Learning Experience 1.6
Food for thought: Can food fuel more than
our bodies?
Biomass can be burned for fuel.
But what is biomass?
Biomass means plants or organic matter that is renewable. It includes crops,
trees, agricultural food and feed crops, animal wastes, and other waste
materials.
Biomass can then be used to produce biofuel – a renewable energy source!
If advanced technologies are used, the carbon in biofuel has been taken from
the atmosphere by the growing plants, so burning the biomass (the plants)
does not result in an increase of carbon dioxide in the earth’s atmosphere.
As a result, biofuels are seen by many people as a way to reduce carbon
dioxide emissions by using them to replace non-renewable sources of energy.
So this means that things that we currently look at as food could end up
fueling our cars as well as our bodies.
Could snacks such as potato chips be used as fuel?
Your task is to investigate the amount of energy that can be released when
you burn different types of foods and to decide which food would make the
best biofuel of the future.
The best fuels are those that have a high energy density (where just a small
amount has a lot of energy in it). The amount of energy a substance contains
can be determined by burning a substance to convert the stored energy into
heat energy.
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The heat energy created can be used to heat water.
The increase in the water’s temperature allows the amount of energy
contained within the food to be calculated
Decide which foods you would like to test and then use the following
procedure to plan and conduct your investigation.
You must submit a lab report at the end of your investigation which contains
the following sections
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Aim
Hypothesis
Materials
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Method
Results
Discussion
Equipment
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Matches or Bunsen burner
Test tube
Retort stand, bosshead and clamps
Measuring Cylinder
Food samples
Pin to hold samples
Cork
Electronic balance
Thermometer
Method
1. Using a measuring cylinder pout 20ml (which is approximately 20g) of
water into a test tube
2. Mount the test tube and thermometer on a retort stand as shown in the
diagram
3. Collect your food sample and weigh and record its mass in grams
4. Secure the food to the retort stand as shown in the diagram, if possible.
Otherwise carefully insert a needle through the food sample, then set
the other end of the needle into a cork
5. Measure and record the initial temperature of the water
6. Use a match or Bunsen burner to ignite the food sample and then hold
it under the test tube to heat the water.
7. When the food sample has stopped burning measure and record the
final temperature of the water
8. Calculate the heat energy created by using the formula:
Q = mcΔt
where:
Q = Amount of heat energy in Joules (J)
m = mass of water being heated (g)
c = the specific heat capacity of water = 4.183 J g-1 K-1
Δt = change in temperature of the water
Set up the laboratory equipment as identified below:
You are required to present an investigation comparing the energy
contained in different food types. Options such potato chips,
marshmallows and nuts such as walnuts and brazil nuts provide good
options. These nuts should be used instead of peanuts if there is any
concern of students being affected due to allergies to nuts.
Results
Food
Sample
Mass of
food
sample
(grams).
Initial
temperature
of water.
Final
temperature
of water.
Amount
of energy
used to
heat the
water.
Amount
of energy
per
kilogram
of food
Discussion
1. Is this a realistic calculation of the amount of energy contained
within a food source? Why or why not? Where has the rest of
the energy gone?
2. How much energy would be contained within a kg of the
different food sources? If we could burn them safely and
effectively, how would this compare to the amount of energy
contained within more traditional fuels? Use the table below to
compare:
Energy Content of Fuels
Petrol
LPG (Liquefied petroleum gas)
Diesel
Black Coal
Bagasse (cane stalks)
Wood
MJ per kg
44.21
46.01
43.21
19.92
9.62
16.22
1
3. If we consider that on average, peanuts contain approximately
25.7MJ per kg (you can check this on the package you use) how
much energy was lost in this activity? Check other food
packaging to find out other energy quantities of food products.
4. Consider the following table that outlines the amount of CO2
that is produced per MJ of fuel:
CO2 Emissions of Fuels
Petrol
g per MJ
66.72
Source: BP Australia
Source: Australian Greenhouse Office “Technical guidelines for the
estimation of greenhouse emissions and energy at facility level”
1
2
LPG (Liquefied petroleum gas)
Diesel
Black Coal
Bagasse
Wood
59.62
69.22
92.92
93.12
92.12
5. Graph the energy per kilogram against the CO2 emissions of
fuels. Interpolate and extrapolate the results to estimate the
CO2 emissions for the food products. Is this a realistic process
for us to follow to estimate the amount of CO2 emitted by food
products? Why?
6. Would any food products be an effective replacement for fossil
fuels?
7. What ingredients in the food products allow us to compare
them with fuels like petrol and coal?
8. What other foods may contain more energy than those tested?
How could you measure this?
9. What effects do such foods have on the human body when
eaten?
Learning Experience 1.6 Extension
Society & Environment Extension Activity
Using a SWOT (Strength, Weaknesses, Opportunities and Threats)
analysis framework, research the viability of peanut energy (or another
bio-fuel), on the international market, considering the ecological and
economic costs.
Strengths
Weaknesses
Opportunities
Threats