WEEK THREE POSTINGS ON 'BIOMASS' - BIOGAS TECHNOLOGY
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1. From: "UCS" <ucs@mail.com.np>
Subject: Welcome to the third week e-conference on RETs
Date: Mon, 3 Dec 2001 12:32:02 +0530
This is the third week (Dec. 3 - 9, 2001) of the conference and it is devoted to biomass, especially biogas and
improved cooking stove. I will be moderating the discussion on biomass with emphasis on 'biogas' in the first half of
this week.
Biogas technology is a sustainable source of energy especially for the rural people. It is one of the most
trusted and popular sources used mostly for cooking and
lighting and slurry as fertilizer. Several countries in the world have produced biogas from animal dung,
night soil and agricultural residue. They are mostly of family sized plants that are used for cooking and lighting. In some
countries, community plants are used for running engines especially for generating power.
Wood and biomass including agricultural residue are important energy sources in developing countries. If these
residues are densified, they can be burnt more efficiently. One of the causes for increased fuel wood uses in the
rural households is the traditional design of the mud stove producing smoke hazard to the users. Improved cooking stoves
are simple and low cost technology that offers multiple benefits to the users.
Despite the difficulties biogas technology has been widely used in developing countries. In some countries like Nepal,
India and China they have been relatively successful.
There are many issues and questions related to biomass particularly biogas.
*How is the development trend of biomass, its end use application and promotional activities? What is the
innovative mechanism to deliver modern energy services to poor communities in the developing countries?
*How biogas can be efficiently and cost effectively used by the rural poor?
*What are the social and environmental impacts of biomass in the surroundings and how can we promote effectively?
*What are the future potentials and prospects of biogas technology?
*What policies need to be in place to give the benefits of biomass to people?
All the participants working in this field are requested to share information and exchange their views in this e-conference. You are requested to send case studies of
your RET projects, uses and economics of biomass, government policies for the development, promotion and
dissemination of RETs, findings of various
research activities. I am sure this will contribute enormously to this discussion.
Govinda Prasad Devkota
Moderator - Week 3 - Biogas
2. From: "UCS" <ucs@mail.com.np>
Subject: [RETs] Week 3: Bio-Briquettes
Date: Mon, 3 Dec 2001 13:56:25 +0530
BIO-BRIQUETTES
Wood and biomass are important sources of energy especially in rural areas of the developing countries
of South Asia and the Pacific Region. These resources
including agricultural residues are being used in increasing quantities to meet the demand of growing
population. If these residues are densified they can be burnt more efficiently.
Briquetting technology was introduced in Nepal in 1982 using rice husk and saw dust as main raw materials.
Pyrolyzing technology was developed in India and relies on partial pyrolysis of rice husk, which is mixed with
molasses as binder and then made into pellets by casting and pressing. Another technology is the direct extrusion,
where rice husk is dried and directly compacted. This technology was imported from Taiwan.
Pyrolyzed briquettes are used by restaurants, school hostels, army and police barracks and so on. However,
both saw dust and rice husk briquettes made by direct extrusion process produce an irritating smoke when
burnt.
The market for briquettes depends on its price compared with price of other sources of energy. The combustion
of briquettes has been found to be less pollutant than charcoal and coal. Because of their high combustion
temperature there is almost complete conversion of briquettes into usable energy, even though there are some
environmental problems concerning the production of these briquettes.
A large potential exists for the briquetting industries and this technology needs to be encouraged as it is used
by majority of the people and can replace traditional
fuelwood and kerosene both domestic and in small scale industries in developing countries especially in the South
Asia and the Pacific region. Hence briquettes should be subsidized by the government and financial institute should
provide loan to briquettes industries. It has also to focus on better energy efficiency. Equally important in view of
the unacceptable high rate of indoor air pollution of traditional device, it will have to improve the emission
rates significantly.
3. From: "UCS" <ucs@mail.com.np>
Subject: [RETs] Week 3: BIOGAS: A sustainable source of energy for rural people in Nepal
Date: Mon, 3 Dec 2001 14:09:03 +0530
BIOGAS: A SUSTAINABLE SOURCE OF ENERGY FOR RURAL PEOPLE IN NEPAL
Biogas is flammable gas produced by microbes when organic material such as cattle dung, agricultural residue,
night soil and various wastes are fermented in a certain range of temperature and moisture contents. Biogas is a
high quality fuel, can be used for cooking, lighting, running dual fuel engines for agro-processing, pumping
water and generating electricity. Similarly the slurry can be used as fertilizer, feeding fish and animals,
mushroom cultivation, earthworm cultivation and so on. Thus the advantages of biogas are good quality fuel and
fertilizer, environmental pollution control, environmental sanitation through toilet attachment and
drudgery reduction.
There are several factors affecting biogas plants of which the major factors are temperature, retention time, air,
bacteria, C: N ratio, pH, gobar water ratio, solid
contents and so on.
There are various designs of biogas plants such as floating steel drum design, fixed dome design and tunnel
design initially developed by Biogas Company in Nepal.
The cost of the plant varies from size to size and from place to place. At present His Majesty's Government of
Nepal is providing a subsidy of Rs 6000 for the plants installed in Terai and Kathmandu valley, Rs 9000 for the
plants installed in the ills and Rs 11, 000 for the plants installed in the remote hills.
