Turn lawn shavings, food compost and animal manure into sustainable energy using a homemade biogas generator.
You can produce your own natural gas using organic materials normally considered to be household waste. This “biogas” can be used to cook food, light rooms, and heat water. Additionally, it can fuel an absorption cooling system or an engine (such as a chiller or gas refrigerator), replacing the need for fossil-based natural gases.
What is Biogas
Biogas is a combination of flammable gases (mainly methane) and carbon dioxide. It is obtained wherever organic elements break down without the presence of oxygen through a process called anaerobic digestion.
Inside a homemade biogas digester, bacteria that can live in an atmosphere without oxygen dissolves organic components into carbon dioxide, methane and sludge. It begins with acid-producing bacteria decomposing the raw waste into primary fatty acids. A next, methane-producing bacterium absorbs the acids, which in turns produces biogas.
Almost any mixture of discarded food, vegetables, livestock manure, grass shavings, slaughterhouse waste, meat and fats will be sufficient to use, as long that combination is comprised of the proper nitrogen and carbon ratio.
To put it simply, if it can be composted, it can be digested. Preferred biogas components include materials you use regularly, and won’t run out of. Whatever that material is will match the quantity of biogas you produce.(Photo credit: SuSanA Secretariat at flickr cc)
Creating Your Own Biogas Digester
It is very easy to make your own biogas digester, and it takes almost no time at all to make a small one. Most of the ingredients required are likely to be already inside your household. You’ll begin with two small containers in front of you.
• The biogas digester is the unit system where the human, animal or other organic waste is brought in, generally doused in water, so it can decompose anaerobically. We will simply add it to the biodegradable waste.
• A storage canister will contain the gas formed, from which it is siphoned to burn as fuel.
A biogas digester should consist of food scraps (feedstock), water, bacteria (from manure) and a small amount of oxygen (inside of an enclosed container). You will generate biogas if you have each one of these components at room temperature.
How Much Energy You Can Produce
With a homemade biogas generator, you can create enough fuel necessary to cook your food.
Assembled properly, a methane digester can create its own volume of biogas on a daily basis, give or take. 10% to 60% of the waste will transform into biogas during assimilation, so you can anticipate between 3 to 18 cubic feet of biogas energy to be produced for each pound of dry substances used.
A small amount of waste can be used to produce biogas using animal, human and kitchen waste. As a rule of thumb:
• Gas lights require approximately 0.1 m3 (100l) per hour.
• A couple of gas rings to be used for 2 hours per day will require between 1-2 m³.
Advantages and Disadvantages of Home Biogas Systems
• Recycles waste.
• You can generate fuel by combining animal waste and sewage mud.
• You can prevent methane emissions and runoff while producing organic fuel.
• Sanitary and a structured supply of sustainable energy.
• Devours methane, a strong greenhouse gas.
• Decreases pathogen (disease agent) amounts in the waste.
• Residue contributes useful natural fertilizer.
• Easy to assemble and maintain.
• Minimal operation required.
• Can be used to heat, cook, light, as well as power fridges and gas-operated engines efficiently.
• No odor (assuming there is no leak in the unit, and if there is, it should be repaired immediately).
• Best used at the source of the waste material, as the energy required to condense the gas for transfer (or turn it into electricity) is exorbitant, and therefore, decreases the effectiveness of biogas energy generation.
• For safety reasons, primary cautions (see below) must be followed.
Much like other energy systems, methane is safe, as long as the dangers are understood, and precautions are adhered to.
Explosion or Fire Risk
Because methane is flammable, it can be explosive. Be mindful of the following:
• To avoid the build-up of trapped gases, the area surrounding the methane generator digester requires proper ventilation.
• In the area of a digester, no radical flames can be released. Additionally, iron and steel tools (or related power tools) must be kept a safe distance away for explosion prevention purposes. Further, electrical equipment used around the area must be of acceptable quality.
Risk of Asphyxiation
Biogas forces out air, decreasing the oxygen level. As such, all digester areas must be properly ventilated.
While the waste used for biogas generation has likely already lost its pathogens, it may still produce microbial activity during the production process!
Therefore, avoid contact with the contents of the digester contents, and sanitize thoroughly after working in the vicinity of the methane generator (particularly prior to drinking or eating or drinking).