Biogas in Pakistan

Biogas in Pakistan – some facts and figures

By Engr. Naeem ul Zaman & Engr. Asim bin Aziz
BIOGAS IS produced by anaerobic (absence of air) decomposition of organic matter by a bacteria present in the stomach of animals including buffalos, cows etc. Bio Gas is also known as Gobar Gas or Marsh Gas. Chemically it consists of 60-65% Methane (CH4), 35-40% Carbon Dioxide (CO2), and traces of Hydrogen Sulfide, Water Vapors, Nitrogen and other gases.
Because of its Methane content, it burns just like natural gas but has a lower heating value of nearly 600 BTUs/cft as compared to 925 BTUs/cft of natural gas (commonly known as Sui gas) which is more than 98% Methane.
Theoretically, it is very simple and easy to produce biogas by mixing equal amounts of fresh buffalo dung and water and put this in a vessel where there is no air. In summer, the gas will appear within few days time and in winter or in cold climate, it may take a little longer. The bacteria; present in the dung does all the work.
Despite the fact that it looks so simple, the production of biogas is not so popular in Pakistan. Large scale efforts were made to popularize biogas production during 1980s and lot of money was spent by the government, but after some time the efforts died down and only a few biogas plants installed at that time are still in production. At present Pakistan Council of Renewable Energy Technology (PCRET) is trying to propagate biogas production but on low key basis. A number of NGOs as well as commercial organizations are also working on biogas production.
Gas produced in a small bio-digester which contains about 20 kg of dung should be enough to meet the fuel requirement of a small family. Based on these calculations, a bio-digester for any number of animals can be designed.  The thumb rule is one cubic meter (35.5 cft) digester volume for 10 Kg of cow dung (one cow).
Large size digesters use different type of biomass such as potato waste, chicken droppings, tannery waste, green silage (leaves, corn etc), food scrapes, bakery waste, molasses, slaughter house waste (poultry and other) fats and greases to produce biogas at industrial scale, both for electrical power generation as well as for heating purposes.
A biogas production facility is basically a gas tight vessel with possibility of adding fresh slurry and removal of gas and waste slurry. For intermittent use of gas such as domestic needs, gas storage is necessary. In case of industrial use, either a separate storage tank is used or excess gas is flared (burned). Storage may be an integral part of the digester or it may be a separate facility.
For domestic purposes, biogas is produced at very low pressure that is a few inches of water column. It can safely be transported through flexible plastic pipes recommended for natural gas. For transferring gas for a couple of small size burners over a short distance of few feet, heavy duty plastic tube of 6 mm bore can be used. Since biogas is produced in water slurry in relatively warm condition, it is saturated with water vapors and may also contain traces of foul smelling vapors.
Biogas is 60% methane and 40% Carbon Dioxide with traces of hydrogen sulfide, water vapors and sometimes foul smelling substances. For use of biogas as fuel on domestic level, no treatment is required. When large quantity of gas is consumed as fuel, condensate removal and flame arresters may be required for trouble free use.
In case biogas is used as fuel for internal combustion engines for power production, the impurities present in biogas may be undesirable. Some engine manufactures offer engines that accept raw gas; otherwise the advice of engine manufacture may be sought.