The cost for installation of plants varies from one place to another and also from one size to another. The cost of
an 8 cum biogas plant at present is estimated at Rs 27,381 in Hills and Rs 26,741 in the Terai.
It has been assumed that the life of a biogas plant is 25 years, the present purchasing price of firewood and
kerosene is Rs 1.5 per kg and Rs 17 per lit. respectively. Plant nutrient present in the dung is assumed to be N=0.5%,
P=0.25% and K=0.5%.
Similarly the maintenance cost of the plant has been estimated at about Rs 400/year and the plant produces
2.2 cum. of gas per day. The Government provides a subsidy of Rs 9,000 for 8 cum plant installed in the Hills.
Saving and Expenditure
Annual saving
Saving of firewood(6 kg/day at the rate of Rs 1.5/kg)=3240
Saving of kerosene(2.5 lit. /month at the rate of Rs 17/lit.=510
Saving of chemical fertiliser(estimated 17500 kg gobar)=2000
Total saving=5750
Price of NPK saved is based on price of urea, DAP and MoP and 45 percent subsidy in urea, i.e. 20.31/kg of
nitrogen, Rs 15.94/kg phosphorus and Rs 10/kg of potassium.
Annual expenditure
Total investment cost is Rs 27,204
Running cost
Labour cost-15 minutes a day@Rs 70/day=800
Operation and maintenance cost is estimated=400
Miscellaneous cost=100
Total expenditure=1300
Payback period
Payback period is calculated as follows:
Payback period with subsidy=(Total investment cost - subsidy)/ (Annual saving - annual expenditure)
= (27204 - 900)/(5750 - 1300)
= 18204/4450
= 4.1 years
Payback period without subsidy =(Total investment cost)/(Annual saving - annual expenditure)
=(27204)/(5750 - 1300)
=27204/4450
=6.1 years
Thus, when there is no subsidy, it will take 6.1 years to repay the loan whereas with subsidy it will take
only 4.1 years.
It has been felt that other organisations can also play an important role in mobilising the demand for
increasing demand for installation of more biogas plants.
The local NGOs through their networking, could develop awareness conducting workshops/seminars/meetings and
through extension and promotion of the technology.
However, the quality of biogas plant is a major concern for its commercialization. In Nepal each company is being
provided a guarantee for three years on the structural parts of the plants such as dome, digester, inlet, outlet
etc. and one year guarantee on biogas appliances and fittings.
It is interesting to note that 73 parameters have been developed by Biogas Support Programme (BSP) for ensuring
the quality of the plant construction and its proper functioning. These parameters are categorized as penalty
equal to subsidy, penalty from Rs. 10-700, no penalty and providing bonus to companies. Slurry extension programme
has been carried out to increase effective market of biogas plants through proper application of slurry in crop
production.
There are various methods of increasing gas production especially in winter months. Some of these methods are
composting on top of the dome, utilization of waste heat from biogas power generation, solar radiation, insulation
with rice husk or straw etc.
In Nepal national biogas programme has become successful because of the close cooperation of the concerned agencies
such as Alternative Energy Promotion Centre, biogas companies, banks and donors. It has also been supported with
the availability of both loan and subsidy funds for certain period of time, introduction of well proven deign, quality
control, toilet attachment etc.
It has been realized that there should be focus on the integration of biogas technology and commercial uses of
biogas especially for running engines such as agro-
processing, pumping water and generating electricity. Research needs to be carried out in the field of using alternative
feeding material such as industrial waste, vegetable waste and sewage.
4. From: "UCS" <ucs@mail.com.np>
Subject: [RETs] Week 3: Designs of Biogas
Date: Mon, 3 Dec 2001 16:19:21 +0530
BIOGAS RESEARCH AND DEVELOPMENT: DESIGNS OF BIOGAS
Floating steel drum design
The whole set of biogas plant mainly consists of a digester pit, gasholder drum with central guide pipe,
inlet with gobar mixing machine, outlet, and water outlet device.
Drum or the gasholder is of welded steel construction with a steel frame at the opened end. The top of the dome
is slightly coned. Scum breakers or mixing arms are welded between top plates and stiffeners. The smallest size is
of 100 cf. capacity and largest of 1000-cf. capacity. The smaller size plants below 350 cf. have been used for
domestic purposes whereas the larger size biogas plants were used especially on community basis for running engines
for agro-processing, pumping water for irrigation and generating electricity.
The straight design is mainly used in an area where water table is low. As water table is quite high in the
Terai, the taper design is commonly used. The details of the design of the plant and its accessories are as shown in the drawing
below.
Fixed dome design
Due to several difficulties with floating steel drum design, GGC developed fixed dome design, which consists of an
underground digester pit with a concrete dome shaped cover over it for collecting gas from the slurry. In this design
the use of steel and moving parts are eliminated due to which skilled mason with a little bit of training can undertake
their construction. In the ratio of 1:3:3 cement, sand and pebbles from 20-25 mm mixed with appropriate amount of water
is poured over the mud mould covered of with thin layer of sand for casting dome.
The following drawings show the various development of this design in the country. After the several years' research
activities, this design became most successful and popular in the country. As a result, BSP has adopted this design only
for their programme.
