How does a biogas plant work

If you feel like experimenting...

Basically, as the bacterias present in the intestine and consequently in the dung of the cattle are the bacterias that will break down the organic material in methane and carbon dioxid, as a consequence, anything that the cattle is able to digest will be producing methane. Maybe are there other bacterias, present in the intestine of other animals, that would be able to digest other types of organic material: let’s think about insects for exemple? it is said that american scientists are experimenting with termites to breack down lignous material in methan. The bacterias develop when the proper feedstock is available, so crushing a few termites in the slurry might increase the methan production with poor calory material.

How to purchase the ARTI compact biogas system? Cost & Payment

Samuchit Enviro-Tech (SET) Pvt. Ltd., a company set up by members of ARTI, is in charge of commercialising the ARTI compact biogas system. ARTI’s trained technicians install the biogas plants using locally available plastic tanks (commonly used for water storage) and a plumbing kit supplied by SET. SET also supplies a single burned biogas stove made of cast iron, and a gas cock. This set, consisting of the plumbing kit and a single burner biogas stove, costs Rs. 2350 (M.R.P. inclusive of taxes and transport anywhere in India). The total estimated cost of the compact biogas system for a typical household (around 1000-1500 lit capacity) is about Rs.10,000, but the actual cost may vary based on local prices of plastic tanks and local labour costs.

Success story

The design and development of this simple, yet powerful technology for the people, has won ARTI the Ashden Award for Sustainable Energy 2006 in the Food Security category. From 2003 onwards, about 1000 compact biogas plants have been so far installed by ARTI's trained personnel – covering both rural as well as urban households in Maharashtra. At least 1000 more plants have been installed by enthusiasts and hobbyists, using the instruction VCD widely produced and distributed by ARTI (http://www.arti-india.org/content/view/50/48/ for more information on our VCDs and booklets). In Maharashtra, several independent producers have copied the design for themselves. These existing plants are a useful advertisement for the advantages of biogas systems and consequently about 30-50 plants are now being installed per month. The authority in Pune has decided it can no longer dispose city waste in a landfill because of lack of space, and local officials are therefore strongly encouraging the use of biogas plants to dispose of food waste. Local council offices have set up demonstration plants, which use local food wastes and provide gas for making tea for local officials and their visitors.

Alternative Designs

A model with 2 (cleaned!)oil drums

(You can check for leaks by using soapy water.)

An improved model with a gas chamber

A large drum model

A small home model

FIRE/EXPLOSION FOR BIOGAS

Methane, which is makes up from 0% to 80% of biogas, forms explosive mixtures in air!

The lower explosive limit being 5% methane and the upper limit 15% methane. Biogas mixtures containing more than 50 % methane are combustible, while lower percentages may support, or fuel, combustion. With this in mind no naked flames should be used in the vicinity of a digester and electrical equipment must be of suitable quality, normally "explosion proof". Other sources of sparks are any iron or steel tools or other items, power tools (particularly comutators and brushes), normal electrical switches, mobile phones and static electricity.

If conducting a flamability test take a small sample well away from the main digester, or incorporate a flame trap in the supply line, which must be of suitable length (minimum 20 m). View sketches of Flametrap1 and Flametrap2, functionning with water levels

As biogas displaces air it reduces the oxygen level, restricting respiration, so any digester area needs to be well ventilated to minimise the risks of fire/explosion and asphyxiation.

Safety For Biogas

Futher, there are important safety rules to consider: Like water, electricity, automobiles and most of life biogas is not completely safe, but by being aware of the dangers involved you are well on the way to a safe and happy digestion experience.

What kind of problems can occure?

A biogas plant can become acidic and fail if it is over-fed, and this is a particular challenge with a plant using highly digestible organic materials. If this happens, the plant can be recovered by ceasing feeding and then building up the feed rate slowly. This problem was more common with the early smaller systems (0.5 or 0.75 m3) than with the later, larger systems.