Go Green by Growing Green: How to Extract Energy from Grass
AbstractMowing the lawn is hard work, especially on a warm day. Not only do you have to mow the grass, but you also have to dispose of the clippings. Some people add the clippings to a compost pile in their yard, which is a great idea. But did you know that some grasses can be used as a source of energy? In this energy science fair project, you will learn more about a type of energy called biomass energy. You will grow different kinds of grasses and see which type of grass gives you the most biomass, which will produce the most energy.
Michelle Maranowski, PhD, Science Buddies
This project is based on Renewable Energy Activities: Choices for Tomorrow from the National Renewable Energy Laboratory.
To grow three different types of grasses and then determine which grass produces the most biomass and therefore, will produce the most energy.
The energy for cars, appliances, lights, and heating of homes and other buildings can come from two types of sources: fossil fuels and renewable energy. The most common sources are fossil fuels. Coal for electricity production and heat, gasoline for cars, and natural gas for cooking and heating are all examples of fossil fuels. Fossil fuels come from the earth and were made from animals and plants that lived long ago by geological processes that take millions of years. Since we dig up fossil fuels from the earth, there is a limited supply. Once we use the supply up, we would have to wait for millions of years for more! In addition to being limited, fossil fuels have other problems. They have to be burned to release their energy. During the burning, carbon dioxide and other greenhouse gases are released. These greenhouse gases contribute to climate change. The International Energy Agency estimates that 71% of all electricity worldwide was generated in 2020 from the burning of fossil fuels. The other 29% was created using renewable energy.
Renewable energy is energy, like solar and wind, that comes from sources that can be replenished. Neither solar nor wind is a fuel, though. They cannot be pumped into a car's engine or burned to heat a house. For that reason scientists are also interested in creating biofuels (fuels made from plants).
The scientists who work on creating these biofuels are researching ways to make these reactions according to green chemistry principles. The goal of green chemistry is to create useful products, like fuels to run our cars, in an environmentally friendly manner. There are twelve green chemistry principles that cover a number of different ways to make sure that as few resources as possible are used, and that little or no toxic waste is created. Biofuels fulfill several of these principles, including using renewable feedstocks. This means that the source of the ingredients for the product should be replenishable. Plants are replenishable; they change the energy of the Sun into biomass, and new plants can be grown easily from the seeds of older plants. Biomass is the total mass (or weight) of the plant that grows. There is energy stored in the leaves and stalks of every plant; that energy is called biomass energy.
In this green chemistry science fair project, you will learn more about biomass energy. You will grow three kinds of grasses and see which kind produces the most biomass. More biomass means more energy. Do some grasses grow faster than others? Do some grasses grow taller than others? Which would make the best renewable feedstock for a biofuel? This green chemistry science fair project will help you figure out the answers to these questions. Everybody talks about going green and green energy; do this science fair project, and you will be growing green!
Terms and Concepts
- Fossil fuel
- Greenhouse gas
- Renewable energy
- Green chemistry
- Renewable feedstocks
- Biomass energy
- What are some examples of renewable energy?
- What is fossil fuel and what happens when you burn fossil fuel?
- What are the advantages and disadvantages of biomass energy?
If you would like to learn more about energy and power, check out this website:
- Rathjen, D. (2001). Watt's a Joule?. Retrieved May 22, 2009.
Here is an interesting article on Miscanthus giganteus.
- RenewableEnergyAccess.com. (2005, October 12). Hybrid Grass Shows Strong Biomass Potential. Retrieved May 22, 2009.
The following is a link to a radio program on switchgrass:
- National Public Radio. (2006, February 1). Switch Grass: Alternative Energy Source?. Retrieved May 22, 2009.
The Department of Energy's Energy Information Administration publishes information and statistics on this country's energy consumption.
- United States Department of Energy: Energy Information Administration. (2009, May). This Week in Petroleum. Retrieved May 22, 2009.
For help creating graphs, try this website:
- National Center for Education Statistics. (n.d.). Create a Graph. Retrieved May 22, 2009.
