Biochemical Routes & Biofuels

Biochemical Routes

National Policy on Biofuels 2018

Salient Features:
- Target: 20% blending of ethanol in petrol and 5% blending of biodiesel in diesel by 2030.
- Focus on Advanced Biofuels: Viability gap funding scheme for 2G ethanol Bio refineries of $Rs.5000$ crore over 6 years.
  - Includes additional tax incentives and higher purchase price compared to 1G biofuels.
- Categorization of Biofuels:
  - Basic Biofuels: First generation (1G) - Bioethanol & biodiesel.
  - Advanced Biofuels: Second Generation (2G) - ethanol, drop-in fuels, algae-based Third Generation (3G) Biofuels.
- Expanded Raw Material Scope: Encouraging Intermediate (B-Molasses), Sugarcane Juice, other Sugar-containing materials, and damaged/surplus food grains for ethanol procurement.
- National Biomass Repository: Develop by conducting appraisal of biomass across the country.
- Biodiesel Production: Encouraged from non-edible oilseeds, used cooking oil, short gestation crops, and development of supply chain mechanisms.
- Research & Development: Thrust on research, development, and demonstration in Biofuel feedstock production and advanced conversion technologies.
- National Biofuel Coordination Committee (NBCC): Setting up under the Ministry of Petroleum & Natural Gas and a Working Group on Biofuels.
Biofuel: $C2H5OH$

Biofuels Composition

First Generation: Food-related sources
Second Generation: Non-food sources
Third Generation: Algae
Fourth Generation: Other sources

Generations of Biofuels

First Generation:
- Source: Derived from edible plants grown on arable land.
- Production: Ethanol and butanol produced via yeast fermentation.
- Examples: Wheat, sugar cane, and oily seeds.
- Cons: Potential reason for spikes in food prices and net energy negative.
Second Generation:
- Source: Produced from non-edible crops grown on non-arable land.
- Characteristics: High lignocellulosic content (wood and organic waste).
- Pros: Potential to be net energy positive.
Third Generation:
- Source: Produced from algae and other microorganisms.
- Characteristics: Resilient organisms grown from sunlight, $CO_2$ , and brackish water.
- Pros: Does not use arable land, fastest-growing biofuel source, potentially carbon neutral.
Fourth Generation:
- Method: Genetic engineering of organisms for efficient biofuel production.
- Focus: Altering lipid characteristics and introducing lipid excretion pathways.
- Aim: To be carbon negative by creating artificial carbon sinks.

Other Compost Related

Composting
Anaerobic digestion - Bio gas
Methane from biogas and compression - BioCNG
Ethanol production Biochemical routes

