3. WHAT IS BIOGAS
• Biogas produced after organic materials
(plant and animal products) are broken
down by bacteria in an oxygen – free
environment, a process called
ANAEROBIC DIGESTION.
• Biogas systems use anaerobic digestion
to recycle these organic materials, turning
them into biogas, which contains both
energy (gas), and valuable soil products
(liquids and solids).
4. WHAT IS BIOGAS
• Anaerobic Digestion already occurs in
nature, landfills, and some livestock manure
management systems, but can be
optimized, controlled and contained roughly
50-70% methane,
30-40% carbon dioxide and
trace amounts of other gases
The liquid and solid digested material called,
DIGESTATE, is frequently used as a soil
amendment
5. • Some organic wastes are more difficult to break down in a digester than
others.
Food waste
Fats
Oils and
Greases
Are the easiest organic wastes to break down, while livestock waste tends to
be the most difficult.
6. • Mixing multiple wastes in the same digester, referred to as co –
digestion, can help increase biogas yields.
• Warmer digesters, typically kept between 30 to 38 degrees Celsius
(86-100F), can also help wastes break down more quickly.
• After biogas captured, it can produce heat and electricity for use in
Engines
Microturbines
Fuel cells
Biogas can also be upgraded into Biomethane, also called
RENEWABLE NATURAL GAS or RNG, and injected into natural gas
pipelines or used as a vehicle fuel.
7. WHAT KIND OF WASTE CAN PRODUCE
BIOGAS?
• All organic waste can be used to produce biogas.
• You can use raw materials such as;
Agricultural waste
Municipal waste
Plant material
Manure
Human feces
Sewage
Garden (green) waste or
Food waste
For human waste, a Bio – toilet
8. BIOLOGICAL BREAKDOWN
FIRST STAGE
The digestion process is the
Hydrolysis Stage – insoluble
organic polymers (such as
carbohydrates) are broken
down, making them
accessible to the next stage
of bacteria called Acidogenic
Bacteria.
SECOND STAGE
The Acidogenic bacteria
convert sugars and amino
acids into carbon dioxide,
hydrogen, ammonia, and
organic acids.
THIRD STAGE
The Acetogenic Bacteria
convert the organic acids into
acetic acid, hydrogen,
ammonia, and carbon
dioxide. This process makes
the final step possible with
the help of Methanogens.
9. BIOLOGICAL BREAKDOWN
FOURTH STAGE
The Methanogens converts
these final components into
methane and carbon dioxide,
which can be used as
flammable, green energy.
10. THE BENEFITS OF BIOGAS
ENVIRONMENTAL BENEFITS
- Recycle manure and kill odors and pathogens while producing renewable
energy and soil products
- Moving manure from open lagoons to an airtight biogas system reduces
GHG emissions
- Reduce carbon emissions in transportation by at least half compared to
fossil fuels
- Recycling manure creates an opportunity to separate nutrients and keep
them out of waterways
- The use of digestate can replace costly synthetic fertilizers and can
increase plant growth by 10-30 percent compared to synthetic fertilizers
11. THE BENEFITS OF BIOGAS
ECONOMIC BENEFITS
- A cost-effective solution to turning a high-cost deliverable like waste
treatment into a revenue-generating opportunity for farmers and rural
communities
- Can reduce farm costs for animal bedding and fertilizer and generate
new revenue streams.
- Reduce the volume of waste, meaning that costs are often lowered for
facilities like wastewater plants
12. THE BENEFITS OF BIOGAS
ENERGY BENEFITS
- Produce renewable energy 24/7/365 with a reliability rate of 95%–in comparison, the average
reliability rate for solar power is 25% and 35% for wind power
- Biogas supports distributed generation of energy, which means lower transmission and
transportation costs as well as reduced impact and higher reliability of electrical grids
- Systems with gas storage can provide renewable electricity on demand in minutes, reducing
the need to turn on fossil fueled power plants to meet peak demand
- Renewable Natural Gas (RNG) procured from biogas can be used interchangeably with natural
gas for heating, electricity, and the production of quality biomethane and transportation fuel
- By purchasing RNG, large gas customers support their ESG goals, reduce fossil fuel use, and
decrease their carbon footprint
13. BIOGAS ADVANTAGES
1. BIOGAS IS ECO-FRIENDLY
- It is renewable, clean source of energy that relies on a carbon – neutral
process.
2. BIOGAS GENERATION REDUCES SOIL AND WATER POLLUTION
- It helps divert food waste from landfills, positively impacting the
environment and economics.
3. BIOGAS GENERATION PRODUCES ORGANIC FERTILIZER
- The by-product of the biogas generation process is enriched organic
digestate, which is a perfect supplement to, or substitute for, chemical
fertilizers.
14. BIOGAS DISADVANTAGES
1. Few Technological Advancements
- An unfortunate disadvantage of biogas today is that the systems used in
the production of biogas are not efficient.
2. Contains Impurities
- After refinement and compression, biogas still contains impurities.
3. Effect of Temperature on Biogas Production
- biogas generation is also affected by the weather.
