Biogas Plant

Introduction

Today we are facing severe environmental problems like climate change, greenhouse effects, energy crisis, depletion of natural resources, biodiversity loss, pollutions at various levels and so on. These problems range from local to global. The ever increasing population and changing lifestyles worsen environmental problems. The time has come to protect the natural environment through systematic efforts. As environmental sustainability is an increasingly important issue all over the world now, the role of higher educational institutions in relation to environmental sustainability becomes more prevalent. Education is something that binds many individuals together. It is through (higher) education we can come together and solve many problems in the society. Education also plays an important role in developing the modern society, bringing economic wealth, social prosperity and political stability in easy reach.

The Second Campus of Asutosh College which is dedicated to environmental research activities is also meant to build as a sustainable green campus. Various eco friendly initiatives are being taken to designate the campus as a Green Campus. Enhanced energy security and climate change mitigation are the main drivers for the transformation of the energy system from fossil to renewable sources. Biomass has to play a key role in this transformation to a low carbon economy. Worldwide, biomass (including putrescible waste and bio-wastes) accounts for more than two thirds of all renewable energy supplies. Among biomass sources, biogas is an interesting option with a large potential, offering many exciting possibilities to supplant and therefore reduce our dependence on fossil fuels.

To meet the increased demand for energy needs and to reduce greenhouse gas emissions, the capacity of worldwide installed renewable energy systems has been doubled over the last decade. This also applies to biogas as a source of renewable energy.

The bio-gas produced from food waste, decomposable organic material and kitchen waste, consisting of methane and a little amount of carbon-di-oxide is an alternative fuel for cooking gas (LPG). Methane is a very powerful greenhouse gas: its global warming potential it 23 times higher than that of CO2. In this way, recovering of biogas is very interesting to limit the greenhouse effect. Furthermore, biogas is a renewable energy form because biomass naturally releases biogas by decomposition. By using biogas as an energy source, we can reduce our dependency on fossil resources as coal, oil and natural gas. Also, the waste materials can be disposed off efficiently without any odour of flies and the digested slurry from the bio-gas unit can be used as organic manure in the garden.

A specific advantage of biogas technology is in the utilisation of organic wastes and other organic by-product for energy production, as opposed to disposal via landfills, which inevitably leads to further emissions of greenhouse gases by the process of slow decomposition.

In the mission to advancement of learning in a sustainable way and nurturing of Mother Nature, Asutosh College envisaged into the setting up of a Bio Gas Plant at the Second Campus. Most important and unique part of the plant is that it’s a single feed system. The plant is totally running on the food and kitchen waste generated in canteen located there. Vivekananda Institute of Biotechnology, Sri Ramakrishna Ashrama Nimpith, West Bengal lent their technical support in the formation of the plant.

THE BEGINNING

The Plant started working under leadership of Dr. Dipak Kumar Kar, Principal of the College, Dr. Subhayan Dutta, SACT in Environmental Science, and other members from 2013.

OBJECTIVE

  • Conversion of Waste to wealth
  • Production of Clean Energy
  • Maintenance of Hygiene & Environment
  • Generation of Nutrient rich fertilizer

COMPONENTS OF THE BIO�GAS PLANT

  • Empty PVC can 50 ltrs capacity: 1 No. ( to be used as Digester tanker)
  • Empty PVC can 40 ltrs capacity: 1 No. (to be used as Gas Holder Tank) (Make sure the smaller can fits inside larger one and moves freely)
  • 64 mm diapvc pipe : about 40 cm long ( to be used for feeding waste material)
  • 32 mm diapvc pipe: about 50 cm long (fixed inside gas holder tank as a guide pipe)
  • 25 mm diapvc pipe: about 75 cm long (fixed inside the digester tank as a guide pipe)
  • 32 mm diapvc pipe: about 25 cm long ( fixed on digester tank to act as outlet for digested slurry)
  • M-seal or any water proof adhesive.
  • Gas outlet system: Please see Step 4 below for required materials and constructions.
  • A single burner bio-gas stove.

50 ltrs capacity PVC can, which will act as the digester unit and removed the tio portion of the can, by cutting it with a hack saw blade, The smaller white can, will act as a the gas holder 64 mm, 32 mm and 25 mm dia PVC pipes which will be used for feeding the kitchen waste, guide pipe for the gas holder and gude pipe fixed with the digestion chamber respectively. A small piece of 32 mm dia pipe will be used as outlet for the slurry:

ITEMS REQUIRED FOR THE GAS DELIVERY SYSTEM

  • Ball valve : one no ( to adjust the gas flow)
  • “T” joint : one no ( to connect the gas holder and the ball valve)
  • Cap to block one end of “T” joint : one no
  • Coupling or adapter: one no ( to connect vertical end of “T” into the gas collector)
  • Nipple: one no (added to the coupling into the gas collector)
  • Gas pipe (flexible) : two meters
  • Barb: one no (fitted with the gas pipe, to join with the ball valve.
  • Clip: one no (used for crimping the barb with the gas pipe and make it leak-proof.
  • Teflon tape : One roll (used as thread tape in all joints)

Initially, cow dung mixed with water will be fed in to the system, which will start the gas formation process. Subsequently, food waste, decomposable organic material and kitchen waste will be diluted with water and used to feed the system. The gas holder will rise along the guide pipes based on the amount of gas produced. We can add some weight on the top of the gas holder to increase the gas pressure. When we feed the system, the excess digested slurry will fall out through the outlet pipe, which can be collected, diluted and used as organic manure.

USE

Initial production of gas will consist of oxygen, methane, carbon-di-oxide and some other gases and will not burn. These gases can be released to the atmosphere by opening the ball valve at least three/four times.

Subsequent gas will consist of about 70 to 80 percent and the rest carbon-di-oxide, which can be used in a single bio-gas stove.