Composting

Definition: Controlled biological decomposition of organic materials.
- Biological degradation process of heterogeneous solid organic materials.
- Conditions: Controlled moist, self-heating, and aerobic to obtain a stable material that can be used as organic fertilizer.
Organic farming examples: Sikkim, Uttarakhand.
Humic Breakdown: Breakdown products from one microbe type serve as food/energy for another microbe type.
- Chain of succession continues until little decomposable organic material remains.
Microbial Dynamics:
- Depletion: If preferred organic substrate is depleted/unavailable, certain microbes may reduce in numbers, go dormant, or die off.
- Competition: Occurs between microbe groups.
- Dominance: Dominant groups emerge based on compost pile conditions.
- Succession: Continues as long as adequate decomposable organic matter is present.
Process Control:
- Natural biological process.
- Requires controlled environmental conditions (engineering input) for rapid composting and consistent quality.
End Product:
- Bears little resemblance to original wastes.
- Typically dark brown to black in color.
Volume Reduction: Typical reductions exceed 50% of the original waste volume, making it an effective waste diversion strategy.
Safety: Good compost is devoid of organisms harmful to human health.
Composition of Stable End Product (Compost):
1. Living/dead microbial cells and cell fragments.
2. Byproducts of microbial decomposition.
3. Undecomposed particles (organic and inorganic).
Finished Compost Characteristics:
- Humus-like, resembling rich topsoil.
- Resistant to further microbial decomposition.
Uses of Compost
- Valuable soil amendment due to high organic matter content.
- Low-grade fertilizer to supplement plant nutritional needs.
- Soil conditioning for heavy clay or mineral soils.
- Promotes proper balance between air and water in soils.
- Aids water infiltration, absorption, and ion exchange in soils.
Why Composting?
- Organic Waste Percentage: About 70% of municipal waste is normally organic.
- Problems with Organic Waste: Can cause smell, leachate, gas, and stray animals in landfills.
- Recycling at Source: Most economic and environment-friendly method of waste management.
- Compost Value: Valuable resource for farmers.
- Source Separation: Keeps inorganic waste clean, making it easier for recycling.
What Can Be Composted?
- Potential Candidates: Any waste material with a high organic matter content.
- Historical Use: Used for centuries to stabilize human and animal wastes.
- Modern Uses:
  - Sewage sludge
  - Industrial wastes (food, pulp & paper etc.)
  - Yard and garden wastes
  - Municipal solid wastes (up to 70% organic matter by weight)
Advantages and Disadvantages of Composting
- Advantages:
  - Segregation and recycling at the source.
  - Economic and environment-friendly waste management.
  - Simple methods available.
  - Compost is a valuable resource for gardeners/farmers.
- Disadvantages:
  - Waste segregation at a large scale is required.
  - Slow process.
Composting Concept
- Definition: Process of decomposition of organic waste by microorganisms.
- Natural Process: Can be made faster and more effective by mixing various types of waste and adjusting moisture, temperature, and aeration.
- Nutrient Content: Contains NPK and other plant nutrients, including microorganisms.
- Steps of Composting:
  - Preparation (segregation and sizing).
  - Production of compost.
  - Marketing (may be included).
Composting Preparation
- Waste collection
- Sorting into organic and inorganic
- Reduction of size if necessary
- Adjustment of moisture content
- Adjustment of $C:N$ ratio
Controlling Composting
- Environmental Conditions: Certain environmental conditions must be maintained in the compost pile to maximize composting.
- Classifications: Interdependent biological, physical, and chemical conditions/environments.

Biological Environment

Key Organisms:
- Bacteria and Fungi: Play an active role in decomposing organic matter.
Secondary Organisms:
- Earthworms, insects, other soil invertebrates: Play a less significant role in the decomposition process compared to microorganisms.
- Importance: More important in the mechanical breakdown of wastes (chewing, burrowing, movement, aeration).
Microbial Consumption:
- Carbon-containing compounds are consumed by microorganisms and converted to:
  - Microbial tissues
  - Carbon dioxide
  - Water
  - Humic breakdown products
- Heat Release: Released as a result of microbial metabolic activity, increasing temperature in the pile.
Microorganism Availability:
- A wide variety of microorganisms are naturally present in most nontoxic agricultural wastes, yard wastes, or mixed municipal wastes.
- Limiting Factor: Number and type of available organisms generally not a limiting factor.
- Predominance: Depending on environmental conditions, certain microbial groups may predominate at certain stages in the decomposition process.

