This post is based on an article by David Chiaramonti, CREAR and Arianna Giovannini, Chemtex published in April 2012 in BE-Sustainable Magazine.
Background
Ligno-cellulosic ethanol can play a key role in developing the “low carbon future”. This biofuel can be produced worldwide from many different lignocellulosic biomasses, residual or dedicated, assuring high productivity per hectare, very favorable greenhouse gas performances and without direct competition with the food market.
Since 2007 the M&G/Chemtex group focused its efforts into a comprehensive industrial development plan to achieve the development of the 2nd generation ethanol technology. The main strategic objective was the development of a sustainable low-cost sugar production platform which can constitute the basis for efficient sugar conversion into ethanol
or other products. The technology aims at achieving economic sustainability without incentives, thus competing with the fossil fuel markets: in this respect, another pillar of the system is represented by the high feedstock flexibility of
the plant.
The overall industrial and technological development named PRO.E.SA.TM started in 2007-2008: today it is exclusively licensed worldwide by Beta Renewables – a joint venture between M&G and TPG Biotech.
Research components
The R&D activities carried out at Chemtex on lignocellulosic bioethanol mainly focus on the following issues:
• agronomy: field trials, identification and characterization of best energy
crops;
• biomass pre-treatment and viscosity reduction: continuous process developed
and piloted to produce cost-effective and clean fermentable sugars;
• hydrolysis and fermentation: unique hybrid SSCF process scheme yielding
high ethanol concentrations.
The most relevant research components of this programme are PRIT, which focuses on the pretreatment phase and is supported by the Italian National Programme Industria 2015 and BIOLYFE, which investigates hydrolysis
and fermentation and is supported by the European Commission DG Energy.
The goal of the FP7 BIOLYFE project is to develop technologies allowing an increased and economically viable utilization of lignocellulosic feedstock for the production of 2nd generation bioethanol. In order to achieve this objective, the focus of Biolyfe is to develop and build an industrial demonstration unit forthe steps of hydrolysis and fermentation. The project specifically investigates on technologies which have the highest undiscovered potential to enhance the
technical and economic feasibility of the hydrolysis process and the complete conversion of all sugars (C5 and C6) into ethanol, through an optimized fermentation process.
Industrial demonstration
The overall effort, carried out by Chemtex in collaboration with various research institutions, aims at demonstrating
the 2nd generation bioethanol technology. On 12th April 2011 Chemtex broke ground on a 40.000 tons per year
cellulosic ethanol plant in Crescentino, in the Piedmont region of Italy, that should be completed in the first half of
2012. Approximately 180.000 tons of dry biomass per year, sourced from the surrounding agricultural areas will be
transported to the bioethanol plant to produce 40.000 t/y of ethanol. The main feedstock will be cereal straw and giant
reed (Arundo donax). Approximately 4.500 ha of marginal land are available in the area for the cultivation of Arundo
donax.
In the current configuration, lignin (the main co-product of the process) will be used for generating 13 MWe of power;
however, since no chemicals are used in the pre-treatment phase, this material constitutes a very interesting and promising feedstock for further conversion into chemicals. The industrial complex will avoid the production of 50.000
ton of CO2 each year, which equals the GHG emissions of 7.000 vehicles.
The plant will incorporate all the technology features developed during the R&D project phases, such as a commercial
scale new pre-treatment technology (PRIT) and the innovative hydrolysis and fermentation step developed as part of the Biolyfe project.
Positioning of fermenters in Crescentino September 2011
Biomass pre-treatment
The new advanced pretreatment concept developed by the BIOLYFE project is thought to:
• by-pass the inhibitor formation drawback of standard
steam explosion processes;
• increase the extraction of hemi-cellulose and cellulose.
A pilot plant was built at Chemtex labs and is operating in continuous mode since June 2009. It can be fed with several
materials of a size up to 5 cm: the system (20-50 kg/hbiomass input) has demonstrated at pilot scale that different
feedstocks show similar behavior during pretreatment.
Optimization of the simultaneous hydrolysis and fermentation processes
The technology of the pilot plant is able to produce high yields of both C5 and C6 sugars. The process is based on a pre-hydrolysis pretreatment step able to work at high solid concentration followed by simultaneous saccharification
(hydrolysis) and co-fermentation (SSCF) that are performed in a SSF reactor. Hydrolysis of cellulose and hemicelluloses is carried out with an ad-hoc designed enzymes cocktail developed by Novozymes, yielding a variety of sugars, among which glucose and xylose are the most important ones. Then special yeasts coferment glucose and xylose at the same time. This is the novelty of the proprietary process and will bring an optimization of ethanol yields and a reduction of overall complexity of the process and capital costs. The system implements a very efficient continuous high
solid viscosity reduction step which allows for:
• a dry matter content up to 40%;
• a significant reduction of energy demand for mixing;
• a complete liquefaction in less than 8 hours even at
low enzyme load;
• an easy pH and temperature control.
Research activities are carried out with the scientific and industrial collaboration of Novozymes, Lund University and
ENEA. In addition to these activities, during the Biolyfe project a xylose fermenting yeast will also be evaluated in
novel industrially relevant pentose rich hydrolyzates and process tuning with respect to enzyme cocktail composition,
fermentation procedures and yeast preparation will be performed.
Sugar release in the Chemtex pre-treatment process
In order to demonstrate the full supply chain for second generation ethanol and to demonstrate the advantage of the
technology, Biolyfe includes the setup of a fuel distribution infrastructure with E85 fuel pump plus E10 pump, this
will be run in Tortona (AL) nearby Crescentino. The final goal is to promote Flexi Fuel Vehicles (FFV) among local end-consumers, private users as well as and public and company fleets. In addition, the produced fuel will be tested in a dedicated test fleet of at least 5 vehicles. Biolyfe provides a multi-criteria evaluation of the 2nd generation bioethanol technological, environmental, economic and social aspects. This integrated assessment will generate descriptions
and conclusive assessments of sustainability of both the basic and the optimised bioethanol systems. In addition, SWOT analyses will be performed in order to reveal the most sustainable pathways for bioethanol from lignocellulosic materials.
