biogas plant design in pakistan
BIOGAS TECHNOLOGY – EXPERIENCE OF PCRET
DOWNLOAD pdf
Introduction
Biogas plants could be broadly classified into three types:
Plants with moveable gasholder
Plant with built-in fixed dome gasholder
Low cost bag / balloon type plant
PCRET has installed all the three types of biogas plants on experimental basis in a quest of
selecting an appropriate design that could suite the socio-cultural norms & skill level of the rural
masses. A brief history is given below:
Pakistan Council of Appropriate Technology (PCAT), now PCRET undertook propagation of
Biogas Technology (BT) in the mid of 1976 and 21 fixed dome (Chinese type) biogas plants
were installed in order to assess the workability of Chinese design. These plants did not work
due to leakage of gas from the hairline cracks developed in the domes / gasholder. Thus Chinese
design could not get ground due to lack of the experience and for want of proper technical skill
required for construction of leak proof biogas plant.
Henceforth, Indian design (Moveable gasholder) was adopted with certain modification and for
the first time, in the year 1979, 10-biogas plants were installed in Distt. Mirpur, Kotali and
Rawalakot (AJK) in collaboration with Local Government and Rural Development (AJK). These
plants worked satisfactorily. The first biogas plant installed by this Council is reported to be still
functional.
Encouraged by the performance of biogas plant installed in AJK, 100-biogas plants were
installed through out the country in the year 1980 under a PSDP project. These plants worked
satisfactorily. As a result a number of Provincial Departments started installation of biogas plants
in the country with technical assistance of PCAT. About 350-biogas plants were installed by this
Council upto 1983 in collaboration with Provincial Government Departments.
In the mean time, Directorate General of New and Renewable Energy Resources (DGNRER),
got mandate for mass scale installation of biogas plants in the country, and the activities of
PCAT were curtailed to R&D and installation of pilot plants only.
DGNRER installed about 4000 biogas plants under a PSDP project upto 1986. However, due to
lack of technical know how and poor field experience, they could not implement this project
properly. The implementation methodology was not well devised, particularly involvement of
the contractors devastated the things and as a result most of the plants failed to work. It causes
a great set-back to the technology.
PCRET, however, continued R&D activities for development and promotion of Biogas
Technology (B.T), as summarized below:
o Community size biogas plants based on poultry dropping were designed and
installed at poultry farms in Karachi for meeting cooking needs, besides
generation of electricity.
o A portable type biogas plant consisting of metallic Digester and Rubber tube
Gasholder was developed for a private entrepreneur at Karachi with a view to
promote this technology as a commercial product / activity. However it could not
be adopted as commercial activity.
o A bag type, low cost biogas plant made of low density polyethylene was also
design and installed for field testing. It was observed that high density
polyethylene or some other composite material having good elasticity and pierce
strength is required for a sustainable bag type biogas plant.
o R&D studies on integrated biogas generation system were conducted in
collaboration with PCSIR labs. Lahore and Karachi. Different substrates were
used in combination and in different composition, so as to develop appropriate
composition and evolve optimum parameters for better functioning of biogas
plants.
In the year 1993, the functions of DGNRER, particularly, “Dissemination of Biogas
Technology” was again entrusted to PCAT (Now PCRET). Henceforth, this Council re-started
revival and promotion of biogas technology in the country. After concerted and dedicated efforts,
50-biogas plants were installed in the out-skirts of Islamabad / Rawalpindi in collaboration with
and financial suppot of an NGO, “Initiative for Rural and Sustainable Development (IRSD) for
demonstration purpose. Efficient performance of these biogas plants helped removing skepticism
of the stake holders about biogas technology.
Consequently, a project (PC-1) was approved in June 2002 at a cost of Rs.22.02 million for
installation of 1200 biogas plants in a period of 4 years. This project was completed well in time
and 1600 biogas plants were installed vis-à-vis target of 1200 plants, upto June 2006. Under an
other PSDP project commencing from June, 2007, this Council has to install 2500 biogas plants
in a period of two years (ending June 2009) on 50% cost sharing bases.
PCRET has standardized two family size models of biogas plants; 3M3 and 5M3 daily gas
production capacity. As per demand of the beneficiaries mostly 5M3 biogas plants are being
installed. The total cost of 5M3 biogas plant including appliances is Rs.35000/=. As such the cost
per cubic meter of gas production comes to be Rs.7000/=, viz-a-viz Rs.14666/= of fix dome
biogas plants installed by RSPN.
Both the movable gasholder type biogas plant and fixed dome type biogas plant have their
advantages and disadvantages as given below:
Advantages
Moveable Gasholder
• Gas pressure is regulated by the weight of the
gasholder.
• Gasholder helps in stirring / scum breaking
• Easy to construct, (can be constructed in a week
time) easy to repair.
• Due to black painted metallic gasholder, the
green house cover works effectively, to raise
temperature in the top layer of slurry in
winter season.
• Easy disposal of exhaust slurry due to gravity
flow
Fixed dome gasholder
• Since it is underground, the plant space can be utilized.
• Fairly steady temperature can be maintained inside the digester.
• Post installation maintenance like painting, plastering is seldom needed.
Disadvantages
Moveable Gasholder
• Metallic gasholder is exposed to the
atmosphere and causes heat losses.
• As it dips in the slurry anti corrosion
treatment is required.
• Periodical painting of gasholder is required
to avoid rusting.
Fixed dome gasholder
• Construction needs special skills.
Stirring and scum breaking is generally
difficult.
Gas pressure control is difficult.
Leakage of gas from hairline crack developed
in the dome.
Leakage of gas from sides of manhole cover.
A good quantity of gas produced in the slurry
displacement chamber is not captured /
utilized and is emitted in the air.
Exhaust slurry is to be taken out manually.