Chemical Environment

Influence: Largely determined by the composition of the waste materials to be composted.
Important Factors:
- Adequate food / energy sources for microorganisms.
- Balanced amount of nutrients.
- Adequate water content.
- Adequate oxygen.
- Acceptable $pH$ range.
- Lack of toxic substances that could inhibit microbial activity.
Food / Energy Sources for Compost Microbes
- Energy Needs: Microbes rely on organic carbon compounds to meet energy needs.
- Degradability: Carbon in natural or synthetic organic substances varies in degradability.
  - Sugars: Easily metabolized by most microbes.
  - Lignins: Degraded more slowly, by fewer groups.
  - Plastics: Very resistant to breakdown.
Decomposition Process:
- Small Portion: Carbon goes into microbial cells.
- Large Portion: Carbon converted to $CO_2$ and lost to the atmosphere.
- Result: Reduction in weight and volume of waste.
Resistant Carbon Compounds:
- Form the matrix for the physical structure of finished compost.
Waste Adequacy: Most municipal, yard, and agricultural wastes have adequate biodegradable carbon to support microbial activity.
Nutrients for Compost Microbes
- Most Important: Nitrogen, phosphorus, and potassium.
- Limiting Nutrient: Nitrogen is usually the limiting nutrient.
- $C:N$ Ratio: Critical in determining the rate of decomposition.
Typical $C:N$ ratios for waste products:
- Manure - $15:1$ to $20:1$
- Yard wastes - $20:1$ to $80:1$
- Municipal wastes - $40:1$ to $100:1$
- Wood chips - $400:1$ to $700:1$
- $C:N$ ratio established on the basis of decomposable rather than total carbon.
- Ratio lower than $30:1$ is desirable
- Higher ratios result in slower decomposition rates
- Adjusted by co-composting with different materials
Composting Progress:
- Carbon dioxide is lost to the atmosphere.
- $C:N$ ratio narrows.
- Finished compost has a $C:N$ ratio between $10:1$ and $15:1$
Moisture in Compost Piles
- Ideal moisture: $50\%$ to $60\%$ by weight.
- Most wastes do not contain enough moisture.
- Slowing: Composting process slows down unless water is added.
- Excess Water: Causes leachate generation, anaerobic conditions, rotting, and obnoxious odors.
- Moisture Loss: Occurs through evaporation.
- Control: Controlled by adjusting the size and shape of the compost pile.
Oxygen in Compost Piles
- Requirement: Aerobic decomposition is required for odor-free, rapid composting.
- Pile Structure: Should have enough void space to allow gas exchange with the atmosphere.
- Concentration: $5\%$ to $15\%$ oxygen concentration is considered adequate.
- Aeration: Piles aerated by mechanical turning or air injection.
$pH$ in Compost Piles
- Ideal $pH$ : $6 - 8$
- Level of acidity / alkalinity affects nutrient availability, solubility of (potentially toxic) heavy metals and overall metabolic activity of microbes
- Adjustment: $pH$ may be adjusted upwards by the addition of lime (calcium carbonate).
- Buffering: Most organic substances are naturally well-buffered with regard to $pH$ change.
- Acidification: Slight tendency towards acidification as compost matures, due to production of carbonic acid.

Physical Environment

Includes factors such as:
- Particle size
- Temperature
- Mixing
- Pile size and shape
Physical Environment: Particle Size
- Small Particle Size: Promotes rapid decomposition due to increased surface area-to-volume ratio.
- Density: If all the particles are small, they pack together and create dense, anaerobic compost.
- Balance: Particles should have enough surface area to promote microbial activity, but have enough air spaces to permit gas exchange with the atmosphere.
- Mixing: Used to achieve better balance of particle sizes (e.g. small-particle sewage sludge mixed with large-particle wood chips).
- Size Reduction: Grinding is occasionally done before composting; sometimes undertaken after composting to improve the aesthetic appeal of finished product.
Temperatures in the Compost Pile
- Different Microbes: Have different optimal temperature ranges:
  - psychrophiles (cool - below $20$ $^o C$ )
  - mesophiles (warm - $20^o$ to $40^o C$ )
  - thermophiles (hot - $40^o$ to $80^o C$ )
- Sub-optimal Temperatures: Interfere with metabolic activity and reproduction of microbes.
Temperatures in the Compost Pile
- Maximum Threshold: As temperatures increase above the maximum threshold, cell proteins are destroyed and the microbes die.
- Effective Range: Most effective temperature range for efficient composting is $55^o$ to $75^o C$ (thermophile range).
Thermophile
- Promote rapid decomposition
- Destroy pathogens
Pathogen Destruction: Temperatures in excess of $55^o C$ are required for at least 3 days to ensure pathogen destruction
Insulation: If compost pile is large enough, internal heat will allow composting in subzero conditions as well

