In this section, you will learn about and work through the engineering design process as you think about ways to remove CO2 from the atmosphere and store the carbon in forms where it will not contribute to global warming. As you work through this section, think about how you might use the engineering design process in your instruction.
The Role of Carbon
Most of Earth’s carbon is stored in rocks. The rest is in the ocean, atmosphere, plants, soil, and fossil fuels. Carbon moves between each of these reservoirs in an exchange called the carbon cycle. The carbon in rocks and fossil fuels enters the carbon cycle primarily through human activities—the burning of fossil fuels and the manufacture of such products like cement which involves the heating of limestone rock, releasing significant quantities of CO2. Any change in the cycle that shifts carbon out of one reservoir puts more carbon in the other reservoirs. Changes that put carbon gases into the atmosphere result in warmer temperatures on Earth. Over the long term, the carbon cycle seems to maintain a balance that prevents all of Earth’s carbon from entering the atmosphere (as is the case on Venus) or from being stored entirely in rocks. This balance helps keep Earth’s temperature relatively stable, like a thermostat.
Watch the "NASA: Keeping Up With Carbon" video. As you listen, keep track of where the carbon in the Earth's system comes from and where it goes. How does this carbon cycle affect life on Earth? Where is the largest reservoir of carbon on our planet? As you view the visualizations notice how carbon dioxide levels have increased over the millennium. Researchers are learning that future climate change will depend on carbon levels in the sea, on land, and in the atmosphere and how these levels respond to human disturbance. The Earth has not experienced carbon dioxide levels this high for the past several million years.
Next, view this visualization from NASA’s Jet Propulsion Laboratory retrieved by the Atmospheric Infrared Sounder (AIRS) on the Aqua spacecraft. It is overlain with a graph of the seasonal variation and interannual increase of CO2 measured at the Mauna Loa Observatory in Hawaii. The two most notable features of this visualization are the seasonal variation of CO2 and the trend of increase in its concentration from year to year. The global map clearly shows that the CO2 in the northern hemisphere peaks in April-May and then drops to a minimum in September-October. As you look at this visualization, think about the triggers for the dramatically increased CO2 levels through the years, and specifically within the last 25 years.
Climate scientists have identified the problem of climate change, including its history, mechanisms, and possible future scenarios. It takes engineers, however, to come up with technological solutions that have the potential to reduce the rate of climate warming. Read "What can we do about global warming?" from NASA's Climate Q&A blog. As you read, make a list of adaptations and potential solutions that require technology and engineering skills to put into action.
It has been determined that there are a few solutions open to us to address global warming:
- Dramatically change consumption and energy use behaviors.
- Restrict use of fossil fuels and develop new technologies of energy extraction around renewable resources.
- Identify ways to remove CO2 from the atmosphere and store it so that it will not contribute to greenhouse warming (carbon sequestration).
- Geoengineer our climate.
Engineering a carbon sequestration solution actually consists of two challenges: capturing and removing CO2 from the atmosphere, and finding a storage solution.
Capturing and Storing CO2
Processes already exist for capturing CO2, the same processes that are used today to fizz our sodas and make dry ice. CO2 is routinely captured as a by-product from industrial processes such as synthetic ammonia production, hydrogen production, and limestone calcination. Engineers are exploring strategies that would allow the capture of CO2 from coal-burning power plant emissions, including newly emerging coal gasification processes. Learn more about emerging carbon capture technologies here by watching "Clean Coal?" from PBS LearningMedia. What are some of the obstacles and dangers associated with carbon capture and storage? What would be some possible solutions?
Read the information presented by the National Academy of Engineering on their website "Grand Challenges for Engineering." Next, see how engineers are workings on ways to capture and store excess carbon dioxide to prevent global warming in "Develop Carbon Sequestration Methods."
The Engineering Design Process
How can we apply the engineering design process to the problem of carbon sequestration? PBS Design Squad is the Peabody Award-winning TV show on PBS in which teenage contestants tackle engineering challenges for an actual client. They design everything from a hockey practice net for the Boston Bruins to a peanut butter grinder for a women's collective in Haiti. The show is an action-packed look at the design process. Teams compete to create the best product; then their designs are put to the test! NASA has teamed up with PBS Design Squad Nation to create challenges and resources for the problems of the future.
From the Design Squad Nation Teacher's Guide; © 2011 WGBH Educational Foundation.
In the "Online Workshop for Educators," you can experience each stage of the Engineering Design Process with video clips and printable resources.
Click on each part of the process in the diagram to explore each stage. As you look at the resources and examples, consider how you can use the PBS Design Squad process to engage your students in learning about global climate change.
Next, watch "What is the Design Process?" and review the steps of the engineering design process. The video highlights the building of a skyscraper, but the process used is applicable to any sort of project with the goal of finding a solution that has the potential to remove large quantities of CO2 from the atmosphere.