In case it is desired to store and use biogas for automobile use (as it is being done elsewhere) the gas should be purified before compression. There are a number of methods available for purification of bio gas (chemical treatment, membrane separation etc)
Nearly 10,000 BTUs of thermal energy is required to generate one KWt of electricity by internal combustion engines. Since the heating value of bio gas is close to 600 BTUs per cft, to generate one KWt of electricity, 17 cft or 0.5 M3 of biogas is required. Thus to run a 5 KWt generator for one hour, 85 cft (2.5 M3) of biogas is required. To operate a 5 KWt water pump for five hours a day, 425 cft or 12.5 M3 of gas is required. This quantity of gas can be generated from the cow dung of twenty cows. In case of dairy farms with high milk yield cows, the power production would be much higher.
Bio gas can run a petrol engine without any major modification. Even a diesel engine (Peter Engine) can run on a mixture of 50:50 diesel and biogas. There is a lot of potential of power generation from biogas in our rural areas and the economics of farmers can be improved.
Refrigeration units running on gas are available in the market. These units are ideal for chilling milk and preserving agro products before these are sent to the market.
The cow dung contains 16 % dry matter and nearly half of this is converted into gas. Since the slurry to the digester is fed with 8% solids the slurry leaving the digester contains only 4% solid organic matter. While planning a biogas plant, the disposal of this slurry must be accounted for. Totally composted and free from pathogens, it is an ideal crop food.
The biogas digester produces slurry daily; however, the requirement in the fields is intermittent, therefore, the storage of slurry is a must. In case of small bio digesters, the slurry is sun dried and stored in the open before it is used. In case of lager installations, the slurry may be stored in large size ponds. In case of large size dairy farms, where the slurry cannot be consumed in house, it may be dewatered, blended with chemically produced N P K, pelletized and sold as biofertiliser.

BIOGAS FOR A SUSTAINABLE FUTURE

Biogas for a sustainable future

by ALBERT FERNANDES
CANACONA: Biogas technology is being promoted in India chiefly under the aspect of energy. It is based on the anaerobic digestion of organic material to produce clean fuel for cooking, lighting and running machinery.
The bio-digested slurry besides providing plant nutrients, benefits the soil by bringing about physical, chemical and biological enrichment. In the days of energy crisis, biogas becomes handy for the farming community as it supplies gas for fuel and enriched bio-manure from cow dung.
Among the renewable sources of energy, biogas technology is the most mature in terms of use and number of units installed. Economically, too, biogas technology has the lowest financial input per kilo watt of output energy. It provides not only energy but also value added bio-fertilizer, in addition to providing other benefits like sanitation, cleaner environment with less pollution and better quality of life.
Looking beyond the years, it seems certain that we are moving to an era when the energy costs are going to rise and the pressure on fossil fuels and wood is going to become more and more acute.
The rising commercial energy demands worldwide also threaten the environment. Power sector growth is estimated to come mainly from fossil fuels, coal, oil, gas and large hydropower developments. Renewable energy resources and energy efficiency can help address some of the global growing energy needs without adverse environmental impacts.
So why should people today prefer biogas plants in their homes? Precisely because of its zero or low cost fuels, low gestation period, quicker benefits, social relevance and economic viability, besides providing security to developing economies. The biogas energy is comparatively cheaper as compared to conventional sources.
Biogas plants can be easily installed in remote tribal areas where electricity is not viable and/or available. It can also help in the reduction of indiscriminate felling of trees for fuel and consequent deforestation, besides improving rural sanitation and reducing the incidences of eye-diseases among the village women and children. biogas plants, if installed in the rural remote areas, offers huge employment for the less-skilled rural people.
Speaking to this reporter, the ZAO Canacona, Mr Rajesh Desai informed that biogas production, like the septic tank, is an anaerobic digestive process, which is the simplest and safest way for treating human excreta and animal manure to prevent the spread of diseases. He also informed that it converts these renewable resources to a clean fuel to replace other conventional fuels. When burnt, biogas gives a blue flame which may be used for cooking, lighting as well as alternative fuel for petrol and diesel engines.
Mr Desai points out that biogas technology also reduces the build-up of carbon dioxide in the atmosphere and reduces the smoke in the area. He further tells that a biogas plant is an asset to a farmer’s family, because it is based on the biological decomposition of organic materials in the absence of air. Since India has the largest cattle population in the world, this strategy can work and is viable to the Indian rural community in particular.
Mr Desai further informs that there shouldn’t be big trees near the selected sites for the installation of biogas plants since this may prevent the sun’s rays from falling on the plant. The roots, too, may cause damage.
The ground water level should be at least 2-3 metres below the surface and the selected site shouldn’t have in its vicinity a drinking water well, for at least 50 feet around. There should be enough space for storage of digested slurry pits or construction of compost pits, Mr Desai asserted.
Mr Desai also pointed out that septic tanks can be connected to biogas plants.  He confirmed that in Belgaum, most of the septic tanks have been connected to biogas plants.
Moreover, the government gives 90 per cent subsidy for the construction of a biogas plant. On an average per day, 15-25 kg of cow dung is sufficient to run a domestic biogas unit in one household.
Today, in Canacona taluka, there are more than 50 installations of biogas plants.

