Biogas production in climates with long cold winters - SuSanA

mesophilic ranges of (16-24°C) for nearly eight months and the rest of the year in the
psychrophilic range (l3-14°C). This results in lowering of the gas production by 23-37% in
winter (Kalia and Kanwar, 1998).
Biogas production can occur over a wide range of temperatures, in nature from 0 - 97 degrees
Celsius (Kashyap et al., 2003 and Zeeman et al., 1988). In conclusion, there is a limited
knowledge and a lack of experience concerning psychrophilic digestion, but it is clear that
lower temperatures need a longer HRT to achieve a similar gas production (Zeeman, 1991).
(Singh and Sooch 2004) mention Deenbandu biogas plant operating in Punjab India at 25 0 C
with 40 days HRT. The table below shows, the relationship between HRT and the volume
with temperature. The calculations are presented in appendix 2.
Calculation of HRT and volume at lower temperature for same methane yield
Temperature ˚C 2 5 10 15 20 25
Loading rate at actual T kg/day 2.00 5.00 10.00 15.00 20.00 25.00
HRT at actual temperature days 80.00 200.00 400.00 600.00 800.00 1000.00
Volume m3 14.96 11.08 6.72 4.08 2.47 1.50
2.6 biogas plant
In many countries worldwide biogas plants are in operation, producing biogas from the
digestion of manure or other biomass (GTZ, 2007). In addition, with success small scale biogas
plants are utilized to displace woody fuels and dung in many developing countries. For
example, the Dutch Development Organization, SNV, implemented with success in Nepal and
Vietnam over 220,000 household on site biogas plants (FMO, 2007). Moreover, in China and
Indian millions of plants are in operation. In conclusion, biogas plants have proven to be an
effective and attractive technology for many households in developing countries.
Under the right conditions a biogas plant will yield several benefits for the end-users, the main
benefits are (GTZ, 2007):
1. Production of energy for lighting, heat, electricity
2. Improved sanitation (reduction of pathogens, worm eggs and flies)
3. Reduction of workload (less firewood collecting) and a biogas stoves has a better
cooking performance
4. Environmental benefits (fertilizers substitution, less greenhouse gas emission)
5. Improved indoor air quality (less smoke and harmful particle emission of a biogas stove
compared to wood or dung fuels) (Buysman et al, 2006)
6. Economical benefits (substitution of spending on expensive fuels and fertilizer)
Consequently, biogas plants are of great benefit to the end-users and the environment. Note
however, that this only happens under the right conditions. What these conditions are is
explained in the next section.
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