Growing energy: comparing biofuel crop biomass

The activities are as follows:GLBRC1

Most of us use fossil fuels every day. Fossil fuels power our cars, heat and cool our homes, and are used to produce most of the things we buy. These energy sources are called “fossil” fuels because they are made from plants and animals that grew hundreds of millions of years ago. After these species died, their tissues were slowly converted into coal, oil, and natural gas. An important fact about fossil fuels is that they are limited and nonrenewable. It takes a long time for dead plants and animals to be converted into fossil fuels. Once we run out of the supply we have on Earth today, we are out! We need to think of new ways to power our world now that we use more energy than ever.

Biofuels are made from the tissues of plants that are alive and growing today. When plants are harvested, their tissues, called biomass, can be converted into fuel. Biofuels are renewable, meaning we can produce them as quickly as we use them up. At the Great Lakes Bioenergy Research Center sites in Wisconsin and Michigan, scientists and engineers are attempting to figure out which plants make the best biofuels.

GLBRC2

Gregg is a scientist who wants to find out how much plant biomass can be harvested from different crops like corn, grasses, weeds, and trees. The bigger and faster a plant grows, the more biomass they make. The more biomass the more fuel can be produced. Gregg is interested in maximizing how much biomass we can produce while also not harming the environment. Each plant species comes with a tradeoff – some may be good at growing big, but need lots of inputs like fertilizer and pesticide. Corn is an annual, meaning it only lives for one year. Corn is one of the best crops for producing a lot of biomass. However, farmers must add a lot of chemical fertilizers and pesticides to their fields to plant corn every year. These chemicals harm the environment and cost farmers money. Other plants harvested for biofuels, like switchgrass, prairie species, poplar trees, and Miscanthus grass are perennials. Perennials grow back year after year without replanting. Perennials require much less chemical fertilizers and pesticides to grow. If perennials can produce high levels of biomass with low levels of soil nutrients, perhaps a perennial crop could replace corn as the best biofuel crop.

Gregg out in the GLBRC

Gregg out in the WI experimental farm.

To test this hypothesis, scientists worked together to design a very large experiment. Gregg and his team grew multiple plots of six different biofuel crops on experimental farms in Wisconsin and Michigan. The soils at the Wisconsin site are more fertile and have more nutrients than the soils at the Michigan site. At each farm, they grew plots of corn to be compared to the growth of plants in five types of perennial plots. The types of perennial plots they planted were: switchgrass, Miscanthus grass, poplar saplings (trees), a mix of prairie species, and weedy fields. Every fall the scientists harvested, dried, and then weighed the biomass from each plot. They continued taking measurements for five years and then calculated the average biomass production in a year for each plot type at each site.

Featured scientist: Dr. Gregg Sanford from University of Wisconsin-Madison

Flesch–Kincaid Reading Grade Level = 8.5

This Data Nugget was adapted from a data analysis activity developed by the Great Lakes Bioenergy Research Center (GLBRC). For a more detailed version of this lesson plan, including a supplemental reading, biomass harvest video and extension activities, click here.

This lesson can be paired with The Science of Farming research story to learn a bit more about the process of designing large-scale agricultural experiments that need to account for lots of variables.

For a classroom reading, click here to download an article written for the public on these research findings. Click here for the scientific publication. For more bioenergy lesson plans by the GLBRC, check out their education page.

Aerial view of GLBRC KBS LTER cellulosic biofuels research experiment; Photo Credit: KBS LTER, Michigan State University

Aerial view of GLBRC KBS LTER cellulosic biofuels research experiment; Photo Credit: KBS LTER, Michigan State University

As a hook before beginning the Data Nugget, students can watch the following video for an introduction to biofuels:

For more photos of the GLBRC site in Michigan, click here.

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The ground has gas!

Measuring nitrogen (N2O) gas escaping from the soil in summer.

Measuring nitrogen (N2O) gas escaping from the soil in summer. Photo credit: Julie Doll, Michigan State University

The activities are as follows:

If you dig through soil, you’ll notice that soil is not hard like a rock, but contains many air pockets between soil grains. These spaces in the soil contain gases, which together are called the soil atmosphere. The soil atmosphere contains the same gases as the atmosphere that surrounds us above ground, but in different concentrations. It has the same amount of nitrogen, slightly less oxygen (O2), 3-100 times more carbon dioxide (CO2), and 5-30 times more nitrous oxide (N2O, which is laughing gas!).

Measuring nitrogen (N2O) gas escaping from the soil in winter.

Measuring nitrogen (N2O) gas escaping from the soil in winter. Photo credit: Julie Doll Michigan State University.

Nitrous oxide and carbon dioxide are two greenhouse gasses responsible for much of the warming of global average temperatures. Sometimes soils give off, or emit, these greenhouse gases into the earth’s atmosphere, adding to climate change. Currently scientists are working to figure out why soils emit different amounts of these greenhouse gasses.

