Industry testing shows potential for isobutanol in marine engines
It’s no secret the marine industry has been worried about E15. From lawsuits to lobbying, many of the trade groups have been working to make sure it doesn’t end up in marine engines.
Testing by the National Marine Manufacturers Association shows that the 15-percent ethanol gasoline blend damages marine engines. Several bills have been introduced in Congress to stop the use of E15. The NMMA, Marine Retailers Association of the Americas and others have filed suit with the U.S. Supreme Court challenging the Environmental Protection Agency’s waiver that allows E15. While the EPA says that E15 should not be used in marine engines, industry advocates are concerned about the potential damage from misfueling if E15 is available at gas stations across the country.
But the industry is also hoping to come up with a technological solution to the E15 problem. A multi-year research project into the use of isobutanol as an alternative to ethanol is showing great potential for fuel, producing a potentially more eco-friendly product that is easier to make and doesn’t cause the engine damage of ethanol.
Isobutanol, like ethanol, is a biofuel that can be mixed with gasoline to produce a blend that uses less fossil fuels.
The isobutanol now being produced is derived from corn, but unlike ethanol, isobutanol can be derived from any biomass or cellulosic feedstock, such as switchgrasses. That could eventually mean less corn being diverted from food and feed to fuel.
It’s just one of several benefits the testing is showing for isobutanol, said Jeff Wasil, engineering manager for emissions testing and regulatory development at BRP Evinrude.
Wasil is one of the lead researchers into isobutanol as part of a joint program between the industry and the Department of Energy. Initial industry research in 2010 and 2011 showed promising results for a 20-percent isobutanol fuel blend in marine engines. That research caught the attention of the DOE, launching the joint project with the Argonne National Laboratory that started last year.
Now, a year into the project, the results are even more encouraging, Wasil said.
The on-water testing is evaluating a 16-percent isobutanol blend (B16) for not only its ability to power the engines, but also to see if it causes any long-term damage.
“A large component of that is a durability study in which we took several outboard engines from different engine manufacturers,” Wasil said. “We’re looking not only for emissions, but wanted to see how the engines will perform over the entire useful life of the engine.”
The group tested two Tohatsu 10-hp engines, two Mercury 90-hp four-stroke engines and two Evinrude 200-hp engines. One in each pair was run on a 10-percent ethanol blend (E10) and one was run on B16 for 350 hours per engine. During that time, the engines continued to run without any problems. As that testing wraps up, the next step is to do a complete teardown and inspection of the critical parts of the engine to look for any problems that weren’t immediately apparent. Fuel is also being tested on inboard and sterndrive engines.
Even if new engines can be built to work on E15, it’s not unusual for boaters to be using outboards that are decades old. To address that issue, BRP Evinrude provided an unused 1999 150-hp Johnson that had been in storage in its emission area.
“There are a lot of those older technology engines still out in the field today so we wanted to see how that engine would run on isobutanol,” Wasil said. “Based on that study, we saw similar things” as the testing of the newer engines.
So far, there are no red flags for the use of isobutanol as a fuel, and there are benefits over ethanol, Wasil said.
Emissions are at least as good or improved over ethanol blends. Isobutanol is not hydroscopic like ethanol, so phase separation shouldn’t be an issue. (When gasoline containing ethanol sits too long and comes in contact with water in liquid form or in the air, the ethanol will absorb water and separate into layers.)
Isobutanol also has almost 90 percent of the energy content of gasoline, whereas ethanol has only 67 percent. That means more isobutanol can be blended into gasoline, displacing more fossil fuels without hindering performance.
The next step
Researchers will continue to evaluate isobutanol this year, with a detailed analysis of the combustion of B16 and cold-weather testing. The DOE also asked the researchers to evaluate a tri-fuel blend of 5 percent ethanol, 8 percent isobutanol and 87 percent gasoline.
It almost sounds too good to be true, and there are still more obstacles to overcome before you’ll be able to drive down to the corner gas station and fuel up with an isobutanol blend.
Most notably, production needs to be ramped up, as only small quantities are currently available. The two major players in the field are Gevo, which is working to convert existing ethanol plants to isobutanol plants, and a joint venture between BP and DuPont called Butamax.
While widespread use of isobutanol is probably a few years off, Wasil said he would expect to see small quantities, specifically targeted at marinas, available later this year.
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