Abstract

Objective

To compare the amount of biogas that is produced from different types of biomass.

Introduction

It can be fun to take a drive through the beautiful countryside on a summer day, with the windows rolled down and your hair flying in the breeze. If you drive past a cattle farm though, you may be inclined to roll your windows back up! Although the smell of manure from cows and other ruminants can be strong and unpleasant, the waste is a rich source of energy that can be used to run the farm.

Manure is not the only waste that is a rich source of energy. What you might think is "just garbage," might actually be turned into energy. Dead plants, rotting food, wood chips, sawdust, leftover crops, nut shells, and paper products are all examples of biomass, which are natural materials or organic matter that can be used to make energy.

Watch this video to see a real-world example of trash, in this case restaurant kitchen grease, being converted into biogas, methane. The process solves the problem of where to dump all that grease, while producing energy!

Is it hard to get energy out of biomass? No; in fact, people have been doing it for thousands of years. If you've ever sat around a campfire or fireplace, you've been warmed by burning biomass. Biomass can be burned on a larger scale to create electricity. Biomass (such as decaying plant matter, farm waste, wood waste, or industrial waste) is brought by large trucks to a huge incinerator where it is burned and the heat is used to boil water, create steam, and drive a steam generator that can produce electricity. Biomass energy is considered a form of renewable energy, meaning it can be replaced by nature. Biomass energy, along with other renewable sources, like hydroelectric, solar, geothermal, and wind energy, provide 7 percent of the total energy needs of the United States, and that percentage is expected to rise.

What other ways, besides burning, can you get energy out of biomass? You can turn it into a liquid or a gas. Turning it into a liquid involves a process called fermentation, which changes some forms of biomass—like corn, sugarcane, or switchgrass—into an alcohol-based fuel, called ethanol, which can power cars and be used as cooking fuel. Turning it into a gas is basically what cows do naturally in their digestive system, using bacteria to change biomass into methane, which is the main component in natural gas. Natural gas is an important fuel for heating homes; running stoves, ovens, and dryers; producing electricity and fertilizers; and running special cars and trucks. When made from biomass, natural gas is called biogas.

In aerobic sports—like running, walking, swimming, dancing, and bicycling—oxygen is used to generate the energy needed to continue the physical activity for a long period of time. For the creation of biogas, the opposite type of environment is needed to generate energy. Biogas is made by special anaerobic bacteria, microorganisms that live in environments without oxygen. The anaerobic bacteria break down the biomass into methane in a series of processes called anaerobic digestion. Biogas can be tapped directly from landfills,where sanitation workers dump and cover up everyone's trash, or from biogas generators where farmers or engineers mix biomass with anaerobic bacteria.

In this energy science fair project, you'll explore what kinds of biomass are good at making biogas. You'll fill empty soda bottles with different types of biomass, seal each bottle with a balloon, and measure the inflation of the balloons over several days to see which type of biomass creates the most biogas.

Terms, Concepts, and Questions to Start Background Research

• Manure
• Ruminant
• Energy
• Biomass
• Organic matter
• Steam generator
• Renewable energy
• Hydroelectric
• Geothermal
• Liquid
• Gas
• Fermentation
• Ethanol
• Methane
• Natural gas
• Fertilizer
• Biogas
• Aerobic
• Anaerobic bacteria
• Microorganism
• Anaerobic digestion
• Landfill
• Biogas generator
• Global warming
• Carbon-neutral
• Delignification
• Lignin
• Negative control

Questions

• How can you get energy out of biomass?
• Does biomass energy impact global warming?
• Is biomass energy a carbon-neutral source of energy?
• What is special about the bacteria that make biogas?

