Energy With Olives Seeds

The seeds of the olives can be converted into bioethanol, a renewable fuel that can be produced from plant matter and used as an alternative to petrol or diesel. This gives the processing industry of olive oil a valuable opportunity to make use of 4 million tons of waste from the seeds of olive oil are generated each year and sets a precedent for the recycling of waste products as fuels.

Researchers from the Universities of Jaén and Granada in Spain show how this can be achieved in a study published in the latest edition of the Journal of Chemical Technology and Biotechnology of the Society of Chemical Industry (SCI).

“The low cost of transport and processing of olive pits makes them attractive for biofuels,” says researcher Sebastián Sánchez.

Bioethanol is increasingly used in cars, but production of food crops as corn is controversial because it uses valuable land resources and threatens food security. It also makes use of only a small part of the whole crop.

The seed of the olive oil, produced in processing of olive oil and table olives, makes about a quarter of the total fruit. It is rich in polysaccharides (cellulose and hemicellulose) that can be broken down into sugar and then fermented to produce ethanol.

“This research raises the possibility of using olive oil seeds, which would otherwise be wasted, in producing energy. Thus, we can use all the food crop, “says Sanchez.

The team pre-treated seeds using high pressure hot water (essentially a pressure cooker) then added enzymes which degrade plant matter and generate sugars. The hydrolyzate obtained from this process is fermented with yeast to produce ethanol. Yields of 5.7kg of ethanol per 100 kg of seeds of olive oil have been achieved

The quantities of seed produced are relatively small compared to other agricultural and forestry waste. However, if similar principles were employed in all agricultural industries, the benefits would be significant.

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