Source: http://www.navhindtimes.in/south-goa-monitor/biogas-sustainable-future

Biogas power plant design and construction

 Biogas power plant design and construction

A Biogas, Bio bio gas, or gobar gas plant uses the process of biological fermentation to generate renewable electricity and heat. It ferments natural waste products and energy crops to generate green energy.

Biogas, Bio bio gas, or gobar gas plants have an important place in a sustainable energy policy. This is because they have some important advantages that other alternative forms of energy such as solar power and wind power do not have.

- Highest energy efficiency: Biogas, Bio bio gas, or gobar gas is converted in a combined heat-& power coupling (CHP), with an efficiency of 85%.
- Continuous operation: The anaerobic fermentation is a biological process that occurs continuously
- Waste: Various wet waste flows can be processed into energy
- Flexibility: Flows from different sources can be processed together

Input

The starting point for each project is always based on the input flows that are available on-site and in the region. There are many different input flows that can be fermented:

·         Energy crops such as corn, beet, ...

·         Manure from pigs, chickens, ...

·         Organic Biological Secondary flows and products

·         Organic sludge

All organic biodegradable flows in the plant can be inserted and that a similar Biogas, Bio bio gas, or gobar gas potential without hazardous waste to be.

Fermentation in the Biogas, Bio bio gas, or gobar gas power plant

Through parallel fermenters, the Biogas, Bio bio gas, or gobar gas can be derived from the composition of input streams. The Agri-bio power plant uses wet fermentation, which means that the input flow has a minimum humidity of 40% and the reactor contents has dry matter percentage of maximum 12%.

Output

As mentioned above, after fermentation the Biogas, Bio bio gas, or gobar gas plant generates 3 outputs(*).

Electricity: the electricity that is generated can lower or eliminate your energy bill. Excess electricity can be resold on the electricity grid. This means that a Agri-bio power plant can convert your waste into electricity!

Heat: the heat generated during the combustion of Biogas, Bio bio gas, or gobar gas can be used for use in other processes that require significant heat.

Digestate: The digestate can be transformed into pellets suitable for fertilization of the fields or energy. In this way nothing is lost and we can turn this flow into an economically valuable product.

(*) renewable CO2 is also possible, this means that the facility is eligable for CDM’s (clean development mechanisms)

Energy Alliance Agreement: innovative cooperation with benefits for both parties!

Apart from the obvious connection to the grid or the use of heat for the drying of the digestate, the En-Bio experience to draw up a so-called energy alliance. It is heat and / or electricity traded to a customer in the area, which both parties can obtain a more favorable rate.

Energy Alliance Agreement: innovative cooperation with benefits for both parties!

Apart from the obvious connection to the grid or the use of heat for the drying of the digestate, the En-Bio experience to draw up a so-called energy alliance. It is heat and / or electricity traded to a customer in the area, which both parties can obtain a more favorable rate.

Options

Option 1: After-treatment of the digestate

After fermentation of organic material remains on a digestate. It may also be appropriate for this digestate through after-treatment into economically valuable products, by drying or crushing.

Option 2: Injection of Biogas, Bio bio gas, or gobar gas in the natural gas network

Through a filtering installation, we can upgrade the Biogas, Bio bio gas, or gobar gas so that we obtain Biogas, Bio bio gas, or gobar gas with quality comparable to natural gas.

Option 3: Biofuel expansion

For a continuous supply of electricity and / or heat to ensure is often chosen for an extension with a dual fuel engine based on PPO.

Option 4: Use of Biogas, Bio bio gas, or gobar gas in transportation vehicle

Biogas, Bio bio gas, or gobar gas can also be used as fuel for vehicles. This allows your vehicles to driving on a renewable and ecological fuel that you produce yourself!

