Renewable Renewable ResourcesResources

Biogas Biogas

The All NaturalThe All Natural

GasGas

I. Where is biogas used:I. Where is biogas used:

Biogas has been used all over the Biogas has been used all over the world.world.

It is primarily used by farmers and It is primarily used by farmers and in rural areas to reduce costs of in rural areas to reduce costs of cities powering stationscities powering stations

Becoming more popular in higher Becoming more popular in higher populated areas.populated areas.

II. What is the raw II. What is the raw material for producing material for producing biogasbiogas??

Biodegradable Waste Materials:Biodegradable Waste Materials: Poultry Manure Poultry Manure Human ManureHuman Manure Poultry Offal (the blood, guts and gore)Poultry Offal (the blood, guts and gore) Commercial Food Waste StreamsCommercial Food Waste Streams

Onions, green beans, potatoes, Onions, green beans, potatoes, cooking oils, cheese wastes, eggs and cooking oils, cheese wastes, eggs and graingrain

Fat: 3.5 - 7.5 %Fat: 3.5 - 7.5 % Protein: 13.7-15.6 %Protein: 13.7-15.6 % Carbohydrates: 59.9-62.1 %Carbohydrates: 59.9-62.1 % Cellulose: 14.5-25.0 %Cellulose: 14.5-25.0 % Hemicellulose: 2.0-19.3 %Hemicellulose: 2.0-19.3 % Lignin: 6.8- 9.0 %Lignin: 6.8- 9.0 % Inerts: 16.0-29.0 %Inerts: 16.0-29.0 % Total ~12% total solids 11% volatile solids Total ~12% total solids 11% volatile solids

Typical Raw Material Typical Raw Material Composition : Cow ManureComposition : Cow Manure

III. What are the III. What are the technological limitations technological limitations

of the resource?of the resource?

Supply of raw material: variation of Supply of raw material: variation of the capacity and the qualitythe capacity and the quality

Processing technology: Relatively slow Processing technology: Relatively slow process and limited productivity. Could process and limited productivity. Could not be treated as usual production not be treated as usual production process (automation, etc.)process (automation, etc.)

Require future research to improve the Require future research to improve the technology, that can substitute the technology, that can substitute the conventional fuel.conventional fuel.

Biochemical Process: Anaerobic Digestion

Biological degradation of organic volatile solids in Biological degradation of organic volatile solids in the absence of oxygen: the absence of oxygen:

1. Hydrolysis1. Hydrolysis

2. Fermentation2. Fermentation

3. Acetogenesis3. Acetogenesis

4. Methanogenesis4. Methanogenesis Products of anaerobic digestion include water, Products of anaerobic digestion include water,

undigested volatile solids, inert materials and undigested volatile solids, inert materials and biogasbiogas

IV. Biogas Production

4.1. Anaerobic Digestion Process (1)4.1. Anaerobic Digestion Process (1) the raw organic residue (raw sewage, manure and other the raw organic residue (raw sewage, manure and other

such resources) that is required in this process is such resources) that is required in this process is converted to it usable energy state by bacteria breaking converted to it usable energy state by bacteria breaking down methanedown methane and releasing CO and releasing CO22, which is the energy , which is the energy source sought after in this conversion.source sought after in this conversion. Since it is a Since it is a cycling of carbon so it isn’t actually released into the cycling of carbon so it isn’t actually released into the atmosphere.atmosphere.

happens though a series of chemical breakdown happens though a series of chemical breakdown (see (see chart on next slide)chart on next slide)

required bacteria in this process, the raw material must required bacteria in this process, the raw material must be be belowbelow a temperature a temperature ofof 6060cc oror 140140F F . This helps the . This helps the material to be broken down material to be broken down

process is also naturally occurring as well. process is also naturally occurring as well.

