Biogas : A Clean Energy Alternative
Deteriorating
quality of life in urban hubs of India, especially in cities like Delhi,
shackles our overall growth potential. “Delhi wakes up to air 5 times worse
than safe standard”, was reported by Times of India on the Christmas this year.
Delhi has been ranked the most polluted city in the World. The cases of paddy
straw burning in Punjab and Haryana during paddy harvesting season, further
deteriorate the air quality in Delhi and northern part of India. This burning
increases pollution level many folds. NASA has been alerting about the same
since last few years. This alarming raise in air pollution is a grave health
concern for us all, forcing the government to take drastic steps like
‘Odd-Even’ scheme in Delhi.
Furthermore, our huge import bill for
petroleum is a constant drain on our forex reserves. The world is now looking
to green energy technologies for the future. Renewable energy is an excellent
solution for this problem. Our mother nature is full of miracles and has very
simple solution for such big problems like Renewable Natural Gas (RNG) or
Biogas.
Biogas is produced from anaerobic digestion
(without oxygen) of any organic material. Generally, biogas consists of methane
(50–70%), carbon dioxide (30–45%), traces of water vapor and hydrogen sulfide
(H2S). Biogas can be utilized for cooking, lighting, power
generation and automotive fuel. For automotive fuel application, raw biogas
needs to be upgraded to natural gas quality. This means carbon dioxide (CO2), hydrogen sulphide (H2S),
ammonia, particles and water (and
sometimes other trace compounds)have to be removed so that the product gas has
a methane content of more than 90% by volume.This upgraded gas is generally
referred to as Biomethane. This
upgraded gas or Biomethane is bottled at pressure of 200 bar, referred as Bio– CNG. The
Bureau of Indian Standards had already issued a standard for Biomethane to be
utilized for transport application
Biogas
production from various available biomass resources, is a viable option for our
country as it is environment friendly, clean, cheap and versatile fuel.
Harnessing such a resource will promote rural industries, agriculture, dairy
and animal farming in a sustainable way. Also it will help regulate environmental
cycles effectively as nutrients such as nitrogen, phosphorus and potassium are
conserved in the process in the slurry and can be returned to the soil.
Digested slurry is also a good source for several micronutrients like zinc,
iron, manganese and copper. It has been
observed that use of slurry
as fertilizer has many advantages as compared to farm yard manure. Weed seeds in the substrates are
destroyed completely during the digestion process and is richer in nutrients compared to farm
yard manure.
India has
the largest cattle population in the world. The cows and buffaloes stand at
29.96 crore, and contributes 58.5% of total livestock population in the
country. Biogas Development and Training Centre, research team at IIT
Delhi estimated the total
biogas generation potential in India is nearly 50,000 million cubic metre annually. This calculation includes biogas from dairy farms, municipal solid
waste, crop residue and agricultural waste, vegetable market, food waste,
community toilets, wastewater sludge, industrial waste (including
distilleries), dairy plants, pulp and paper, poultry ,slaughter houses, sugar
industries (excluding wastewater). This estimate is equivalent to 30,000 million
cubic metre per year of upgraded biogas which can be utilized as Bio – CNG for
vehicles. The upgraded and bottled biogas can be utilised as a vehicle fuel or
as a cooking fuel substituting CNG. This amount of upgraded biogas can replace
86.8% of petroleum fuel used in transportation and 83.4% petroleum fuel in
cooking sector.
The
National Capital Region itself has potential to produce nearly 800 million
cubic metre of biogas per year from its own available bio–waste resources, i.e.
cattle dung, slaughter waste, sewage treatment plant waste, municipal solid
wastes, vegetable fruit market waste, food leftover and kitchen waste etc.
This quantity of
biogas if upgraded to Bio – CNG quality, can produce nearly 350 million kg of
CNG per year, which can run more than 5,000 buses and 2 lakh cars.
At present
Delhi NCR alone has more than 8 lakh CNG vehicles and 325 CNG gas stations. Bio
– CNG can easily be implemented as a transport fuel with this infrastructure.
Small sewage treatment plants installed at housing clusters across the city
will provide a potential source for replacing CNG in vehicles for local
transportation in various cities.
The Biogas
Development and Training Centre (BDTC) at IIT Delhi is supported by Ministry of
New and Renewable Energy (MNRE), Govt. of India under National
Biogas and Manure Management
Programme (NBMMP) for providing
technical training and publicity support for quality implementation of biogas
programmes. At IIT Delhi a passenger car testing on Bio
– CNG is going on. This vehicle has already
covered 40,000 km run on upgraded biogas and exhaust emissions were found lower
than petrol/diesel and similar to CNG. Also, existing CNG vehicles need not to
undergo any modification and are to be compatible to Bio CNG. The water scrubbing based
biogas upgradation and compression/ bottling
system developed at IIT Delhi is now patented.
This technology promises a green and low
cost fuel for automobiles and various thermal
applications. Thus, biogas has a potential in India towards achieving energy sustainability
using locally available organic wastes,
which may also help
in reducing greenhouse emissions and supplying
good quality bio-fertilizer for farmers.
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