Tunnel design
The digester of this design is also underground as that of fixed dome design but like a tunnel and hence its name is
given like this. The slurry is fed at one end and discharged at the opposite end. Gas is stored in the roof of the plant,
which is lined with plastic sheet and displaced slurry flows into a slurry reservoir at the overflow end of the plant.
The tunnel design has certain advantages over the dome design. It is simpler to build and special skills for cement
plastering are not required. It requires a shallow digester pit, so is useful where water table is high. It is of modular
type of construction, using pre-cast concrete sections, so can be made of any size by adding extra sections. However,
it is difficult to transport the pre-casted slab and is impractical to fabricate the pre-caste slab at the site.
Plastic bag biodigester
The PVC plastic bag digester received by GGC from the courtesy of UNICEF was tested in research unit at Butwal
from April to June 1986 by the author. A tunnel type cavity was dug on the ground according to the intended size of the
digester. Since PVC plastic is of 1 mm thick and is a flexible grade plastic, it was fixed with the help of 3/4'' GI pipes
and several hooks fixed in the wooden planks. It is easy to install and transport the whole system. Such models are
currently used in Taiwan and other countries.
Brick mortar dome
Brick mortar dome plant was made by the author at the Research Unit of GGC at Butwal in 1986 to reduce the cost
of the plant and to make the technology affordable for rural Nepali users. Except the dome, the rest of the plant was
constructed as the concrete dome. In brick mortar dome, two courses of burnt bricks in cement mortar were laid around
the circumference of the dome. About 335 bricks were laid on top of the mud mould covered by thin sand layer. A mortar of
sand and cement of 6:1 was poured on and around the bricks. Once it was completed, thin plastering (5mm) was made both
from inside as well as outside the dome. About 10 -15 % of the cost was reduced. The plant is still functioning well.
Appliances development
Thirteen biogas appliance manufacturers have developed various biogas appliances in their workshop in different places of the
country. The appliances include: gas pipe, stove both square as well as taper, main gas valve of various design, biogas lamp,
water drain or water outlet device both for drum as well as drum plants. Similarly, GGC on top of this has also developed gas
meter, manometer, pressure gauge, conversion kit, and iron running with biogas.
Alternative feed
Various alternative feedstocks were fed inside the digester and were limited in research and reports. However, the
following alternative feedstock were tested and experimented.
Rice straw
Unchopped 440 kg of rice straw was fed to a 10-cum. brick mortar dome plant with 265 kg of effluent mixed with 440 kg of
dung mixed with equal amount of water. This experiment was performed in Research Unit of Gobar Gas Company at
Butwal. Dry matter percentage of rice straw was found to be about 87
percent. At first the percentage of methane was only 20 when measured with an electronic gas analyzer. It was due to low
nitrogen in the rice straw and the gas was not burnt due to high percentage of carbondioxide present in the gas. The pH at that
time was 5 and the smell of the gas was like that of rotten egg. To make C: N ratio 25:1, 8.36 kg of urea was added and the
percentage of methane increased gradually up to about 35. Then 1.5 kg each of lime and molasses was added inside the reactor.
The methane percentage was gradually increased to 40 and the gas started burning.
Water hyacinth
Water hyacinth of which the dry matter percentage of 9.3 was also used as alternative feed stock for producing biogas. This
experiment was conducted both at laboratory as well as field-testing in an 8 cum tunnel plant. The gas production was almost
double to that of gobar feeding plant. However, the problem of floating water hyacinth in the digester was noticed.
Banmara (Eupatorium species)
Unchopped Eupatorium species was fed to the first 10 cum biogas digester installed in Nepal with about 35 percent
effluent from a working biogas plant where the other 10 cum. brick mortar biogas digester was fed with equal quantities
of 15 cm. long chopped Eupatorium species and cattle dung. About 15 percent of the effluent from the previously working
plant were added as seeds of methanogenic bacteria. This experiment was conducted from September to December 1983,
under a project financed by the Swiss Association for Technical Assistance (SATA). The gas production was found
0.09 cum. per kg dry matter whereas in rice straw mixed dung it was 0.198 cum per kg dry matter.
Industrial waste
Building biogas digester on a large scale would become a practical approach to improving the environmental pollution
in the respective area. In Nepal, the wastes from the industries such as Bhrikuti Paper Factory in Nawalparasi
district, Gorakh Kali Rubber Industry in Gorkha district, and the sugar mills, and distilleries at various places can
be used for producing biogas. These industrial wastes were tested and experimented in the laboratory at the R&D Unit of
GGC at Butwal. As a result a 10 cum plant was installed at Lalbandi running with the waste from a local distillery.
Similarly, urban sewerage can also be used for producing biogas. A 20 cum plant was installed in Nepalgunj municipality
in the western Terai using the wastes from the municipality.
Application of slurry
The slurry obtained from the dome plant installed in research unit of GGC at Butwal was tested and applied to various crops
both cereals and vegetables in the field of GGC at Butwal under R&D activities. The physical and chemical properties of the
slurry were found as follows:
Dry matter: 7-14%
pH: 6-8
C: N ratio = 16:1
Nitrogen: 1.76%
Phosphorus pentoxide: 2.07%
Potassium oxide: 2.30%
Besides these, other nutrients such as calcium, magnesium, sulfur, zinc, manganese, copper, boron in traces were also
found.
