Frequently Asked Questions

Biogas is a byproduct of the decomposition of organic matter by anaerobic bacteria, typically composed of about 60% methane and 40% CO₂. It is similar to natural gas (about 99% methane) and can substitute for it in cooking, producing steam or hot water, or generating electricity. Methane is one of the greenhouse gases identified by the UN.

Organic waste is loaded into a sealed tank called a digester (or bioreactor), typically mixed with water at a 1:1 ratio. In the absence of oxygen, anaerobic bacteria consume the organic matter, multiply, and produce biogas as a result.

Almost any organic waste can produce biogas: human excreta, manure, animal slurry, fruit and vegetable waste, slaughterhouse waste, meat-packing waste, dairy and brewery waste, and more. Fibre-rich waste such as wood or leaves makes poor feedstock, as it is difficult to digest.

Yield depends on the waste itself and the digester design. Some systems yield around 20 m³ of biogas per tonne of waste, while well-designed systems can yield as much as 800 m³ per tonne.

Methane has a greenhouse gas heating factor around 21 times higher than CO₂. Combusting biogas converts methane into CO₂, cutting its greenhouse impact by more than 20 times. Extracting methane from waste for energy also prevents it degrading openly in the environment, and displaces fossil fuels — making biogas energy essentially carbon-neutral.

Each cubic metre of biogas holds roughly 6 kWh of calorific energy. Converted to electricity via a biogas generator, this yields about 2 kWh of usable electricity — enough to power a 100W light bulb for 20 hours, or a 2000W hair dryer for one hour.

The volume of waste leaving the digester is nearly equal to what went in, but its quality improves significantly: less odour, better fertiliser value, and reduced organic load. The solid output can be composted, while the liquid part can be used as liquid fertiliser or treated further.

Waste disposal always costs money — and if it doesn't cost you anything, it's likely creating an environmental hazard elsewhere. A digester turns a cost centre into a potential revenue and resource centre, whether on a farm (better fertiliser, lower odour) or in agro-food industry (offsetting energy costs and reducing secondary waste treatment).

Biogas units are suited to domestic waste, kitchen waste and waste water; animal husbandry waste; hotel and bakery/market waste; fish markets; urban waste; and toilet waste — across households, hotels, hospitals, forces camps, government institutions, religious sites, prisons, factories and training centres.