Why Ethanol In Gasoline Doesn’t Reduce CO2 Emissions

Many governments have mandated 10% ethanol blended into gasoline to reduce carbon dioxide emissions at the tailpipe, and some are contemplating increasing the blend to 15% to reduce emissions even more. Science doesn’t support this claim.

The same amount of carbon dioxide is emitted at the tailpipe for the same distance driven in the same vehicle regardless if the gasoline contains ethanol or not.

We should remind ourselves why we started putting ethanol into gasoline in the first place. Let’s go back to the 1970’s era of muscle cars, smoking inside airplanes, and using DDT to get rid of nuisance insects.

Refiners used to add tetraethyl lead to gasoline as an octane booster to stop engine knock, and car manufacturers liked it because the lead deposits on the valve seats allowed for higher engine compression ratios.

When leaded gasoline was banned due to elevated cancer risks, it was discovered that most substitutes for tetraethyl lead were even more carcinogenic, except ethanol.

Three percent ethanol in regular gasoline stopped engine knocks and manufacturers dropped their engine compression ratios (bye-bye muscle cars).

A second step in adding ethanol to gasoline was in 2007 when the US Energy Independence and Security Act mandated an increase to 10% ethanol in gasoline to reduce foreign oil dependency.

Ten percent ethanol-blended gasoline was not introduced to reduce CO2 emissions; it was a measure to both replace tetraethyl lead and increase the American domestic automotive fuel supply.

The concept that ethanol reduces CO2 emissions is from a carbon-dioxide offset theory that is accepted by the 2015 Paris Agreement, even though it is widely known that tailpipe CO2 emissions are unchanged.

The offset theory is that physical CO2 emissions from the burning of ethanol are not counted as increased human emissions because they are offset by the atmospheric CO2 consumption during photosynthesis by the plants grown by humans as feedstock for ethanol.

That implies that the ethanol source plant—in North America that is corn—has increased the amount of photosynthesis that would have otherwise occurred.

The physical CO2 released by the ethanol in the blended gasoline is simply not counted in the total emissions because it is offset by increased photosynthesis.

If this theory were correct, then carbon dioxide emissions in 10% ethanol-blended gasoline would drop by 10%.

By applying this offset theory, governments want refiners to increase the ethanol content by as much as 15% in regular gasoline (the limit your current automobile can likely handle).

The premise that ethanol offsets CO2 emissions is false. Either the corn would have been grown anyway for human or cattle consumption, or some other plant (crop or forest) would have grown.

There is no idle farmland on a planet with nearly eight billion mouths to feed. Diverting farmland from food to ethanol does not increase photosynthesis; it increases the demand and prices for farm yields as now they can be sold as either food or fuel.

Let’s take ethanol out of the political arena and put it in a lab. Ethanol releases only about two-thirds of the energy on combustion than gasoline does, so the more ethanol that is blended into gasoline, the more volume of the blend is required to drive the same distance.

Reports available from the US Energy Information Administration show that the same amount of CO2 is physically released from 10% ethanol-blended gasoline as regular gasoline for the same distance driven.

But now there is another CO2 stream to track: in the process of converting corn to ethanol, more CO2 is produced.

The assumption to date has been that this food-grade CO2 has been conserved by using it in carbonated beverages, commercial greenhouses, or other industrial applications.

I don’t think anyone really knows if that is true or an aspiration, but at some point, the market for CO2 will become (or already is) saturated and the corn-to-ethanol production facilities may vent their CO2.

In that case, the atmospheric CO2 emissions (tailpipe plus ethanol manufacturing facility) of corn-derived 10% ethanol-blended gasoline increases by 3% over regular gasoline for the same distance driven in the same vehicle.

If the ethanol content of gasoline is increased to 15% in this scenario, the tailpipe CO2 combined with ethanol manufacturing vented CO2 increases by about 5% over normal unblended gasoline.

That’s not all the downside to producing ethanol:

• Corn makes up 20% of all the calories consumed by humans. One result of the USA 2007 mandate for 10% ethanol in gasoline was that by 2012, 40% of all corn grown in the USA was converted to ethanol. This is more corn than is consumed by humans on the entire continent of Africa. It caused world corn prices to increase by 30%, a significant economic blow for families in developing countries who spend up to half their household income on food.
• Consider the freshwater used to grow that 40% of the US corn crop. Irrigation in the U.S. uses 38% of all the freshwater withdrawn from lakes, rivers, and aquifers; and corn makes up 25% of the irrigated acreage. It is not a stretch to make a rough estimate that 4% of U.S. freshwater usage is for corn-derived ethanol.
• Even your mechanic has a negative opinion; increased ethanol can cause engine stalling, accelerated breakdown of aluminum and rubber components, and clogging of fuel lines. (If your gasoline-fueled lawn mower does not start next spring, and the carburetor is full of a green-tinged gel, that’s the result of 10% ethanol-blended gasoline left stagnant in the fuel system.)

The real paradox is that this all helps to meet Paris Agreement goals simply because of the bureaucratic assumption that more photosynthesis has taken place than otherwise would have. That’s not true.

Ethanol in gasoline does not physically achieve the claimed carbon dioxide emissions reduction; it does not achieve any carbon dioxide emissions reduction at all. It’s a cheap accounting trick.

Ron Barmby (www.ronaldbarmby.ca) is a Professional Engineer with a Bachelor’s and Master’s degree, whose 40+ year career in the energy sector has taken him to over 40 countries on five continents. He recently published “Sunlight on Climate Change: A Heretic’s Guide to Global Climate Hysteria” to explain in understandable terms the science of how both natural and human-caused global warming work.