Growing Plastic in Switchgrass

When we think of plastic we might immediately picture carrying our grocery purchases home in those ubiquitous bags that end up floating on the breeze or being re-used to pick up after your dog. But no matter how they are used far too many of them are ending up in the “Great Pacific Garbage Patch” and causing problems for marine wildlife.

We have grown accustomed to seeing plastic in everything from toys to electronic products to cars, boats, trains and planes. Traditionally, plastic has been made from petroleum, that substance we all love to hate but are unfortunately doomed to need until we adopt a better and cleaner energy replacement.

One company has found an alternative method of producing plastic. Massachusetts-based biotech company Metabolix has discovered a way to actually grow the plastic in the leafs of perennial plants. So far, switchgrass is the leading candidate to host this process. Anything left over after the harvest can go towards ethanol production.

By applying the knowledge gained from metabolic engineering, scientists at Metabolix have been able to produce what is being called biobased plastic. Their proprietary line of bioplastics is known as Mirel and can be used for everything from credit cards to plastic containers and even vehicle components.

Three immediate advantages of growing plastic instead of using petroleum is that, one, it becomes part of the movement to eliminate our dependence on fossil fuels, two, it makes a positive impact on global climate change by reducing greenhouse gas emissions and three, it will biodegrade to carbon dioxide and water in all environments with biological activity including soil, home composting, industrial composting, septic systems, wetlands, rivers and oceans.

Many plastics breakdown into smaller components over time (usually a very long time) but according to company statistics, Mirel will completely disappear in marine water within just over 40 days.

They tested injection molded bioplastics cups through 20 dishwashing cycles and found no change in either dimensional form or molecular weight. What this tells me is that injection molded bioplastics will still take time to break down and since most people use these type of cups once and toss them out, they will remain in the environment, however, probably not as long as traditional plastic cups. They do not give any stats on how long this form of bioplastics will break down. Bioplastic drinking cups, picnic plates and utensils will surely end up on the market, so we will require an adjustment in how we view them as throwaways since they will obviously have a longer useful life.

In 2006, Metabolix and Archer Daniels Midland Company (ADM) formed a joint venture company operating under the name of Telles to commercialize Mirel bioplastics. ADM has begun construction of the world's first Mirel biorefinery located in Clinton, Iowa. This new facility will produce 110 million pounds of Mirel plastic resin per year with start up scheduled for late 2008. Telles is responsible for the manufacturing, marketing and sales of Mirel worldwide.

Currently applications they are targeting are packaging, consumer disposables, erosion control, agriculture and any other application that requires sustainability, and/or biodegradability.

Finally, we will be able to bring our love affair with plastic back out into the open.