An issue that’s definitely been putting the pinch on boaters everywhere is the general unavailability of ethanol-free gasoline. The issue’s roots dates back to the mid-90′s when Congress buckled to lobbyists in the 11th hour and saddled us with ethanol-oxygenated gas. The petroleum industry had long extolled the virtues of MTBE as an oxygenator. But agrobusiness saw dollar signs in this potentially enormous new market for their corn-based product and the rest as they say is history.
In September, the National Marine Manufacturers Association, along with the Engine Products Group, filed a suit challenging the rules regarding gas pump misuse controls for gas pumps containing up to 15 percent Ethanol. According to the NMMA, the new rules would not do enough to prevent possible damage to marine engines from possible mis-fueling with E15 fuel, and petitioned to require E10 fuel to also be sold at gas stations.
“Current proposals by the ethanol industry to increase the amount of ethanol in gasoline should seriously concern all boaters and owners of other small engine equipment,” said Thom Dammrich, NMMA president. “Although NMMA strongly supports renewable fuels as a means to reduce America’s dependence on foreign sources of oil and improve the environment, there is growing evidence that ethanol is not the answer to America’s energy challenge.”
The results from two studies conducted by the National Renewable Energy Laboratory on the effects of E15 on marine engines were released late in 2011, showing that the gasoline and ethanol blend can cause issues including drivability, materials compatibility, increased emissions, and long-term durability in outboard, stern drive and inboard engines.
The High Ethanol Fuel Endurance study tested the effects of E15 and E0 on four-stroke and two-stroke Mercury outboard engines that included the 9.9HP four-stroke, the Verado 300HP Supercharged four-stroke and the 200 EFI two-stroke. In addition to increase fuel consumption in two of the engines, the study showed that E15 caused damage to two out of three outboards and complete failure in the Verado 300HP engine, as well as “degraded emissions performance outside of engine certification limits,” according to the release. The results of the study reinforced the industry’s concerns about proper warning labeling at fueling stations.
One of the issues with higher amounts of ethanol in gasoline is water. The ethanol in gas tanks is uniformly dissolved in the gasoline. Alcohol tends to absorb and hold water, and in concentrations in the tank up to about 0.6 percent, any water remains in solution presenting no problems. (Yes, there are other problems with alcohol in the fuel system, but we’ll get to them later.) How does water get into the fuel tank? It’s possible that water dripped into the tank at the gas station or refueling depot, or a stray raindrop or snowflake made its way into your tank or refueling can, but most water infiltration is from condensation. As the temperature in a tank changes, air has to be vented in and out or the tank will bulge or split. Incoming air carries moisture. When the H2O in the gas gets above a critical percentage—its saturation point—all of the water and alcohol drops out and settles into the bottom of the tank. This is what chemists call phase separation; the various components of the fuel are no longer a homogeneous mixture.
But phase separation does not occur only from increased water concentration, which is actually unlikely in a modern, emissions-sealed automotive fuel system (but it is a definite issue in boat fuel systems). The temperature of the fuel is a factor as well. Here’s the scenario: You fill up the car or gas can with fuel that, for a variety of reasons, is near its water-saturation point and at 60 degrees. Overnight, the temperature drops 20 degrees, and all the water and alcohol settle out even though no extra water has crept in. Guess what? The engine won’t run when the fuel pickup is sucking up the alcohol–water mix.
Worse yet, the gasoline remaining above the water has probably lost three octane points, because today’s gasoline relies heavily on the high-octane equivalence (130) of alcohol to achieve its octane rating. It’s also missing a bunch of additives that stayed in the alcohol—so the entire tank full should be drained and disposed of as hazardous waste. Should be fun in a marine environment, huh?
And that’s not all; alcohol is also corrosive and can degrade plastic, rubber or even metal parts in the fuel system that weren’t engineered to use alcohol-bearing fuel. Consequently, that antique Evinrude outboard you bought at the swap meet might need some upgrading to stay together on today’s gas. That means corrosion-resistant tanks, alcohol-tolerant rubber lines, seals and fuel-pump diaphragms, and plastic fuel-system parts that won’t swell up in the presence of alcohol. Vintage boats with internal fiberglass tanks often have issues with the coating inside the tank failing, sometimes requiring massive structural modifications. Highly tuned two-stroke engines will run leaner (and consequently hotter) on the lower Btu/gallon alcohol mix, potentially leading to melted pistons and scuffed cylinder walls. Alcohol will also scour varnish and deposits out of the fuel system that have remained in place for years, which will eventually wind up in the filter or main jet, choking off the engine’s fuel supply. Worse yet, the alcohol itself oxidizes in the tank and produces a tenacious brown glop that’s far more damaging to fuel systems than the varnish we’re used to seeing in pure petroleum fuels. In warmer weather, you can see varnish starting to form within a month of dispensing fresh fuel into a vehicle tank or storage can. So, there is a very good reason that the auto manufacturers and the NMMA are both suing the government to stop the mandatory E15 legislation.
http://www.nrel.gov/docs/fy12osti/52909.pdf
http://www.nmma.org/assets/cabinets/...forReview2.pdf
http://www.nrel.gov/docs/fy12osti/52577.pdf
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