Ask any mechanic who works on outboard motors for reasons boaters curse ethanol and you’ll hear several hundred – as in the several hundreds of dollars it can cost to rebuild carburetors or repair other engine parts damaged by ethanol in the gasoline/ethanol blends that have become the de facto fuel for gasoline engines in this country.
Even at its lowest concentration – the ubiquitous “E10” blend of 10 percent ethanol, 90 percent gasoline – ethanol can play havoc with outboards and other “small” engines such as those powering all-terrain vehicles, chain saws and grass trimmers.
For more than a decade – since ethanol replaced methyl tertiary-butyl ether which proved an environmental and health threat, as an oxygenating agent mixed with gasoline to meet government-mandated reductions in engine emissions – boaters have struggled to deal with the damage ethanol can do to their equipment and searched for viable alternative fuel formulations that don’t have the downsides associated with ethanol.
They have a new option in the later case, albeit one currently with limited but expanding availability and a significantly higher cost, in a fuel that replaces ethanol with isobutanol. The Houston area and a handful of other spots in Texas are scheduled to see that fuel – Gulf Marine fuel – become available over the coming months. More on that in a moment.
That there is a market for such alternatives, even at a considerably higher price, speaks to the problems associated with ethanol/gas blends and the specter that fuels with even higher percentages of ethanol are coming as federal rules mandating increasing volume of “renewable fuels” – so-called biofuels such as ethanol, produced in this country almost exclusively from corn -be used in the nation’s fuel supply.
Other than producing less energy than gasoline, thus reducing miles-per-gallon, ethanol-blend fuels cause few if any problems in modern motor vehicles. The engines powering motor vehicles are designed to burn the fuel blends and have closed fuel systems that prevent the problems that can occur in marine engines and other motors with vented fuel systems.
Those problems are tied to ethanol’s characteristics, the characteristics of marine engines and their fuel systems and how those engines are used.
Marine engines, even those built today, are not designed or warranted to run on fuels containing more than 10 percent ethanol. Increasing the percentage of ethanol in gasoline blends to 15 percent, as is being pushed by federal agencies, especially if it replaces the current E10 blend, would be catastrophic to those engines.
Even at the current E10 blend, boat motors and other non-motor-vehicle engines can develop serious problems, ranging in severity from reduced performance to catastrophic mechanical damage.
Ethanol – ethyl alcohol – is a potent solvent. This can be a good thing, keeping “varnish” and other deposits from accumulating on engine parts exposed to fuel. But, in marine engine systems – even those designed to run on E10 – those solvent qualities can prove problematic. In some boats and motor systems, material used to construct fuel tanks, fuel lines, gaskets and other components is susceptible to deteriorating – dissolving, sloughing, flaking – under ethanol’s influence. That material clogs filters, fuel pumps and damage carburetor parts. Even some fuel system components designed to resist ethanol’s corrosive properties can fall victim if the fuel pools or otherwise collects in bends, dips and kinks in lines and sits for long periods, a common occurrence because it is not unusual for boat motors to sit weeks or even months without being run.
Even more problematic is ethanol’s hygroscopic properties; ethanol absorbs water. It absorbs moisture from the air, and there’s plenty of moisture in the humid air where boats are used and even in the air in garages and storage sheds. Because boat fuel systems, unlike those in motor vehicles, are vented, air and the moisture in it has easy, constant access to fuel tanks where ethanol leeches atmospheric moisture and the moisture from condensation inside the tank.
A small amount of water suspended in fuel isn’t a great problem. But when ethanol absorbs enough water to reach saturation, “phase separation” occurs, with the heavier ethanol/water separating from the gasoline and dropping to the bottom of the tank.
When this water, ethanol or water/ethanol combination is drawn into the fuel system several things can happen, all bad. At minimum, the water can trigger rusting of metal that flakes off and clogs filters, carburetors or injectors. At worst, a slug of water in combustion chambers can result in hydro-lock and catastrophic damage to internal engine parts. If pure ethanol or ethanol/water is drawn into the combustion chamber, the burning of this extremely “lean” fuel can destroy an engine.
Boaters and others with engines susceptible to ethanol-related problems can take measures to minimize potential for trouble. Fuel additives designed to prevent or at least forestall phase separation have become very popular. With marine motors, installing a fuel/water separating filter with 10 micron filtration is now almost a given. And not allowing ethanol-blend fuel to sit unused in a fuel tank weeks or months, giving it time to absorb enough moisture to trigger phase separation should be standard procedure.
Some boaters and owners of small-engine equipment such as chain saws, grass trimmers, ATVs and lawn mowers have gone even further, doing their best to avoiding using gasoline containing ethanol.
Ethanol-free unleaded gasoline remains available in some areas, mostly in smaller towns and, not surprisingly, at marinas. And there’s even a website – pure-gas.org – dedicated to listing businesses selling “E0” gasoline. But supplies are increasingly limited and cost per gallon is as much as $2 higher than E10 gasoline; pushed by economics and federal regulations, refineries have almost wholly ceased producing and shipping ethanol-free gasoline.
For those using small quantities of fuel, quart containers of ethanol-free gas are sold in many businesses aimed at owners of lawn mowers and other equipment powered by small engines. But the “pure” gas comes at a steep price, about $6 a quart – far too expensive to use in even a mid-size outboard.
Boaters and others looking for an alternative to ethanol-blend gasoline now have another option – gasoline blended with isobutanol.
This past month, the National Marine Manufacturers Association announced it has given its approval to isobutanol as a “suitable and safe alternative biofuel to ethanol.” The move comes after five years of testing of fuel containing as much as 16 percent isobutanol. The boating industry-funded testing was conducted under guidance of the U.S. Department of Energy and the Argonne National Laboratory.
Like ethanol, isobutanol is an alcohol produced through distillation of organic material, with corn being the most common source. But isobutanol lacks negative properties of ethanol.
“One huge thing is it’s not hygroscopic like ethanol, so you don’t have the problems with moisture and phase separation,” said Jess Hewitt of Gulf Racing Fuels which is marketing a pair of gasoline/isobutanol blends under the Gulf Marine brand.
The “biobutanol” also packs a bigger energy punch – isobutanol produces 85 percent of the energy of the same amount of gasoline while ethanol yields 65 percent.
Gulf Racing Fuel uses corn-based isobutanol produced at a refinery in Minnesota for its Marine brand of fuels aimed at boaters and owners of ATVs or small-engine equipment. Gulf rolled out the products – 93-octane and 100-octane – in 5-gallon and 55-gallon containers.
The biobutanol blend has been available at a handful of locations in Texas for several months, but plans are to steadily expand distribution over coming months. The 5-gallon containers will begin showing up in Houston-area businesses selling Gulf gasoline, with stations in Dallas and Austin to soon follow, Hewitt said.
Within the year, some Gulf stations could have pumps dedicated the isobutanol/gasoline blend, he added. At $4.50-$5 per gallon, the biobutanol/gas blend isn’t cheap. But neither is rebuilding an outboard’s carburetors.
Just ask any marine mechanic.