Technical possibilities of bioethanol production from coffee pulp: a renewable feedstock

Abstract

The present paper investigated the technical possibilities of bioethanol production from coffee pulp in a sustainable manner. Coffee pulp is a largely underutilized waste stream and has the potential to become a bioethanol feedstock if processing is economically viable. This study aimed to characterize the chemical composition of coffee pulp with relevance to bioethanol production and to compare results to other bioethanol feedstocks. Based on the total sugar yield, we investigated bioethanol production using AspenPlus simulation software. In the sugar characterization part, total carbohydrates were measured after complete acid hydrolysis of dry pulp, while water-soluble carbohydrates were measured after acid hydrolysis of soxhlet extracted solutions. Moisture, lignin, and ash contents were measured gravimetrically after appropriate heating treatments. The results showed sugar contents, expressed as percentages of dry mass, as follows: 5.8, 5.2, 20.2, 4.2, and 4.7 % for arabinose, galactose, glucose, xylose, and mannose, respectively. Arabinose, galactose, and glucose were the only water-extracted simple sugars, at 1.0, 1.4, and 2.6 % of dry mass, respectively. AspenPlus simulation was based on processing 10,000 ton/day of coffee pulp. The results demonstrated sugar and ethanol yield of 2100 and 1050 ton/day, respectively. This would make annually profit of $0.13 million. The simulation estimated the capital investment cost was about $2 million. In order to satisfy the process economy, the process operation cost must be operated at minimum of $1.87 million annually. The life-cycle analysis showed the net value of energy of the whole process is an economical as well as the balance of CO 2 emission/reduction was on the environmental favor.

LCA of 1,4-Butanediol Produced via Direct Fermentation of Sugars from Wheat Straw Feedstock within a Territorial Biorefinery

“…According to Groot et al [ 68 ], this was the result of the reductionof: (i) feedstock related impacts (by about 94%, respect to fossil-based BDO), thanks to the substitution of acetylene and formaldehyde with the renewable wheat straw C feedstock; (ii) process related impacts (by about 50%, respect to fossil-based BDO). With regard to the second point, the modeled bio-based supply chain required less net non-renewable foreground energy input for feedstock processing at the industrial plant (about −40%), thanks to the combustion of unconverted biomass residues in the cogeneration unit, as usually highlighted for advanced integrated systems of biorefinery [ 69 , 70 , 71 ].…”

Environmental Impact Associated with the Supply Chain and Production of Grounding and Roasting Coffee through Life Cycle Analysis

“…Two main scenarios were presented for this phase. In the base case or scenario A (S-A), the residual pulp, generated from the de-pulping process within the wet processing stage for the coffee [1,40], was treated through a composting process to produce a stabilized waste that was proposed to be used as fertilizer in the nursery stage [41,42]. Similarly, the residual straw, a solid sub-product generated during the hulling stage [3,43,44], was considered as fuel to supply hot air for the drying process of the coffee bean [45,46].…”

“…It is the second most commercialized product in the world after petroleum. It is so popular due to its aromatic and flavor characteristics as well as its stimulating and refreshing qualities [1][2][3]. Coffee is a high interest product to the agro-industrial sector in Mexico, second only to corn.…”

A Sequential Steam Explosion and Reactive Extrusion Pretreatment for Lignocellulosic Biomass Conversion within a Fermentation-Based Biorefinery Perspective

“…Energy balance is another important aspect for evaluating the economic feasibility of the process [39]. In this context, the present work provides the basic scenario to set optimal conditions for the future success of the process.…”