I am back from a month in Kenya. I arrived in the UK worn out, dusty, dirty, smelly (after a 9 hour trip on an old bus then straight onto a plane) and hungry.
At home, a shower, a meal, a cup of tea (strong, little milk and sugar, rather than Kenyan-style), and I could sit back and figure out what has been achieved on this trip.
Our biggest achievement was to build an anaerobic digester. We didn’t follow any of my designs as funds were limited and a “proper” system would have cleared out my wallet long before I was due to come back. So we compromised. We scoured the markets of Kisii for plumbing connections and fittings, eventually finding enough bits and pieces that actually fitted together to make the first build.
After a bit of negotiation (bartering) we acquired a 45 gallon oil drum, fitted all the bits and pieces and filled it with cow slurry and waited. A digester usually takes about a week to start producing gas.
But we were impatient, so a couple of days later, we opened the tap. The smell that came out of the tap was awful – as you can well imagine – and it didn’t burn. We purged all the gas out and hoped that any gas that wasn’t methane had been expelled.
Another two days passed and we tried again. This time, we attached the Calor burner from home to the pipe and lo!, we had a flame, not very strong, not very hot, but it was a flame.
This was cause for celebration as we were to travel to Bungoma the following day to meet people from an organisation looking for ways to use the nuisance weed, water hyacinth. Would it make methane? Yes, it will.
Following our initial success, we bought a Calor table-top stove, modified the air intakes and connected it up to the digester. After a little purging, we got a pretty blue flame. We had to take off the diffusers, but we had a proper flame, nice and blue and hot. We boiled water on it, then we ran out of gas.
The fundamental flaw with our “modified” design is that the feed stock and gas are stored in the same container. So, as gas is produced, it builds up pressure, compressing the feed stock until it cannot release more gas. So, we need a second container for storage. I knew this and there is provision to add one at a later date, when funds permit.
In the meantime, we opened the digester and stirred the feed stock. It was like porridge. So we added a couple of litres of water. We got a better, longer flow of gas, but we were still hampered by the fact that there was very little space in the top of the barrel to store gas.
However, the exercise was to produce a flammable gas for cooking and we have achieved that. The addition of a storage tank and a header tank to keep the gas under pressure will be a vast improvement and will allow us to store 45 gallons of gas under pressure, which should be enough to cook a meal for several people, but proof will have to wait until my next trip and the funds to buy a second drum and a few other bits.