Bibliography

These sources describes what biomass is and how it can be used to make energy:

• Energy Information Administration. (2007, November). Energy Kid's Page: Biomass—Renewable Energy from Plants and Animals. Retrieved February 26, 2009, from http://www.eia.doe.gov/kids/energyfacts/sources/renewable/biomass.html
• California Energy Commission. (2006). Chapter 10: Biomass Energy. Retrieved January 24, 2009, from http://www.energyquest.ca.gov/story/chapter10.html
• National Renewable Energy Laboratory. (2008, July 25). Biomass Energy Basics. Retrieved January 31, 2009, from http://www.nrel.gov/learning/re_biomass.html
• Chevron Energy Solutions. (n.d.) Wastewater Plant Turns Kitchen Grease Into Biogas. Retrieved April 13, 2011 from http://www.waterandwastewater.com/videos/view_video.php?viewkey=1a42470269d56260243a

This source describes the different types of renewable energy and the role each plays in the United States:

• Energy Information Administration. (2007, November). Energy Kid's Page: Renewable Energy. Retrieved February 26, 2009, from http://www.eia.doe.gov/kids/energyfacts/sources/renewable/renewable.html

This source describes what biogas is, how it is made, and how to build a biogas generator:

• The Pembina Institute. (2007). Build Your Own Biogas Generator. Retrieved February 9, 2009, from http://www.scribd.com/doc/8679538/Build-Your-Own-Biogas-Generator

This source describes how a California power, gas, and electric company gets auto fuel from cow manure:

• Environmental Leader. (2008, March 5). PG&E Gets Energy from Cow Manure. Retrieved January 31, 2009, from http://www.environmentalleader.com/2008/03/05/pge-gets-energy-from-cow-manure/

Visit these pages, from PG&E, a California power, gas, and electric company, for more information about electricity:

• Pacific Gas and Electric Company. (2002). Electricity Generation and Distribution. Retrieved March 4, 2009, from http://www.pge.com/microsite/pge_dgz/more/electricity_gen.html
• Pacific Gas and Electric Company. (2002). Alternative Energy Sources. Retrieved March 4, 2009, from http://www.pge.com/microsite/pge_dgz/more/alternative.html

For information about white rot fungus, particularly if you try one of the Variations found at the end of this science fair project, check out this website:

• Biggs, A.R., Rytter, J.L., and Travis, J.W. (n.d.). White Rot. Retrieved March 1, 2009, from http://www.caf.wvu.edu/Kearneysville/disease_descriptions/omwhiter.html

For help creating graphs, try this website:

• National Center for Education Statistics (n.d.). Create a Graph. Retrieved February 26, 2009, from http://nces.ed.gov/nceskids/CreateAGraph/default.aspx

Materials and Equipment

• Soda bottles, 2-L, empty and clean (9)
• Masking tape
• Wax paper
• Scissors
• Disposable gloves; available at drug stores
• Fresh cow manure, approximately 1 cup; available from farms and some petting zoos. To find a small, local dairy farm, try this source: www.realmilk.com/where2.html
• Kitchen scale, capable of distinguishing between 1-g quantities, or a mini balance scale and weights; available from www.sciencekit.com, catalog #WW17115M04.
• Two types of biomass, approximately 1 cup of each:
  1. Uncooked, chopped-up vegetable peelings (can be all one type of vegetable or mixed vegetables)
  2. Mashed banana
• Latex balloons, large, round (9)
• Distilled water (20 L), available at grocery and drug stores
• Kitchen funnel
• Bleach
• Tape measure, cloth or vinyl, metric
• Lab notebook
• Graph paper

Disclaimer: Science Buddies participates in the Science Education Affiliate Network (SEAN). For more information, visit our Science Fair Supplies & Materials page.

Experimental Procedure

Preparing the Soda Bottles for Filling

1. Wash and dry the soda bottles. Throw their caps away.
2. With masking tape and a pen, label three of the bottles Cow Manure.
3. With masking tape and a pen, label three of the bottles Cow Manure + Vegetable Peelings.
4. With masking tape and a pen, label three of the bottles Cow Manure + Mashed Banana.
5. Cut out 15 small, equally sized (approximately 1-inch) squares of wax paper to use with your mini balance scale. These small papers will be placed on the scale before you take each measurement. They will help you carry your biomass from the scale to the bottles, and will help keep your scale and hands clean.

Preparing Cow Manure Bottles

1. Put on a pair of gloves.
2. Lay one of the pieces of wax paper on the balance scale, and measure out 10 g of cow manure on top of it. Place the 10 g of cow manure (not the wax paper) in one of the soda bottles labeled Cow Manure. Throw the piece of wax paper away.
3. Repeat step 2 until all three bottles with this label have each been filled with 10 g of cow manure.

Preparing Cow Manure + Vegetable Peelings and Cow Manure + Mashed Banana Bottles

1. Using the balance scale and a fresh piece of wax paper, measure out 5 g of cow manure and place the 5 g of cow manure (not the wax paper) inside one of the soda bottles labeled Cow Manure + Vegetable Peelings. Throw the piece of wax paper away. Repeat this step until all three bottles with this label have 5 g of cow manure inside.
2. Using the balance scale and a fresh piece of wax paper, measure out 5 g of vegetable peelings and place the 5 g of peelings inside one of the bottles labeled Cow Manure + Vegetable Peelings. Throw the piece of wax paper away. Repeat this step until all three bottles with this label have 5 g of vegetable peelings inside.
3. Repeat steps 1–2 for the Cow Manure + Mashed Banana bottles, substituting mashed banana for the vegetable peelings.
4. Take off your lab gloves and throw them away. Wash your hands with soap and warm water, and dry them well. Put on a fresh pair of lab gloves.

Finishing the Bottles

1. Place the funnel in one of the soda bottles.
2. Carefully fill the bottle to the top with distilled water. Pour very slowly as you near the top so that the bottle does not overflow.
3. Cover the mouth of the filled soda bottle with an uninflated balloon and secure the balloon at the mouth of the soda bottle with a strip of duct tape.
4. Repeat steps 1–3 until all soda bottles have been filled and topped with balloons.
5. Take off your lab gloves and throw them away. Wash your hands with soap and warm water. Because you were working with waste, it's important to thoroughly clean the scale, funnel, and work area with a bleach solution. Review the Science Buddies Microorganisms Safety Guide for more information.

Testing the Bottles

1. Place the soda bottles in a well-ventilated area, away from open flame or sparks of electricity, such as outdoors on a porch or balcony.
2. Each day, at approximately the same time, use the measuring tape to measure the circumference (in mm) of each balloon, at its fullest part. Record the date, time, and measurements in a data table in your lab notebook.
3. Repeat step 2 for a total of 12 days.

Analyzing Your Data Table

1. For the bottles labeled Cow Manure, make a graph that plots the circumferences of the balloons on the y-axis and the day number (1–12) on the x-axis. You can make the graph by hand or use a website like Create a Graph to make the graph on a computer and print it.
2. For the bottles labeled Cow Manure + Vegetable Peelings, make a graph that plots the circumferences of the balloons on the y-axis and the day number (1–12) on the x-axis.
3. For the bottles labeled Cow Manure + Mashed Banana, plot the circumferences of the balloons on the y-axis and the day number (1–12) on the x-axis.
4. Comparing the three graphs, which type of biomass produced the fastest inflation of the balloons? Which type of biomass produced the greatest inflation of the balloons?

Variations

• Investigate how the following affect biogas production:
  1. Temperature
  2. pH
  3. Antibiotics
  4. Detergent
• Using the resources in the Bibliography, above, and with the help of an adult, devise a way to test whether the biogas you produced is flammable.
• Biogas production can be increased by delignification (removing lignin) in the biomass before putting it into the biogas generator. One way to achieve delignification of a biomass is through white rot fungus. For more information about white rot fungus, check out the Bibliography, above. Compare the biogas production of the same biomass with and without an initial treatment of white rot fungus.
• Add negative controls to the main experiment above by including six additional test bottles. Fill three of the bottles with 5 gm of mashed banana only (add no manure), and three of the bottles with 5 gm of vegetable peelings only (add no manure). Add distilled water to the bottles, then seal and test them with the other nine bottles, as directed above. How do your negative controls compare to the mashed banana and vegetable peelings test bottles that do contain cow manure? What happened with the addition of the cow manure? What component of the cow manure do you think accounts for the differences?

• For more science project ideas in this area of science, see Energy & Power Project Ideas.

Credits

Kristin Strong, Science Buddies

This science fair project idea was based on an 8th grade, first-prize-winning project:

• Osegueda, A. (2005, October). Retrieved January 31, 2009, from http://www.adelaide.edu.au/biogas/fair/sciencefair.pdf

Last edit date: 2011-05-24 08:33:00