The slurry was applied to rice, wheat, maize and tomato, potato, cauliflower, chili and so on for several years in
GGC office land at Butwal by the author. The field was irrigated as needed until harvesting of all cereal crops.
The field was divided into 16 plots (200 square meter each) where manure such as dung, chemical fertilizer,
bio-slurry was applied. Dung and bio slurry was applied with equal nitrogen contents.
Dung battery
Dung battery may produce 3-12 volts of electricity. The effluent obtained from the plant was used in making dung
battery, which can be used, for lighting fluorescent light, for running radios as well as clocks. About 30 such batteries
were installed by GGC at Dukuchhap of Lalitpur district in September 1991. Similarly, the clock hanging in the GGC
Head office of the company was running without any problems for 4-5 months even without changing dung.
Methods of increasing gas production
There are various methods of increasing gas production, especially in winter months. Some of these are described
below.
Compost for Heat Generation
One of the most important factors affecting biogas is the temperature. The optimum temperature for methane producing
bacteria is about 35 degree Celsius. When the slurry temperature is low, the gas production is greatly reduced.
At 10 degree, the production of biogas more or less stops. Insulation of dome with compost is one of the best methods
for heat generation for smaller dome type biogas plants.
A compost pile can generate significant amount of heat from decomposition of organic materials such as agricultural residue,
straw, grasses etc. Decomposition can be accelerated by the addition of water with effluent from the plant. The effect of
compost for heat generation greatly varies with the height of the compost pile and the time it takes to decompose. The height
should be not less than a meter or so. The compost should pile on the top of the plant for insulation.
This experiment was done in GGC at Butwal in October 1982, in a 10 cum dome plant. The plant was daily fed with 60 kg of
dung. Daily gas production, temperature of the slurry as well as compost was measured.
A similar 10 cum plant at Kalikanagar, near Butwal was used as control measuring daily gas production as well as temperature.
It was also fed with equal amount of dung daily with that of the first plant. The slurry temperature inside the digester
was 2.03 degree Celsius more in the plant with compost. The gas production was increased by about 22.3 percent. Similar
experiment was conducted in Kathmandu, and the gas production was increased by about 51 percent. This shows that the effect
of composting is more in cooler place (Kathmandu) than in warmer place (Butwal).
Thus the compost is more than a fertilizer and soil conditioner. The compost generates heat for the plants, but also builds good
soil texture and structure, provides and releases plant nutrients, protects against drought and stops nutrient loss through leaching
but also stimulates the growth of the plants.
Utilization of Waste heat from biogas power generation
A heat exchanger was applied in a 500-cf. steel drum plant at Bhutaha of Nawalparasi district, the gas of which was used in
7 HP engine for agro-processing on experimental basis. The gas production was increased by about 37 percent in winter,
assuming that only 50 percent gas could be produced in a similar plant of the same capacity without having heat
exchanger. Similar experiments were conducted in R&D unit of GGC at Butwal as well.
The engine installed was of water-cooling system. One heat exchanger assembly is made up of concentric GI pipes
connecting between the engine and heat exhaust silencer and uses waste heat from the exhaust gas to heat water. The other
part of the heat exchanger was placed one foot above the digester base and heats the slurry in the digester. A valve
can adjust the amount of cooling water flowing through the engine. Maximum heat was generated when the water was flowing
at the rate of 2 lit. /min. as the flow rate increased the temperature decreased and vices versa.
Thus using gas heat from an engine is one of the best ways to maximize biogas production in winter in large size plants,
by increasing the temperature of the slurry.
Solar radiation
In this process the influent (dung mixed with water) in the inlet can be warmed under the sun by covering with a plastic
sheet and let the influent enter inside the digester at about 2-3 p.m. This experiment was conducted at research unit of
GGC at Butwal by the author. GGC experiments showed that this process could increase about 5 - 8 percent of the gas
production.
Insulation with rice straw
Insulation can also be done with rice straw, rice husk and so on. Their thermal conductivity is 23 times lower than that of
soil and condenses to run off leaving the insulation dry.
Similarly plastic sheets like polyethylene can be used as a cover over insulating materials to reduce the amount of
materials required. As light penetrates the plastic, it is transformed into the longer heat waves. The heat enhances
evaporation of moisture from the insulating material and ground below. This experiment was conducted in a 10 cum plant of Mr.
Kunda Dixit's premises at Patan Dhoka in Lalitpur district in Kathmandu Valley.
The gas can further be increased when dung was mixed with other feeding materials such as poultry dropping, piggery
and night soil.
Cold climate and high altitude biogas plant
A 10 cum dome plant was installed at Sorgadwari at an altitude of about 7500ft. above sea level in Puthayan district in 1989.
The gas was used for cooking and lighting. The gas production was found about 50 cf. in winter and about 80 cf. in the summer
although the bottom slurry temperature in winter was 10 - 15
degree celcius only. It has proved that biogas plants could be operated at an altitude of about 7500-ft. as well.
5. From: "UCS" <ucs@mail.com.np>
Subject: [RETs] Week 3: Biogas Technology: Trend in Nepal
Date: Mon, 3 Dec 2001 16:40:36 +0530
In Nepal, the development trend of biogas technology is very encouraging. This is mainly due to the introduction
of well proven biogas design and biogas appliances, construction companies guarantees, promotion materials
development and distribution, continuous subsidy and loan is being providing, compulsory toilet attachment in the
plant, good capacities and organizational networking, introduction of slurry extension program and establishment
of organizations such as ADB/N, Alternative Energy Promotion Centre, Nepal Biogas Promotion Group and Biogas Support
Program.
