Friday, July 21, 2017

Sustainability Series Part - 2 - The plastics

Ask a Process engineer working in the oil and gas industry -  what the most valuable product coming out of refinery is, more often than not she/he would point at the plastics!! Yes Plastics!! They are a broad range of chemical compounds that have revolutionized our life. Take a moment to look around, the paints on the chair or the chair you are sitting, the window frames, your coke bottle, your favorite snickers wrapper and many more. You can throw a random dart and the probability of hitting some plastic coming out of a refinery is very high!! The fuels (diesel et al) are just a good byproduct that have some value and use. In this post let us look into what plastics are and how they influence our life!!

1. Are plastics really bad for environment? 
YES . There are several reasons why plastics are bad!!
a.Plastics are mostly non biodegradable. Meaning in not disposed in the right way, they will remain a few million years.
b. They are mainly produced from fossil fuels. You can never say goodbye to oil and gas until plastics' usage is reduced or an alternative is found.
c. The impact it has on animal diversity both on land and in ocean is damaging.
d. Many plastics are considered carcinogenic. Long term effects are not fully known yet, but research is putting plastics at the forefront of many physical damages.

2. What are the major types of plastics ?
While plastics can refer to a lot of synthetic materials, they can be broadly classified into 7 different types. Any plastic container or material that we use, has a marking in the bottom that helps us identify what kind of plastic it is. This identification is also used in segregating them for recycling when we dispose them.  
A good overview of the types of plastics can be found in:
https://www.lifewithoutplastic.com/store/common_plastics_no_1_to_no_7#.WWwfnoSGNhE.
Summarizing,


Code Plastics Exp Recycling%   Toxicity     Use
1 PET Polyethyleneterapthelate     <30 td="">    medium     Avoid for storing food
2 HDPE
High Density Polyethylene
   <30 nbsp="" td="">    Low     Good for use
3 PVC Poly Vinyl chloride    less    high     avoid  
4 LDPE
Low density poly ethylene
   less    low     Good for use
5 PP Polypropylene    less    low     Good for use
6 PS Polystyrene    less    high     avoid
7 Other many types    N/A    Low  high    depends on the type 

Only number not complete in the article is number 7. More on that  later.

3. If plastics are this bad, why are we using?
Plastics are not all bad. They have immensely helped the world fight hunger and wastage (ironic is it not). They are light, resistant to heat and long lasting. This has helped in preserving food, transport different manufactured goods at fractional energy expense, make things waterproof etc etc.

4. Can plastics be made degradable?
Yes. There are couple of additives that can make plastics (bio)degradable.
a. Oxo additives for plastics. They are metallic additives and they make plastics degradable in a landfill. Jury is still out on this process as they leech out precious metals,
b. Enzyme based additives: Bio based additives that make plastics biodegradable. Still lot of research is underway.
It is important to note that these are just additives to normal plastics that we use.

5. What are green plastics? Are they biodegradable?
Green plastics are one of the most misunderstood terms. Not all green plastics are biodegradable. Green plastics are mostly normal plastics (from answer 2), but produced from bio based feedstock. They have have the same problems as the normal plastics. But they are better, as we become less dependent on fossil fuels and the production process emits lower CO2.

But there are other plastics that are completely different like PLA (poly lactic acid). The plastic made from lactic acid is biodegradable. They also come under code no 7 in question 2, with biodegradable written on it. Remember to throw them with compostable waste rather than  plastics. PLA is nowadays used extensively in 3D printing and food packaging. Some places where I have seen them are:,
1. TU delft campus (most of the disposable cups at least in the chemical engineering building are PLA.
2. The coffee company milkshake cups.
3. Leon restaurant in schipol airport

6. What is this Code no 7 then?
There are 2 main types of code 7, that I have seen. PC (Poly carbomate) - which are very bad as they are known carcinogenics. Other ones are the compostable ones - PLA. Usually there is no recycle foe this number.

Plastics are very much necessary for our sustenance. At the same time we much understand the consequence of using them and be sensible in using the right kind of plastic for the right use (Eg - Water bottles should not PET/PS and use PP, Using PLA for packaging and disposable plastic cutlery ).