Composting Techniques

Small-scale home composting:
- Simple compost heaps
- Box or barrel composters
- Commercial composter units
Commercial composting:
- Windrows
- Aerated static piles
- In-vessel composting systems
Processing of Municipal Waste
- Removal of bulky items
- Particle size reduction (grinders, shear shredders, hammer mills)
- Screening (size requirements)
- Magnetic separation
- Moisture addition and mixing
- Composting –Windrows, Aerated static piles, In-vessel composting system
- Post processing: screening, curing, storage, marketing, application

Biochemical Conversion: Anaerobic Process

The process makes use micro-organisms to break down biomass to produce liquid and gaseous products.
Under anaerobic condition biogas and ethanol production are two prominent end products.
Anaerobic digestion/process
- The treatment is done in absence of oxygen (anaerobic).
- In India, anaerobic digestion plants are commonly known as Gobar Gas Plants. In such plants slurry of cow dung and water is fed to the digester and allowed for 4-6 weeks residence time.
- In India resultant gas, without any treatment, is used for domestic cooking/small engines
- Recently GOI started BioCNG concept
Biogas history
- 1776 : Marsh gas, By Volta
- 1808 : Humphry Davy, Methane
- 1859 : Leper colony, Mumbai, Digester
- 1895 : Gas lamps in Exeter, England
- 1907 : First Patent in Germany
- 1930 : R&D activity started
- 1980s: Government of India-biogas mission-did not work, family and community size
- 2018 : Gobardhan Yojna

Opportunity

Large amount of agricultural and forest residues available (600 - 700 MT)
Total number of Livestock : $535.8$ million
Animal dung: $800 - 1000$ MT per annum
Approximate biogas generation from animal dung : $30-35$ $BNm^3$
Present annual CNG consumption: 67 $BNm^3$
Sewer plants in India: 1,841 with1095 operational 26,840 MLD
Industries with high BOD effluents - distilleries, 2.7 BL; 285 milk processing, sugar, post harvest industries etc.
Biomass is a $CO_2$ neutral resource
Biogas production is environment friendly
European countries have taken a big lead

Why biogas in India?

