Decision Support for the Construction of Farm-Scale Biogas Digesters in Developing Countries with Cold Seasons
Abstract
:1. Introduction
1.1. Construction and Management of Simple, Small Digesters
2. Materials and Methods
- Animal slurry is a mixture of manure and water mixture. The composition is determined by the manure:water ratio.
- The heat capacity of the slurry is equal to that of water.
- The density of the slurry is equal to that of water.
- The temperature of the input slurry is equal to the ambient air temperature [19].
- Ground temperature is constant from the top to the bottom of the digester, and the mean monthly soil temperature is equal to the mean monthly air temperature.
- The flow rate of the slurry does not influence heat losses from the digester [24].
- Only the exact amount of water needed to heat the digester is heated.
- The water used to heat the digester is all heated from the ambient water temperature to the required temperature of 50 °C.
- Water is used as a heat exchange fluid and is circulated through tubes in the digester once daily.
2.1. Digester Design
2.2. Heat Transfer
Parameter | Abbreviation | Heat transfer coefficient (W.m−2.K−1) |
---|---|---|
Radiative heat transfer coefficient from the slurry to the digester dome | 4.65 | |
Convective heat transfer coefficient from the slurry to the digester dome | 4.4 | |
Radiative heat transfer coefficient from the digester to the atmosphere | 4.65 | |
Convective heat transfer coefficient from the digester to the atmosphere as affected by wind speed u (m s−1). | 5.7 + 3.8 u | |
Heat transfer coefficient inside the hose/plastic pipe | 400 | |
Heat transfer coefficient outside the hose/plastic pipe | 400 |
2.3. Heating the Digester
Parameter | Thermal conductivity (W.m−1.K−1) | Thickness (m) | Diameter D (m) | Temperature T (°C) | Heat capacity (J.kg−1.K−1) | Density (kg.m−3) |
---|---|---|---|---|---|---|
Digester dome () | 0.5 | 0.15 | - | - | - | - |
Earth layer above the dome () | 1 | 0.3 | - | - | - | - |
Earth () | 1 | - | - | - | - | - |
Hose:plastic pipe () | 0.3 | 0.002 | 0.02 | - | - | |
Input slurry () | - | - | - | 4180 | 1000 | |
Input hot water () | - | - | - | 50 | 4180 | 1000 |
Output hot water () | - | - | - | 40 | 4180 | 1000 |
Fresh water () | - | - | - | 25 | 4180 | 1000 |
2.4. Methane Production
2.5. Characterization of the Biomass Resource
VS component | Number of atoms | VS fraction | ||||
---|---|---|---|---|---|---|
C | H | O | N | Pig manure | Cattle manure | |
VS (VFA) | 2 | 4 | 2 | 0 | 0.072 | 0.036 |
VS (protein) | 5 | 7 | 2 | 1 | 0.229 | 0.15 |
VS (lipid) | 57 | 104 | 6 | 0 | 0.137 | 0.069 |
VSED (carbohydrate) * | 6 | 10 | 5 | 0 | 0.347 | 0.434 |
VSSD (carbohydrate) ** | 6 | 10 | 5 | 0 | 0.166 | 0.191 |
VS (lignin) *** | 10 | 13 | 3 | 0 | 0.049 | 0.121 |
Total | 1 | 1 |
2.6. Evaluation of Energy Outcomes
Variable | Abbreviation | Value |
---|---|---|
Time of heating per day | 2 h | |
Constant for non-insulated vertical side walls [21] | 1.37 | |
Distance from the bottom of the digester to the groundwater level [21] | 5 m | |
Efficiency of the biogas boiler | 55% | |
Thickness of the dome [21] | 0.15 m | |
Thickness of the earth layer above the dome [21] | 0.3 m | |
Thickness of the hose | 0.002 m | |
Diameter of the hose | 0.02 m | |
Ground temperature (monthly average) | (°C) | |
Wind speed – monthly average | 2.5 m.s−1 | |
Lower heating value of methane gas | 36,000,000 J.m−3 | |
Number of times the water circulates inside the digester | 1 |
2.7. How Does the Model Work
3. Results and Discussion: Case study in Hanoi
3.1. Energy Requirements and Biogas Production
3.2. Daily Biogas Production as Affected by Hydraulic Retention Time and Dilution
3.3. Heating the Digester
4. Conclusions
Abbreviations:
Area of the slurry in contact with the biogas in (m²) | |
