Carlos Cardona: Small and High scale Biorefineries. Definition based on sensitivity analysis
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 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.
Following this case Mr Cardona presented another case study about biorefineries that use pine and cut stems of coffee plants as feedstock (classified as energy producing biorefinery). He gave an outlook about the intended technology to be used which shall be gasification. Referring to the hydrogen production through gasification Mr Cardona showed economical calculations that showed positive net present values (NPV) for both feedstocks from a plant capacity of 50 Mt/year.
The conclusion of Mr Cardona’s presentation was that the scale is the basis for understanding the type of products to obtain in the biorefinery. Biofuels for example cannot be produced at low scale and the high added value products cannot be produced at high scale.
The small scale is a relative concept and it should be defined in any case. Technical recommendation for this purpose can’t be made, but the sensitivity analysis for NPV or profit is seen as a good beginning to objectively define the limits for the potential scale.