A better biogas plant for your home
Biogas typically refers to a gas produced by the biological breakdown of organic matter in
the absence of oxygen. Organic waste such as dead plant and animal material, animal feces, and kitchen
waste can be converted into a gaseous fuel called biogas. Biogas originates from biogenic material and is
a type of bio fuel.
The use of waste food instead of dung as feedstock makes this biogas plant distinct and more practical
to use by people in both rural and urban areas
The use of biogas – a mixture of mainly methane and some carbon dioxide – as an alternative to
conventional fuels such as coal and LPG in rural households is not new. However, the size of the plant
and its reliance on large quantities of cattle dung has acted as a dampener for urban households. Also,
because of the dung’s low calorific value, the energy produced per kilogram of dung is low vis-à-vis
waste food. It was this that made Dr Karve decide on replacing the traditional feedstock with waste food
as the input. “It is known that methane gas can be produced from sugar, starch, cellulose and fat, and
one kg of food waste (dry weight) – which contains starch, sugar, protein or fat – yields about 250 gms
of methane. So I decided to replace dung used in a conventional biogas plant with waste food,” says Dr
Karve, who runs Appropriate Rural Technology Institute (ARTI), an NGO. The result was an efficient and
less cumbersome device that can also be used in urban households.
Since 2006, nearly 3,000 such plants have been installed both in India and abroad in rural and urban
households and in commercial establishments such as hostels and hotels.
So why has this biogas plant aroused a lot of interest? There are several reasons behind this.
One, the conventional biogas plant produces 250 gms of biogas from 40 kgs of excreta in 40 days. In
contrast, the new plant requires just 1 kg of sugar or starch – in the form of waste food from household
or hotels, spoilt grain, overripe fruit, non-edible seeds, kitchen waste, etc. – to produce the same
quantity of methane in just 24 hours. According to Dr Karve, through the use of this compact system it
has been demonstrated that using feedstock having higher calorific value increases the efficiency of
Two, the choice of feedstock facilitates its use in urban households. Reliance on cattle excreta has been
one of the major restricting factors limiting its usage in urban homes. Traditional plants require
approximately 40 kg of input on a daily basis, and have a high retention period of 40 days. The large
quantity of input and the longer period require plenty of storage space, which is a major constraint in
plant produces biogas and bio-fertilizers from biological wastes and energy crops by means of oxygen-
free wet fermentation (wet anaerobic digestion). Industrial biogas plant is a construction project which
consists of equipment for 70-80%. Main part is closed reactors (or digesters, methane tanks,
bioreactors) made of reinforced concrete or glass-fused-to-steel tanks.
Liquid biological wastes are pumped to biogas plant by sanitary pump through the pipeline. They initially
come to the primary tank, where they are homogenized and heated (sometimes cooled) to required