Biogas FAQ

What is Biogas?

• Biogas is a form of fuel made from organic waste such as food, crop waste and manure. The waste is broken down in an oxygen-free environment. As it decomposes in a process called anaerobic digestion, organic molecules break down and release energy. This energy is the biogas. It is typically composed of 60% methane and 40% CO2. It is similar to natural gas which is composed of 99% methane.

Why do the women cook over the open fire indoors? Why not do most of the cooking outside? I understand the wood smoke problem will still exist but not be as bad.

• Harsh weather conditions like wind, rain and sun. A lot of wind means more firewood. Sometimes there are interferences by animals and mostly mothers cook as they do other things. Some live in communal settings and cooking outside means everyone knows what you are cooking so indoors comes with privacy
• Cooking practices are deeply ingrained in cultural norms. Women often follow traditional methods passed down through generations.
• Cooking indoors provides security and privacy, especially in households where women are responsible for both cooking and childcare.

Why is Biogas Important in Kenya?

• Kenya faces several energy challenges, including high costs, environmental degradation, and health risks associated with traditional fuels. Biogas offers a sustainable solution by utilizing locally available resources and transforming them into usable energy forms.

Why no vents on the roofs to let smoke out?

• Mostly the structures you see used for cooking are not usually built for Kitchen but a house that people use at night to sleep in. The modification of roofs to include a vent comes with an extra cost therefore most households avoid them.

What is a bio-digester?

• It is a sealed tank or container specifically built to provide anaerobic conditions for the breaking down of organic matter to produce biogas. To generate enough biogas to use, the process requires a steady stream of organic waste.

What do you need to operate a bio digester?

• Sufficient feedstock (waste) preferably, cow dung or any other animal waste. For those who own dairy cattle, a minimum of two cows in zero-grazing unit would provide sufficient feedstock to qualify for a biogas plant.

Which has the worst greenhouse gas emissions wood fire or biogas?

• Wood fires emit more CO₂ and have additional environmental impacts. Biogas is produced from organic materials such as food waste, agricultural residues, and sewage. Biogas is considered a renewable energy source because it captures methane (a potent greenhouse gas) that would otherwise be released during decomposition.

Does each family have a herd of cows and how many cows are owned by each family?

• Yes, the family receiving a biogas unit generally have 4 cows. The livestock they own must be sufficient to feed the biogas unit. The number of livestock depends on the size of the biogas unit and the gas required. These units require 3-4 cows or equivalent in chickens goats etc or a combintion. The units can also digest vegetable waste and the later units can also process human waste as well to improve sanitation. Part of the previous 6T project was installing water tanks. For a family to get a water tank they also had to install a toilet. The toilet and sanitation facilities in the area where the biogas units are being installed are very crude.

What is the total cost of a Biogas system?

	KES	US$	A$
Total Cost Includes Planting Trees and Biogas construction, equipment and other associated expenses	196,620	1,343	2067
Beneficiary/Community Contribution (cash or in kind) In kind. The family and community help with construction, feed and accommodate the contactors etc.	-52,000	-354	-547
Biogas Unit Cost to us is: (subject to exchange rates, overheads and inflation)	144,620	1000	1542

We have set the cost of  ‘sponsor a biogas unit’ at US$1050 or A$1650 for a complete unit.  The extra is to allow for the Rotary Foundation 5% fee and exchange rate fluctuations, bank fees and a little for inflation.

How long will a Biogas system last ?

• Over 25 years

How much are ongoing maintenance costs?

• It is expected that the units will be working well for the first two years and not need any maintenance costs (subject to users following instructions and using the unit correctly)

Maintenance	Description	Est Cost Kshs	Est Cost US$
Scheduled Service (Every 24 months)	Periodic inspection and cleaning by a qualified technician. Replacement of worn out desulphurisation pellets, hoses and filters	1500	11
Desludging (Every 10 years)	Removal of accumulated solids from the digester tank	10,000	76
Routine Maintenance	Water trap, burner cleaning and maintaining (as required)	1500	11

Are there health and safety issues with generating, storing and burning gas?

• The same as having a natural gas stove in the house in Australia. The only difference is that the gas is filtered by a small filter and pressure regulator at the home to remove any traces of hydrogen sulfide rather than at a large gas processing plant. This is mainly done because of the smell and it can corrode parts of the stove.

Do you have plans for assisting other villages and locations?

• The project is for small subsistence farming families in the whole rural area around Nakuru Kenya. This is a big area. The 6T project has installed 6,500 water tanks to the same families so far since 2003. So we have our hands full with plenty of potential beneficiaries and could not cope with any more for the time being.

Are solar panels and induction cookers another option?

• Very unlikely for the beneficiaries of this project. The number of solar panels and a battery to support an induction cooktop would be expensive. Induction Cooktop Wattage: Typically starts from 1250 to 1750 watts and can go higher. Solar Panel Requirements: For a 1500-watt induction cooker, approximately three to four 100-watt solar panels are needed. Battery Bank: A battery bank with a capacity of 3000 to 4000 watt-hours is recommended to support the cooker’s usage. This option does not have the other advantages of capturing the methane from animal waste, nor supply processed fertilizer for a kitchen garden. Biogas digestion also deactivates pathogens and parasites to reduce the incidence of waterborne diseases.
• It may however be an option for families without the ability to feed a biogas digester. Something to look in to.

Indoor Air Pollution Key facts

• Around 2.3 billion people worldwide (around a third of the global population) cook using open fires or inefficient stoves fuelled by kerosene, biomass (wood, animal dung and crop waste) and coal, which generates harmful household air pollution.
• Household air pollution was responsible for an estimated 3.2 million deaths per year in 2020, including over 237 000 deaths of children under the age of 5.
• The combined effects of ambient air pollution and household air pollution are associated with 6.7 million premature deaths annually.
• Household air pollution exposure leads to noncommunicable diseases including stroke, ischaemic heart disease, chronic obstructive pulmonary disease (COPD) and lung cancer.
• Women and children, typically responsible for household chores such as cooking collecting firewood, bear the greatest health burden from the use of polluting fuels and technologies in homes.
• It is essential to expand use of clean fuels and technologies to reduce household air pollution and protect health. These include solar, electricity, biogas, liquefied petroleum gas (LPG), natural gas, alcohol fuels, as well as biomass stoves that meet the emission targets in the WHO Guidelines.