Theoretical methane production potential (LCH4.Kg−1VS) | |
Thermal capacity (J.kg−1.K−1) | |
Diameter (m) | |
FAO | Food and Agriculture Organization of the United Nations |
Heat transfer coefficient | |
Convective heat transfer coefficient (W.m−2.K−1) | |
Depth of the digester (m) | |
Height of the loops in the hose (m) | |
Radiative heat transfer coefficient (W.m−2.K−1) | |
Hydraulic retention time (days) | |
Dimensionless kinetic parameter | |
Length (m) | |
Distance from the bottom of the digester to the groundwater level (m) | |
Lower heating value of methane (MJ.m−3CH4) | |
Mass rate (kg. day−1) | |
Mass rate of manure excreted per animal and per day (kg.animal−1.day−1) | |
Mass rate of slurry (kg.animal−1.day−1) | |
Mass rate of water mixture used in the slurry (kg.animal−1.day−1) | |
Number of times the water circulates inside the digester | |
Number of loops of the heating pipes | |
Number of animals | |
Perimeter of the digester at the bottom (m) | |
Energy required or produced by x (J.day−1) | |
Heat losses from x (J.day−1) | |
S0 | concentration of organic material in the feed (KgVS.m−3feed) |
SNV-VN | Netherlands Development Organization: Biogas program for the animal husbandry sector in Vietnam |
SRT | Solids Retention Time (days) |
Temperature (K) | |
Air temperature (K) | |
Average temperature inside the digester (K) | |
Heating period (s) | |
Wind speed (m.s−1) | |
Thermal transmittance (W.m−2.K−1) | |
Velocity inside the pipes (m.s−1) | |
Volume (m3) | |
Volumetric flow (m3.day−1) | |
VFA | Volatile Fatty Acids |
VS | Volatile Solids |
Easily digestible carbohydrates | |
Slowly digestible carbohydrates | |
Methane fraction in biogas |
Greek Symbols
Constant value for non-insulated vertical side walls | |
Biochemical methane potential determined by a batch fermentation test (LCH4.Kg−1VS) | |
Cumulative methane production during period t (NLCH4.Kg−1VS) | |
Thickness of the pipe (m) | |
Thermal conductivity (W.m−1.K−1) | |
Microorganism growth rate (days) | |
ξ | Percentage of energy requirements of the heating water provided by the biogas |
Density (kgm−3) |
Subscripts
From a to b | |
Atmosphere | |
Circulation | |
Digester | |
Dome of the digester | |
Earth | |
Earth layer above the digester dome | |
External | |
Fresh Water (water from the tap before heating) | |
Biogas | |
Ground | |
Hot water used to heat the digester | |
Input to the digester | |
Internal | |
Output of the digester | |
Pipe | |
u | Slurry: excreta and washing water |
summer | Summer period |
Upper part of the digester | |
Winter period |
Acknowledgments
Conflicts of Interest
References
- Rosemarin, A.; Schröder, J.; Dagerskog, L.; Cordell, D.; Smit, B. Future Supply of Phosphorus in Agriculture and the Need to Maximize Efficiency of Use and Reuse; ISBN 978-0-85310-322-6. International Fertilizer Society (IFS): Cambridge, UK, 10 December 2010; pp. 1–28. [Google Scholar]
- Zhang, J.; Smith, K.R.; Ma, Y.; Ye, S.; Jiang, F.; Qi, W.; Liu, P.; Khalil, M.A.K.; Rasmussen, R.A.; Thorneloe, S.A. Greenhouse gases and other airborne pollutants from household stoves in China: A database for emission factors. Atmos. Environ. 2000, 34, 4537–4549. [Google Scholar] [CrossRef]
- Food and Agriculture Organization of the United Nations (FAO). FAO Energy. Available online: http://www.unece.org/efsos2.html (accessed on 13 December 2011).
- Sari, R.; Soytas, U. The growth of income and energy consumption in six developing countries. Energy Policy 2007, 35, 889–898. [Google Scholar] [CrossRef]
- World Energy Council (WEC); Food and Agriculture Organization of the United Nations (FAO). The Challenge of Rural Energy Poverty in Developing Countries, London. 1999. Available online: http://www.fao.org/sd/EGdirect/EGre0048.htm (accessed on 13 December 2011).