15. IS BIOGAS GOOD OR BAD?
• Biogas is an excellent source of clean
energy.
• It has lower impact on the environment
than fossil fuels.
• While not having a zero impact on the
ecosystems, biogas is carbon neutral –
that’s because is produces from plant
matter, which has previously fixed carbon
from carbon dioxide in the atmosphere.
• A balanced between the carbon released
from biogas and the amount absorbed
from an atmosphere is maintained.
16. BIOGAS FEEDSTOCKS
• FOOD WASTE
Most of this waste is sent to landfills, where it produces methane as it
breaks down. While landfills may capture the resultant biogas,
landfilling organic wastes provides no opportunity to recycle the
nutrients from the source organic material.
As just one example, with 100 tons of food waste per day, anaerobic
digestion can generate enough energy to power 800 to 1,400 homes
each year. Fat, oil, and grease collected from the food service industry
can also be added to an anaerobic digester to increase biogas
production.
17. BIOGAS FEEDSTOCKS
• LANDFILL GAS
Landfills are the third largest source of
human – related methane emissions in
US.
Landfills contain the same anaerobic
bacteria present in a digester that break
down organic materials to produce
biogas, in this case Landfill Gas (LFG).
Instead of allowing LFG to escape into
the atmosphere, it can be collected and
18. BIOGAS FEEDSTOCKS
• LIVESTOCK WASTE
1,000 – pound dairy cow produces an average of 80 pounds
of manure each day.
This manure is often stored in holding tanks before being
applied to fields.
Not only does the manure produce methane as it
decomposes, it may contribute to excess nutrients in
waterways.
When livestock manure is used to produce biogas, anaerobic
digestion can reduce
a) greenhouse gas emissions,
b) reduce odors, and
c) reduce up to 99% of manure pathogens.
19. BIOGAS FEEDSTOCKS
• LIVESTOCK WASTE
The EPA estimates there is the
potential for 8,241 livestock biogas
systems, which could together
generate over 13 million megawatt
– hours of energy each year.
20. BIOGAS FEEDSTOCKS
• WASTEWATER TREATMENT
Many wastewater treatment plants
(WWTP) already have on – site
anaerobic digesters to treat sewage
sludge, the solids separated during the
treatment process.
However, many WWTP do not have
the equipment to use the biogas they
produce, and flare it instead.
Of the 1,269 wastewater treatment
plants using an anaerobic digester,
only around 860 use their biogas.
21. BIOGAS FEEDSTOCKS
• CROP RESIDUES
Crop residues can include stalks, straw, and plant trimmings.
Some residues are left on the field to retain soil organic content and
moisture as well as prevent erosion. However, higher crop yields
have increased amounts of residues and removing a portion of these
can be sustainable.
Sustainable harvest rates vary depending on the crop grown, soil
type, and climate factors.
Crop residues are usually co – digested with other organic waste
because their high lignin content makes them difficult to break down.
22. BIOGAS END USES
• RAW BIOGAS AND DIGESTATE
With little no processing, biogas can be burned on – site to heat buildings
and power boilers or even the digester itself.
Biogas can be used for combined heat and power (CHP) operations, or
biogas can simply be turned into electricity using a
a) Combustion engine
b) Fuel cell or gas turbine
With the resulting electricity being used on site or sold onto the electric grid.
23. BIOGAS END USES
• RAW BIOGAS AND DIGESTATE
Digestate is the nutrient rich solid or liquid material remaining after the digestion
process; it contains all the recycled nutrients that were present in the original organic
material but in a form more really available for plants and soil building.
The composition and nutrient content of the digestate will depend on the feedstock
added to the digester.
Liquid digestate can be easily spray applied to farms as fertilizer, reducing the need
to purchase synthetic fertilizers.
Solid digestate can be used as livestock bedding or composted with minimal
processing.
The biogas industry recently has taken steps to create a digestate certification
24. BIOGAS END USES
• RENEWABLE NATURAL GAS
RNG or Biomethane, is biogas that has been refined to remove
carbon dioxide, water vapor and other trace gas so that it meets
natural gas industry standards.
Can be injected into the existing natural gas grid (including pipelines)
and used interchangeably with conventional natural gas.
25. BIOGAS END USES
• COMPRESSED NATURAL GAS AND LIQUEFIED NATURAL GAS
Like conventional natural gas, RNG can be used as a vehicle fuel
after it is converted to Compressed Natural Gas (CNG) or Liquefied
Natural Gas (LNG)
The fuel economy of CNG powered vehicles is comparable to that of
conventional gasoline vehicles and can be used in light to heavy duty
vehicles.
LNG is not as widely used as CNG because it is expensive to both
produce and store, though its higher density makes LNG a better fuel
26. BIOGAS END USES
• COMPRESSED NATURAL GAS AND LIQUEFIED NATURAL GAS
Most of investments in fueling infrastructure, CNG and LNG are best
suited for fleet vehicles that return to a base for fueling.
The National Renewable Energy Laboratory estimates RNG could
replace 5% of the natural gas used to produce electricity and 56% of
the natural gas used to produce vehicle fuel.
