Producer Magazine I wouldn’t really be doing my job if I didn’t answer the unasked question. If gas contains toxic compounds, how can we reduce those levels? The answer is that ethanol is a source of octane that can be added to gas to replace other, more toxic chemicals commonly used in gas. 

Check out this press release from the Nebraska Ethanol Board, which reveals that testing in Omaha, Nebraska, showed base gasoline sold there contained high levels of toxic compounds known to cause cancer. When 10 percent ethanol was added to the fuel, the toxic compounds dropped by 23 percent.

Here’s something else to consider. A recent Oak Ridge National Laboratory report about ethanol’s high octane rating concluded that adding between 20 and 40 percent ethanol to gasoline could add up to more fuel efficient vehicles that are more environmentally friendly. Specifically, higher ethanol content could result in vehicle efficiency gains of about 10 percent and reduce greenhouse gas emissions by about 30 percent. Watch for more about that later, once I’ve recieved the report.

To take that a step further, the Research Triangle Energy Consortium, which represents three universities and a, RTI International, a research institute, posted something in 2012, which concluded that, with today’s engines, higher octane doesn’t necessarily mean better. Vikram Rao, the executive director of RTEC wrote that, a super-high compression engine, with a compression ratio of about 16, could result in very high fuel efficiency for ethanol, methanol (octane rating of 117) or methane (125). “One could expect the energy density disadvantage to be completely eliminated,” he said. Although Rao concluded methanol, particularly biomass-based methanol, would be the fuel to watch, the point is that, if engines were redesigned to better take advantage of the octane levels of fuels like ethanol, the disadvantages would melt away and the advantages would become even more attractive.