During the summer of 2010, Iurii and his fellow researchers at Michigan State University studied nitrous oxide (N2O) emissions from farm soils. They measured three things: (1) the concentration of nitrous oxide 25 centimeters below the soil’s surface (2) the amount of nitrous oxide leaving the soil (3) and the average temperature on the days that nitrous oxide was measured. The scientists reasoned that the amount of nitrous oxide entering the atmosphere is positively associated with how much nitrous oxide is in the soil and on the soil temperature.

Featured scientist: Iurii Shcherbak from Michigan State University

Flesch–Kincaid Reading Grade Level = 9.2

More information on the research associated with this Data Nugget can be found hereInformation on the effects of climate change in Michigan can be found here.

Data associated with this Data Nugget can be found on the MSU LTER website data tables under GLBRC Biofuel Cropping System Experiment. Bioenergy research classroom materials can be found here. More images can be found on the LTER website.

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Fertilizing biofuels may cause release of greenhouse gasses

An aerial view of the experiment at MSU where biofuels are grown

An aerial view of the experiment at MSU where biofuels are grown. Photo credit: K. Stepnitz, MSU

The activities are as follows:

Greenhouse gases in our atmosphere, like carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), trap heat from the sun and warm the earth. We need some greenhouse gases to keep the planet warm enough for life. But today, the majority (97%) of scientists agree that the levels of greenhouse gases are getting dangerously high and are causing changes in our climate that may be hard for us to adjust to.

Scientist Leilei collecting samples of gasses released by the growing of biofuels

Scientist Leilei collecting samples of gasses released by the growing of biofuels. Photo credit: K. Stepnitz, MSU

When we burn fuels to heat and cool our homes or power our cars we release greenhouse gasses. Most of the energy used today comes from fossil fuels. These energy sources are called “fossil” fuels because they come from plants, algae, and animals that lived hundreds of millions of years ago! After they died, their tissues were buried and slowly turned into coal, oil, and natural gas. An important fact about fossil fuels is that when we use them, they release CO2 into our atmosphere that was stored millions of years ago. The release of this stored carbon is adding more and more greenhouse gases to our atmosphere, and much faster than today’s plants and algae can remove during photosynthesis. In order to reduce the effects of climate change, we need to change the way we use energy and think of new ways to power our world.

One potential solution could be to grow our fuel instead of drilling for it. Biofuels are a potential substitute for fossil fuels. Biofuels, like fossil fuels, are made from the tissues of plants. The big difference is that they are made from plants that are alive and growing today. Unlike fossil fuels that emit CO2, biofuel crops first remove CO2 from the atmosphere as the plants grow and photosynthesize. When biofuels are burned for fuel, the CO2 is emitted back into the atmosphere, balancing the total amount that was removed and released.

Scientists are interested in figuring out if biofuels make a good replacement for fossil fuels. It is still not clear if the plants that are used to produce biofuels are able to absorb enough CO2 to offset all of the greenhouse gases that are emitted when biofuels are produced. Additional greenhouse gases are emitted when producing biofuels because it takes energy to plant, water, and harvest the crops, as well as to convert them into fuel. In order to maximize plant growth, many biofuel crops are fertilized by adding nitrogen (N) fertilizer to the soil. However, if there is too much nitrogen in the soil for the crops to take up, it may instead be released into the atmosphere as the gas nitrous oxide (N2O). N2O is a greenhouse gas with a global warming potential nearly 300 times higher than CO2! Global warming potential is a relative measure of how much heat a greenhouse gas traps in the atmosphere.

Leilei is a scientist who researches whether biofuels make a good alternative to fossil fuels. He wondered what steps farmers could take to reduce the amount of N2O released when growing biofuel crops. Leilei designed an experiment to determine how much N2O is emitted when different amounts of nitrogen fertilizer are added to the soil. In other words, he wanted to know whether the amount of N2O that is emitted into the atmosphere is associated with how much fertilizer is added to the field. To test this idea, he looked at fields of switchgrass, a perennial grass native to North America. Switchgrass is one of the most promising biofuel crops. The fields of switchgrass were first planted in 2008 as a part of a very large long-term study at the Kellogg Biological Station in southwest Michigan. The researchers set up eight fertilization treatments (0, 28, 56, 84, 112, 140, 168, and 196 kg N ha−1) in four replicate fields of switchgrass, for a total of 32 research plots. Leilei measured how much N2O was released by the soil in the 32 research plots for many years. Here we have two years of Leilei’s data.

Featured scientist: Leilei Ruan from Michigan State University

Flesch–Kincaid Reading Grade Level = 10.1

More information on LTER climate change research can be found hereInformation on the effects of climate change in Michigan can be found here.

Data associated with this Data Nugget can be found on the MSU LTER website data tables under GLBRC Biofuel Cropping System Experiment. Bioenergy research classroom materials can be found here. More images can be found on the LTER website.

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