A five-year project that tested more than 15 marine engines of various technologies — in the lab and on the water — shows that biobutanol can be a viable alternative to ethanol-blended gasoline, the marine industry says.
“We can now state as [engine] manufacturers that we have tested this fuel very comprehensively, and it is absolutely much better than ethanol and compatible with marine products,” says Jeff Wasil, Evinrude’s engineering manager for emissions testing, certification and regulatory development. “Our hope is that this will make it easier for the adoption of biobutanol in the marketplace. At this point, we have opened the door for manufacturers [of biofuels] to supply the fuel.”
The use of government-mandated ethanol-blend gasoline, which can damage marine and other types of engines, has stood out as one of the industry’s most important regulatory challenges for the past decade. The congressionally mandated Renewable Fuel Standard requires that 36 billion gallons of renewable fuel be blended into the U.S. gasoline supply by 2022. Ethanol has been the primary substance used to build toward and meet that mandate.
However, ethanol-blended gasoline can cause myriad performance, maintenance and durability problems, such as engine and fuel-system corrosion and degradation, and rough running.
With these known problems associated with ethanol fuels and the ongoing push toward higher quantities of ethanol, such as E15, the marine industry came together in 2010 to evaluate an advanced biofuel with properties better suited for the marine environment than ethanol.
After several thousand hours of testing by five engine manufacturers and the Coast Guard, the industry appears to have found one in biobutanol. It’s substantially less susceptible to phase separation in the presence of water than ethanol, which means biobutanol behaves similarly to conventional non-ethanol gasoline when water is introduced to a boat’s fuel tank, Wasil says.
Biobutanol has an energy content closer to gasoline, which means consumers face less of a compromise on fuel economy at higher blend ratios. At 16.1 percent in gasoline (Bu16), biobutanol has the exact energy content of 10 percent ethanol fuel (E10). Biobutanol contains nearly 90 percent of the energy content of gasoline, compared with 67 percent for ethanol.
“We want the message about biobutanol to get out there with no confusion,” says Mark Riechers, director of regulatory development for Mercury Marine. “This is a far better alternative to ethanol blends, especially in the marine market. … Maybe we can derail the ethanol train at some point. This stuff works.”
In addition, when it’s added to gasoline, biobutanol lowers the vapor pressure of the finished gasoline blend, translating to lower evaporative emissions.
Most important, however, is biobutanol’s much lower risk for phase separation, testers say. Phase separation occurs when ethanol-blended fuel surpasses a certain water saturation point and the ethanol and water separate from the gasoline, forming a layer at the bottom of the tank where the fuel exits and heads to the engine. The gasoline remains on top of the ethanol-water layer.
The project brought together marine engine manufacturers, the National Marine Manufacturers Association, the American Boat & Yacht Council and the Coast Guard. The NMMA and Argonne National Laboratory carried out the project with funding from the U.S. Energy Department’s Office
of Energy Efficiency and Renewable Energy, says John McKnight, NMMA vice president of government affairs.
“Everybody came together and made this happen,” McKnight says. “We finally got to the point where we had enough data to feel extremely comfortable to say that this is a preferable alternative to E15.”
Volvo Penta, Yamaha, Evinrude, Tohatsu, Indmar, Honda, Mercury and OMC/Johnson engines were tested. Electronic-fuel-injection and carbureted 4-stroke outboards, sterndrive engines (with both closed loop control and open loop control or catalyst vs. non-catalyst), and carbureted and direct-fuel-injection 2-strokes, were tested.
“I am a believer in not complaining about a problem but doing something about them,” Yamaha president Ben Speciale says. “I don’t dislike renewable fuels; I dislike problems, and E15 — if it is coming — is a problem. This testing we’ve done is part of our effort to do something about the problem. In biobutanol we have [an additive] chemical that you can use that doesn’t cause the problems that ethanol does, so why not use it?”
The next step is to promote the production of biobutanol so it becomes available to the marine market. Strides have been made there, as well, Wasil says. The marine industry knows of two biofuel companies — Gevo and Butamax (a BP/DuPont joint venture) — that have developed technologies to produce biobutanol. In fact, Gevo supplied all of the biobutanol fuel for the industry’s testing, says Patrick Gruber, Gevo’s chief executive.
“Right now we are just beginning to ramp up sales,” Gruber says. “We have to build more capacity. We want to hear feedback from consumers once they use this fuel. What I expect is that people will like it a lot because it solves problems — the problems of sputtering, fouling, water separation and corrosion, to name a few. We started making biobutanol about 18 months ago in large quantities. We are still working out the full-scale production technology.”
Gevo is planning to launch a pilot program with a boatyard or marina to sell biobutanol-blend gasoline at its fuel dock, Gruber says, adding that the cost of biobutanol-blend gas would be competitive with ethanol-blend gas.
Gevo has already secured the necessary testing and regulatory approvals to begin selling gasoline that is 16.1 percent biobutanol in off-road locations, so “there’s no reason the fuel cannot be made available right away in the marine environment,” Gruber says.
The company also has approval to sell gas with 12.5 percent biobutanol for on-road applications, and getting approval for a 16.1 percent blend at gas stations shouldn’t be a problem, either, Gruber says.
The marine industry is an attractive market for a small company such as Gevo, Gruber says. “If you are a start-up company and trying to compete against the 14-billion-gallon ethanol market, you have to find ways to get your foot in the door, and the marine market is a great way for us to start integrating biobutanol into the market.”
The marine industry is also attractive to biobutanol makers because its engines are subject to extreme conditions, which makes the positive test results even more impressive, says McKnight, who helped test a pair of Evinrude 135-hp E-TEC 2-strokes on a pontoon boat for 116 hours. One engine ran on gasoline with 16.1 percent biobutanol and the other on E10. Those engines have more than 200 hours of test time on them now, adds Wasil.
The Coast Guard also played a major role, testing a pair of 2011 300-hp Mercury Verado 4-strokes on a 38-foot SPC (special purpose craft). The engines had about 380 hours of run time on them before the Coast Guard began the biobutanol test.
“We went out there in June 2013 and replaced all of the fuel system components on the engines and gave them a health check — measured compression, cylinder leak down, valve lash, etc. — before the biobutanol testing began,” says Dave Hilbert of Mercury, who worked with the Coast Guard on the test. “We also did a quick drivability assessment at that time, finding no issues. Once we were done with our assessment, the engines were put in service, using the biobutanol-blend fuel.”
The Coast Guard tested for 13 months, logging 460 hours and burning 2,937 gallons of Bu16. During the testing the SPC-TB performed typical duties, such as coxswain training, and made designated test runs to generate acceptable baseline data using regular E10 gasoline and Bu16.
Bu16 testing focused on operation, performance and maintenance, and crew health and safety, with the goal of experiencing no effects that would be considered worse than the status quo.
Without resting on its laurels, the industry deserves a pat on the back, says Mercury’s Riechers. “We all shared information with each other,” he says. “The marine engine industry actually works well together on programs like this.”
This article originally appeared in the August 2015 issue.