Bioethanol is considered a more climate-friendly alternative to petroleum fuels but its production requires vast amounts of freshwater. Current technology can incur a water footprint of more than 1,000 liters of fresh water University of Huddersfield researcher Dr. Chenyu Du. Source: University of Huddersfieldto produce a single liter of the fuel. A seawater-based system engineered by an international team of researchers may alleviate such pressure on freshwater resources.

The process uses the marine yeast strain Saccharomyces cerevisiae and demonstrates that seawater can substitute freshwater for bioethanol production without compromising production efficiency. The yeast produced 93.50 g/l ethanol in 15 l bioreactors with a yield of 83.33% (of the theoretical yield) and a maximum productivity of 2.49 g/l/h when using seawater-yeast extract peptone dextrose media.

Use of seawater in industrial scale bioreactors could yield about 7 l of high-quality distilled freshwater with each liter of ethanol produced. Other advantages of using seawater in fermentation for bioethanol production include the co-production of sea salt as an additional product, and production of salted high-protein animal feeds that can be used to eliminate the cost of adding minerals to animal diets.

Scientists from the University of Huddersfield and University of Nottingham in the United Kingdom, and Cairo University in Egypt contributed to this research, which is published in Scientific Reports.