- Bruun, S.; Jensen, L.S.; Vu Thi Khanh, V.; Sommer, S.G. Rural household biogas digesters—An option for global warming mitigation and a potential climate bombs (Feature article). Renew. Sust. Energy Rev. 2013. submitted. [Google Scholar]
- Dawson, C.J.; Hilton, J. Fertiliser availability in a resource-limited world: Production and recycling of nitrogen and phosphorus. Food Policy 2011, 36, S14–S22. [Google Scholar] [CrossRef]
- Cordell, D.; Drangert, J.-O.; White, S. The story of phosphorus: Global food security and food for thought. Glob. Environ. Chang. 2009, 19, 292–305. [Google Scholar] [CrossRef]
- Chanakya, H.N.; Rajabapaiah, P.; Modak, J.M. Evolving biomass-based biogas plants: The ASTRA experience. Curr. Sci. 2004, 87, 917–925. [Google Scholar]
- Wang, C.B.; Zhang, L.X. Life cycle assessment of carbon emission from a household biogas digester: Implications for policy. Proc. Environ. Sci. 2011, 13, 778–789. [Google Scholar]
- Cu, T.T.; Cuong, P.H.; Hang, L.T.; Chao, N.V.; Anh, L.X.; Trach, N.X.; Sommer, S.G. Manure management practices on biogas and non-biogas pig farms in developing countries using livestock farms in Vietnam as an example. J. Clean. Prod. 2012, 27, 64–71. [Google Scholar] [CrossRef]
- Kalia, A.K.; Singh, S.P. Case study of 85 m3 floating drum biogas plant under hilly conditions. Energy Convers. Manag. 1999, 40, 693–702. [Google Scholar] [CrossRef]
- Khoiyangbam, R.S.; Kumar, S.; Jain, M.C. Methane losses from floating gasholder plants in relation to global warming. J. Sci. 2004, 63, 344–347. [Google Scholar]
- Rajendran, K.; Aslanzadeh, S.; Taherzadeh, M.J. Household biogas digesters—A review. Energies 2012, 5, 2911–2942. [Google Scholar] [CrossRef]
- Food and Agriculture Organization/Consolidated Management Services (FAO/CMS). Biogas Technology: A Training Manual for Extension. Session 1: System Approach to Biogas Technology. 1996. Available online: http://www.fao.org/sd/EGdirect/EGre0022.htm (accessed on 13 December 2011).
- Kashyap, D.R.; Dadhich, K.S.; Sharma, S.K. Biomethanation under psychrophilic conditions: A review. Bioresour. Technol. 2003, 67, 147–153. [Google Scholar] [CrossRef]
- Tiwari, G.N.; Chandra, A. A solar-assisted biogas system: A new approach. Energy Convers. Manag. 1986, 26, 147–150. [Google Scholar] [CrossRef]
- Yadav, Y.P.; Tiwari, G.N.; Chandra, A. An improved solar assisted biogas plant: A transient analysis. Energy Convers. Manag. 1987, 27, 153–157. [Google Scholar] [CrossRef]
- Perrigault, T.; Weatherford, V.; Martí-Herrero, J.; Poggio, D. Towards thermal design optimization of tubular digesters in cold climates: A heat transfer model. Biores. Technol. 2012, 124, 259–268. [Google Scholar] [CrossRef]
- Gupta, R.A.; Rai, S.N.; Tiwari, G.N. An improved assisted biogas plant (fixed dome type): A transient analysis. Energy Convers. Manag. 1988, 28, 53–57. [Google Scholar] [CrossRef]
- Kishore, V.V.N. A heat-transfer analysis of fixed-dome biogas plants. Biol. Wastes 1989, 30, 199–215. [Google Scholar] [CrossRef]
- Anand, R.C.; Singh, R. A simple technique, charcoal coating around the digester, improves biogas production in winter. Bioresour. Technol. 1993, 45, 151–152. [Google Scholar] [CrossRef]
- Khoiyangbam, R.S.; Kumar, S.; Jain, M.C.; Gupta, N. Methane emission from a fixed dome biogas plants in hilly and plain regions of northern India. Bioresour. Technol. 2004, 95, 35–39. [Google Scholar] [CrossRef] [PubMed]
- Gebremedhin, K.G.; Wu, B.; Gooch, C.; Wright, P. Simulation of Heat Transfer for Biogas Production. ASAE/CSAE Meeting Presentation, Ontario, Canada; Available online: http://elibrary.asabe.org/abstract.asp?aid=16833&t=2&redir=&redirType= (accessed on 1 March 2013).