Biogas technology can be efficiently and cost effectively used by the rural and urban poor if some of the low cost
design such as plastic bag or brick mortar dome or PVC digester could be introduced. It is socially accepted and
environmentally sound technology. I believed that such proven technology can be transferred in South Asia and the Pacific
region. It has very good future potentials as many households have good cattle population. If other alternative feeding
materials such as industrial waste from paper factory, sugar factory or distillery and sewage are used it could be used
in urban areas as well.
It could further be improved if biogas technology is integrated with agriculture, health, livestock, environment
and so on. I believe that the use of biogas should not be limited only in cooking and lighting but also in running
engines for agro-processing, pumping water and generating electricity.
Govinda Prasad Devkota,
Moderator - Week 3
6. From: "Nienhuys" <s.nienhuys@chello.nl>
Subject: [RETs] Week 3: Re: Designs of Biogas
Date: Mon, 3 Dec 2001 13:58:23 +0100
We have closely studies the highly successful application of Biogas in rural Nepal, that was developed and implemented by
the SNV, Netherlands Development Aid Programme. The conditions to implement biogas are quite specific and close
control on customer services and education is needed to guarantee sustainability. One of the observations was that
there is a minimum size of digester to make it work and function during the winter. This is important as it is mainly during the
winter at the higher altitudes that cattle is in the stables and the slurry collection is optimised.
To use biogas at higher altitudes it is necessary to insulate the ground tank. The information below also indicates that gas
production goes down. In other projects, half of the gas production was needed to warm the slurry.
BACIP, in the Northern Areas of Pakistan developed a wall insulation technique that can be adapted/used for slurry tanks.
The tank in the ground is made one foot wider than required for the slurry tank.
In the inside of the tank-wall a thin and insulating inner wall is manufactured by masoning wooden pegs of 20" in the outside
wall, sticking out towards the centre. The pegs are sticking 4" out of the wall (towards the inside). Pegs are placed at
least one per sq ft. On the pegs a thick plastic sheet (0.15mm) is attached with expanded metal mesh on top (3/4"holes). Behind
the plastic the 4" space is stuffed with straw. This inner-wall is plastered with strong cement plaster, pushing it partly
through the expanded metal.
Depending on the depth of the tank, one or two layers of expanded metal and strong cement plaster are applied. This way a
Ferro-cement waterproof and rather thin wall is built on the inner-side. This way the future content will not loose its warmth to the
surrounding soil.
Naturally this is only one of the many conditions for realising domestic biogas production at higher altitudes.
Our advice is to consult the SNV project, rather than experimenting.
Sjoerd Nienhuys
7. From: "Gehendra Gurung" <gbg@mos.com.np>
Subject: [RETs] Week 3: ACAP's Experience with Biogas and ICS
Date: Mon, 3 Dec 2001 22:42:09 +0545
1. ACAP has also experiences with Biogas and ICS. With biogas you cannot go above 1,200m asl for economic utilisation of
the plant. This is in the case of Annapurna Conservation Area, Nepal (28.50 north). Whereas people in the highlands burn
animal dung (Yak dung, sheep and goat manures) for cooking and heating. They are compelled to use animal dung simply
because there is no forest. So the biomass from the grasslands is converted into fuel through animals (grass
-> animal -> dung -> fuel). Alternatively they have to depend on bushes where the practice is to uproot them, as the underground biomass is
more than aboveground biomass in this high, cold and dry zone of the Himalaya.
The limiting factor is 'low temperature' required to activate the microbes in the biogas digester. There is a need to
generate technology where the digester can be made more warmer to function the plant throughout the year or at least for the
economic period of the year. In addition to compost piling and straw cover on the digester, solar heat trapped into water
may be used. Studies are required.
Secondly the present cost level has become high for the farmers. Even with around 50% subsidy of the total cot they show little
interest on biogas. So cost minimising studies should be given a high priority. When we are talking of biogas we are targeting
farmers who may be communities with less risk bearing capacity.
Thirdly the extension aspect of biogas is to be aggressive, especially to the sites where environment is most appropriate.
Large number of households in potential areas have still not installed biogas simply because the people do not know what
biogas is. Many have not even seen it. We have experienced in the ACAP that local people had known very little before ACAP
started promoting biogas, and once the people knew it there is a big demand. Today ACAP install some 100 plants a year in the
potential villages inside the Annapurna Conservation Area. The demand was created after the farmers knew about the technology.
2. Regarding ICS we started with mud-made-ICS. But this stove was not as flexible as the traditional hearth. The traditional
tripod is so flexible that you can use it for any size of pot (large, small, heavy, light etc.). The mud-ICS could not be
used for varieties of cooking vessels. Secondly this was useful in lower warmer areas, not in highlands where, in addition to
cooking, the fire is meant for warmth through radiation to the people to protect from cold. Thirdly a large quantity of heat
escaped through the smoke outlet. And again the heat was lost from the room which otherwise would be used for space heating
through convection. Additionally if the smoke outlet pipe is not properly fixed the air suction through it accelerates the
heat loss. So this was not found heat efficient as well in addition to inflexibility for the highlands.