Import reduction of natural gas and crude
A boost towards fulfillment of national commitments in achieving climate change goals - 2005 levels by 2030
Providing a buffer against energy security concerns and crude/gas price fluctuations
Lowering pollution and carbon emissions
Contribution towards Swachh Bharat Mission-Gramin under Gobar-Dhan scheme through responsible waste management. 15 MMT CBG by 2023 with 5000 plants having 2000 kg/day minimum capacity
Providing additional source of revenue to the farmers, rural employment and amelioration of the rural economy
Average biogas production from different feed stocks:
- Dung: $350$ Litre /kg of dry matter, $60\%$ Methane content
- Night-soil: $400$ Litre /kg of dry matter, $65\%$ Methane content
- Poultry manure: $440$ Litre /kg of dry matter, $65\%$ Methane content
- Dry leaf: $450$ Litre /kg of dry matter, $44\%$ Methane content
- Sugar cane trash: $750$ Litre /kg of dry matter, $45\%$ Methane content
- Maize straw: $800$ Litre /kg of dry matter, $46\%$ Methane content
- Wheat straw powder: $930$ Litre /kg of dry matter, $46\%$ Methane content
- *Average gas production from dung may be taken as 40 lit/kg of fresh dung
Typical composition of biogas
- Methane: $50-70\%$ Volume
- Carbon dioxide: $25-50\%$ Volume
- Moisture: Saturation level, max @ $30$ $^o C$ $47 g/Nm^3$
- Nitrogen: $0.4-1.2\%$ Volume
- Hydrogen: $0-0.4\%$ Volume
- Hydrogen sulphide: $50-2200$ $mg/Nm^3$
- Oxygen: $0-0.4\%$ Volume
- Ammonia: $10-40$ $mg/Nm^3$
Stages in Biogas Production
- BIOLOGICAL AND CHEMICAL STAGES OF ANAEROBIC DIGESTION
  - Hydrolysis: Complex molecules break down to simpler molecules
  - Acidogenesis: Carbonic acid etc.
  - Acetogenesis: Acetic acid, Hydrogen?
  - Methanogenesis: Methane and carbon dioxide gas forming
Indian biogas scenario: Gobar based
- DUNG + WATER -> BIOGAS PLANT -> BIOGAS + SLUDGE
  - BIOGAS -> DOMESTIC COOKING, FUEL FOR KILNS & FURNACES, FUEL FOR BIOGAS IC ENGINE
  - SLUDGE -> TO MANURE
Types of biogas plants
1. Fixed dome type (Janta design)
2. Floating dome type
COMPARISON OF FIXED AND FLOATING DOME BIOGAS PLANTS
- Janta/Fixed dome type
  1. Gas is released at variable pressure
  2. Identifying defects is difficult
  3. Cost of maintenance is low
  4. Capital cost is low
  5. Space above the drum can be used
  6. Temperature is high during winter
  7. Life span is comparatively longer
  8. Requires move excavation work
- Floating Dome type Biogas Plant
  1. Gas is released at constant pressure
  2. Identifying the defects in the gas holder easy
  3. Cost of maintenance is high
  4. Capital cost is high (for same capacity)
  5. Floating drum does not allow the use of space for other purpose
  6. Temperature is low during winter
  7. Life is short
  8. Requires relatively less excavation
ADVANTAGES AND DISADVANTAGES OF FLOATING DOME DESIGN
- Advantages
  - The slurry is constantly submerged below the dome.
  - The pressure is naturally equalised.
  - No danger of excessive pressure.
  - No danger of mixing between biogas and external air. Hence no danger of explosion.
  - Gas is obtained at uniform and constant pressure.
  - Gas does not leak through the dome as the slurry provides natural screen.
- Disadvantages
  - Higher cost due to fabricated dome construction.
  - Dome upper surface is exposed to sunlight and external atmosphere. The heat is lost during winters.
  - The outlet pipe between the floating dome and fixed external connection should be of flexible hose type. It is subjected to sun rays, rain and movement. It needs regular attention and maintenance.
SIZES OF BIOGAS PLANTS
- Very small Biogas plant: $0.65$ $m^3$ /day - For small family of 3 members having 2 cattle.
- Small biogas plant: 2 $m^3$ /day - For family of 6 members having 8 cattle.
- Medium (family size) biogas plant: 3 $m^3$ /day 1.6 m dia, 4.2 m heightFor family of 12 persons having 12 heads of cattle.
- Large (farm size) biogas plant: 6 $m^3$ /day 3.3 m dia, 4.65 m heightFor a farm having poultry diary etc., 20 cattle.
