Hydrogen is the most abundant component in the world. It doesnâ??t exist by itself on earth, but it can be produced from a variety of sources like coal, natural gas, oil, water and biomass using different process technologies [1][2]. Hydrogen is nowadays a promising source of energy that can be used directly and indirectly as storage fuel with less environmental issues, especially without CO2 emissions [1]. Hydrogen has the highest energy density with an energy yield of 122 KJ per kg, in comparison with other hydrocarbon fuels [1]. The most common industrial applications of hydrogen are in the automobile, fertilizer, food, cosmetic, glass and electronic industries [3].
Only 4% of hydrogen is produced from renewable sources [1]. Some renewable sources for hydrogen production are biomass and the use of solar and eolic power. Only biomass can produce hydrogen directly. However, biomass is often dumped or used directly as feedstock for combustion processes where its energy density is very less [2][4]. A wide range of technologies exists for transforming the energy rich biomass into hydrogen. Thermochemical and biochemical methods are two modes for hydrogen production from biomass. Biochemical methods such as photo and dark fermentation require feedstocks rich in starch or sugar, or a lignocellulosic pre-treatment (e.g enzymatic-acid hydrolysis) to obtain a sugar rich feedstock [5][6][7] . Bio-chemical routes are more hydrogen-selective methods. However biochemical methods are still being operated in batch regime. In the other hand, thermochemical methods such as pyrolisis, combustion and gasification allow an extensive range of feedstocks, being much faster but less selective. Pyrolisis, combustion and gasification seems to be the most promising options for renewa ble hydrogen production [1][2][8].
This paper evaluates the production of hydrogen via dark fermentation and gasification using lignocellulosic residues coming from agroindustrial process by energetic and environmental analysis. The feedstocks selected to this study are Colombian agroindustrial residues. The raw material was characterized by measuring moisture content (AOAC
928.09 method), klason lignin content (TAPPI 222 om-83 method), acid-soluble lignin content (TAPPI 250UM-85 method) holocellulose content (ASTM Standard D1104 method), cellulose content (TAPPI 203 os-74 method) and ash content (TAPPI Standard T211 om-93 method).
The dark fermentation process started with the feedstocks pretreatment on mild conditions to avoid sugar decomposition. Then the dark fermentation takes place for hydrogen production using Clostridium Butyricum in shake-flasks. In the other hand the thermochemical method of gasification was performed using CaO-based catalyst to obtain a gas product (CO, H2, CO2) in a gasifier â??GEK Gasifier (10 KW/h) Power Palletâ?. The gas produced enriched in hydrogen was analyzed by a portable syngas infrared analyzer (GASBOARD-3100P).
Figure 1 and 2 shows the block diagram for the hydrogen production using dark fermentation and gasification.
Fig 1. Dark Fermentation Block Diagram

Fig 2. CaO-based Gasification

Finally the energetic and environmental analysis was carried out using simulation tools for both processes. For the energetic analysis, the simulation tool used was the commercial package Aspen Plus v8.0 (from Aspen Technology, Inc., USA). The energetic analysis was made based on the energetic cost of each process. The environmental analysis, the Waste Reduction Algorithm WAR, developed by the National Risk Management Research Laboratory from the U.S was used. Besides, the Green House Gas (GHG) analysis was developed to calculate the emissions associated to both processes.
The results show that biomass gasification with CaO-based catalyst is a feasible technique to produce H2-enrichment gas by decreasing CO2 content in the mixture. The energetic and environmental analyses show that both processes were sustainable.

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