The local initiatives, however, have modified ICS into a semi-closed cook-stove. In this stove the flame is directed to the
cooking vessel while the semi-closed structure lets the heat circulate inside the room through convection and radiation.
ACAP is now promoting cast iron cook stoves. It is comparatively costlier than the mud-made-ICS but for the
higher elevation zones where fire is also meant for heating the room through both radiation and convection, this has
been in demand by the communities. To trap the residual heat that escapes through smoke outlet pipe, a water drum is
fixed around the pipe so that the water absorbs the heat from the smoke before it escapes from the roof. This system has
been called 'smoke water heating system'. As you know cooking with hot water takes less time than starting with cold water.
Gehendra Gurung
8. From: "Suman Rai" <srai@icimod.org.np>
Subject: [RETs] Week 3: Re: Biogas Technology: Trend in Nepal
Date: Mon, 3 Dec 2001 19:23:09 -0575
I am a complete novice regarding biogas technology. The few good things about it in my understanding are those of
opportunities in terms of what it offers for forest conservation (but on expense of fertiliser required for agriculture),
perhaps time saved from collection of firewood, efficiency in terms of being able to immediately start fire but on the other
hand the pungent smell sometime deter especially old members in families to go for
biogas. 8 years ago I noticed in the
village of Barpak in Gorkha district (alt. must have been approximately around 2500 ft.) that a family was using
biogas. This was unusual as temperature I understand is vital for running of a
biogas which could mean less scope for mountain areas. But in Barpak the person had chosen a sunny slope and
was making biogass possible. I was wondering on the potential of biogas for mountain areas.
Suman
Comment from the moderator
Biogas plant has been installed successfully at an altitude of about 6500 ft.at Sorgadwari of Pyuthan district which is
above Barpak height. In high altitude insulation with composting can be done to generate heat inside the digester,
which significantly increases the temperature and ultimately gas production.
- Govinda Prasad Devkota
9. From: "sudhirendar" <sudhirendar@vsnl.net>
Subject: [RETs] Week 3: Biogas Technology: Some Issues
Date: Tue, 4 Dec 2001 12:45:05 +0530
If we are to discuss the biogas technology, its social adoption and dissemination strategies, then I'm afraid
we will not be making any contribution to the issue of
rural energy in general and renewable options in particular. Haven't these options (including numerous improved cookstove
designs) been there for long along with their incentive packages (subsidy or market support, as the case may be)
without any major impact on the mountain energy scenario? Isolated cases of successes are of course there but
exceptions don't always prove the rule.
Though more often than not efforts are made to indulge in discourses that aim at universalising technology, the
results of such exercises only add few more pages to the already existing literature (of course, nothing tangible
on the ground). The challenge, however, is to look for diversity in technology to match varied diverse situations
on the ground. Tragically, however, the technological options, be it biogas or cookstoves, are so very limited that any
discussion on the subject ends up leafing through the same book and same issues - the cost of technology, availability
of trained manpower, saving on fuelwood, drudgery reduction index etc etc. How far we can continue to follow the beaten
track?
Another shortcoming of visualising energy scenario through the technology route is that that it favours the technology
only, the effort being to justify the technology as a panacea to the problem. To my mind, the energy scenario hasn't been
fully understood till now. Had that been the case, search would have been on to fill in the gaps by improvising and/or
developing options that would have fitted in snugly into those gaps. Current approach is to fill the glaring gaps with limited
number of options. The end result being; neither the energy need gets satisfied nor the technology gets optimally utilised.
Dr Sudhirendar Sharma
10. From: "Yuvaraj Dinesh Babu" <ydbabu@teri.res.in>
Subject: [RETs] Week 3: Re: Biomass Briquetting
Date: Tue, 4 Dec 2001 13:42:58 +0530
Biomass Briquetting - Need for the hour
This sector though introduced in Nepal long back lacked government supported R&D and the essential services
from the suppliers .
Further the machinery imported did not come with much guarantee as regards the life of the wear parts,
i.e, the screw extruder (which worn out within hours.)
which had a telling effect on the mahines performance.
This lead to the blanket ban by the financing institutions and banks in Nepal on financing such briquetting projects,
though the projects which failed were based on pyrolysed char briquetting .
Here one should clearly understand the technicalities of the briquetting technology. While Briquetting technology
of Die & Punch are quite successful , the screw extruder have miserably failed in India and Nepal due to the pyrolysed
biomass. It should have been noted in the initial stage itself that neither the screw extruder nor the punch could
last for more than few hours for briquetting pyrolysed biomass since the char is highly abrasive. It was less than common
sense which should have prevailed before installing number of machines which were to fail immediately both in India and
Nepal.
Having experience in the design , development , manufacturing and selling of more than 15 energy efficient briquetting
machines (both Screw Extruder and Die & Punch) in India and one in nepal, I would like to comment few things for better
understanding by the forum and the technical people who are working in the field of briquetting.
Biomass Briquetting Machines are of basically two types:
01. Screw extruder and
02. Die & Punch
While the Screw Extruder were successful in Europe / Japan /Thailand / Malaysia / Taiwan, it miserably failed in India
and Nepal due to various reasons. One main reason being the easy wear on the screw extruder (in one case it did not even
stand for 1 hour). Efforts by various local and Japan experts in working on different hard faced alloys on the screw
extruder did very little to improve its life. Further the variety of biomass in India posed a major threat to the
briquettability by the screw extruder. A few lakhs were spent by IIT, New Delhi , sponsored by University of
Twnete, the Netherlands, and marked improvement in the life of the screw and reduction in specific power consumption were
reported, only on a lab scale. These results are yet to be proved commercially as there are literally no market for
screw extruders in India.
