CLEAN ENERGY LESSON FROM MY UNCLE – MY BIOGAS EXPERIENCE
I was only about 5 years old when I first encountered an alternative source of energy. It was during the December holiday and my family had visited an uncle who lived upcountry. My uncle is a farmer. It is from him I acquired my first farming lesson. He is very passionate about all things ‘farm’ and as a result, has perfected farming. Having been born and raised in a small town in the semi-arid areas of Kenya’s Eastern province, we were used to an urban kind of life. So for my siblings and I, a visit to the countryside felt like going for a cruise in the Royal Caribbean.
On this particular holiday, I was introduced to biogas. Although I was too young to absorb everything, I remember thinking to myself how interesting it was. It was almost fictitious. I couldn’t believe how something as ‘disgusting’ as waste from his animals sheds, left over foods and the excess weeds and grass from his farm could be praised so much and regarded with so much importance.
Uncle used biogas as an alternative source of energy for lighting and cooking. He would also collect high quality organic fertilizer for use in the farm. How clever!
These fond memories have spurred me to take a closer look at biogas from a different perspective…
What is biogas?
Biogas is the name given to the mixture of gases generated by the biodegradation of organic substances under anaerobic conditions of which the main component is methane ch4.
Looking at direct and indirect benefits of biogas;
- Eliminating animal waste frequently prevents diseases and ensures animals remain healthy.
- Long term improvement in the financial situations of households by reducing fuel and chemical fertilizer expenses.
- Improvement of soil fertility and reduction of soil degradation by use of organic fertilizers.
- Reduction of pollution caused by chemical fertilizers.
- Reduced workload as no fuel gathering is required and also in cleaning pots and pans covered in soot.
- Reduction in CO2 emission and reduce deforestation pressure by substituting fossil fuels with biogas.
A biogas plant is a working process;
- The mixing tank- Tank M
This is where materials are fed in; Organic input materials such as foodstuff remnant, fats or sludge, manure and dung, weeds, grass or trimmed branches from the farm and water are used as feed. This tank is built on the surface and connects to the digester through an inlet pipe (I)
- Digester Tank – Tank T
The content from the mixing tank if transferred into the digester (T) and a chemical (biochemical) reaction takes place. This is where digestion/fermentation takes place. The tank is heated to approximately 38-40oC, the substance is decomposed by microorganisms under exclusion of light and oxygen.
After fermentation, the mixed liquor (W) is transported via pipe O to the fermentation residues storage tank/ overflow tank (F) awaiting further utilization.
The residues can be utilized as high quality fertilizer on the farms. You can also dry it for use as dry fertilizer.
- Floating gas holder H
A renewable fuel (biogas) is created from the digestion process in tank T. The biogas generated is stored in the roof of the digestion tank and from there it is burned in the combined heat and power plant (CHP) to generate electricity and heat. This electricity can be fed directly into the power grid. The heat generated can be used to heat buildings, dry wood, etc.
Processing of biogas to make pure methane (natural gas) can be done for added value like supply to the national grid or gas filling stations.
Many years have gone by, and am still fascinated at how waste could be so important. At how something many consider as filth, dirt and disgusting could be used to make energy, fuel, useful products and profit!
When I started working at Eenovators Limited where we advocate for energy management and clean energy initiatives in this dear planet of ours, I then understood. People like my uncle, who prefer clean and renewable energy sources rather than burning fossil fuels, not only save some coins while enjoying many benefits, but also contribute a lot to conserving the environment. If all of us would avoid excessive use of fossil fuels and manage energy efficiently both at our workplaces and homes…maybe turn to biogas like my uncle or embrace solar and other renewable energy solutions like many of us are already doing, then we make the world a better place for all of us and generations to come.
Written by Karen Thuranira
Communications and Business Development Assistant at Eenovators Limited