page 1
page 2
page 3
page 4
page 5
page 6
page 7
page 8
page 9
page 10
page 11
page 12
page 13
page 14
page 15
page 16
page 17
page 18
page 19
page 20
page 21
page 22
page 23
page 24
page 25
page 26
page 27
page 28
page 29
page 30
page 31
page 32
page 33
page 34
page 35
page 36
page 37
page 38
page 39
page 40
page 41
page 42
page 43
page 44 page 45
page 46
< prev - next > Energy Biogas KnO 100619_Biogas Digest vol 1 (Printable PDF)
Environmental Frame Conditions of Biogas Technology
Climatic conditions for biogas dissemination
Biogas technology is feasible in principle under almost all climatic conditions. As a rule,
however, it can be stated that costs increase for biogas production with sinking
temperatures. Either a heating system has to be installed, or a larger digester has to be built
to increase the retention time. Unheated and un-insulated plants do not work satisfactory
when the mean temperature is below 15 °C. Heating systems and insulation can provide
optimal digestion temperatures even in cold climates and during winter, but the investment
costs and the gas consumption for heating may render the biogas system not viable
Figure 18: Global 15oC isotherms for January and July, indicating the biogas-
conducive temperature zone
Not only the mean temperature is important, also temperature changes affect the
performance of a biogas plant adversely. This refers to day/night changes and seasonal
variations. For household plants in rural areas, the planner should ensure that the gas
production is sufficient even during the most unfavorable season of the year. Within limits,
low temperatures can be compensated with a longer retention time, i.e. a larger digester.
Changes of temperature during the course of the day are rarely a problem as most simple
biogas digesters are built underground.
The amount of seasonal and annual rainfall has mainly an indirect impact on anaerobic
Low rainfall or seasonal water scarcity may lead to insufficient mixture of the
substrate with water. The negative flow characteristics of substrate can hamper
Low precipitation generally leads to less intensive systems of animal husbandry. Less
dung is available in central locations.
High precipitation can lead to high groundwater levels, causing problems in
construction and operation of biogas plants.