How does biogas work?

How do we take waste and make it into energy?

Accessing energy today and in the future is a real problem all over the world; nowhere is this truer than in rural Kenya.  Farmers in Kenya have long relied on traditional, wood-based fuels or kerosene for their main energy needs (cooking, heating water and lighting).  Solar lights are helping address the need for lighting but, as deforestation and increasing demand raise the price of firewood and charcoal, it is becoming ever harder to secure the fuel needed to cook even basic meals.

Fortunately, most farmers have the answer to this problem on their very own farms. Farmers who own cows, pigs and chickens can collect the waste from these animals, and, by loading it daily into a biogas system, can generate all the biogas they need, not just for cooking, but also to heat their homes, heat water, power a lamp and even run farm equipment.  Additionally – the system also produces a biofertilizer that has more than doubled crop yield for some Takamoto Biogas clients.

By installing a biogas system, the farmer produces two very important products: biogas to replace unreliable, unhealthy and expensive fuels, and biofertilizer to increase their crop yield. With these needs attended to, a farmer can look beyond the daily needs of his farm and plan for a better future for his family and community.

So how does this work?

The biogas digester is a specially designed reactor which contains bacteria that process SUBSTRATE into BIOGAS and DIGESTATE; this DIGESTATE is a nutritious FERTILIZER.

SUBSTRATE: Organic wastes such as human feces, cow dung, vegetable scraps, greases and green waste…really anything that can rot can be used to produce biogas. The waste is mixed with water and loaded into an anaerobic digester. The digester maintains an oxygen-free environment suitable for methane-producing single celled organisms metabolize proteins, lipids and carbohydrates in the waste into biogas.

BIOGASThe biogas is approximately 65% methane and 35% carbon dioxide and several other gases at low concentrations. The anaerobic digester collects the biogas as it bubbles to the surface.

DIGESTATEAfter the bacteria have consumed the energy from the waste there are still leftover solids. This digestate contains less pathogenic bacteria than the original substrate. The digestate can be used as an organic agricultural fertilizer.

FERTILIZER: Organic fertilizer from digestate also contains more micronutrients than chemical fertilizer, which will replenish the soil for long lasting soil fertility.  It can be used to increase production of cattle feed, creating a virtuous cycle that improves biogas output and farm productivity.

The virtuous biogas cycle

Virtuous Biogas Cycle