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Tech Talk: Exploring the limitations of ethanol

Ethanol absorbs water, can be corrosive, acts as a solvent and varies in its amount in gas

Published August 24, 2012

A couple weeks ago, I addressed the use of ethanol as an octane-enhancer in gasoline and struck a nerve with some readers.

Several pointed out I hadn’t addressed the problems that can be experienced when using ethanol-containing fuel in some older vehicles. Which I didn’t, given that the subject was octane-enhancement.

So let me address those issues.

Some readers cited their own negative experiences with ethanol-enhanced fuel, ranging from starting difficulties to seal-and-gasket damage to valve-damage to fibreglass-gas-tank degradation — primarily in older vehicles or marine or other small engines, such as those used in lawn mowers.

They are legitimate concerns in many of those applications.

Among its other properties, ethanol absorbs water. Water is insoluble in gasoline, and, if present, sinks to the bottom of the tank.

But water is soluble in ethanol and can be carried through an engine’s fuel system, potentially affecting its operation. It can also cause premature rusting.

In addition, ethanol can be corrosive. It can have deleterious effects on fibreglass and some rubber and plastic materials, such as those used in older seals and gaskets.

Which is why most new road-going vehicles built since the late 1980s have been designed with ethanol-resistant materials in those applications. So have modern marine engines. But many small engines have not.

Ethanol is also an effective solvent and cleansing agent. High levels of ethanol can dissolve and break down solid material, including varnish and rust, which may travel through the fuel system and engine, resulting in clogging or premature wear.

The use of ethanol-containing gasoline in small or older engines won’t necessarily cause problems, but it might.

It wasn’t a problem until relatively recently as ethanol was not widely used as a gasoline additive before the 1990s, when the U.S. approved concentrations of up to 10 per cent ethanol in gasoline.

It became a bigger concern in 2005, when both the U.S. and Ontario governments mandated a minimum of five per cent ethanol in gasoline (by volume).

Canada’s federal government followed suit with a five-per-cent minimum mandate that took effect Dec. 15, 2010.

Those governments did not embrace the addition of ethanol to gasoline as an octane-enhancer, but as a means of reducing greenhouse-gas (GHG) emissions.

They also encouraged it as a way to boost the agricultural industry.

Most ethanol is derived from corn.

There is a loophole of sorts in the rules. Specifically, the five-per-cent requirement is based on a “pool average.” That is, the total amount of ethanol used in the gasoline sold by a given company must equal at least five per cent of the total quantity of gasoline sold by that company.

Which means that not every litre of gasoline sold in Canada has to contain five per cent ethanol.

Some can be sold with zero ethanol content if every litre with none in it is matched by one with 10 per cent in it — or some other combination that works out to a five-per-cent average across the board.

That provision is important as it allows petroleum companies to continue to provide some ethanol-free fuel for older vehicles as well as the marine and small-engine markets.

Typically, fuel suppliers in Canada use up to 10 per cent ethanol content in their regular (87-octane) gasolines and five per cent in their mid-grades (89-octane), while keeping their premium grades (91-octane) ethanol-free. But this is not a universal practice.

Ethanol content may vary by regions. Check for a label on the pump to see if what you’re pumping contains ethanol.

Given the corn shortages in the U.S. mid-west caused by this summer’s dry conditions, President Obama is under pressure to relax temporarily the minimum ethanol content in gasoline there. But he has taken no such action yet.

In fact, the U.S. Environmental protection Agency (EPA) this spring approved a waiver to its regulations, permitting up to 15 per cent ethanol in gasoline (E15), over the protests of automakers and the petroleum industry, itself.

The ruling specifies that E15 be used only in 2001 or newer light cars and trucks and that it be labeled accordingly. But concerns about mis-fueling by customers, based on experience with the use of unleaded versus leaded gasoline, are cause for skepticism.

The Alliance of Automobile Manufacturers, Global Automakers, Grocery Manufacturers Association, oil industry and other groups potentially affected filed suit to stop the implementation of the ruling, but it was thrown out by the U.S. Court of Appeals recently, on a technicality.

Whatever your position on ethanol, the one thing you can be sure of is that it’s not going to go away.

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