However India has good experience in Die & Punch briquetting machines as there are more than 100 plants installed now in
India with a success percentage of about 40-50. The major reasons for the failure of such plants during the 1980s and
early 1990s were due to poor design , poor quality of machines, poor service, very poor awareness among the fuelwood/coal users
(about the benefits of briquettes) and discouragement from the bankers for lending working capital for stocking raw
material.
For the plant suppliers, IREDA in India was a gold mine as they funded briquetting projects when no other FIs or banks
were into it. As a result more plants were implemented in India under the financing of IREDA and they failed. Most of
the plants failed due to Technical, Managerial and Financial problems as given below :
Technical reasons: poor design , poor quality of machines and poor service Managerial reasons : first generation
entrepreneurs, poor market, poor raw material sourcing and collection, poor operational management
Financial Reasons : Local commercial banks simply refusing to extend working capital for biomass (which was a new
concept - asset for them)
IREDA subsequently setup a Technical back-up cell which provided useful operational solutions for the plants suffering
from technical problems but little resulted to improve the financial situation since it mainly depends on the security
(collateral) that the briquettor posses and the rapport he enjoys with the local commercial banks.
However the briqueting plants continued to be implemented in India and most of the self-financing briquettors are
doing excellent business, especially in Western and Southern region. A conservative estimate says that around 1,50,000
tons of briquettes are consumed annually by the tea Industry in the state of Tamilnadu, 20,000 tons by Indian Tobacco Company
in the state of Karnataka, besides Textile dyeing units, Tyre retreading units and process industries.
These plants have established their viability and quick return (as fast as 12 months) with improved design in the
machniery, good upkeeping of the machinery, continued efforts on expanding the market for briquettes (latest news is that
even the steel rolling mills have started using briquettes) and continued search on sourcing biomass for consistent
production and sales.
Recently, Indian Institute of Science, Bangalore in state of Karnataka is working on gasification of briquettes which
have shown encouraging results. And as a result, a private company namely DESI Power Ltd., is working on implementing
one such commercial plant based on rice husk in the State of Bihar.
Now briquetting can be looked as a means of providing a sustainable livelihood for the rural population as a means
for power from briquettes based gasification, revenue generation by marketing of surplus briquettes to the nearest process
industries, collection , storing and selling biomass (an employment generating activity).
Once right sourcing of biomass and market is established, the right kind of machinery falls in place (good manufacturers
are available these days) and the project is an assured success.
Nepal government may first initialize the biomass assessment at the rural level and also plan implementation of small scale
agro-based industry in rural areas (viz., rice mills to generate biomass) to provide another chance for briquetting to become a
success in Nepal. This time it should be briquetting of agro-waste and not pyrolysed char.
What is essential at this point of time is the right kind of government policy in promoting such rural based technologies.
N. Yuvaraj Dinesh Babu
11. From: "Bikash Pandey" <bpandey@winrock.org.np>
Subject: [RETs] Week 3: Can biogas subsidies be paid for by Carbon Trading?
Date: Tue, 4 Dec 2001 14:04:48 +0545
As has been acknowledged by Sjoerd Nienhuys in an earlier submission, the Biogas Support Program has provided a
successful scaling-up of this technology in Nepal. The rapid expansion of the number of biogas plants now means
Nepal has more biogas plants per capita than India and the country is catching up with China! Just over half of these
plants are in the mountains and valleys, the rest being in the flat Terai in the South. One remaining issue is that
the program is still dependent on subsidies to operate. The piece below examines the possibility of using the
upcoming trade in carbon through the Clean Development or other Mechanisms as a way to at least partially substitute
for the subsidy.
Bikash
------
Case Study: Scaling-up Biogas Technology in Nepal
Summary
Some 80,000 families in Nepal are using methane from biogas digesters for cooking, with around a quarter of the users
also using it for lighting. An additional 24,000 families are expected to purchase digesters in the coming year.
Plant sizes are in the range of 4 cu.m. to 10 cu.m.. The most popular size is 6 cu. m. and costs US$300. Of this,
around $100 comes as subsidy support from the Government of Nepal plus German and Dutch bilateral aid. The users themselves
invest the rest together with bank loans. Some 48 private companies are certified to construct plants. The plants
have high reliability with almost 98% of them working well after three years of operation. Biogas is the only renewable
energy technology that can realistically substitute for burning of firewood and other biomass for cooking in rural areas. In
addition to substantial benefits to the users from reduced indoor air pollution and reduction in firewood collection
and cooking times, to the local environment through reduced pressure on forests, biogas can also provide significant
global climate benefits through lowered emissions of Greenhouse Gases. It may be possible to substitute a large part of the
government subsidy by selling the GHG benefits from biogas plants in the developing global carbon market.