Anaerobic Digestion Process (2)Anaerobic Digestion Process (2)

Anaerobic Digestion Process (3)Anaerobic Digestion Process (3)

4.2. Typical Anaerobic Digestion Process (Complete Mix)

WasteManure

De-Watering

De-Watering

Engine /Generator Set

Engine /Generator Set

CAPTURED WASTE HEAT

•Methanecapturedcarbon credits

•Slightly reduced N•P – 40-60%•Useable for on-farmfertilizer

•Bedding (on-farm) - or -•Compost / OrganicFertilizer

Anaerobic

Digester

AnaerobicDigester

Filtrate

Solids

•Peak production•Long-term contract•‘Green Tag’premium

ELECTRICITYBIOGAS

•NPK mineralized•Odor reduced•Pathogens, weedseeds controlled

DIGESTED MANURE

•Farm heat $offsets•Farm

refrigeration $offsets

Farm UseFarm Use

CAPTURING ADDED VALUE

4.3. Waste-to-Energy System Characteristics

Covered Lagoons: 0.5 -3.0% total solidsCovered Lagoons: 0.5 -3.0% total solids Complete Mix: 3-10% total solidsComplete Mix: 3-10% total solids Plug Flow: 10-13% total solidsPlug Flow: 10-13% total solids

Temperature Regimes:Temperature Regimes: Psychrophilic:Psychrophilic: 50- 77 F 50- 77 F Mesophylic: 77-104 FMesophylic: 77-104 F Thermophilic: 120-140 FThermophilic: 120-140 F

4.4. Types of Digesters4.4. Types of Digesters

0

5000

10000

15000

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Time (days)

Bio

gas

Pro

duct

ion

(ml/l

)

Thermophilic

Mesophilic

Psychrophilic

4.5. Digester Temperature 4.5. Digester Temperature RegimesRegimes

V.V. Use of Biogas.Use of Biogas.

In the Past:In the Past: it is believed that a form of this gas it is believed that a form of this gas

was used was used by the Babylonians to heat by the Babylonians to heat water.water.

By 1850 the concept of biogas was By 1850 the concept of biogas was starting to become better understood starting to become better understood and in sewage processing plant was and in sewage processing plant was built to create biogas, and this energy built to create biogas, and this energy was used to illuminate streetlights.was used to illuminate streetlights.

Present and Future UsePresent and Future Use

Biogas has been used for many purposes, Biogas has been used for many purposes, it best to used for direct use such as it best to used for direct use such as heating and cooking.heating and cooking.

It can be used as the fuel for vehicle It can be used as the fuel for vehicle engines, with higher efficiency and less engines, with higher efficiency and less pollutants than using gasoline fuel.pollutants than using gasoline fuel.

It may also be used to produce electricity It may also be used to produce electricity using gas turbine or engine, with less than using gas turbine or engine, with less than 30% of the energy of the biogas converted 30% of the energy of the biogas converted to electricityto electricity. .

VI. How do the production, VI. How do the production, transportation and use of biogastransportation and use of biogas affect the environment:affect the environment:

cleanest and least toxic in the world. machinery required cleanest and least toxic in the world. machinery required to heat the raw materials is non-polluting, and it is a to heat the raw materials is non-polluting, and it is a completely natural process completely natural process

Also through manufacturing biogas landfills and sewage Also through manufacturing biogas landfills and sewage systems become smaller and the process creates an systems become smaller and the process creates an odourless gas, and a high nutrient fertilizer odourless gas, and a high nutrient fertilizer

in a way the production of this form of gas is better for in a way the production of this form of gas is better for the environment than not producing it.the environment than not producing it.

transportation of biogas is done through trucks transportation of biogas is done through trucks similar to those that transport any other gas. similar to those that transport any other gas.

clean burning and completely natural so it has no clean burning and completely natural so it has no adverse effects on the environment. It also reduces adverse effects on the environment. It also reduces the amount of methane and carbon dioxide the amount of methane and carbon dioxide released into the environment.released into the environment.

Pros and ConsPros and Cons ProsPros RenewableRenewable High nutrient fertilizer High nutrient fertilizer

produced in excess.produced in excess. Environment friendly.Environment friendly. Reduces methane and carbon Reduces methane and carbon

dioxide release into the air.dioxide release into the air. Cheap to produce.Cheap to produce. Many different uses.Many different uses. Reduces landfill sites, sewage Reduces landfill sites, sewage

drainage, and farm manure.drainage, and farm manure. Clean/ quiet fuel for cars and Clean/ quiet fuel for cars and

trucks.trucks.  

ConsCons Reduced power Reduced power

from vehicles.from vehicles. Extra time required Extra time required

to produce in to produce in comparison to comparison to other energy other energy resources.resources.