Green Energy Times has published a number of articles about plastics. As I work on this one, one article that was printed in the August, 2015 issue stands out in my memory. It was called, “Good Plastics? Really?” (www.bit.ly/GET-good-plastics). In it, we covered plastics that are biodegradable and are not made from fossil fuels.
Now, we have word of another kind of plastic that was developed in Germany and is just now coming to market. The interesting thing about it is that its manufacture is carbon-negative. That means making it draws down more carbon dioxide from the atmosphere than it releases. According to an article in CleanTechnica, manufacture of Made of Air (also the name of the maker) draws down two tons of carbon dioxide from the air for every ton of plastic produced (www.bit.ly/carbon-negative-plastic).
That might sound like some sort of smoke-and-mirrors act to some people, so an explanation may be in order. The Made of Air plastic is 90% carbon. This is not at all unusual. The basic unit in polyethylene is a molecule with a formula of C₂H₄. Since that means there are four hydrogen atoms in every molecule, it really looks like the material is largely made up of hydrogen. In fact, it is, if we are just counting atoms. But when we are finding the weight, we have to take into account that the atomic weight of hydrogen is 1, and the atomic weight of carbon is 12. So, the ratio of weight in C₂H₄ is 24 parts carbon to 4 parts hydrogen. It is nearly 86% carbon, by weight.
If we consider CO₂, we see that the atomic weight of the oxygen is 16, but there are two oxygen atoms, so the weight of the carbon is only 27% of the total weight of the molecule. Going further, we can find that if we made a ton of polyethylene using only carbon dioxide from the atmosphere, it would actually take over three tons of CO₂ to give us the carbon we would need. So, the amount of draw-down reported by Made of Air is believable.
The plastic Made of Air is derived from waste from the agriculture and forest industries, along with some cane sugar. The company has broadly described the process. The source materials are waste from agriculture and forestry, as mentioned above. This waste is rendered into biochar, which is made by heating the source materials.
The heat used to make biochar is usually created by burning the gases released as it is made, and the combustion does allow some CO₂ to return to the atmosphere. In the case of Made of Air, there is sufficient heat left over from the process that it can be used for other purposes.
Biochar is often used to provide fertility to the soil for gardening and farming, but in this case, it is a main part of the plastic. It is infused with a binding material made from cane sugar. The result of this process is a thermoplastic, which means it can be cast and welded in the same ways as polyethylene and polypropylene.
Made of Air products have already been brought to market, but not in great volume. The products made from it range from frames for sun glasses to siding for buildings. Made of Air siding was used at an Audi dealership in Munich.
Made of Air claims that every step in the process of making the plastic is carbon-negative. The company is scaling up production and hopes to make about 100 times as much of it next year as it does now.
There is one thing about Made of Air that might raise a few eyebrows. As a thermoplastic, it can be reused, but the company says that it does not decompose, and the only way to release the carbon from the plastic is to burn it. The way we think these days might make this seem bad. But in this case, decomposition would put the carbon back into the atmosphere, precisely where we want it not to be. Made of Air is taking carbon dioxide out of the atmosphere and rendering it into a form we can sequester permanently. That is what we really need.
The Made of Air website is www.madeofair.com