From Poop to Fuel

Falling in Love with Daisy

It has taken three months to get to know and understand Daisy, my name for the 2.45M3, fixed-dome biogas digester, which I financed and built on my property as a model or proof of concept for TRL's bio-gas digester project.

Only after late December, 2024, when we finally had our low-flush toilet connected to the digester, could we truly begin to learn from experience how to balance the components of successful biogas production. For the small size of the digester, it takes 2.5 gallons of fresh cow manure added every other day, the humanure of three residents and occasional guests entering from the 3L flush toilet, plus green kitchen scraps ground in a garbage disposal system, to produce methane gas for approximately 2.5 hours a day. Adding more manure would produce more gas.

The gas available in the morning lasts approximately 1+ hour. It is constantly replenished, so that within a short time one can have gas available again to heat a tea kettle or some task requiring less time. By dinner time, there is enough gas again to cook your food.

The process also requires that the user remove approximately the same amount of liquid digestate from the compensation tank as one puts into the system, on a daily or every other day basis. Eventually, we will need to remove solid matter collected on the bottom of the tank, via a special outlet pipe.

The digestate (liquid fertilizer) gives spectacular results -- use it for milpas, coffee and avocado groves, citrus and banana trees, berries, flower gardens or vegetables. Roses love it! The plants respond with rapid growth and remain hardy, sturdy and productive.

Now that we understand all that is involved in achieving success with a fixed-dome biogas digester, we can begin to find the proper placement for our large demonstration model in the community. It must be a situation where there is abundant manure to be disposed of in order to feed the digester.The system is not for the faint of heart. It demands constant participation to glean the benefits and requires an owner who desires a free source of cooking fuel and fertilizer.

For me, Daisy is all that I had hoped to achieve in a home-sized, Chinese fixed-dome, biogas digester.  We've got free cooking gas and fertilizer, while keeping fecal matter out of Lake Atitlan by processing it in a closed-cycle biogas- producing digester. I’ve fallen head over heels in love with Daisy!