Reducing independence on electricity thanks to biogas

Reducing independence on electricity thanks to biogas

While the increasing electricity price and insufficient supply are creating many difficulties for enterprises due to lack of power for production, many farm owners are still at ease thanks to biogas. The proof is that the disposal of agricultural and industrial waste in combination with power generation has been applied quite effectively in many areas.

 Success from small scale…

As the most successful province in developing the model of using household scale biogas, up to now, Ninh Binh has had over 1,400 biogas pits for cooking, lighting and production. After three years of implementation, it has been estimated that the amount of saved fuel is 84kg of gas per household per year; the amount of saved electricity is about 50 kWh per month. The whole 1,400 households have saved VND 3.7 billion on gas and more than VND 1 billion on electricity. Each construction with the volume of 6-7 cubic meters costs more than VND 7 million, and the investment capital can be retrieved in just 2 years.

In Phu Tho, only from the fourth quarter of 2009 to the second quarter of 2010, the project "Building energy saving biogas model for household use in the province of Phu Tho” has built 240 biogas pits for households in the area. According to initial calculations, the project has provided an amount of clean energy equivalent to 4.8 TJ per year. This energy source can replace 420 tons of agricultural wastes for cooking, 600 tons of firewood, 60 tons of coal, 11.3 tons of kerosene, 67.5 MWh and 8 tons of liquefied gas. The total amount of saved money is nearly VND 2 billion.

The farm of Mr. Tran Xuan My, Phong Chau town, Phu Ninh district, Phu Tho, has saved 50% of electricity cost and 60% of diesel cost by using biogas generators. His farm is raising 1000 super-lean pigs; he has invested in building two large Biogas pits, a 100m3 pit and a 50m3 pit.

Similarly, Mr. Hoang Van Tam in Tan Thinh village, Hop Thinh commune, Ky Son district, Hoa Binh, has invested in an innovated biogas generator with the capacity of 2.5 KW, creating ​a ​great power source for expanding production. After investing in the biogas generator, each month, his family has saved VND 200 - 300,000 on electricity.

According to Mr. Nguyen Quang Khai, Director of the Biogas Technology Center, each household scale biogas construction can run a generator with the capacity of about 15 cubic meters and requires an investment of about VND 8-9 million. With this scale, a peasant family can comfortably use gas for cooking and lighting, and can even use devices with greater capacity, such as televisions, refrigerators, washing machines, water heaters, totally without dependence on grid power supply.

… to biogas in industry

As a closed food processing unit, from slaughterhouse to sausage factory, Duc Viet Foods JSC (Hanoi) is carrying out a project of a breeding complex in combination with the waste disposal system using German biogas technology to produce electricity, heat and fertilizer.

Each year, the slaughterhouse of the company receives about 120,000 marketed pigs. The Biogas plant of the company processes about 100,000 tons of waste per year. The amount of biogas generated from animal waste and other organic agricultural waste can produce 32 million kWh of electricity per year, enough to provide electricity for the entire farm, including systems of pumping, cooling, lighting, heating, sterilizing, cleaning, deodorizing, automatic food providing, drying and producing animal feed ... In addition, the biogas plant can also provide thousands of tons of high quality fertilizer to agricultural production.

Mr. Mai Huy Tan, director of Duc Viet Company, said the company would associate with a Germany company to build a biogas plant for farm waste treatment. The German side shall contribute capital by technologies and equipment, with revenue of CO2 emission reduction targets and retrieve investment capital by reselling this criterion. About the remaining capital, the company will contribute by shareholders’ capital and borrowed capital.

In addition, Duc Viet Foods JSC is also aiming to connect businesses in the Mekong Delta with European businesses to develop a large scale renewable bio-energy project by utilizing the sources of organic agricultural waste.

According to experts, the potential of applying biogas in production and agriculture in our country is still great. Many businesses have saved a large amount of cost thanks to this model, but in fact, the number of businesses interested in energy saving issues is still small. Many businesses are still using very low quality technologies which not only consume a lot of energy and raw materials but also lower product quality and increase prices. Therefore, while electricity price is still increasing, it is very necessary to encourage enterprises to invest in and renovate equipment using energy saving technologies.

By Minh Duc

Source:http://tietkiemnangluong.com.vn