Alcohol, such as ethanol, is obtained from the fermentation of sugars and starches with the use of yeasts. This is the normal first-generation process, based on edible feedstock such as corn, sugar cane and the like. These agricultural raw materials have relatively short molecules and are likely to be “digested” by enzymes.
But non food sugars – contained in agricultural waste or in non-food crops/biomass – are made up of long molecules of polysaccharides, that yeasts cannot easily attack. And this is not all. Cellulose and hemicellulose are entrapped in a matrix of lignin, which prevents the access of enzymes. Therefore, the problems to be solved are two: separate lignin from cellulose and hemicellulose and then break down the molecules that constitute them (polysaccharides) into simple sugars.
At laboratory level, some companies were able to obtain bioethanol through the use of non-food biomass but were faced with very high costs for the transfer of these processes onto an industrial scale.
Thanks to PROESA™ costs are very competitive.
The process is based on a first phase in which the biomass is subjected to high temperatures and pressures. This process allows to separate the cellulose and hemicellulose from the lignin. Subsequently, the polysaccharides are treated with enzymes that release the simple sugars, then fermented by yeast into ethanol.
The lignin, together with the biogas derived from the processes, is recovered to be used in the boiler that generates power and heat.