How do you build a biogas generator?

Tools

• Tubing cutter
• Scissors
• Adjustable wrench
• Rubber gloves
• Electric drill with ¼" bit, or cork borer
• Hot glue gun, with glue sticks
• Electrical or Duct Tape
• Sandpaper (metal file will also work)

The materials and tools you'll need to build a biogas generator.

Materials

• Used 18L clear plastic water bottle
• Large Mylar helium balloon
• Plastic water bottle cap (with the "no-spill" insert-see photo)
• Copper tubing (40 cm long, 6.5mm (1/4") inside diameter)
• T-connector for plastic tubing (barbed, 6mm or ¼" long)
• 1 cork (tapered, 23mm long)
• Clear vinyl tubing (1.5 m long, 4mm or ¼-inch inside diameter)
• 2 barb fittings (¼" x ¼")
• Ball valve (1/4")
• 6-8L manure pellets (goat, sheep, llama, rabbit, or other ruminant)
• Rubber gloves
• Large plastic funnel (can be made from a 4L plastic milk jug with bottom removed)
• Wooden dowelling or stick (30 to 50 cm long, 2-3 cm thick)

Inserting copper tubing
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Taping neck
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Gluing cork
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Installing the barb fittings on the ball valve.
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Assembly of the biogas collection system.
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Scooping manure
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Slurry level
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1. Prepare the biogas collection system

1. Cut a 20cm piece of copper tubing. Round off the sharp edges of the freshly cut tubing using sandpaper or a metal file.
   
   

1. The Mylar balloon has a sleeve-like valve that prevents helium from escaping once it is filled. This sleeve will help form a leak-proof seal around the rigid tubing. Push the tubing into the neck of the balloon, past the end of the sleeve, leaving about 2cm protruding from the neck of the balloon, as shown below.
   
   

1. Test the tube to be sure air can enter and leave the balloon freely, by blowing a little in through the tube. The balloon should inflate with little or no resistance, and the air should be able to escape easily through the tube.

1. Securely tape the neck of the balloon to the tube as shown in the illustration.
   
   

1. Using a drill or cork borer, make a small (4mm) hole in the center of the stopper. Add a few drops of hot glue around and inside the hole and insert the stem of the ¼-inch T-adapter into the cork.
   
   

1. Screw the two barb fittings into the body of the ball valve. Tighten with the adjustable wrench.
   
   

1. Cut two sections of vinyl tubing, each 25cm long. Use them to connect the balloon to the T-adapter, and to connect the ball valve to the Bunsen burner. Assemble the rest of the gas collection system according to the diagram below.
   
   

1. Prepare the manure mixture
   This is a job best done outside, with rubber gloves!
2. 1. Cut the bottom off a 4L plastic milk jug to make a wide-mouthed funnel.
   2. Place the funnel into the neck of the plastic water bottle and scoop in small amounts of manure.
      
      
   3. Use a stick or piece of dowelling to push the manure through the neck of the bottle if it gets plugged.
   4. Add enough water to bring the level close to the top of the water bottle.
      
      
   5. Use the stick to stir up the manure and water mixture, releasing any bubbles of air that might be trapped.
   6. Clean up carefully. Use soap and wash hands thoroughly.

1. Final Set-up
   
   

Completed biogas generator
The Pembina Institute

1. Snap the cap onto the top of the manure-filled 18 litre water bottle.
   
   
2. Be sure the ball valve is closed, but that gas moving from the water bottle can pass freely through the T-adapter to the balloon.
3. Set the biogas generator in a warm location, such as over a heat register or radiator or in a sunlit window. If the biogas generator is placed in a window, be sure to wrap the outside of the container in black plastic or construction paper, to discourage algae from growing inside the bottle.

Test It!