BIO-GAS

Bio-Gas

Biogas is a clean and renewable energy source which substitutes, Diesel, LPG and CNG for cooking, steam generation, transportation fuel, electricity generation, etc., Biogas is a by-product generated during the decomposition of any kind of organic matter by means of anaerobic bacteria Substrates such as manure, sewage sludge, municipal solid waste, biodegradable wastes or feedstock are transformed into methane and carbon dioxide The use of biogas as a fuel happens because it reacts with oxygen and releases energy, which is clean in nature.

How to Generate Bio Gas

Biogas is generated by decomposition of any kind of ORGANIC WASTE by means of ANAEROBIC DIGESTION.

Organic Waste

It is Biodegradable waste such Food remains, Livestock manure, Sewage sludge, Yard waste.

Disposal Method

Anaerobic digestion

Aerobic Decomposition

Extra oxygen is available.

C6H12O6 + 6O2 → 6CO2 + 6H2O

Products: carbon dioxide and water vapor.

Anaerobic Decomposition

No additional oxygen, closed environment.

C6H12O6 → 3CO2 + 3CH4

Products: carbon dioxide and methane.

Combustion

Combustion converts methane into CO2

CH4 + 2O2 → CO2 + 2H2O

89% reduction in emissions.

Biogas Potential Of Organic Wastes

Carbon Waste

How much carbon the waste contains / How much of the waste decomposes.

CARBON-TO-NITROGEN (C/N) RATIO

  • Optimal ratios for decomposition: 16-30
  • Livestock manure: high in nitrogen (~3-10)
  • Food remains: high in carbon (~15)
  • Yard waste: very high in carbon (~35-400)

CHEMICAL OXYGEN DEMAND (COD)

  • 318 m3 of CH4 can be generated per ton of COD destroyed

VOLATILE SOLIDS DESTRUCTION

  • Degree of decomposition
  • Tends to be higher for food waste than sewage sludge or livestock manure

CO-DIGESTION

  • Common mix: manure + food/yard waste
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Decomposition Of Organic Waste

  • Biogas Composition mainly depends on the environment where decomposition occurs and the type of organic waste.
  • Biological Process is Breakdown By Microorganisms.Two main Products of process is Digestate and Biogas.

Digestate

Solid fraction is similar to late-stage compost, can be used as fertilizer with some further processing.

Typical Biogas Components

  • 45-75% methane (CH4)
  • 20-45% carbon dioxide (CO2)
  • Less than 5% (typically closer to 1%) of N2O, H2S & other gases

ANAEROBIC DIGESTION

  • Mimics natural decomposition process in a closed system.
  • Much more efficient decomposition (days vs. years in LF).

Temperature

  • Thermophilic (50-60°C)
  • Mesophilic (35-40°C)
  • Psychrophilic (15-25°C)

Feedstock type

  • Dry digesters (25-40% solids)
  • Wet digesters (<15% solids)

Digester setup

  • Continuous
  • Batch system

Complexity

  • Single-stage
  • Multi-stage

GREENHOUSE GASES

Global Warming Potential (GWP) is mass-based measure of how much heat the gas traps in the atmosphere, relative to carbon dioxide. GWP values are published by the Intergovernmental Panel on Climate Change (IPCC) gas Avg. GW

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GLOBAL WARMING POTENTIAL - GWP

  • Organic waste capacity s- 700kg/day
  • Biogas production calculated – 80m3/day
  • Biogas production per annum – 26400m3
  • CH4 % in Biogas - 58% avg.
  • CO2 % in Biogas – 32% avg.
  • Density of CH4 – 0.71kg/m3
  • Density of CO2 – 1.8kg/m3
  • CH4 production per annum – 1087.5 kg or 10.87 tons
  • CO2 production per annum – 15206.4 kg or 15.2 tons
  • CH4 is 21 times more potent than CO2 = 10.87* 21 = 228.27 tons
  • Total Emission (GWP)
  • 228.27 tons + 15.2 tons
  • 243.47 tons of CO2 Equivalent Emission.

GREENHOUSE GAS EMISSION REDUCTION

  • Burn a kilogram of CH4 and you get 2.75 kg of CO2.
  • Utilizing 10.87 tons of CH4 per annum emits 29.89 tons of CO2
  • Release a kilogram of CH4 and you get 1 kg of methane and the global warming effect of 1 kg of CH4, in the GWP scale, is 21.
  • The global warming effect of 1 kg of CO2, in the GWP scale, is 1.
  • So releasing the methane is 21/2.75 = 7.6 times worse than burning it, from a global warming point of view.
  • By Installing anaerobic digester & capturing biogas and utilizing the biogas in kitchen will bring down the emission reduction of CO2 from 243.47 tons to 45.1 tons per annum.