One of the main reasons for building our tiny house was to be fully off the grid and to only use renewable energies. The solar panels on our roof have been working a treat already since they ran all our power tools during the build. We’re so happy with how they and our battery bank perform. Now the panels will power our kitchen appliances as well as electronic devices.
Be prepared for overcast days
But we don’t want to rely only on solar power. We live in a very sunny place but from time to time we still get overcast and cloudy days. On those days we have to watch our electricity usage and make sure that we don’t discharge our batteries below a certain percentage. That’s why we added a small biogas unit to the mix. The biogas will run our gas cooktop in the evenings or on overcast days.
How does the biogas digester work?
Essentially, the biogas digester mimics a cows’ stomach. We feed the unit daily with organic waste and eventually get biogas in return. Easy! But how does it work?
The main part of the digester is a big tank. This tank is filled with water, so the food scraps are completely submerged. Bacteria in the water eat or digest the organic waste (hence the name) and produce biogas. This is called anaerobic digestion. The biogas is directed into a second tank where it is stored. The “gas tank” is connected to the gas cooktop in the kitchen via a gas pipe.
Before we can produce biogas though we have to “activate” the biogas digester by adding animal manure to it. After a few weeks, the bacteria in the water should produce gas. As we feed the digester tank with more organic waste every day, the tank releases water. This water is very nutritious and can be used as a liquid fertilizer for the garden. Double win!
Another thing to keep an eye on is the temperature of the unit. We placed the biogas digester in a sunny spot because the temperature can’t fall below 25 C degrees. In winter we will probably insulate it to ensure that the digester stays warm.
Clean biogas for us
I’m sure there are a few different biogas systems out there suitable for a normal household. We went for the Home biogas system. So far we’re happy with it but we’re also still in the “activate” phase of our biogas production. It will be very interesting to see how the system performs. We’re very excited about producing our own clean cooking gas and can’t wait to use it.