July 18, 2014
The use of food crops for the production of fuel is somewhat controversial. 2014 will see, however, the commissioning of the first commercial-scale cellulosic ethanol production facilities that will increase the utilization of plant waste, reduce competition for food crops and provide a substitution for fossil fuels. And nickel-containing alloys are central to this game-changing revolution.
Evolution of an industry
The current dominant ethanol production process involves the fermentation of sugars and starches in food crops such as sugar cane, corn, potato and cassava. These raw materials have short molecules which are quite easily digested by enzymes and are the feedstock for the first generation ethanol industry.
Major research has taken place over the last decade to find a way to be able to use agricultural waste products, such as the corn stover (stalks, leaves and other residue) and sugar cane bagasse (plant mass after the removal of sugar). The unutilized sugars contained in these types of biomass are made up of long molecules of polysaccharides which cannot easily be converted into ethanol by simple fermentation. In addition, cellulose and hemicellulose are entrapped in a matrix of lignin, preventing the enzymes’ access to the sugars and thus their transformation into ethanol.
The key is a pre-treatment phase to be integrated into the production process. Numerous pre-treatment process designs were developed using either acid or enzymatic hydrolysis or a combination of both; or thermo-mechanical technologies. The challenge was to move such technologies from small scale pilot and demonstration plant production to cost-efficient commercial scale production.
The first company to reach commercial scale production of cellulosic ethanol was Beta Renewables in Crescentino, Italy. Its patented Proesa™ process technology subjects the biomass to high temperature and pressure, enabling the necessary separation of the cellulose and hemicellulose from the lignin, followed by subsequent enzymatic treatment releasing simple sugars which are fermented by yeast into ethanol. The lignin and biogas derived from the processes are recovered and used as fuel in the boiler, generating heat and power.
Construction of the Crescentino plant started in 2010 and became operational in 2012. Its success has given confidence to others and as a result cellulosic ethanol plants are presently under construction in the US (Alpha Project and CanEnergy) and in Brazil (Granbio), using energy grasses, wheat straw and corn stover as feedstocks. In early 2014 the technology was also licensed in China (Fuyang Bioproject).
Many other industry participants have also progressed to commercial scale production with their cellulosic ethanol process technologies: Inbicon in Denmark, Enerkem in Canada and Raizen in Brazil.
In the United States, commercial scale cellulosic plants will begin production in 2014: Abengoa Bioenergy in Hugoton, Kansas, Poet-DSM in Emmetsburg, Iowa and Dupont in Nevada, Iowa. The cellulosic ethanol will both be used as fuel and feedstock for the production of bio-based chemicals, a fast emerging industry.