Solid Biofuel Database Potential of using Vegetal Biomass in Biogas Production

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1 Solid Biofuel Database Potential of using Vegetal Biomass in Biogas Production ADRIAN EUGEN CIOABLA 1 *, IOANA IONEL 1, ADRIAN TENCHEA 1, GABRIELA-ALINA DUMITREL 2, VASILE PODE 2 1 Politehnica University of Timisoara, Faculty of Mechanical Engineering, 1 M. Viteazu Blv., 3222, Timisoara, Romania 2 Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, 2 Victoriei Sq., 36, Timisoara, Romania In the current context of increasing the share of renewable energy sources at the expense of the fossil fuels, the present study on plant biomass potential can be essential in future research. The paper presents details related to different sorts of vegetal biomass that are to be included inside a solid biofuel database in order to further study the potential of biogas production through anaerobe fermentation from the point of view of chemical and physical properties of the considered materials. Keywords: Solid biofuels, anaerobe fermentation, biogas Depletion of fossil fuels (coal, natural gas and oil) in a relatively short time has been generated concerns worldwide in finding alternative sources to produce electricity, heating and to power the transport sector [1-3]. Another reason that has supported this idea was that burning fossil fuels produce gases responsible for global warming and thus has a negative effect on the natural environment and population. Alternative sources on which scientists headed were: biomass, solar, wind, geothermal, hydroelectric, tidal energy and nuclear [2]. At European level, 29/28/EC directive of the European Parliament and of the Council of 23 April 29 on the promotion of the use of energy from renewable sources was adopted [4,5]. In this directive, we can find biogas as an alternative to fossil fuel. Biogas is generated from the anaerobic digestion of biomass feedstocks and the composition is influenced by the composition of the substrate used (particle size, C:N ratio, etc.) and by operational parameters (temperature, ph, pretreatment, agitation, etc.) [1,6]. Biomass feedstocks include wood, food crops, grass and other plants, agricultural and forestry waste and residue, organic components from municipal and industrial wastes [7,8]. According to Romania s Progress Report under Directive 29/28/EC, the production of electricity from biogas was.247 GWh in 29 and.245 GWh in 21. The production of heating and cooling from this renewable resource was.641 ktoe in 29 and.859 ktoe in 21. As concern the transport sector, the biogas was not used for this purpose [9] İn the above context, the present paper attempts to present a small database with information on different vegetal substrates used to produce biogas by anaerobic digestion. Experimental part This paragraph underlines some of the details related to creating a solid biofuel database. Some of the materials used inside the database were subject to a fermentation process inside a small scale installation for a period of 4 days under controlled conditions (temperature of C and corrected ph during the process) and another fraction of the materials were subject to an anaerobe fermentation inside a pilot * adriancioabla2@yahoo.co.uk; Tel.: installation in order to better monitor the process parameters (ph, temperature and pressures derived from the fermentation) and the partial quality and quantity for the produced biogas. The database will contain some of the physical and chemical characteristics for the analyzed materials before and after the fermentation process in order to better understand the influence of the fermentation process over the degraded biomass and the possibilities involved in using the remaining residue after the process in co-firing or as nutrient for the soil. The small scale installation is presented in figure 1. The pilot installation used for the analyzed materials is presented in figure 2. From the biomass deposit, the used material is passed through a mill, and then is sent to the tank where the preparation of the suspension of biomass is made (1). The biomass suspension is transported using the pump (2) and introduced into the fermentation reactors (3). The correction agent tank for the ph assures, through the control system, the conditions for the process of anaerobic Fig. 1. General schematics for the small scale installation 1 glass reactor with a total volume of 6 L; 2 magnet placed on the bottom of the 6 L glass reactors for magnetic stirring; 3 small glass reactor for biogas washing with water, with a total volume of 5 ml; 4 thermocouple; 5 ph sensors; 6 system for ph correction and sample collecting; 7 ph controllers; 8 temperature controller; 9 gas bags for biogas samples; 1 pressure gauges; 11 heating system 186

