Biogas is a gas produced by anaerobic digestion (in the absence of oxygen) of organic material, largely comprised of methane (about two-thirds). Biogas is often called "marsh gas" or "swamp gas" because it is produced by the same anaerobic processes that occur during the underwater decomposition of organic material in wetlands.

A biodigester is a tank that processes the organic material that produces biogas. A biodigester can come in different shapes and sizes, depending on the needs of the people using it and the local possibilities in building materials.

In theory, any organic material can be decomposed anaerobically to produce biogas, but some materials work better than others. In general, materials need to be rich in energy and easily digestible. Manure works very well, coming from cows, pigs, or horses. Biodigesters can be fashioned from septic tanks, but the waste production is often not enough to produce enough biogas, and cleaning agents (bleach etc.) kill the anaerobic bacteria necessary for digestion. Plant material can be used, but acidic matter should be avoided, for they disturb the anaerobic processes. Plant matter is also often low-energy and slow to digest, creating a number of difficulties for digesters relying solely on such material.

This is probably THE MOST frequently asked question, and is the most difficult to answer for the following reasons:

• Biogas production is best measured by scientific processes not common in rural areas.
• Biogas production varies with the type of material you use to feed the biodigester.
• Biogas production varies with the temperature of the mixture inside the tank.
• Biogas production varies with the acidity or alkalinity of the mixture inside the tank.
• Other factors, such as defects in manufacturing, leakages in pipeline, leakages in biogas domes, biogas storage balloon, leakages in biogas handling equipments (blower or pressurizing unit),can make true measurements of biogas production very difficult.

Yes, There are many different styles of biodigesters.

Tropical climates generally have no problems with temperature because the anaerobic bacteria thrive in higher temperatures. If you live in a more temperate climate, you may need to heat the digester during colder months. The ideal temperature for the mesophilic bacteria is 38°C.

There are a number of things that can affect the biogas production in a biodigester.

•Biogas leaks
If there is very little biogas, there may be a leak somewhere. The biogas balloon and biogas pipeline should be checked for leakage. A simple soap solution can be used to detect the leakage.

•Temperature problems
As stated before, if temperatures reach below 20°C, you will experience a drastic decrease in biogas production. If this is the case, look to adapt a heating system to your biodigester.

•Problems with the biodigester's pH
The pH in the biodigester tank should be as close to neutral (7) as possible. Since the anaerobic processes in a biodigester produce acids, the most common pH problem is one of acidity. If you do a simple litmus test on the biodigester's contents and the result is below 7, you should add a small amount of lime or grounded lime stone to normalize the tank's pH. Since excessive amounts of lime will not be soluble in the mixture and may harm the bacteria, you should never exceed a lime concentration of 500mg for every litre of mixture in the biodigester tank.

•Other problems
There are a number of other problems that can arise during the life of a biodigester. To investigate problems, it is best to think back to the basics of what makes a biodigester work (organic material, strong seals, warmth) and eliminate anything else that could possibly harm its functioning. For example be careful not to introduce unnecessary chemicals into the tank, and try not to use livestock that has recently been given antibiotics or other medications, for these chemicals present in the manure may cause damage to the bacteria in the biodigester tank. Also, make sure to use non-corrosive materials for handling the gas and water. Cement and plastic cause no harm to the mixture in the tank, but metals should be avoided for use in the tank, or any of the tubing through which the biogas travels.

If Biogas doesn’t fill inside the biogas balloon please check the biogas outlet from the biodigester and the pipeline which connects the biogas balloon and the biodigester. If there is enough pressure to break the water column inside the gas fluid separation chamber then gas can easily escape from the chamber and will not be filled in the biogas balloon.

The digested material that comes out of the biodigester is a liquid material with little amount of solids in it eventually forced out as more undigested material enters the tank. This liquid can be used as a convenient growth stimulant for nearby plants.

The installation period totally depends on the size of the biogas plant to be installed and for plants of 1000 kgs per day and above will generally take 45-60 days of installation period. Whereas we have smaller plants which are fabricated at our fabrication unit and the installation period will be less than a day.

These details will be completely informed by us to the client as this will be the key part of the project and although there are thumb rules available by which anyone can understand these parameters but based on our experience in this field we can get much more gas than the standard parameters available in the text books.

Naked flames should not be allowed at the project site when the plant is in running condition.

Biogas can be used either directly for thermal application or electricity generation or after upgradation as vehicular fuel or for thermal and electrical application.

Theoretically there is no limit for the storage but in practice it is advisable to have a storage capacity that can take care of around 12 hrs of biogas generation.

IBA provides the traning for O & M with our regional partners. Quarterly, a workshop is also arranged esp. to educate the operators from day to day problems. We are also planning to offer a diploma courses with the help of IIT.

MNRE has listed the recommended consultants on their website. IBA can also help to find a suitable consultant based on your need on non-profit basis.

The biogas yield from waste varies greatly dependant on the type and quality of waste, digester technology and the correct operation of the facility

Biogas with a methane content of 60% will have an energy content of around 4-6kWh /m3. If utilised for electric generation, 2kWh of useable electric is produced with the remainder turning into heat energy. The energy content can be increased considerably by upgrading the biogas to Bio-CNG or Bio-Methane, removing the CO2, providing a gas of suitable quality for injection into the national gas grid or for use as a transport fuel.

Methane has a greenhouse gas (GHG) factor 21 times greater than CO2. Capturing methane from any substrate (example- waste), which would otherwise be emitted to atmosphere, and utilizing it for other purposes will obviously reduce the GHG impact. Biogas energy is considered to be carbon neutral since carbon emitted by its combustion comes from organic matter that fixed the carbon from atmospheric CO2. Additionally utilising biogas will replace fossil fuels, a main contributor to GHG

Bio – Methane or Bio - CNG means pipeline-quality gas derived from organic material. It is identical in properties to natural gas, but it is not derived from fossil fuels. Bio – methane/ Bio - CNG can be produced from biogas which has been cleaned or “upgraded” to meet natural gas pipeline specifications, by the removal of gases such as CO2 and hydrogen sulphide to leave an almost pure (90 - 98%) methane gas. Bio – methane/ Bio - CNG can be injected into the gas network or compressed for use in natural gas vehicles. Once in the gas network, it can be used in exactly the same way as natural gas (which is a fossil fuel).It can provide domestic or commercial cooking and heating, or be used as vehicle fuel in locations remote from the source of the gas. Bio – methane/ Bio - CNG injection offers increased scope to maximise the energy contained in biogas by moving it to where it is needed.

Yes, you can visit the working plant to see and understand how a biogas plant works, please contact/visit our website to understand more on this topic

Please visit our website and take a personal appointment to understand more on the same topic or if you want some more information on Biogas.