- Very Large (community size) 2600 $m^3$ /day 1000 $m^3$ Cattle 1000
Modern biogas plants - Capacity
- Raw Material
  - Cow dung 110 MT /day
  - Press Mud
  - Fruit-Vegetable Waste
- Raw biogas production ~10000 $Nm^3$ /day
- Bio-Fertilizer (Dry) production 21000 kg/day
- BioCNG production 4000 kg/day
  - Project cost: 6.00 crores
Available technological options for BioCNG production
1. Physical scrubbing
2. Chemical scrubbing
3. Pressure swing adsorption
4. Membrane separation
5. Cryogenic separation
Physical Scrubbing
- Selexol: Dow Chemicals, Dimethyl ether of polyethyelene glycol
- Genesorb: Clariant , Polyethylene glycol dialkyl ethers
Chemical Scrubbing
- Working Principle
 - $CO2$ is more reactive than $CH4$
 - Raw biogas flow through a counter flow of a chemical solution in a column
 - Reaction rate between $CO_2$ and chemical solution is directly proportional with temperature
 - Chemical solution absorbs $CO2$ leaving biogas with high content of $CH4$
- Type of Chemical
 - Mono ethanol amine (MEA) or di-methyl ethanol amine (DMEA) for amine scrubbing
 - Alkaline solution for inorganic solvent scrubbing
 - Different type of solution resulting in different $CH_4$ purity
- Current Status: As of 2015, 88 plants were operated
- Feature
 - Power demand (\/m^3 biogas): 0.42
 - Pre-treatment: $H_2S$
 - Operation pressure (MPa): 0.1-0.2
 - Outlet Pressure (MPa): 0.4-0.5
 - Temperature ( $^oC$ ): Up to 180
 - $CH_4$ losses (\%): <1
 - $CH_4$ purity (\%): >99
- Advantages
 - More $CO_2$ dissolved per unit volume
 - High methane purity
 - Low methane loss
 - Faster process than physical scrubbing
- Disadvantages
 - High energy needed to produce steam
 - Pre-treatment required
 - Difficulties in handling solvent
 - Salt precipitation, foaming and poisoning of amine
Pressure Swing Adsorption
- Working Principle
 - $CO_2$ adsorb on surface of an adsorbent by the van der Waals forces
 - Pressure increase result in gas adsorbed and vice versa
 - Four steps: adsorption, depressurization, desorption and pressurization
- Adsorption Techniques
 - Pressure swing adsorption (PSA)
 - Temperature swing adsorption (TSA)
 - Electrical swing adsorption (ESA)
- Adsorbent Material
 - PSA: Carbon, zeolites
 - TSA: Carbon cryogel microspheres (CCM) and carbon xerogel microspheres (CXM)
 - ESA: Activated carbon
- Current Status
 - Fourth most operated biogas upgrading techniques with 88 units operating (data from 2015)
- Feature
 - Power demand ($\/m^3 $biogas): 0.25</li> <li>Pre-treatment: H2S</li> <li>Operation pressure (MPa): 0.4-1</li> <li>Outlet Pressure (MPa): 0.4-0.5</li> <li>Temperature ($ ^oC $):</li> <li>$ CH_4 losses (\%): <4
 - CH_4 purity (\%): 96-98
- Advantages
 - High gas quality
 - Low methane losses
 - Dry process
 - Low energy demand
 - No chemical use
- Disadvantages
 - Complex process
 - Pre-treatment needed
Membrane Separation
- Working Principle: Separation of biogas components using membrane as permeable material
- Current Status
 - Joint second with chemical scrubber for most operated biogas unit as of 2015 with 88 units operating
- Feature
 - Power Demand ($\/m^3 biogas): 0.50
 - Pre-treatment: Yes
 - Pressure (MPa): 0.5-0.8
 - Outlet Pressure (MPa): 0.4-0.6
 - $CH_4$ losses: <1 $\%$
 - $CH_4$ purity: 92-96 $\%$
- Advantages
 - Environmental friendly
 - Low energy consumption
 - Low cost
 - Simple process
- Disadvantages
 - Low membrane selectivity
 - Pre-treatment necessary
 - Low $CH_4$ purity
Cryogenic Separation
- Working Principle: Different gases condense at different temperature-pressure domains
 - Current Status
 - Only one operating unit making it the most underutilized technique
- Feature
 - Power demand: n/a
 - Pre-treatment: $H_2O$
 - Operation pressure (MPa): 1-8
 - Outlet pressure (MPa): 0.8-1
 - Temperature ( $^oC$ ): -25~-110
 - $CH_4$ losses (\%): <2
 - $CH_4$ purity (\%): 97-98
- Advantages
 - High gas quality
 - Produce LBM with low extra energy
