The Division of Biofuel Industrial Technologies focus mostly on the engineering, processing and equipment design aspects of bioethanol production.
Concerning ethanol industrial processes, the main challenges are related to increasing productivity (amount of ethanol by sugarcane ton), energy saving, water saving and minimizing environment impacts of the process as a whole. Several advances are expected in specific technological topics of sugarcane reception; juice extraction; hydrolysis processes; fermentation; distillation and waste recycling and disposal and co-generation. Alternative industrial processes could be also studied and developed.
Research on cellulosic ethanol and hydrolysis is one of the main goals of the Division. Lignin cellulose fiber and hemicelluloses sugarcane can be employed to produce fermentable sugars by hydrolysis, leading to an increase in ethanol production. The hydrolysis technology agenda includes topics as: pretreatments, enzymatic hydrolysis systems and processes, equipments, product separation, waste management, and others.
Hydrolyzed lignin, once successfully separated, can be burned to improve energy balance of the new process.
Commercial development of hydrolysis technologies is directly related to the success of the energy-sugarcane new paradigm. Enzymatic hydrolysis technologies promise best results from a medium and long run perspective. Hydrolysis through the acid route is presently the only feasible technology, and can also become a relevant pretreatment for enzymatic methods. Thus, research in both hydrolysis technologies, acid and enzymatic, is necessary and has a strategic nature.
It is well known that Brazil in general and the sugar and ethanol segment in particular have the best conditions for introducing commercial production of ethanol from cellulosic materials, considering that there is a large and active fuel ethanol program and bagasse is probably the most adequate lignocellulosic resource for hydrolysis.
Bagasse has the lowest price compared to other sources since it is already available at the production site and it does not need practically any prior treatment for processing. Bagasse cost is two to three times less expensive as compared to the price of biomass cultures for lignocellulosic materials in developed countries (switch grass for instance). Sugar and ethanol production generates an excess of bagasse and, if required, the available quantity can still be increased. Agricultural trashes are discarded today at the crop site but, it can be forecast as a novel resource for hydrolytic conversion by direct use or by substitution of bagasse as the fuel used by the sugar sector.
A model for introduction of hydrolysis in Brazil is strengthened due to the integration of sugar mills and distilleries. Those will provide their infrastructure for energy production, maintenance and administrative support, effluent treatment, ethanol storage and transporting. The ethanol market for local consumption and export is well established and all the network for transporting, local and export exists.
The use of lignin-cellulose biomass remaining after juice extraction will be able to raise the ethanol yield per hectare, diminishing the pressure for new areas for sugar crops.
FROM FIELD TO FUEL
The state of the art in Brazil is advanced compared to developed countries. Research conducted in Brazil by the private and public sectors brought an important contribution in terms of:
Research lines in the BIOEN Division of Ethanol Industrial Technologies should now address:
The work to be done does not stop at scientific level, basic and process engineering as well as feasibility studies must be done in order to arrive to a commercial process.
Fermentation processes convert sugar raw material to ethanol. Ideally, it must be fast, efficient, flexible, and with low costs in terms of initial investments, maintenance, control, inputs and work.
Brazilian ethanol fermentation process must and can be improved in terms of yield, integration, micro organisms’ population and by-products control, final ethanol concentration, batch time and equipment design and maintenance.
There are several ways to improve fermentation process yield, including the use of high convertible carbon sugarcane varieties and incremental gains from:
Additionally, due the dual nature of sugar/ethanol facilities, it is required high flexibility and resilience to easily shifting between ethanol or sugar production, and to deal with different sugarcane composition or maturation.
Microbiological studies about yeast ecology and population dynamics are perhaps one of essential themes to improve fermentation. Sugarcane juice fermented by yeasts with high alcoholic tolerance will increase its alcoholic content and therefore minimize steam consumption in the distillation and residues produced.
It is also important to develop yeasts with high thermal tolerance given that control of temperature becomes more expensive as temperature of cooling water increases, due the necessity of significantly amounts of energy to water pumping around fermentation tanks.
Ecology of the alcoholic fermentation process must be controlled, avoiding the development of contaminant bacteria that today cause productivity reduction and increasing costs with biocides and antibiotics. Flocculation problems in fermentation reactors, caused from undesirable yeasts or bacteria in proper ambient conditions.
Succession patterns of yeast ecology during fermentation cycle need to be better understood. This is essential to improve the composition and genetic quality of fermentation starters.
Finally, it is important to expend efforts in research of new process technologies. Some have been recently proposed, as the vacuum extractive fermentation, which provides a better productivity – tree fold higher – and lower steam consumption and residues production at distillation. The whole cost reduction with this system is estimated to be as high as 10%.
The mainly research goal in distillation consists of reducing steam consumption by introduction of multiple stage distillation processes. In the new energy sugarcane paradigm it would facilitate energy balance optimization of the industrial facilities.
Also the diffusion of molecular sieves and evaluation of vacuum distillation, absorption and pervaporation processes, as forms to extract anhydrous ethanol, should be considered. These technologies could substitute petrochemical products and reduce steam consumption.
Technological alternatives for treatment and use of distilling residues (vinasse), as for example, biodigestion and concentration, should be re-analyzed under the light of the new paradigm. Leaves blanket on field could change nutritional requirements.
Vinasse, so far has been applied as fertilizing, however research is still necessary in following topics: technologies of concentration, strategies of applications, measurement of environmental impacts and evaluation of impacts of biodigested vinasse effluent versus in natura vinasse. Other possibilities include vinasse combustion and protein production. It is important to point out that development of adequate solutions to each producing region becomes necessary, according to its local characteristics.
Other by-products of industrial operations, like filter cake, fusel oil and boiler leached ashes could be also subject of study, aiming recycling and environmental benefits.
Finally, it is necessary to reduce the water use for processing. CTC (at Piracicaba-SP) has developed several approaches to reducing industrial water consumption. Water use can be reduced of current 3m3/t to less than 1m3/t, producing less effluent and reducing costs, facing the governmental trend to enforce taxes for rivers water use.
Regarding thermodynamic cycle of generation and use of energy, the sector is beginning to change from using old 22 bar boilers to use 40 and up to 60 bar units. This change is motivated by energy saving considerations, involving the modification of procedures and systems that allow for more efficient electricity generation. A more relevant technological improvement, gasification technology, will also make energy generation more efficient, however it still needs to be developed and demonstrated.
An equally important task is to comply with the obligation of sugarcane harvesting without burning, which will imply is the collection of trash and its subsequent burning in boilers.
Two environment related topics are energy overall optimization of industry and controlling of burning emissions from industry facilities.
Thermo-chemical processes called BTL ("biomass to liquids") include pyrolysis and gasification technologies to be developed and compared with usual biochemical routes.
Pyrolysis is the chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents, except possibly steam. The pyrolysis (or devolatilization) process occurs as the carbonaceous particle heats up. Volatiles are released and char is produced, resulting in up to 70% weight loss for coal. The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions.
The gasification process occurs as the char reacts with carbon dioxide and steam to produce carbon monoxide and hydrogen. The resulting gas is called synthesis gas and may be more efficiently converted to energy such as electricity than would be possible by direct combustion of the biomass, as the biomass is first combusted in a boiler and the heat is used to produce steam to drive a steam turbine. Synthesis gas could be converted into liquid fuels (ethanol, 1-butanol or others) when passing in catalytic stream beds (Fischer-Tropsch process).
Other alternative is the biodigestion of the entire crop, that has potential in generating liquid fuels at lower costs to the ones of the oil.