Small- and medium-scale biogas plants in Sri Lanka: Case study on flue gas analysis of biogas cookers
Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences, Department of Sustainable Technologies, Kamýcká 129, CZ-165 00 Prague, Czech Republic; *Correspondence: email@example.com
Biogas technology has received attention in Sri Lanka already from the initial days of the energy crisis in 1973. Biogas production by anaerobic fermentation is a promising method of producing energy while achieving multiple environmental benefits. The study was carried out in the different areas of Sri Lanka at the level of biogas plants owners (n = 51) and local consultants (n = 4) in August 2014. Methods of data collection included semi-structured personal interviews and questionnaire survey. Further, at 51 biogas plants flue gas analysis was done through the portable device TESTO 330-2, which is capable of capturing the gas concentration of CO and NO; consequently by recalculating the concentration of CO2 and NO2. Surprisingly, the quite high concentration of CO was detected c(CO) = 1,008.92 mg m-3, which might be caused by one and/or various combinations of the following factors such as insufficient burning, inappropriate biogas cookers and inappropriate maintenance. The concentration of NO is under the value of 0.046 mg m-3, which is under the permissible exposure limit of nitric oxide. Average temperature of flue gas is within the typical flue gas exit temperature for burning in biogas cookers (TS = 449.16 °C) and flue gas excess air (4.0%), however the air/gas efficiency (54.0%) was recognized at lower value than the optimal one for small- and medium-scale biogas plants. Easy energy access is a trigger for development, especially in terms of human, social and economic development and biogas plants represents a boon for farmers and rural people to meet their energy needs. However, further factors must be also examined and evaluated, such as exploration of gas composition and its microbiological content, emission analysis exploring particle size distribution, emission rates and potential harmful exposures.