Frequently Asked Questions
If you have any questions about this topic please email Dr. Ann Wilkie at acwilkie@ufl.edu
What are the advantages of using biogas as fuel for cooking?
Biogas burns very cleanly, and produces less pollutants during cooking than any other fuel except electricity
Cooking on biogas is faster than on a three stone firewood stove
Depending on the type of gas stove used, the handling of biogas for cooking is easy and allows for strong heat as well as for small simmering heat
It can decrease the workload of women as it is often they who are responsible for collecting firewood for cooking
What are the disadvantages of using biogas as fuel for cooking?
Investment costs: digester, gas stove and installations for the gas to get into the kitchen
It can increase the workload of women as it is often they who are responsible for feeding raw materials into the plant
The use of gas stoves usually requires a sitting or standing position. Cooking outside is not recommended (and not necessary because of the absence of smoke) This change can be welcomed, but some target groups prefer cooking at low level above the ground
Installations (depending on material and location) must be protected against theft and damages
Cultural rules might limit the acceptance of handling animal or human waste and their indirect use for cooking
What about the taste of food cooked with biogas?
While biogas has a particular smell given the presence of hydrogen sulfide, this smell is not transported to the food being cooked
Some users mention that there is a difference in food taste compared to firewood but that is mainly a matter of taste than the biogas itself
What are some other benefits of anaerobic digestion in developing countries?
Biogas can be used for lighting
The by-product (effluent) from the digester is a good fertilizer and source of organic matter
It is a renewable fuel that is ‘carbon negative’ creating and burning biogas releases less greenhouse gases than if the dung was left on the ground to decompose naturally
What are some of the issues with anaerobic digestion systems in developing countries?
The complex fermentation process in the biogas plant needs a continuous supply of suitable feedstock (preferably dung of other animal waste). This requires an appropriate farming system which may be a problem especially for poorer families
It requires a continuous supply of water, which is a problem in arid areas
The need for a continuous supply of dung requires, in most cases, that livestock is kept confined for at least some of the time
Slurry or effluent may need to be transported before use as fertilizer
What are some of the risks and benefits of treatment of human waste in a biodigester?
Typical biodigester effluent is not sterile
Anaerobic digestion creates a competitive environment where pathogens are out competed by non-infectious microorganisms and therefore are edged out in terms of populations. This means that pathogens are reduced, but not entirely eliminated.
Completely eliminating pathogens is not necessary when adequate care is given to applying the effluent. Biodigester effluent can be used for non-edible crops and in some cases forage crops, and applied directly to land.
These systems are scalable from the household, community level to the larger industrial scale applications.