Engineers at MIT may have made a breakthrough in the production of renewable diesel fuels using a hyper-efficient version of a common food product, yeast.

Researchers have reprogrammed a strain of yeast to more efficiently convert sugars to fats, also known as lipids, which can then be used to produce high-density fuels like diesel. While yeast will naturally produce these fatty oils from sugar, scientists needed to improve the efficiency of the process o make it more economically viable for fuel production.  

Engineers found that by modifying the metabolic pathways of a particular type of yeast, it can convert sugars into fats with 30% more efficiency. This latest discovery has allowed scientists to produce the same amount of oil using only 2/3 the amount of sugar as is required with unmodified yeast.

The goal is to use plentiful, cheap crops such as sugar cane and corn to produce high-density fuels at lower costs. With these latest modifications, the researchers believe using yeast to produce fuel could be economically feasible right now, using cornstarch at current prices. However, the goal is to increase efficiency to require even less glucose to produce a gallon of oil.

Researchers believe the process can be made even more efficient, saying that they are at about 75% of full efficiency currently. Follow up work will hopefully yield the remaining 25%.

Current renewable fuels, such as ethanol, have a low energy density compared to diesel and are less suitable for large commercial applications. While cooking oil has been used as a renewable source of diesel fuel, it is not scalable and expensive.

The research was funded by the U.S. Department of Transportation and was led by Gregory Stephanopoulos, the Willard Henry Dow Professor of chemical Engineering and Biotechnology at MIT.