The use of renewable energy sources may get a shot in the arm through extended integration with an existing technology.

According to a recent study conducted at the University of Minnesota, some scientists have determined that 20-percent-ethanol automotive fuel does not negatively affect the engines of late-model vehicles.

While the results of the study may be seen as promising for the future of ethanol, some still question the use of higher percentages of ethanol in fuels because, generally, late-model car engines are not constructed to run on differing fuel mixtures.

According to a news release about the study, the study examined the driveability and maintenance issues of vehicles over a period of 13 months. Drivers of cars using E20 and normal fuel filled out questionnaires about these topics daily. The study found no statistically significant difference between the two fuels.

Song-Charng Kong, assistant professor of mechanical engineering, said there is still much more to be learned about the performance of ethanol in engines.

“If you keep increasing the percentage of ethanol in the fuel mixture, you increase the risk, since the engine is not originally designed for it,” Kong said.

He said adding more ethanol could cause a loss of engine power, since ethanol has a lower energy content.

Ethanol is also more difficult to evaporate than normal gasoline, which can cause incomplete combustion, Kong said. At the same time, Kong said a slight loss of power is not normally noticed in today’s engines.

Kong said the fact that ethanol is a renewable fuel is an advantage of using it, but ethanol may cause some potential problems in fuel systems that are not necessarily easy to identify. Kong said that, despite these negative performance effects, gasoline-ethanol fuels are not unsafe in any way.

Kong also said the effects of higher-ethanol fuels on harmful emissions are unclear.

The researchers at the University of Minnesota have taken a step toward building experience with and understanding of using E20.

However, Kong said engine manufacturers performing durability tests using E20 would be more convincing in showing the positive effects of the fuel blend.

“If a vehicle does have problems when it uses E20, it is still difficult to determine if the problem is due to E20 or something else,” Kong said, explaining that engines are complex systems which are not always easy to analyze.

David Plazak, associate director of the Center for Transportation Research and Education, said the decision to use E20 will ultimately be up to vehicle manufacturers, who have decided that E10 was workable and would not void vehicle warranties.

Some manufacturers, he said, already offer flex-fuel vehicles that run on anything from regular gasoline up to E85. Plazak said General Motors currently offers the most flex-fuel vehicles, which have elements of their fuel systems specifically designed to be more compatible with ethanol blends.