Carlos Cardona: Techno-economic and environmental assessment of an integrated biorefinery from two plantain processing residues: Pseudostem and Peel
The next presentation of Carlos Cardona, organizer and host of the workshop and Professor of Chemical Engineering at the National University of Colombia at Manizales was about an integrated biorefinery from two plantain processing residues.
Starting, Mr Cardona gave a brief overview about bioenergy in Colombia, which mainly focuses on the production of ethanol and biogas from wastewater treatment sludges. Then, Mr Cardona led to the case study of the plantain pseudostem and plantain peel.
The plantain pseudostem shall be used as feedstock for the production of sugars to obtain other added-value products. The feedstock occurs in considerable amounts in Colombia, for example in 2014, 7.3 million tons of plantain pseudostem were produced. Plantain peel represents 30% to 40% of the total fruit weight. The main applications aimed for are starch extraction for the food industry, extraction of phenolic compounds and antioxidants. Mr Cardona then showed the planned biorefinery concepts for both biorefineries and explained in detail the processes occurring in the plants. In the plantain pseudostem biorefinery, bioethanol, biogas, electricity and steam shall be produced. In the plantain peel biorefinery, bioethanol, electricity and steam and biomethane are the aimed products. Continuing, Mr Cardona presented an economic assessment for both biorefinery concepts. For each biorefinery concept, a low scale and a high scale scenario was shown with the related economic consequences, resulting that a low scale scenario is not economical viable. The most economical viable scenario was shown for a plant capacity of 4,000 tons per day. An environmental assessment completed the case study overview.
Concluding, Mr Cardona stated that the use of residues form plantain allows the production of different types of bioenergy such as bioethanol, biomethane, electricity and steam. The minimal scales in terms of raw materials needed should be considered as high.
However, the stand-alone processes for energy supply in secluded areas, together with starch and sugars production is an alternative to be analyzed at low scale.
The production of high added-value products can compensate the productivity problems, such as in the case of the peel biorefinery, where the low ethanol productivity is compensated by biomethane production, for which in Colombia a high interest exists.
The afternoon sessions started with a presentation of Carlos Cardona, who is a Professor of Chemical Engineering at the National University of Colombia at Manizales about the definition of small and high scale biorefineries.
Mr Cardona started with a short overview about the design and conception of biorefineries and showed then examples of scale for product driven biorefineries, being the more realistic and feasible cases when the small-scale concept is applied. Corn and sugar cane biorefineries for example are defined as high-scale biorefineries, as they have high scale consumption of the products. However, they generate only low added value and moderate profit (%). Small-scale biorefineries then show a low scale consumption of products with high added value and a high profit. For this combination Mr Cardona stated that almost no biorefinery of such a combination exists, except of some biorefineries based on exotic fruits which are at the moment under design.
Most of the existing biorefineries are a combination of the aforementioned scales.
Mr Cardona then defined the scale of a biorefinery with regards to the raw materials (feedstock), either on the feedstock availability, the access to the feedstock as well as logistic aspects. The definition can also be made by a policy driven definition or justification. Examples for this are high scale biorefineries under government support to boost agriculture development in rural areas (e.g. palm or jatropha biorefineries). Small-scale biorefineries are supported to ensure the communities’ development meanwhile they have a low or negative added value (subsidies from the government are needed there). Such designs are used for communities in zones that aren’t interconnected with the rest of the country (e.g. in Colombia: communities in the Amazon region). Concluding the definition topic Mr Cardona then showed how to self-design technically a small or high scale biorefinery.
Next Mr Cardona presented as another example (not included in the project) a biorefinery case in the Amazon region of Colombia where the Macambo fruit shall be used. The products are pasteurized pulp, seed butter, residual cake (a paste that should be used as an ingredient in the food industry) as a substitute for cacao, phenolic compounds, biogas and bio fertilizer.