Background
While most of the renewable energy community has concentrated its focus on electricity provision, the vast majority of rural
communities in the South will continue to derive the bulk of their energy needs from biomass sources for the foreseeable
future. The continued use of firewood, agricultural residue, and animal waste for cooking by ever-increasing rural
populations, in many parts of Asia, Africa, and Latin America has resulted in deforestation as well as reduced organic
fertilizer available for the fields. A high level of indoor pollution from burning of solid biomass fuels in poorly
ventilated rooms results in serious respiratory infections and
is a leading killer of children under five. Biogas, largely methane and carbon dioxide, is produced by the anaerobic
digestion of animal waste and other biomass. While the technology is well understood and widely used, particularly in South and
South East Asia and China, few programs have been able to achieve the rates of growth of high quality plants as seen
in the last decade in Nepal. The technology has been available in Nepal since the mid 70's. However, it was not until the
early 1990's that the number of installations was substantially scaled up by the Biogas Support Program (BSP).
Approach
Nepal's Biogas Support Program can be described as subsidy-led while at the same time being demand-driven and market-oriented.
A simple, transparent, and sustained subsidy policy has been instrumental in increasing the adoption of biogas plants
substantially. Subsidy has been justified to make up for the difference between higher social benefits (maintenance of
forest cover, prevention of land degradation, and reduction in emissions of greenhouse gases) and more modest private benefits
(reduction in expenditure for firewood and kerosene, savings in time for cooking, cleaning, and firewood collection, increase
in availability of fertilizer, and reduction in expenditure to treat respiratory diseases) accruing to users. A progressive
structure, which provides lower subsidy amounts to larger
plants, has encouraged smaller plants that are affordable to poorer households. BSP has been able to leverage quality
standards in installations through effective use of subsidy. All participating biogas companies have to be certified by BSP
and must build plants to one fixed design according to approved standards. Quality control is enforced by carrying out detailed
quality checks on randomly selected plants built in the last three years.
The number of units checked corresponds to at least 5% of the plants built in the most recent year. Companies found in breach
of strict guidelines can receive anything from a warning to fines to being barred from participation in the program depending
on the seriousness of the infringement. Ratings, from A to E, are revised each year to encourage companies to improve their
performance. This focus on high quality has increased the confidence in the program among users, banks, supplier
companies and donors. Despite the availability of subsidy, users themselves must invest a substantial amount in cash and
labor. Companies must thus market themselves aggressively to generate demand for plants. BSP encouraged the number of
participating companies to grow from a single semi-government
entity in 1991 to 48 today. The reduction in real prices of installations by 30% in the last ten years demonstrates that
there is fierce market competition on the supply side. The subsidy itself has remained constant in nominal Rupee amounts
since the beginning of the program, even decreasing for the larger plants.
Impacts
Biogas plants in Nepal have had positive impacts on a number of fronts. Reduction in indoor air pollution in beneficiary
households has lowered respiratory infection, particularly among children. Firewood collection time has been reduced, as
has the time to cook and clean pots. Women have saved an average of 3 hours per day on these chores. Houses using the
produced gas for lighting are saving on kerosene bills. Increased stall-feeding of animals has made more organic
fertilizer available to farmers. Almost 45% of the owners of biogas plants have also attached new toilets to them leading
to improved sanitation and hygiene. There is anecdotal evidence of regeneration of forests in areas where there is
high penetration of biogas plants, although the exact extent of this has not been documented. The first attempts are being
made to quantify the anticipated climate benefits from biogas plants. Preliminary calculations show that a typical family
biogas plant in Nepal saves between 20 and 40 tons of Carbon Dioxide equivalent over its 20-year life, depending on whether
all greenhouse gases are included or only those within the Kyoto Protocol. The price per ton of carbon dioxide would
need to be $2.5 to $5 to cover the subsidy presently provided to biogas plants in Nepal.
Lessons Learned
The Nepal biogas experience gives a very good example of how a national program can, through a subsidy mechanism, bring
commercial companies to the table and with their participation leverage high quality installations. Free market conditions,
particularly when regulations are weak and when the customer does not have full information regarding the product, often
result in competition between suppliers based on price alone, at the expense of quality. For a program like BSP to succeed,
a major prerequisite is that the national program must be independent and free from political interference.
A second lesson is that freezing technology to one approved design makes it easier to control quality while at the same
time lowering barriers of entry to allow in a large number of competing companies all working to the same standards.
Although such a strategy may not be suitable for a fast changing sector such as solar PV, this has turned out to be
quite effective for biogas, a much more established technology. BSP will, however, need to develop ways to introduce
technological innovation into the sector in the long run.
References:
-Biogas Support Programme, 2000: Annual Report 2000. Kathmandu.
-Smith, K.R., R. Uma, V.V.N. Kishore, J. Zhang, V. Joshi, and M.A.K. Khalil, 2000: Greenhouse Implications of Household
Stoves: An Analysis for India. Annual Review Energy Environment 25:741-63.
-Mendis, M. and W.J. van Ness, 1999: The Nepal Biogas Support Program: Elements for Success in Rural Household Energy
Supply. The Hague.
-Silwal, B.B. 1999: A Review of Biogas Programme in Nepal. Winrock International, Kathmandu.
Contacts
Sundar Bajgain
Programme Manager
Biogas Support Programme
Jhamsikhel, Lalitpur
PO Box 1966 Kathmandu
Tel: +977-1-521742/534035
Fax: + 977-1-524755
Email: snvbsp@wlink.com.np
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