Solutions already exist to replace oil-based plastics with corn-based Polylactic Acid (PLA) and Crystallised PLA (CPLA).  Currently, a wide range of PLA / CPLA products are commercially available that can substitute plastic straws and films (as outlined in the cases).  For simplicity, we will describe PLA from now on, understanding that CPLA can be used at higher temperatures without degrading (such as moulding for the tops of hot drink cups).

A good example is the list of products manufactured by a Scottish-based packaging company called Vegware (http://www.vegware.com/).  They have further developed Recyclable CPLA/PLA.  

Vegware produces PLA see-through containers with attached lids (removing the need for plastic film lids); straws; films for packaging and CPLA lid tops.  

The result of our research is that great solutions already exist to replace their plastic counterparts!

PLA has considerable benefits over normal plastic:

• Technically, PLA is "carbon neutral"
• PLA will not emit toxic fumes when incinerated.
• PLA can break down into its constituent parts (CO2 and water) within three months in an industrial composting facility heated to 140 degrees Fahrenheit and fed a steady diet of digestive microbes.
• PLA products require certain conditions for degradation which includes the appropriate amount of heat, moisture and air, etc. Generally, conventional landfills do not fulfil these necessary conditions.
• The end-product from PLA composting is lactic acid - which is formed by natural fermentation in products such as cheese, yoghurt, soy sauce, sourdough, meat products and pickled vegetables.  Unlike Lactose, Lactic Acid is fine for Vegans to consume.

So why aren't we replacing plastic with PLA with the necessary urgency that is required to stop oil-based plastic packaging?  The picture is complex, but it probably comes down to a combination of some of the following drawbacks:

• PLA is not microwave-safe.  CPLA can handle the heat (for lid-tops).
• PLA degrades very slowly (unless it is subjected to industrial composting- see below).  A PLA bottle, for instance, could take anywhere from 100 to 1,000 years to decompose in a landfill and is not much better than oil-based plastics that are thrown away into landfill.
• PLA products require certain special conditions for degradation (which includes the appropriate amount of heat, moisture and air, etc.).  There is currently a shortage of PLA local industrial composting facilities that will perform such degradation.
• The current recycling system (which is only ~14% effective) gets fouled up if it has to process both oil-based and corn-based PLA plastic materials.
• Most PLA uses genetically-modified corn and truly "green" consumers may well get "religious" and prefer (rightly) to go the extra mile and use reusable containers (like we used in the olden days) with cloth bags, baskets etc. as well as non-plastic drinks bottles.
• PLA is sourced from corn - and demand for ethanol fuel (also made from corn) is rising.  This might have an impact on the price of PLA in the future.

The main issue preventing wide scale uptake appears to be the fact that PLA and oil-based plastics don't mix well and need to be treated as separate "recycling" streams. 

To scale this solution, we need to:

• design more effective communications via brands (such as supermarkets, coffee chains etc.) so that consumers understand the benefits of using and separating out PLA containers over oil-based plastic materials - as well as the fact that PLA needs to be composted in specialist local industrial composting facilities (LCIFs - my term)
• design collection mechanisms that are close to the point sale so that consumers are more likely to drop the PLA containers in the right "recycling" stream.
• design a system that can separate out PLA containers that are put into plastic "recycling" streams (through the redesign of labelling/marking and sorting processes).
• implement many local industrial composting facilities (LICFs) that can process PLA locally and will prevent the PLA "recycling" streams from being exported (like current practice for plastic to places like China etc.).

The business case would appear to be compelling looking at the opportunity top-down - but more work needs to be done here to prove the point!  (Unless readers know where it already has been done?)

One obvious way to pilot this idea would be to start with selected Transition Towns and their associated local supermarkets and cafes.  The Transition Town movement is already thinking ahead on issues like this and the learning in the early stages of the project would likely be accelerated dramatically so that we could scale the best solutions found in the pilot stage.

References:

http://www.vegware.com/

https://www.biogreenchoice.com/category_s/1866.htm

https://www.thoughtco.com/pros-cons-corn-based-plastic-pla-1203953

http://www.designinsite.dk/htmsider/m0953.htm

https://transitionnetwork.org/

https://www.transitiontowntotnes.org/about/what-is-transition/