BIOFUEL - THE FUEL OF THE FUTURE
Biofuel From
Waste
Biofuel also called as agrofuel and is derived from biomass
and may be in solid, liquid or gaseous form. The use of
waste biomass to generate energy can decrease waste
management problems, pollution, greenhouse gaseous emissions
and the use of fossil fuels. There is a huge potential for
bioenergy obtained from waste to decrease the speed of
global warming. As per a recent report, by the year 2020, 19
million tons of oil equivalents could be derived from
biomass. Out of this, 46% is obtained from bio-wastes like
farm waste, agricultural waste, municipal solid waste and
other biodegradable waste streams.
The waste buried in landfill site undergoes anaerobic
digestion and generates gases. The gases so produced are
called landfill gases (LFG). These gases can be burned and
looked up to as a source of renewable energy. The LFG
comprises of almost 50% methane, which is the same gas found
in natural gas. This LFG can be used to generate electricity
for public consumption or can be burned for heat.
If LFG is not used properly, it would add to the atmosphere.
Methane is a greenhouse gas. It has a global warming
potential of 23 relative to carbon dioxide. Thus, one ton of
methane results in the same greenhouse gas as 23 tons of
carbon dioxide. Thus, there are two advantages of harvesting
and burning LFG. Firstly, the global warming potential is
decreased by a factor of 23. Secondly, energy is provided
for heat and power.
A separate waste management strategy is anaerobic digestion.
This decreases the amount of waste sent to landfill to
generate methane or biogas. In anaerobic digestion, any sort
of biomass can be utilized. This waste breaks down and gives
rise to methane. This methane is harvested and burned to
create heat, power or to run some automotive vehicles.
The statistics related to landfill power plants are as
follows: A 3 MW landfill power plant can supply power to
1900 homes. Due to this, it is possible to avoid 6000 tons
of methane per year from entering the atmosphere. 18,000
tons per year of carbon dioxide from fossil fuel replacement
would be eliminated.
First generation biofuels are those that are prepared from
animal fats, vegetable oil, starch and sugar by the use of
conventional technology. The anaerobic digestion of organic
materials by anaerobes gives rise to biogas. This biogas can
be produced from biodegradable waste materials. Digestate is
a solid byproduct that can be used as a fertilizer or a
biofuel. The biogas comprises of methane and this can be
obtained from anaerobic digesters or mechanical biological
treatment systems. LFG is a lesser clean form of biogas.
Thermal depolymerization of waste results in the extraction
of methane and other oils in a manner similar to petroleum.