Materials and Equipment
Flowerpots with drainage holes (9) at least 3.5-inch wide or make your own pots from cleaned ½-gallon paper milk or juice cartons
- If you are making your own pots from cartons you will also need a Philips head screwdriver, ¼ inch and a pair of scissors
- Ruler, metric
- Kitchen towel
- Potting soil (1 bag)
- Hand trowel; available at your local garden center
- Masking tape
- Wheat or rye seeds (90); can be purchased from your local health food store
- Corn seeds (90); available at your local garden center
- Oat seeds (90), whole and not milled; available from your local health food store
- Watering can, small or a cup or any other container you can put water in
- Optional: Grow lamp, if you are doing this science fair project without several days of warm and sunny weather; can be purchased online from websites such as www.amazon.com
- Optional: Container to hold excess water from the plants (1–3, depending on how many trials you are running; see the Experimental Procedure for details)
- Bucket or large waterproof container for rinsing plants
- Paper towels (1 roll)
- Plastic baggies, sandwich size (1 box)
Digital scale with high resolution, such as the digital pocket scale from
- The scale should be able to reliably measure changes as small as 1 gram (g) and 0.1 ounce (oz.).
- If you don't have a digital scale in your kitchen, you could ask to borrow one from your school, or purchase one from your local home goods store.
- As an alternative, you could also borrow a triple-beam balance from your school.
- Lab notebook
- Graph paper
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Performing the Experiment
If you have bought pots with drainage holes, skip to step 2. If you are making your own pots from cartons you will need to prepare them as follows:
- Make sure your cartons have been well cleaned.
- Use a ruler and pen to measure and mark the cartons half way up their height.
- Use the scissors and carefully cut all of the cartons in half at the mark you measured.
- Discard the upper halves of all of the cartons. You should now have nine paper plant pots. Make sure that all of the pots are the same height.
- Place a towel on a hard surface, like a table top, then place the first pot on top of it, with the open end up. Use the Philips head screwdriver and carefully poke six drainage holes in the bottom of the carton. These holes will allow excess water to drain out. Repeat this step with all of the cartons, using a towel underneath each one to protect the surface underneath.
- Now fill three of the pots with potting soil, using the hand trowel. Fill the pot at least half way with soil. You can fill it as much as 1 centimeter (cm) from the top. Lightly pack the soil into the pot with your hand.
Label the three containers, using masking tape and a pen, as follows;
- Pot 1: Trial 1: Wheat (or Rye)
- Pot 2: Trial 1: Corn
- Pot 3: Trial 1: Oats
- Take 30 wheat or rye seeds and plant them in the first pot that is labeled Wheat or Rye. You should plant the seeds in an orderly fashion. For example, you should plant five rows of six seeds each, with the seeds evenly spaced. Gently push each seed 1/2 inch into the soil. Cover the seeds with soil, and put a little more soil on top, filling the container all the way to the top.
- Repeat step 4, planting 30 corn seeds in the Corn pot.
- Repeat step 4, planting 30 oats seeds in the Oats pot.
Check the seed packet to determine the temperature range for each plant.
If you are doing this science fair project while it is still warm and sunny outside on most days:
- You can place the plants outdoors.
- You can then run two additional trials at the same time. The purpose of performing more than one trial is to minimize error and uncertainty in your data.
- Repeat steps 3–6 two additional times, labeling the pots with trial numbers 2 and 3. Place each set of three pots, one of each seed type, at three different sunny and warm locations in your yard.
If it is too cold outside:
- You should use a grow lamp to provide light to your plants.
- The top of the plants should be 7 1/2 –10 centimeters (cm) from the grow lamp.
- If you are using a grow lamp as the source of light, then you will have to wait until the first trial is completed before starting the second trial, and then wait for the second trial to complete before starting the third trial.
- If you are doing this science fair project while it is still warm and sunny outside on most days:
Carefully water each pot of seeds with the watering can. You should water the pots with enough water that they start to drip from the drainage holes.
- If the plants are inside you may want to use a container underneath the pots to catch the extra water that drips out of the drainage holes.
- Note down in your lab notebook the date that you planted the seeds in a data table, like the one shown below.
|Plant Growth and Development|
|Plant||Planted Date||Date of 1st Sprout||Date of 10th Sprout||Date of 20th Sprout||2 days||4 days||6 days||8 days||10 days||12 days||14 days|
|Wheat or Rye|
- Observe your pots daily, and keep the soil moist. As soon as you see the first seedling, mark down the seed type and the date in the data table. Continue observing each day and record when you see the 10th and the 20th seedling for each seed type.
- Start measuring the height of the seedlings two days after the first sprout comes up. Record the height and type of each seedling in another data table, like the one shown below. You should have nine height data tables, one for each seed type for each trial. Then calculate and record only the average, by day, in your Plant Growth and Development data table.
|Day||Seedling heights||Average seedling height|
- Fourteen days after seeing the first sprout (not of each type, but the first one among all of the plants), weigh the wheat or rye seedlings, the corn seedlings, and the oat seedlings, as follows:
- First fill a bucket with water and then gently wash the soil off the leaves and roots. Try to get rid of as much dirt from the roots as you can. This will take time so be patient. See Figures 1 and 2, below. Note: Don't clean all of the plants from the different seed types together. Just clean one group of plants at a time.
- Once a group of plants is clean, dry it completely with paper towels and then temporarily store the group of plants in a plastic baggie. Label the plastic baggie with the seed type and trial number. If you have been growing the seeds outdoors, you will have nine baggies: three with wheat or rye seedlings, three with corn seedlings, and three with oat seedlings. If you used a grow lamp, you will only have three baggies right now, one for each seed type.
Figure 1. Put a group of seedlings in a bucket of water to clean the dirt.
Figure 2. Gently loosen the roots of the seedlings from the dirt.
- Now place a new paper towel on the digital scale. Open the first wheat or rye baggie and weigh the group of seedlings. This is the "fresh weight." Record the fresh weight of the seedlings in a data table, like the one shown below.
|Seed Type||Trial||Fresh Weight||Dry Weight||Percent Changes|
|Wheat or Rye|
- Weigh the seedlings from all of the baggies, one at a time, recording the seed type, the trial, and the fresh weight.
- Now dry the seedlings. Follow the procedure detailed in the Science Buddies document Measuring Plant Growth to consistently dry the different grasses. This procedure keeps the drying variables to a minimum, which is important if you are conducting trials on different days.
- Once all of the plants are crisp, reweigh them using the digital scale. Record the "dry weight" in your lab notebook. Calculate the percent change in the weight of each of the groups of seedlings. Use Equation 1 to calculate the percent change in weight.
- If you used a grow lamp to provide light for the plants, repeat steps 3–17 two more times. The purpose of performing more than one trial is to minimize error and uncertainty in your data. Record all your data in your lab notebook.
Analyzing the Data
- Now you can analyze and graph your data. You can make your graphs by hand or if you want to learn more about graphing or make your graphs online, try the following website: Create a Graph.
- Graph the average height of each seed type versus time. Label the x-axis Days and the y-axis Height.
- Make another graph, plotting the fresh weight and the dry weight for each of the seed types that you used. Label the x-axis Seed Type and the y-axis Weight.
- You can also plot the percent change in weight between fresh and dry for each seed type. Label the x-axis Seed Type and the y-axis Percent Change in Weight. Looking through the data, can you determine which of the seeds you chose yields the most biomass and would be the best converter of light energy to biomass energy?
Ask an Expert
- Try repeating this science fair project using different grasses, such as rice or barley.
- Extract and compare the energy of the grasses that you grew. Review the following Science Buddies science fair project to learn one way to extract the energy from the different grasses: Burning Biofuels: Comparing Nonrenewable and Renewable Fuels.
- Allow the grasses to grow for a longer time and mature, and then extract the energy, as described in the Science Buddies science fair project, Burning Biofuels: Comparing Nonrenewable and Renewable Fuels. How does the maturity of the grass affect the energy extracted?
If you like this project, you might enjoy exploring these related careers:
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