Do you think the steps of the design process are similar to or different from the scientific process (scientific method)? Neither process is necessarily linear and both include iterations between steps as needed. The scientific process and the engineering design process are really parallel processes. However, at the end of a scientific investigation you may have an idea or new knowledge and at the end of the design process you have a product—something that has been created. On the other hand, sometimes the processes do not yield a useable result, so the cycle starts another iteration. The iterative process is an important characteristic of both the scientific and the engineering design processes.
Look at the following comparison of the activities scientists and engineers complete while conducting their work:
|Scientific Method||Engineering Design Process|
|Question||Identify the Problem/Design Challenge|
|Hypothesis||Brainstorm & Design|
|Conclusion—new knowledge||Rebuild—new product|
I. Identify the Problem/Design Challenge
Conduct a web-based inquiry of the carbon cycle by looking at the "How Does the Carbon Cycle Work?" interactive. Focus on Sections 2, 3, 4 and 5 and pay attention to the boxes showing carbon reservoirs and fluxes. When exploring the interactive you can return to the home screen by clicking on the Table of Contents from the bottom navigation. After your exploration, think about what other reservoirs you can name where the contribution of carbon to climate is minimal.
Remember, the carbon cycle includes the following major reservoirs of carbon interconnected by pathways of exchange:
- The atmosphere;
- The terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon;
- The oceans, including dissolved inorganic carbon and living and non-living marine biota;
- Sediments, including fossil fuels;
- The Earth's interior—carbon from the Earth's mantle and crust is released to the atmosphere and hydrosphere by volcanoes and geothermal systems; and
- The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth.
Can you identify possible storage solutions that would keep CO2 out of the atmosphere and reduce its immediate impact on climate?Answer
Possible storage solutions that would keep CO2 out of the atmosphere and reduce its immediate impact on climate include:
- Longest term storage potential: Locking up carbon in rocks, freezing in ice, injecting into the deep earth, storing in ocean sediments.
- Shorter-term storage potential: soils and biomass, like grass and trees, removes CO2 for some period of time from the atmosphere.
Compare your ideas for capturing carbon with the interactive, "Capturing Carbon: Where Do We Put It?" The interactive identifies potential means of storing carbon dioxide (CO2) captured from industrial sources. The technologies featured deliver compressed CO2 to underground cavities, saline aquifers, and the deep seabed. Storing, or sequestering, captured CO2 could be a key factor in limiting global warming. Consider how likely these technologies could solve the problem of carbon capture or storage. What are the pros and cons of each as shown in this interactive?
If you would like more information, read "The Carbon Cycle" from NASA's Earth Observatory. This web page provides a clear explanation and images demonstrating the carbon cycle.
Now that you have identified the problem, continue working through the engineering design process by brainstorming ways to remove CO2 from the atmosphere, and store it in carbon storage reservoirs that interact with climate change primarily over long time scales.
How can we encourage the creative abilities of students so they can harness their intellect and create innovative engineering solutions? Where do ideas come from? Ideas are all around. Here are examples of engineering solutions that were inspired by structures in nature:
Watch this video from PBS LearningMedia and consider the challenges the engineers faced and what things in nature inspired their work.
Design Inspired by Nature
Watch this video from PBS LearningMedia and think about the advantages of studying the natural world before creating something for people to use.
Students should not feel like they are at a disadvantage in the brainstorming process just because they are young—their fresh approach to problems, unconstrained by knowledge of conventional solutions helps them to "think outside the box!" See how one young woman was inspired by nature to create a carbon-capture solution of her own in this video "Capturing Carbon." As you watch, consider why it took the engineers 10 years to come up with a workable design. How is this an example of the scientific and design process working together?
The most critical carbon reservoir implicated in global climate change is the CO2 added to the atmosphere by human activities. Brainstorm ways to remove CO2 from the atmosphere, and store it in carbon storage reservoirs that interact with climate change primarily over long (geological) time scales.
If you would like more information about carbon sequestration, visit the EPA site “Carbon Sequestration in Agriculture and Forestry.
If you would like to listen to a scientist describing a carbon sequestration solution, listen to Farouk El-Bas describe how oil production can sequester carbon.
What ideas do you have about combining the engineering design process with your global climate change instruction?
Do you see how the scientific process and the design process complement each other?
III. Design a Solution and Build a Prototype
Once a solution to a problem has been identified, it needs to be designed and deployed. There are still many steps before you would be able to take your carbon sequestration solution to this stage.
However, you can explore the kinds of technical, logistical, and budget challenges associated with deployment of an engineering solution by testing a remote site power prototype, in the design challenge "Power Through the Night." This is a computer program designed to analyze the outcome of each of your experiments, so when you build a successful prototype, it lets you know. You are now ready to build your remote site power station! As you participate in this challenge, think about how you might implement this activity with your students.
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