BIOGAS TECHNOLOGY – EXPERIENCE OF PCRET
DOWNLOAD pdf
Introduction
Biogas plants could be broadly classified into three types:
Plants with moveable gasholder
Plant with built-in fixed dome gasholder
Low cost bag / balloon type plant
PCRET has installed all the three types of biogas plants on experimental basis in a quest of
selecting an appropriate design that could suite the socio-cultural norms & skill level of the rural
masses. A brief history is given below:
Pakistan Council of Appropriate Technology (PCAT), now PCRET undertook propagation of
Biogas Technology (BT) in the mid of 1976 and 21 fixed dome (Chinese type) biogas plants
were installed in order to assess the workability of Chinese design. These plants did not work
due to leakage of gas from the hairline cracks developed in the domes / gasholder. Thus Chinese
design could not get ground due to lack of the experience and for want of proper technical skill
required for construction of leak proof biogas plant.
Henceforth, Indian design (Moveable gasholder) was adopted with certain modification and for
the first time, in the year 1979, 10-biogas plants were installed in Distt. Mirpur, Kotali and
Rawalakot (AJK) in collaboration with Local Government and Rural Development (AJK). These
plants worked satisfactorily. The first biogas plant installed by this Council is reported to be still
functional.
Encouraged by the performance of biogas plant installed in AJK, 100-biogas plants were
installed through out the country in the year 1980 under a PSDP project. These plants worked
satisfactorily. As a result a number of Provincial Departments started installation of biogas plants
in the country with technical assistance of PCAT. About 350-biogas plants were installed by this
Council upto 1983 in collaboration with Provincial Government Departments.
In the mean time, Directorate General of New and Renewable Energy Resources (DGNRER),
got mandate for mass scale installation of biogas plants in the country, and the activities of
PCAT were curtailed to R&D and installation of pilot plants only.
DGNRER installed about 4000 biogas plants under a PSDP project upto 1986. However, due to
lack of technical know how and poor field experience, they could not implement this project
properly. The implementation methodology was not well devised, particularly involvement of
the contractors devastated the things and as a result most of the plants failed to work. It causes
a great set-back to the technology.
PCRET, however, continued R&D activities for development and promotion of Biogas
Technology (B.T), as summarized below:
o Community size biogas plants based on poultry dropping were designed and
installed at poultry farms in Karachi for meeting cooking needs, besides
generation of electricity.
o A portable type biogas plant consisting of metallic Digester and Rubber tube
Gasholder was developed for a private entrepreneur at Karachi with a view to
promote this technology as a commercial product / activity. However it could not
be adopted as commercial activity.
o A bag type, low cost biogas plant made of low density polyethylene was also
design and installed for field testing. It was observed that high density
polyethylene or some other composite material having good elasticity and pierce
strength is required for a sustainable bag type biogas plant.
o R&D studies on integrated biogas generation system were conducted in
collaboration with PCSIR labs. Lahore and Karachi. Different substrates were
used in combination and in different composition, so as to develop appropriate
composition and evolve optimum parameters for better functioning of biogas
plants.
In the year 1993, the functions of DGNRER, particularly, “Dissemination of Biogas
Technology” was again entrusted to PCAT (Now PCRET). Henceforth, this Council re-started
revival and promotion of biogas technology in the country. After concerted and dedicated efforts,
50-biogas plants were installed in the out-skirts of Islamabad / Rawalpindi in collaboration with
and financial suppot of an NGO, “Initiative for Rural and Sustainable Development (IRSD) for
demonstration purpose. Efficient performance of these biogas plants helped removing skepticism
of the stake holders about biogas technology.
Consequently, a project (PC-1) was approved in June 2002 at a cost of Rs.22.02 million for
installation of 1200 biogas plants in a period of 4 years. This project was completed well in time
and 1600 biogas plants were installed vis-à-vis target of 1200 plants, upto June 2006. Under an
other PSDP project commencing from June, 2007, this Council has to install 2500 biogas plants
in a period of two years (ending June 2009) on 50% cost sharing bases.
PCRET has standardized two family size models of biogas plants; 3M3 and 5M3 daily gas
production capacity. As per demand of the beneficiaries mostly 5M3 biogas plants are being
installed. The total cost of 5M3 biogas plant including appliances is Rs.35000/=. As such the cost
per cubic meter of gas production comes to be Rs.7000/=, viz-a-viz Rs.14666/= of fix dome
biogas plants installed by RSPN.
Both the movable gasholder type biogas plant and fixed dome type biogas plant have their
advantages and disadvantages as given below:
Advantages
Moveable Gasholder
• Gas pressure is regulated by the weight of the
gasholder.
• Gasholder helps in stirring / scum breaking
• Easy to construct, (can be constructed in a week
time) easy to repair.
• Due to black painted metallic gasholder, the
green house cover works effectively, to raise
temperature in the top layer of slurry in
winter season.
• Easy disposal of exhaust slurry due to gravity
flow
Fixed dome gasholder
• Since it is underground, the plant space can be utilized.
• Fairly steady temperature can be maintained inside the digester.
• Post installation maintenance like painting, plastering is seldom needed.
Disadvantages
Moveable Gasholder
• Metallic gasholder is exposed to the
atmosphere and causes heat losses.
• As it dips in the slurry anti corrosion
treatment is required.
• Periodical painting of gasholder is required
to avoid rusting.
Fixed dome gasholder
• Construction needs special skills.
Stirring and scum breaking is generally
difficult.
Gas pressure control is difficult.
Leakage of gas from hairline crack developed
in the dome.
Leakage of gas from sides of manhole cover.
A good quantity of gas produced in the slurry
displacement chamber is not captured /
utilized and is emitted in the air.
Exhaust slurry is to be taken out manually.