- Deublein, D.; Steinhauser, A. Biogas from Waste and Renewable Resources; ISBN 978-0-470-02674-8. WILEY-VCH Verlag GmbH & Co. KGaA: Weinheim, Germany, 2008; pp. 411–412. [Google Scholar]
- Kätterer, T.; Andrén, O. Predicting daily soil temperature profiles in arable soils in cold temperate regions from air temperature and leaf area index. Acta Agric. Scand. Sec. B Soil Plant Sci. 2009, 59, 77–86. [Google Scholar]
- The Uplands Program, University of Hohenheim, Last Update: 24 February 2011. Available online: https://sfb564.uni-hohenheim.de/data_climate.html?data_no=418 (accessed on 2 March 2013).
- Pham, C.H.; Triolo, J.M.; Sommer, S. Algorithms for predicting methane production in simple psychrophilic biogas digesters. Water Res. 2013. submitted. [Google Scholar]
- Symons, G.E.; Buswell, A.M. The methane fermentation of carbohydrates. J. Am. Chem. Soc. 1933, 55, 2028–2036. [Google Scholar] [CrossRef]
- Møller, H.B.; Sommer, S.G.; Ahring, B.K. Methane productivity of manure, straw and solid fractions of manure. Biomass Bioenergy 2004, 26, 485–495. [Google Scholar] [CrossRef]
- Triolo, J.M.; Sommer, S.G.; Møller, H.B.; Weisbjerg, M.R.; Jiang, X.Y. A new algorithm to characterize biodegradability of biomass during anaerobic digestion: Influence of lignin concentration on methane production potential. Bioresour. Technol. 2011, 102, 9395–9402. [Google Scholar] [CrossRef] [PubMed]
- Pham, C.H.; Vu, C.C.; Sommer, S.G.; Bruun, S. Factors affecting process temperature and biogas production in small-scale rural biogas digesters during winter in northern vietnam. Asian-Austral. J. Anim. Sci. 2013. Submitted. [Google Scholar]
- Vu, Q.D.; Tran, T.M.; Nguyen, P.D.; Vu, C.C.; Vu, V.T.K.; Jensen, L.S. Effect of biogas technology on nutrient flows for small- and medium-scale pig farms in Vietnam. Nutr. Cycl. Agroecosyst. 2012, 94, 1–13. [Google Scholar] [CrossRef]
- Weather Forecast, BBC, Consulted on the 10/12/2012. Available online: http://www.bbc.co.uk/weather/1581130 (assessed on 10 December 2012).
- Singh, K.J.; Sooch, S.S. Comparative study of economics of different models of family size biogas plants for state of Punjab, India. Energy Convers. Manag. 2004, 45, 1329–1341. [Google Scholar] [CrossRef]
- Hansen, T.L.; Sommer, S.G.; Gabriel, S.; Christensen, T.H. Methane production during storage of anaerobically digested municipal organic waste. J. Environ. Qual. 2006, 35, 830–836. [Google Scholar] [CrossRef] [PubMed]
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Rennuit, C.; Sommer, S.G. Decision Support for the Construction of Farm-Scale Biogas Digesters in Developing Countries with Cold Seasons. Energies 2013, 6, 5314-5332. https://doi.org/10.3390/en6105314
Rennuit C, Sommer SG. Decision Support for the Construction of Farm-Scale Biogas Digesters in Developing Countries with Cold Seasons. Energies. 2013; 6(10):5314-5332. https://doi.org/10.3390/en6105314
Chicago/Turabian StyleRennuit, Charlotte, and Sven Gjedde Sommer. 2013. "Decision Support for the Construction of Farm-Scale Biogas Digesters in Developing Countries with Cold Seasons" Energies 6, no. 10: 5314-5332. https://doi.org/10.3390/en6105314