Two John Deere 9650 combines, moving side-by-side through the same Illinois cornfield in the fall of 2001, looked identical in all respects from the outside. But deep inside the engines, there was a major difference between the twin machines. One combine ran on pure diesel fuel, the other on a blend of 10 percent ethanol, 89 percent diesel and 1 percent additive.

“The operators reported that they could not tell the difference between the two machines day to day,” said Alan Hansen, a University of Illinois agricultural engineer who has been conducting side-by-side studies each spring and fall since 2000. “Producers found that the combine running on the ethanol-diesel blend could keep up pretty well with the combine running on diesel only.”

Although performance was not noticeably different to the operators, Hansen said there were still some differences. For example, because ethanol has less energy content than diesel, machinery using the blend had slightly greater fuel consumption — an increase of 3 to 5 percent.

The same increase in fuel consumption showed itself in other side-by-side tests conducted with John Deere 9400 tractors and 9650 Caterpillar Challenger tractors.

The ethanol-diesel blend, better known as E-diesel, may not have as much energy content as pure diesel, but politically it packs a lot of punch. Backers see E-diesel as a major new market for ethanol and Midwestern corn, not to mention an effective way to help engine manufacturers meet tough new emission standards from the U.S. Environmental Protection Agency.

According to Hansen, emission tests performed at national laboratories have shown consistent results: “With a 10 percent blend, you can expect as much as a 25 to 30 percent reduction in particulate emissions — soot and smoke.”

The prognosis for E-diesel is good, Hansen noted, but there are still many hurdles to surpass before engine manufacturers will feel confident backing warranties for engines that run on the blend. In particular, concerns revolve around durability, safety and performance.

UI researchers, led by Hansen, fellow agricultural engineer Qin Zhang and agricultural economist Rob Hornbaker, have been conducting in-lab durability tests since 1999 on engines running on E-diesel. Funding and support have been provided by the Illinois Department of Commerce and Community Affairs, the Great Lakes Regional Biomass Energy Program and the Illinois Corn Marketing Board.

In their first series of laboratory tests, UI researchers used a 15 percent ethanol-diesel blend in a Cummins 5.9 liter engine, which has an injector system that relies entirely on fuel for lubrication.

Ethanol lowers a fuel's ability to lubricate the engine, Hansen noted, although the additive in the blend does contain a small amount of a lubricity agent.

After running for 500 hours in the laboratory, the Cummins engine came through in good condition, but there was some abnormal deterioration of the resin that encapsulates a sensor in the injection system.

“There are some non-metal components in the fuel injection system that you have to be careful about,” Hansen said.

A second 500-hour test was performed on a different engine using a 10 percent ethanol-diesel blend this time. The engine, currently being taken apart and studied, is expected to be in pretty good condition, Hansen said. However, there appears to be some swelling of non-metal seals in the injection pump as a result of the ethanol.

These laboratory tests have proven to be somewhat more severe than in-field tests, he added. The studies of E-diesel used on tractors and combines under actual field conditions have not shown any such wear problems on the engine.

Performance may also be an issue with ethanol, Hansen said, because the rule of thumb is that for every 5 percent of ethanol that you add to a blend, energy content goes down by 2 percent. That is why fuel consumption is slightly higher with E-diesel; it takes more fuel to supply the same power.

When it comes to safety issues, the concern is flammability. Ethanol is not as flammable as gasoline, but it is more flammable than diesel. So to use E-diesel, diesel fuel tanks will need safety features similar to those found in gasoline fuel tanks.

According to Hansen, some of the national laboratories are “looking deeply into the safety issue, developing guidelines on how the blend can be used.”

While researchers search for ways to make E-diesel an effective and economical alternative for off-road vehicles, such as farm machinery, engine manufacturers will be watching closely.

As Hansen pointed out, it can take five to 10 years for manufacturers to phase in new engine designs that reduce emissions and meet tough new EPA standards. But if you switch to E-diesel, the environmental benefits are immediate.


Source: Alan Hansen, 217-333-2969 or achansen@uiuc.edu.