Ethanol added to long list of olive tree by-products

It's long been reported that there are many uses of olive oil. As a foodstuff it has a high concentration of monounsaturated fatty acids, which studies show promote "good" cholesterol (HDL) while lowering "bad" cholesterol (LDL), that it is beneficial for hair, soothes ulcers, prevents gallstones, and the list goes on. However, new research has revealed that the olive tree can be used for yet another thing.

Research carried out by the University of Jaén and presented at the recent Bioptima conference has highlighted the potential use of olive tree biomass in the generation of ethanol as a bio-fuel, as well as other potentially useful products.

The research, headed by Dr. Eulogio Castro, has spanned several years, beginning with the first demonstration of the production of ethanol from olive tree residue. Subsequent projects have expanded to the concept of a bio-refinery based on this biomass.

The research revealed that the process of producing ethanol from olive tree biomass is a simple process made up of four main steps. Sugars that make up the tree are held together by a compound called lignin. The first step of the process involves the degradation of this lignin ‘cement’, followed by the solubilisation of hemicellulose. Then, the cellulose is attacked by enzymes and broken down into the simpler glucose units. As Castro explained: "This step is essential as only single sugar molecules can be converted to ethanol — it is not possible to covert cellulose directly."

Fermentation of this glucose by yeast or other microorganisms to generate ethanol is then carried out. Finally, the ethanol is separated for use as a bio-fuel.

Ethanol produced from olive tree biomass is termed as a second generation bio-fuel, as it is produced from a source that is not viable for other uses. It is therefore an ideal source from which to generate partial fossil fuel replacements.

Castro stated that the use of olive tree biomass in this process had a huge advantage over other primary sources as it was a waste product produced in huge amounts annually (3 tons per hectare in the 2.4 million hectares of olive groves in Spain alone), with no industrial uses. In addition to this it is essential to remove this biomass from fields to prevent the spread of vegetal diseases. Currently tree waste is burned, so rather than spend money on disposing the waste, it makes sense to use it to convert the residue into a useful product.

Despite the advantages of this type of bio fuel production, there are several barriers still hindering further development. Castro explains that “in the specific case of olive biomass, which is obtained by pruning, logistics is one of the main concerns. A collection system is needed that can transport large amounts of biomass from fields to transformation plants, with economic efficiency.”

source: neurope.eu