 - Low methane losses
 - Environmentally friendly
- Disadvantages
 - High investment and operational cost
 - Pre-treatment needed
 - High energy required for cooling
 - Technology is still under development
$CO_2$ removal plants technology in EU countries In India Water Scrubbing is being Implemented
- Total no. of plants: $17$
- Total capacity : 46, 000 kg/day
- Community kitchens
Biogas to Bio CNG - A new concept
- CNG Pipeline Biogas plant Liquid CO2 Gas holder Filtering cum moisture removing unit Compressor Condenser cum separator II Compressor Compressor Cylinder cascade/ small cylinder Biogas plant CW in CW out Odorization CGD Pipeline Condenser cum separator I Liquid (H2S+ NH3)
Developed process - Salient features
- Biogas is subjected to stepwise compression to a specific pressure and temperature range
- No additional chemicals required
- $NH3$ , $H2S$ and $CO_2$ are obtained in liquid forms
- No cryogenic temperature requirement
- Minimum methane loss
- Energy efficient process since the resultant gas is required to be compressed for CNG pipeline injection or filling of cascade of cylinders
The hydrogen sulphide to sulphur as per Claus process
- Reaction: $2 H2S + 3 O2 \rightarrow 2 SO2 + 2 H2O$
- Reaction: $4 H2S + 2 SO2 \rightarrow 3 S2 + 4 H2O$
- Bio CNG injection into CGD/CNG pipeline network The Bio CNG available from Condenser cum Separator II is mixed with Odorizer (ethyl mercaptan) and then can be injected into Primary network of City Gas Distribution (CGD) pipeline network.
- The pressure reduction to a level of 19-26 kg/cm2 may be required depending upon the existing pipeline network pressure requirement.
- The Bio CNG available from Condenser cum Separator II can be injected into main pipeline net work of CNG being operated by GAIL or other company. For this additional compression to a level of 100 kg/cm2 is required to be done.
Bio CNG filling in cascade of cylinders
- The Bio CNG is required to be filled in the cascade of cylinders (50 L water capacity) for supplying to Oil Distribution Companies. For this further compression of the Bio CNG is required.
- The pressure required is in the range of 200 to 250 kg/cm2 .
- The small capacity (5 L water having 0.6 kg of CNG) cylinders used for scooters and motorcycles can also be filled with the same pressure rating i.e., 200 to 250 kg/cm2 .
The $CO_2$ - Supply modes
- Sizes Cylinder: 50 L Cylinder bundles: 15 interconnected 50 L $CO_2$ cylinders
- Bulk $CO_2$ Liquid carbon dioxide can be delivered in liquid form, into onsite storage, for use in high-volume customer applications. Carbon dioxide is stored as a liquid in specialized vessels which can provide several days supply and may be used on demand as either a liquid or gas.
Liquid carbon dioxide gas uses
- Food industry Food chilling and freezing, carbonation and dispensing of beverages, for food extraction, modified atmosphere packaging.
- Welding Metal Inert Gas (MIG) welding - mild steel, carbon and alloy steel, shielding gas in plasma cutting
Liquid carbon dioxide gas uses
- Precision Sand casting
- Water treatment Drinking water treatment and waste water $pH$ control
- Chemical industry Carbon capture and storage (CCS), carbon capture and utilization (CCU), replacement for CFC’s in foamed plastics production Boosting production in greenhouses and pest control
Liquid carbon dioxide gas recovery
- Liquid $CO2$ recovery Plant capacity : 4,500 kg/day of Bio CNG Bio Gas plant capacity : 12,500 $Nm^3$ /day Liquid $CO2$ production : 12,200 kg/day
- Revenue from Bio CNG: @48/kg = Rs 2,16,000/day
- $CO_2$ : @10/kg = Rs 1,20,000/day @30/kg = Rs 3,60,000/day Payback period = ? Rate of CNG today in Delhi: Rs 69.11/kg
IS 16087:2013/2016 (Revised) Specifications
- $CH_4$ , percent, Min 90
- Moisture, $mg/m^3$ , Max 16
- $H_2S$ , $mg/m^3$ , Max 30.3
- $CO2+N2+O_2$ , percent, Max (v/v) 10
- $CO_2$ , percent, Max (v/v) 4 (when intended for filling in cylinders)
- $O_2$ , percent, Max (v/v) 0.5