Biogas Systems Anaerobic Digestion is Very Useful

Image courtesy of Community Composting Network

Anaerobic Digestion in a Diagram Image courtesy of Sustainable Sanitation and Water Management (SSWM)

What is Biogas?

• • • • It is similar to natural gas.

It is 50-70% methane.

The remainder is carbon dioxide and traces of hydrogen sulfide and ammonia. Methane is the important product. It can be burned as fuel, just like natural gas.

What are the benefits of Biogas? • • • • • Sanitation and hygiene Fuel and electricity Reduces indoor air pollution Reduces deforestation and cuts CO2 emissions. Fertilizer Image courtesy of SKG Sangha/The Ashden Awards

Small scale biogas digesters Image courtesy of Dr.-Ing. Arquitecta Joana Forte – Nepal 2011

Image courtesy of the Pace Project

What do you put in?

Images courtesy of Practical Action

• How much biogas is produced?

It depends on what you put in Image courtesy of Smith (DFID) 10

C/N Ratio

Duck dropping

Human Excreta

Chicken dropping Goat dung Pig dung Sheep dung

Cow/Buffalo dung 24

Water Hyacinth Elephant dung Maize stalk Rice straw Wheat straw Saw dust 200 25 43 60 70 90 8

8

10 12 18 19 Human Waste

Hydraulic Retention Time

Human waste Cow/Buffalo Dung 45 days 55 days Low C/N ratio  Low gas production (Need 3 times the plant size to produce same amt of biogas as cow dung) High HRT  Less amount required for feeding into plant

WASH solution – HYBRID PLANT

Cow dung for biogas production Human waste for sanitation

How much biogas is produced?

Size of Digester Daily Cow Dung Required (kg) Gas Production (m3/day) Stove usage (hrs/day) 4m 3 32 1.28

3-4 6m 3 48 1.92

5-6 8m 3 64 2.56

6-8 10m 3 80 3.20

8-10 15m 3 120 4.80

13-15

What does this mean?

Image Courtesy of Practical Action

What does this mean? • • • Rural Scale: dung from 2-4 cows (or 5-10 pigs) can produce enough gas for all a family’s cooking, and sometimes their lighting, too.

Urban Scale: A family or community using just their own food waste can replace between 25% and 50% of their cooking fuel.

Large-scale: electricity can be generated for many families or whole communities.

Variations on Biogas Installations • The following slides will demonstrate the wide variety of biogas systems currently being used around the world. • The major variables are: 1. Size of the installation.

2. Materials used to create the installation.

3. Amount of pressure created within the system.

Fixed Dome Biogas Plant

Sano Khokana, Kathmandu Valley, Lalitpur, Nepal Images courtesy of Prakash Chandra Amatya

Floating Dome Biogas Plant Images courtesy of Practical Action and Ashden Awards Image courtesy of Ashden Awards

• • BIOTECH, India In households and institutions, biogas plants handle kitchen waste and sometimes have toilets connected – Biogas is used for cooking, displacing about 50% of LPG use.

Larger systems used at markets, municipal sites, schools and hostels generate enough e lectricity for lighting Images courtesy of Ashden Awards

Loowatt A new customizable toilet that allows the toilet owner to also have an energy source Image courtesy of Loowatt

Flexible Balloon Biogas Plant Images courtesy of SSWM

Low-Cost Polyethylene Tube Digester Images courtesy of Energypedia

Assess Community Need If you are working with a community that has a waste disposal problem, biogas may be a helpful solution. Work with your community to determine: 1. What types of waste are is the community producing?

2. What quantities of this waste is the community producing?

3. Is the community interested in transforming this waste into useful energy and fertilizer?