Possibilities of Upgrading Solid Underutilized Lingo-cellulosic Feedstock (Carob Pods) to Liquid Bio-fuel: Bio-ethanol Production and Electricity Generation in Fuel Cells - A Critical Appraisal of the Required Processes

The exploitation of rich in sugars lingo-cellulosic residue of carob pods for bio-ethanol and bio-electricity generation has been investigated. The process could take place in two (2) or three (3) stages including: a) bio-ethanol production originated from carob pods, b) direct exploitation of bio-ethanol to fuel cells for electricity generation, and/or c) steam reforming of ethanol for hydrogen production and exploitation of the produced hydrogen in fuel cells for electricity generation. Surveying the scientific literature it has been found that the production of bio-ethanol from carob pods and electricity fed to the ethanol fuel cells for hydrogen production do not present any technological difficulties. The economic viability of bio-ethanol production from carob pods has not yet been proved and thus commercial plants do not yet exist. The use, however, of direct fed ethanol fuel cells and steam reforming of ethanol for hydrogen production are promising processes which require, however, further research and development (R&D) before reaching demonstration and possibly a commercial scale. Therefore the realization of power generation from carob pods requires initially the investigation and indication of the appropriate solution of various technological problems. This should be done in a way that the whole integrated process would be cost effective. In addition since the carob tree grows in marginal and partly desertified areas mainly around the Mediterranean region, the use of carob’s fruit for power generation via upgrading of its waste by biochemical and electrochemical processes will partly replace fossil fuels generated electricity and will promote sustainability.