Environmental Question #32 [Bioplastic Energy Cost]

What is the energy return on investment for making bio plastics right now, and where is it projected to go in the next couple of decades?

Courtesy of Reddit user u/truthsleuth180

Q: What is the energy return on investment for making bio plastics right now, and where is it projected to go in the next couple of decades? Because what I’ve seen so far hasn’t been great.

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A:  That's a great question! Generally making bioplastics is no less energy intensive than making conventional plastics, although it is important to look at the complete picture. Accounting of resource use for conventional plastics is famously poor, because generally plastic producers account for the energy used to make the plastic, but not for the resources used to deal with the plastic once it has reached the end of its life. When accounting for the full lifecycle of the material, bioplastics are almost always better than conventional plastics, however bioplastics still have their own issues.

One of the wonderful things about crude oil for chemists is that it's already pre-digested. As I'm sure you know, crude oil is made of ancient organisms that have broken down over several millennia. From a chemical perspective this means that the chemicals inside those organisms have broken into their basic building blocks, which makes using them for chemistry very easy. As an analogy, think of it like cooking food. If you picked all of your fruits and vegetables fresh out of the field, many would need some pre-preparation before you can begin cooking. Corn needs to be shucked, bananas need to be peeled, meat needs to be butchered. That all takes time and energy that isn't necessary if you buy your ingredients in a ready-to-cook state from the grocery store. Making materials from crude oil is like cooking from ingredients from the grocery store, and making materials from natural sources is like picking it straight from the field. The additional steps required to purify and prepare the natural materials prior to actually synthesizing a product adds onto the required energy inputs. If the products are biodegradable though, some of that extra energy input can be offset by reduced disposal costs.

If you think about this from a systemic perspective though, you'll start to see why bioplastics haven't taken off in a real way. First, remember that disposal costs are almost never considered part of the overall cost, and second, remember that bioplastics require an additional preparation step before the main manufacturing. Taken together that makes it appear as though bioplastics take twice as many resources to produce, when in fact it was just a bit of accounting misdirection. This is why it is so important to make manufacturers pay at least in part for the disposal of the products they create, rather than passing off the cost to consumers and society at large. This would make bioplastics and biodegradable materials more realistically cost competitive, and it would incentivize companies to invest in designing products that actually reduce waste.

This can only be accomplished through governmental regulation though, so to your question of how this will progress in the coming decades, that will depend on who we elect to lead us.