Balancing the Carbon Cycle

Human processes contribute over 29 gigatons of carbon dioxide to the atmosphere every year. Seeing as how carbon dioxide has a density of 1.98 grams per liter, that's a whole lot (thats the scientific term) of carbon dioxide. In fact, carbon dioxide is the primary greenhouse gas released by humans, and makes a significant contribution to the largest problem facing humanity as a whole: global warming. In global warming, our emissions of Carbon Dioxide upset the global carbon cycle (the global exchange of CO2 between the different areas of the earth, like plant biomass, the ocean, and the atmosphere), leading to an increase of CO2 in the atmosphere overall. This leads to the greenhouse effect, where more heat is trapped in the atmosphere from the sun than is irradiated out, causing an overall increase in the temperature of the earth. 

Image Courtesy of livescience.com

Another disastrous effect of these increased CO2  emissions is ocean acidification. CO2 can be taken in by the oceans, reacting with the water to form carbonic acid. This leads to an overall decrease in the pH of the oceans, in some places to a significant degree. The figure below shows just how acidic the oceans are becoming. It is important to note that pH is a logarithmic scale, meaning that an increase in pH of 1 means that there is ten times the concentration of hydrogen ions in the water. 

Change in Sea-Surface pH since the 1700s
Image Courtesy of GLODAP

This acidification is so disastrous due to how sensitive living things are to changes in pH. Organisms like clams and oysters are particularly sensitive, and may be affected first. Thanks to how dependent we, as well as other animals are on these shelled creatures, the entire food web is at risk when these organisms are affected.

So what can we do to fix this? The biggest effort today is all about reducing our emissions of carbon dioxide through clean energy. Chunshan Song, director of the EMS Energy Institute, has something additional to add to this school of thought. What if we looked at CO2  not as a waste product, but instead an ingredient to create fuels and chemicals? Traditionally such products like olefins (which are used to create things like plastic bottles and ziplock bags) are produced using oil, but utilizing novel catalysts, Song is able to use carbon dioxide (along with some hydrogen gas) to create these products. Catalysts are specific substances (commonly metals) that lower the energy needed to be put into a reaction to get it to proceed, enabling new chemical pathways that result in products that you would not originally be able to produce. In the case of the olefins, Song is using a copper and palladium catalyst to produce this very useful chemical.

Song is trying out many different catalysts to see what new products that he may be able to create using carbon dioxide conversion. It is possible that CO2 will be able to be converted into all of the petroleum derived products, reducing and perhaps eliminating our reliance on the unsustainable fuel.  

Catalysts that have been investigated
Image Courtesy of Penn State

 Song hopes that the process will lead to a new "sustainable green energy cycle" that both reduces  CO2  emissions and reduces the global CO2 levels back to a earth-friendly level.

If you'd like to read the paper regarding the Cu-Pd catalyst, you can find it here.