Scientists closer to refining biodiesel for a standard diesel engine

Scientists in Germany have found a way to refine biodiesel so that it works in standard diesel car engines, according to an article appearing on Live Science.

Differences in molecular structure mean that biodiesel made from plant material burns at a different temperature to petrodiesel. As a result, only specially designed engines can run on pure biodiesel or blends that contain substantial amounts of the fuel.

According to the Live Science article, the researchers in Germany have found a way to transform chemicals derived from plants into a biodiesel that meets the boiling characteristics required by the EN 590 standard, set by the European Committee for Standardisation, for commercial diesel sold in the EU.

“If you're going to use biofuel, you need existing infrastructure you can tap into," Lukas Gooßen, a professor of organic chemistry at the Ruhr-Universität Bochum who led the research, told Live Science. "Anything else will be unaffordable to most countries and societies. This has to be the starting point."

The mixture of hydrocarbons that make up petrodiesel boil at different temperatures, giving petrodiesel a broader boiling range than biodiesel. Most diesel engines have been designed with petrodiesel’s boiling range in mind.

Existing processes to convert plant oils into biofuel for a standard diesel engine are energy intensive, meaning a significant proportion of the fuel is burnt in the process. Gooßen and colleagues looked at catalysts – which accelerate chemical reactions, to find a way to refine the biodiesel at low temperatures and using very little energy.

The team’s findings, published in the journal Science Advances, reveal that by using three catalysts they were able to blend rapeseed oil methyl ester and ethylene into a fuel with the same boiling characteristics as petrodiesel. What’s more, they’ve also built a model diesel powered car to demonstrate the fuel’s potential.

A major issue with the findings, which the team admitted to Live Science, is that the catalysts used in their study are expensive and short-lived. Gooßen said that finding a cheaper, more stable alternative for commercial production would ‘be a huge challenge’.

"This boiling point seemed to be a completely insurmountable hurdle," he said. "Now, we are saying, 'How can we make a catalyst that just does this cheaper?' which is a completely different question to, 'How can we even come from biodiesel to something we can put in a car?'"