2 Fig. 2. Schematics of the pilot installation 1 preparation tank; 2 pump; 3 fermentation reactors tanks; 4 discharge tube; 5 filter for retaining the H 2 S; 6 filter for retaining CO 2 ; 7 CO 2 desorption system; 8 user; 9 discharge system; 1 pressure gauges; 11 thermostat heated systems; 12- tubes, 13-tank. fermentation. The resulted biogas is passed through a filter for retaining the H 2 S (5) and after that, through a system used for retaining CO 2 (6), after which takes place the CO 2 desorption and the compression of the CO 2 in the adjacent system and the purified biogas is sent for being used (8). The used material is discharged through the means of a gravimetric system (9), and the solid material is retained for being dried using the natural drying, and after that is sent to a compost deposit for being used as a soil fertilizer. A part of the resulting liquid is neutralized when it is the case, in the system (1) and sent to the sewerage network, or is transported by the recirculation pump (2) to the suspension preparation tank (1). The fermentation reactors are thermostat heated with the system (11). For the homogenization of the suspension is used a bubbling system (12) made by polypropylene pipes to avoid the possible corrosion. Also, for depositing small quantities of biogas of the purpose of analyzing, the installation is equipped with a small tank (13) positioned at the top of the reservoirs. Biogas production was measured daily, the pressure difference being dropped with the help of a semiautomated system and after wards through a gas counter. Methane (CH 4 ) and carbon dioxide (CO 2 ) compositions (v/ v) were measured using a Delta 16 IV gas analyzer. In this paragraph there are presented some of the chemical characteristics for 6 sorts of materials (some before fermentation, after the anaerobe fermentation during the 4 days period and after the 65 days period and other just before and after the 4 days fermentation). The considered materials are: mixture of 75% corn and 25% corn cobs; wheat bran; two row barley; another mixture composed from 4% corn, 4% wheat and 2% sunflower husks; potato peel and rye. The laboratory analyses were made according to the European standards for solid biofuels ([1 16]). In the tables below are presented the obtained values for the considered materials. From the presented values there can be observed the direct influences of the anaerobe fermentation process on the chemical parameters for the analyzed materials (the main modifications are for calorific values, carbon and volatile content). Table 1 EXPERIMENTAL RESULTS (PART 1) REV. CHIM. (Bucharest) 64 No

3 Table 2 EXPERIMENTAL RESULTS (PART 2) Table 3 EXPERIMENTAL RESULTS (PART 3) 188

4 NET CALORIFI VALUE(db) [J/g] CORN 75%; CORN COB 25% Fig. 3. Net calorific value (db) before and after 65 days of anaerobe fermentation Materials before anaerobe fermentation Materials after 65 days fermentation CARBON CONTENT [%] %CORN; 25% CORN COB Fig. 4. Carbon content variation before and after 65 days anaerobe fermentation Materials before anaerobe fermentation Materials after 65 days fermentation VOLATILE MATTER(db) [%] %CORN; 25% CORN COB Fig. 5. Volatile matter variation before and after 65 days anaerobe fermentation Volatile matter before anaerobe fermentation Volatile matter after 65 days fermentation Table 4 EXPERIMENTAL RESULTS (PART 4) REV. CHIM. (Bucharest) 64 No

5 Conclusions One of the main conclusions which can be drawn from the presented material is that the anaerobe fermentation process has an important impact on all the studied materials, having the real potential to be used for different sorts and recipes in order to obtain good quality biogas. From the figure above it can be observed that the general tendency for all four studied materials after 65 days inside the pilot installation is a decrease with a percentage between 4 and 5%, function of the used material, which represents a good indicator of the energy capitalization using this process. Figure 4 underlines the carbon evolution before and after the 65 days anaerobe fermentation process, indicating a decrease by 3 35%, which in its turn affects the C/N ratio, another important parameter associated with biogas production. The last important variation presented in figure 5 indicates a decrease of the volatile component of the used materials with a percentage between 27 31% - another influence factor due to exploitation using anaerobe fermentation. Also the nitrogen content for the analyzed materials has a relatively small decreasing tendency indicating a good potential for using the residues for a part of the presented biomass as fertilizer this involves further study in order to determine the experimental impact for using this kind of fertilizer in agricultural applications. Acknowledgment: This paper was supported by the project Development and support of multidisciplinary postdoctoral programmes in major technical areas of national strategy of Research - Development - Innovation 4D-POSTDOC, contract no. POSDRU/89/ 1.5/S/5263, project co-funded by the European Social Fund through Sectoral Operational Programme Human Resources Development References 1.SANTOSH, Y., SREEKRISHNAN, T. R., KOHLI, S., RANA, V., Biores.Technol., 95,no. 1, 24, p.1. 2.FISCHER, G., PRIELER, S., VELTHUIZEN, H. VAN, LENSINK, S., LONDO, M., DE WIT, M., Biomass & Bioenergy, 34, 21, p VLADAN, S. I., ISOPENCU, G., JINESCU, C., MARES, A. M., Rev. Chim.(Bucharest), 62, no. 1, 211, p DIRECTIVE 29/28/EC on the promotion of the use of energy from renewable sources, 23 April AEBIOM - European Biomass Association, A Biogas Road Map for Europe, September ISLAS, J., MANZINI, F., MASERA, O., Energy, 32, 27, p DELZEIT, R., BRITZ W., An Economic Assessment of Biogas Production and Land Use under the German Renewable Energy Source Act, Kiel Institute for the World Economy, Kiel Working Paper no. 1767, April DZENE, I., BODESCU, F., Scientific Journal of RTU, 3. 29, p *** Romania s Progress Report under Directive 29/28/EC, *** EN Solid biofuels Determination of moisture content Oven dry method (parts 2 and 3); 11.*** EN Solid biofuels - Determination of ash content; 12.*** EN Solid biofuels Determination of calorific value; 13.*** EN 1529 Solid biofuels Determination of major elements; 14.*** EN Solid biofuels Determination of minor elements; 15.*** EN 1514 Solid biofuels Determination of total content of carbon, hydrogen and nitrogen Instrumental methods; 16.*** EN Solid biofuels Determination of the content of volatile matter Manuscript received: