The Biomass Balancing Act (Lesson Plan)
(An Investigation of Biomass as a Sustainable Energy Resource)
Suggested Grade Level
6-8
Overview
Students will work cooperatively to research biomass using the International Energy
Agency’s website. They will use evidence from the web search to assess biomass energy potential
in Pennsylvania as part of a classroom “Alternative Energy Commission.” After preparing and
sharing a fact sheet for biomass energy, students will witness a demonstration illustrating the
presence of carbon dioxide and design an experiment to investigate carbon neutrality. The
suggested time frame for this lesson is three to four (3-4) 50-minute class periods.
Standard Statements
3.2.7 B Apply process knowledge to make and interpret observations.
3.2.7 C Identify and use the elements of scientific inquiry to solve problems.
3.4.7 B Relate energy sources and transfers to heat and temperature.
3.5.7 B Recognize earth resources and how they affect everyday life.
3.6.7 A Explain biotechnologies that relate to related technologies of propagating, growing,
maintaining, adapting, treating and converting.
4.4.7 A Explain society’s standard of living in relation to agriculture.
Content Objectives
Students will know that
1. Biomass is all plant and animal material on the earth’s surface.
2. Biomass energy is a form of stored solar energy.
3. Biomass can be used for heating, power (electricity) generation or transportation.
4. The process of sustainably producing energy with biomass is carbon neutral.
Process Objectives
Students will be able to
1. Identify biomass resources.
2. Describe how biomass is a form of stored solar energy.
3. Explain how a particular biomass resource can be used to produce heat or electricity or
contribute to transportation resource needs.
4. Design an experiment to demonstrate how it can be said that sustainable biomass energy
production is carbon neutral.
Assessment Strategies
1. Participation in small group and whole class discussion.
2. Small group completion of a web-investigation using the International Energy Association’s
educational website on biomass and bioenergy.
3. Evaluation of experimental design.
The Biomass Balancing Act
Lesson Plan
1
Materials
Parts 1 & 2
• 1 Computer with internet access for each student group
• Teacher computer (if presenting video in a large group)
• Projection equipment (if presenting video in a large group)
• 1 Student Handout per group
Part 3
• Carbon Cycle lecture materials (found in the Teacher Notes)
Multimedia Resources
• PA Energy Biomass movie segment [QuickTime video (7:26)]
• Bioenergy Cycle image [bioenergy-cycle-med2.jpg]
External Multimedia Sources
Websites:
• http://www.aboutbioenergy.info (Part 1)
• http://www.ucar.edu/learn (Part 3)
• http://www.ucar.edu/learn/1_4_2_17t.htm (Extension)
Procedure
Part 1: Pennsylvania Biomass Technology
(30 min)
1. Share the PA Energy Biomass movie (Practitioners may elect to project the movie for the
entire class or allow students to view from the internet in small groups). [If pressed for time
with this content, the video may be shown as an introduction to Part 2.]
2. Divide students into small groups [Note: It may be helpful to sort into seven groups since
Part 2 works well with such an organization] and prompt them to help you formulate a
working definition of biomass.
3. Debrief main points of video as a class and develop the concept of biomass from the
offerings of small group work into a large concept map or visual.
4. Display the students’ definitions and concept maps/visuals in the classroom as a reference.
Part 2: IEA Web Investigation
(1-50 min Class Period)
1. To further investigate biomass as an energy resource, refer to the International Energy
Association’s Education Web Site on Biomass, http://www.aboutbioenergy.info/index.html.
Break the class into seven (7) groups to explore the site’s subtopics (Group 1 may focus on
“Definition,” Group 2, “Technologies,” etc.)
2. Present the IEA website and work through all or part of the guided tour and set groups off to
work independently to complete their section of the Student Handout.
3. Bring groups back to a whole class setting to share findings and create a summary document
or fact sheet for biomass and bioenergy.
Part 3: Designing an Experiment
(1-50 min Class Period)
1. Give a short lecture using the diagram of the Carbon Cycle from the page 3 of the Teacher
Notes.
2. Demonstrate an experimental set-up for identifying the presence of carbon dioxide modified
from Activity 17 of Project Learn, “Where in the World is Carbon Dioxide?” found at
The Biomass Balancing Act
Lesson Plan
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3
http://www.ucar.edu/learn from the University Corporation for Atmospheric Research
(UCAR). (Demonstration procedure included on page 6 of the Teacher Notes).
Allow students to work in pairs to select a particular type of biomass and brainstorm and/or
design a short experiment to gather evidence about carbon neutrality and their biomass
source.
Extension
(1-2, 50 min Class Periods)
1. Take it the next step--implement a student-designed experiment (or combination of designs)
to model a life scale investigation to quantify the emissions of various biomass resources.
Using the full experiment sequence in Activity 17 of Project Learn is a fantastic model and
can be found at: http://www.ucar.edu/learn/1_4_2_17t.htm.
The Biomass Balancing Act
Lesson Plan
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The Biomass Balancing Act
(An Investigation of Biomass as a Sustainable Energy Resource)
Courtesy of ORNL at http://bioenergy.ornl.gov/papers/misc/bioenergy_cycle.html
Sub-committee Member Signatures:___________________________________________
___________________________________________
___________________________________________
___________________________________________
Date:_________________________
The Biomass Balancing Act
Student Handout
1
Congratulations! You have successfully been elected as a member of your community’s alternative
energy commission. Your first task is to research a resource that has potential in Pennsylvania:
biomass. Your group will be responsible for informing the rest of your commission members about
important aspects of using biomass as an energy resource. Use the following website to assist you in
getting some answers: http://www.aboutbioenergy.info/index.html.
Step 1. Navigate through the section of the webpage that your group will report on from the tool bar
shown below (The helping hand is pointing to the “Definition” group’s section below):
Step 2. Explore all parts of the section and play with the “Tools” and “Test” tabs to see what you
can find out about biomass and bioenergy. Record your findings for important keywords and sum
up the main points of the text on the main part of your section under Interesting Facts. Don’t forget
to share some information about using the “Tool” and “Test” tabs.
Group:
Important Keywords/Vocabulary:
The Biomass Balancing Act
Website Section Reviewed:
Interesting Facts:
What we learned from the tool and
test…
Student Handout
2
Additional Notes:
Step 3. Now it is time to rejoin your commission (class) for a wrap-up session. Make sure to pay
close attention to other group’s summaries since you will need to take notes to add details to your
handout and understand why biomass might work for your community as a sustainable resource!
The Biomass Balancing Act
Student Handout
3
The Biomass Balancing Act (Teacher Notes)
(An Investigation of Biomass as a Sustainable Energy Resource)
The following notes are an excellent reference on the basics of bioenergy to be used in Part 3 of this
lesson. The following is a public domain document courtesy of the Oak Ridge National Laboratory
(ORNL) that can be accessed at: http://bioenergy.ornl.gov/papers/misc/bioenergy_cycle.html.
Bioenergy is produced in a cycle. Sustainable use of natural energy flows mimics the Earth's
ecological cycles and minimizes the emission of pollutants into the air, rivers and oceans. Most of
the carbon to create it is taken from the atmosphere and later returned to the atmosphere. The
nutrients to create it are taken from the soil and later returned to the soil. The residues from one part
of the cycle form the inputs to the next stage of the cycle.
Carbon dioxide (CO2) is withdrawn from the atmosphere by the process of plant growth
(photosynthesis) and converted into vegetation biomass (trees, grasses, and other crops). Harvested
biomass, together with forestry and crop residues, can be converted into building materials, paper,
fuels, food,
animal feed and
other products
such as plantderived chemicals
(waxes, cleaners,
etc.). Some crops
may be grown for
ecological
purposes such as
filtering
agricultural runoff, soil
stabilization, and
providing habitat
for animals as
well as bioenergy.
The solid biomass
processing
facility
(represented by
the factory
building at the
bottom left) may
also generate
process heat and
electric power. As more efficient bioenergy technologies are developed, fossil fuel inputs will be
reduced. Organic by-products and minerals from the processing facility may be returned to the land
where the biomass grew, thereby recycling some of the nutrients such as potassium and phosphorus
that were used for plant growth.
The Biomass Balancing Act
Teacher Notes
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Selected residues from the town may be combined with forestry and crop residues, animal wastes,
and biomass crops to provide the feedstocks for a different type of biomass processing (represented
by the factory at the top right). This new biomass processing facility (or biorefinery) could make a
range of products -- fuels, chemicals, new bio-based materials, and electric power. Animal feed
could be an important co-product of some processes. Such biomass processing facilities would use
efficient methods to minimize waste streams and would recycle nutrients and organic materials to
the land, thereby helping to close the cycle.
Biomass products (food, materials, and energy) used by the human population are represented by
the town at the bottom of the diagram. The residues from the town (scrap paper and lumber,
municipal refuse, sewage, etc.) are subject to materials and energy recovery, and some may be
directly recycled into new products.
Throughout the cycle, carbon dioxide from biomass is released back into the atmosphere -- from the
processing plants and from the urban and rural communities -- with little or no net addition of
carbon to the atmosphere. If the growing of bioenergy crops is optimized to add humus to the soil,
there may even be some net sequestration or long-term fixation of carbon dioxide into soil organic
matter. The energy to drive the cycle and provide for the human population comes from the sun, and
will continue for many generations at a stable cost, and without depletion of resources.
For additional information, contact the Bioenergy Feedstock Development Program, Oak Ridge
National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6422, (865) 574-576-5132
Additional Resources
Included below is a tremendous compilation from the Renewable Energy Policy Project from the
Center for Renewable Energy and Sustainable Technology (CREST) that may be accessed
electronically with embedded visuals at: http://www.repp.org/bioenergy/link1.htm.
Bioenergy
Forward
The purpose of this paper is to provide the reader with comprehensive knowledge of the biomass
energy sector. Biomass is plant matter and animal waste that can be harvested to create bioenergy in
the form of electricity, heat, steam and fuels.
Biomass has great potential to contribute considerably more to the renewable energy sector.
Already, in the U.S., residues from mill operations are the largest source of biomass for power
plants and combined-heat-and-power projects. Photo Credit: NREL biomass research website
Agricultural residues such as orchard prunings and nut hulls as well as forest residues are also
important contributors to power plants in combined heat and power (CHP) operations, particularly
in California. Landfill gas projects are growing steadily, while animal waste digestion projects and
energy crop plantations are still at an early stage of commercialization. [1]
In Europe, urban wood waste is an important source of bioenergy. In developing nations, a major
source of biomass is timber cut by the rural poor specifically for heating and cooking. [1]
The Biomass Balancing Act
Teacher Notes
2
Biomass Basics and Environmental Impact
Introduction
Biomass is any organic matter, particularly cellulosic or lingo-cellulosic matter, which is available
on a renewable or recurring basis, including trees, plants and associated residues; plant fiber; animal
wastes; industrial waste; and the paper component of municipal solid waste [2].
Plants store solar energy through photosynthesis in cellulose and lignin cells. Cellulose is defined as
a polymer, or chain, of 6-carbon sugars; lignin is the substance, or “glue,” that holds the cellulose
chain together [2]. When burned, these sugars break down and release energy exothermically,
giving off CO2, heat and steam. The byproducts of this reaction can be captured and manipulated to
create electricity, commonly called biopower, or fuel known as biofuel. (Both short for "biomass
power" and "biomass fuel" respectively) [3].
Biomass is considered to be a replenishable resource—it can be replaced fairly quickly without
permanently depleting the Earth’s natural resources. By comparison, fossil fuels such as natural gas
and coal require millions of years of natural processes to be produced. Therefore, mining coal and
natural gas depletes the Earth’s resources for thousands of generations. Alternatively, biomass can
easily be grown or collected, utilized and replaced.
Moreover, using biomass to create energy has positive environmental implications. Carbon dioxide
is a naturally occurring gas. Plants collect and store carbon dioxide to aid in the photosynthesis
process. As plants or other matter decompose, or natural fires occur, CO2 is released. Before the
anthropomorphic discovery of fossil fuels, the carbon dioxide cycle was stable; the same amount
that was released was sequestered, but it has since been disrupted. In the past 150 years, the period
since the Industrial Revolution, carbon dioxide levels in the atmosphere have risen from around 150
ppm to 330 ppm, and are expected to double before 2050! (please see diagram below)
Courtesy of NASA at http://rst.gsfc.nasa.gov/Sect16/carbon_cycle_diagram.jpg
The Biomass Balancing Act
Teacher Notes
3
An overwhelming majority of scientists now link carbon dioxide with rising temperatures in the
atmosphere and other issues associated with climate change. Scientists are predicting a rise in
average temperature 2-10 degrees Celsius. This change may seem insignificant, but note that the
former ice age resulted from an average of 5 degrees Celsius drop in temperature [4]. This small
shift in average temperature has huge implications for melting ice sheets, which would raise global
water levels up to 30 feet, flooding the coastal cities in which most of the world currently resides.
Additionally, more extreme weather patterns are predicted to occur, as well as habitat loss, spread
of disease and a whole host of other problems. The amount of CO2 pumped into the atmosphere
today will remain for at least a hundred years, since the half life will outlive all of us.
In order to curb CO2 emissions, we must take active strides to reduce our emissions. At present, the
United States is responsible for 25% of the world's emissions, and is currently dedicated to a policy
which actually encourages the release of more carbon dioxide into the atmosphere, claiming it to be
an indication of economic growth. Burning biomass will not solve the currently unbalanced carbon
dioxide problem. However, the contribution that biomass could make to the energy sector is still
considerable, since it creates less carbon dioxide than its fossil-fuel counterpart. Conceptually, the
carbon dioxide produced by biomass when it is burned will be sequestered evenly by plants growing
to replace the fuel. In other words, it is a closed cycle which results in net zero impact (see diagram
below). Thus, energy derived from biomass does not have the negative environmental impact
associated with non-renewable energy sources. [5]
Biomass is an attractive energy source for a number of reasons. First, it is a renewable energy
source as long as we manage vegetation appropriately. Biomass is also more evenly distributed over
the earth's surface than finite energy sources, and may be exploited using less capital-intensive
technologies. It provides the opportunity for local, regional, and national energy self-sufficiency
across the globe. It provides an alternative to fossil fuels, and helps to reduce climate change. It
helps local farmers who may be struggling and provides rural job opportunities. [6]
Bioenergy ranks second (to hydropower) in renewable U.S. primary energy production and
accounts for three percent of the primary energy production in the United States [7].
Biomass Energy Conversion
Bioenergy conversion requires a comparison with other energy sources that are displaced by the
bioenergy. Thus, biomass for power must be compared to coal, natural gas, nuclear, and other
power sources including other renewables. While comprehensive data is not available, one study by
REPP shows that emissions from biomass plants burning waste wood would release far less sulfur
dioxide (SO2), nitrogen oxide (NOx) and carbon dioxide (CO2) than coal plants built after 1975.
The comparison with combined cycle natural gas power plants is more ambiguous, since biomass
releases far more sulfur dioxide, similar levels or greater levels of nitrogen oxide, but far less
carbon dioxide than combined cycle natural gas plants.
Life-cycle impacts
Several studies by the National Renewable Energy Laboratory examined the “life-cycle” impact of
bioenergy for power. That is, the studies examined the air, land and water impacts of every step of
the bioenergy process, from cultivating, collecting, and transporting biomass to converting it to
energy. One study found that a bioenergy operation featuring biomass gasification with combinedcycle power plant technology would release far less SO2, NOx, CO2, particulate matter, methane
and carbon monoxide than coal power plants meeting new federal air pollution standards.
The Biomass Balancing Act
Teacher Notes
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Sources Cited:
[1] Center For Renewable Energy and Sustainable Technology (CREST). Biomass FAQs.
Discussion Section. www.repp.org.
[2] "What is Biomass?" American Bioenergy Association.
http://www.biomass.org/index_files/page0001.htm May 12, 2005
[3] "Biomass FAQs." Office of Energy Efficiency and Renewable Energy. Department of Energy.
http://www.eere.energy.gov/biomass/biomass_basics_faqs.html#biomass. July 2005.
[4] "History of Climate Change." Athena Curriculum Earth, an affiliate of NASA. Available Online
at http://vathena.arc.nasa.gov/curric/land/global/climchng.html, as of June 24, 2005.
[5] "Bioenergy." http://www.montanagreenpower.com/renewables/bioenergy/ May12, 2005.
[6] Kirby, Alex."UK Boost for Biomass Crops." BBC News Science and Nature.
http://news.bbc.co.uk/1/hi/sci/tech/3746554.stm. Oct 19, 2004.
[7] See Footnote 3
The Biomass Balancing Act
Teacher Notes
5
Carbon Dioxide Presence Demonstration
(Adapted from Project Learn’s “Where in the World is Carbon Dioxide?” Activity)
This demonstration requires some preparation, but is an excellent way to get students
thinking about how they could quantify the carbon dioxide releases associated with
bioenergy production, especially if your students have not previously worked with indicator
solutions.
Materials:
• Manila folder
• Roll of duct tape
• Pair of heat resistant oven mitts
• Balloons (8 or 10-inch diameter)
• test tubes
• test tube rack
• 1 test tube stopper with a length of flexible tubing attached
• Bromthymol Blue (BTB) solution
• Vinegar
• Baking soda
• Dilute solution of ammonia in dropper bottle
• Cotton balls
• 1” X 1” Aluminum foil square (shaped into a small cone)
• 10-12 twist ties
PART 1: DETECTING CARBON DIOXIDE GAS
BTB is available in either concentrated liquid or powdered form. Do the following to
prepare the BTB solution.
•
If you're using the liquid form
•
•
Fill a gallon bottle nine-tenths full with tap water and add BTB until
the solution is a deep, blue color (this is the working solution).
If you're using powdered BTB
•
Measure 0.5 grams of dry BTB into 500 ml of tap water. This will
provide a 0.1% stock solution.
•
To prepare the working solution, mix 1 part stock solution with 20
parts tap water.
[One liter of working solution could serve a class of 30 students, in two-person teams.]
In Part 1, explain that the demo is an experiment designed to detect the presence of
.
When combined, baking soda and vinegar produce pure
. In this experiment, the BTB
will dramatically change color (from bright blue to yellow) when introduced to the
.
The Biomass Balancing Act
Teacher Notes
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1. Fill tubes A and B approximately 1/3 full with the BTB solution.
2. Note the color of the solution in test tubes A and B. Tube A will be the control,
tube B will be the treatment. Place the tubes in the rack.
3. Fill the unlabeled tube
approximately 1/4 full of
vinegar.
4. Using the foil, make a small
"boat" for the baking soda - fill
1/2 full of baking soda (see
diagram to the left). The 'boat'
should be small enough to
easily fit into the test tube and
float on the vinegar.
5. Carefully slide the foil boat
inside the unlabeled vinegar
test tube (see directly below).
6. Plug the tube with the stopper and
tubing.
7. Place the free end of the tubing in
tube B, making sure the end of the
tubing reaches the bottom of the
tube.
8. Place a cotton ball into the neck of
Tube B.
9. Mix the vinegar and soda
together by GENTLY swirling
the tube from side-to-side. Gas
bubbles will begin to bubble
rapidly out of the tubing into the
BTB solution in tube B.
10. Note color after 1 minute.
The Biomass Balancing Act
Teacher Notes
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PART 2: COLLECTING SAMPLES OF CARBON DIOXIDE FROM VARIOUS SOURCES
(AIR, ANIMALS, AND FOSSIL FUELS)
The demo will compare the
from car exhaust (which will represent fossil fuel), a
volunteer’s breath (representing animals), and the outside air by bubbling a known
amount of each gas though a standard volume of BTB. Students will witness how the
different sources change the color of the BTB solution like the pure
in Part 1.
To make a meaningful comparison, it is important that equal volumes of gases are used.
We suggest using rubber balloons blown up to the same diameter from each source as
collectors. To do this, make a simple balloon diameter template with a piece of cardboard
or half of a manila folder. Draw a circle about 7.5 cm in diameter in the middle. Cut out the
circle and discard, saving the frame for use as a template.
A. Automobile exhaust collection
Materials needed for collecting car exhaust:
•
Manila folder
•
Roll of duct tape
•
Pair of heat resistant oven mitts
•
Balloons (8 or 10-inch diameter)
1. Blow up and allow the balloons to deflate. This will stretch the rubber and make
them easier to fill with the relatively low-pressure exhaust.
2. Prepare a cone to collect the car exhaust by rolling up a manila folder lengthwise.
One end must be larger than the opening for the car's tail pipe and the other end
must be small enough for the balloon to fit over it.
Use plenty of tape to hold the cone in shape
and to make the sides of the cone fairly
airtight. Note: the paper funnel will work for
several fillings without burning. DO NOT use
a plastic funnel. As the exhaust pipe heats
up, the plastic may melt. You may use a
metal funnel, but be VERY careful to avoid
any skin contact with the hot metal.
3. Have an assistant turn on the car
(make sure brake is on).
The Biomass Balancing Act
Teacher Notes
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4. Put the balloon on the end of the cone.
5. Using the heat resistant mitts, approach the exhaust pipe from the side. Place the
large end of the cone over the tail pipe. Use the gloved hand to help form a seal
between the cone and the exhaust pipe. DO NOT BREATHE THE EXHAUST. The
balloon should fill quickly; if not, have your assistant step lightly on the accelerator.
6. When the balloon is filled, have an assistant use a twist tie or two to tightly seal the
balloon. Do this by twisting the neck several times and doubling it over once, then
place the twist tie around the constricted area.
7. It is useful to prepare a few extra filled balloons.
B. Animal carbon dioxide collection
Recruit a student volunteer to fill a second balloon to template size and secure with 2 twist
ties. Emphasize to the volunteer that they should hold air in their lungs for a few moments
to allow plenty of exchange between
being absorbed and
being released in their
lungs. Breaths that are too rapid will contain less
than normal exhalations.
C. Outside air collection
Recruit a pair of student to collect outside air using an air pump (or bicycle or sports ball
pump) to blow up a balloon using the balloon template. Again secure with 2 twist ties. The
sample collection must be done out-of-doors as inside air can be
enriched from
breath.
D. Bubbling
into solution
At this point, you will have three balloons, one of car exhaust, one of student breath, and
one of outside air. Using the set-up shown below, bubble the gases through a BTB solution
in test tubes, and allow students to observe the color changes. They should clearly
observe the rapid and dramatic change with the car exhaust, the less significant change
with their own breath, and the minor change with room air.
1. Place three pre-labeled [E-Exhaust, H-Human, O-Outside] empty test tubes in the
test tube rack.
2. Fill each of the empty test tubes approximately 1/3 full of BTB. You may want to use
the funnel to make this task easier.
3. Begin with the outside air sample (Balloon O). Insert the straw inside the neck of
Balloon O and secure it with a twist tie. Do not remove the first twist tie (holding the
balloon closed) at this time.
The Biomass Balancing Act
Teacher Notes
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4. Insert the other end of the straw into the BTB solution in test tube O. Insert a cotton
ball into the top of the test tube to
help hold the straw in place.
5. Gently release air from the
balloon by slowly untwisting the
neck. Allow the air to bubble out
at a steady rate until the balloon
is empty. BE VERY CAREFUL
TO ALLOW A SLOW AND
STEADY GAS RELEASE.
6. Observe the color change (if
any). Repeat steps 3 to 5 for
each of the remaining balloons.
7. Allow students to observe the results of the test tubes. Arrange the test tubes in
order by color (yellow to blue). Hint: It may be useful to hold a blank sheet of white
paper behind the test tubes to better observe color differences.
8. Using the small dropper bottle, carefully add drops of diluted ammonia to each test
tube. Explain to students (or ask students to explain what adding ammonia does to
the system) that the number of drops of ammonia needed to turn the solution blue
again is directly related to the amount of
it required to change the BTB color in
the first place. Employ student drop counters and bubblers as needed to make the
demonstration as interactive as is feasible.
The Biomass Balancing Act
Teacher Notes
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