Backyard Methane Biogas: Building a DIY Anaerobic Digester
Many homeowners choose to pay local companies to supply gas (either natural gas or propane) for heating and cooking. Some people may not know that methane is actually the primary component of natural gas. Commercial natural gas is largely harvested from oil fields and natural gas fields. There are, however, alternative ways to produce methane (biogas) for personal use. Anaerobic digestion is a process in which biowaste is combined with bacterial culture in a low-oxygen environment to produce useful byproducts (like fuel and fertilizer). In order for methane biogas to be produced, there are a few necessary microorganism-catalyzed reactions that must occur. The sequence is as follows:
- Hydrolysis -- A chemical reaction where particulates are solubilized and large polymers are converted into simpler monomers
- Acidogenesis -- A biological reaction where simple monomers are converted into volatile fatty acids
- Acetogenesis -- A biological reaction where volatile fatty acids are converted into acetic acid, carbon dioxide, and hydrogen
- Methanogenesis -- A biological reaction where acetates are converted into methane and carbon dioxide, while hydrogen is consumed
(Source: Wikipedia)
As Jason Fields from The Urban Farming Guys says in the video below, a great way to seed a new anaerobic digestion reaction is to start with cow manure. The guts of the Bos taurus subspecies contain a great microorganism flora to serve as a starter culture for anaerobic digestion. A DIY bioreactor can be as simple or as complex as one desires. One of the great features of DIY anaerobic digestion is scalability. A bioreactor can be built on a very small-scale to provide supplemental energy for a single household or a very large system can be made to provide for a cluster of households. Since the system utilizes biowaste, reactor materials can often be purchased at very low prices (or given away for free) from local businesses and restaurants.
For people interested in having a little more control over their own energy, starting a DIY biogas anaerobic digester could be one way to achieve another degree of independence — and serve as a baby step toward living completely off-the-grid.
Tagged in: agriculture, alternative energy, sustainability, urban agriculture
