Are plastics flexible enough to go green? Lego is betting on it

Last month, Lego announced plans to go completely green and only use environmentally sustainable plastics in its products by 2030. But can we make it that far in 15 years?

  Can plastic ever become a green technology?   Valeria Montana Bonavides/Flickr  (CC BY 2.0)

Can plastic ever become a green technology? Valeria Montana Bonavides/Flickr (CC BY 2.0)

Public pressure is growing for companies to be more environmentally sustainable, triggering a laudable switch to recyclable or biodegradable plastics. The recent Lego announcement focuses on all aspects of sustainability: referring not only to what happens to plastics after they are discarded, but what they are made of, and how this material is sourced. With 5.2 million Lego bricks produced every hour, the emphasis on changing the source and composition of the plastic they use has huge implications for non-disposable products such as Lego. Lego has committed to invest 1bn Danish kroner (about AUS$200 million) to develop new sustainable plastics to make their iconic bricks. But, considering the green plastic industry is still in its infancy, steering away from the petroleum-based plastics they currently rely on will be challenging. 

  Lego is investing AUS$200m to research environmentally sustainable plastics.   Chris Christian/Flickr  (CC BY-NC 2.0)

Lego is investing AUS$200m to research environmentally sustainable plastics. Chris Christian/Flickr (CC BY-NC 2.0)

From frivolous party accessories in bargain stores, to practical products such as Kevlar and Teflon, plastics comprise a part of almost all products we use daily. Our clothes, building materials and smartphones all contain some kind of plastic. We’ve now produced more plastic in the last ten years than we did in the entire 20th century. Plastics are polymers (chains of repeating units), made from (typically organic) simple carbon building blocks. For the decades that polymers have been in mass production, crude oil and by-products of petroleum refining have provided a cheap, convenient source of carbon monomers (single units of polymer). Lego is no exception. Since 1963, Lego has been made from acrylonitrile butadiene styrene (ABS), a polymer which has three repeating units — acrylonitrile, butadiene and styrene — all of which are sourced from petroleum.

Currently, 300m tonnes of plastics are produced each year. Demand has risen so dramatically that 4% of the entire world’s oil production is used as a starting material for plastics, and a further 4% is consumed as energy during the process. At this rate, we’re quickly going to deplete this non-renewable resource. Clearly, we’re in desperate need of a ‘green’ alternative.

The field of green chemistry — redesigning chemical processes to produce less waste, use renewable feedstocks and be more energy-efficient — is a relatively new one. The term ‘green chemistry’ wasn’t even coined until 1991. Shortly after, research into renewable plastics became popular. Given that research into the chemistry behind petroleum-based plastics started over 100 years ago, it’s not surprising these products are still better than their environmentally sustainable substitutes.

  Corn, wheat and potatoes have all been used to produce renewable green plastics.   Kevin Schraer ,  Charles Knowles ,  United Soybean Board /Flickr (CC BY 2.0)

Corn, wheat and potatoes have all been used to produce renewable green plastics. Kevin Schraer, Charles Knowles, United Soybean Board/Flickr (CC BY 2.0)

Green plastics (or bioplastics) are plastics which are either biodegradable, produced from renewable sources (biobased), or both. Similar to biofuels, biobased green plastics use biomass (plant material) as a carbon source. Simple chemicals, such as sugars, or polymers themselves are extracted from plant material and converted into useful polymers. We are now able to produce plastics from a number of renewable sources including: corn, soy, sugarcane, sugar beet, potato, wood fibre, wheat, agricultural waste products (such as methane), and even bacteria. 

The most commonly used and most promising green plastic available today is polylactic acid (PLA). PLA is produced from the bacterial fermentation of corn starch, making it both biobased and biodegradable. In its early days PLA was quite expensive to produce, but in the last few years this has improved significantly. The cost of PLA (about 0.2 cents per gram) is now comparable to that of disposable, low-grade petroleum-based plastics, such as polystyrene and polyethylene (PET). With rising oil prices, PLA has become a practical alternative for everyday plastic items. The main drawback to PLA is that it suffers from a low melting point, so it can’t be used with hot liquids.

 
 

Despite huge interest globally, there is widespread debate within the scientific community about whether green plastics will ever reach the same potential as petrochemical-based plastics. This is mainly because there have been significant drawbacks to each of the green plastics developed to date. The features that make petroleum-based plastics so desirable, such as water resistance, strength and durability, can be difficult to incorporate into green alternatives. Many green plastics require petroleum-based additives to achieve these characteristics, and can contain up to 50% non-renewable materials. While these obstacles are difficult to overcome, they are certainly not impossible. 

  Dolls and tomatoes could soon have more in common than you think.   Charles Rodstrom/Flickr  (CC BY-NC-ND 2.0)

Dolls and tomatoes could soon have more in common than you think. Charles Rodstrom/Flickr (CC BY-NC-ND 2.0)

The final price of the plastic is another major concern. Converting land that can be used to grow food into producing commodities such as bioplastics, can be fraught with issues — as the first generation biofuel industry discovered in Europe.

Lego isn’t the only company to realise the potential of green plastic alternatives, and to look into more sustainable options. Adidas and Dell have both announced their commitment to incorporating more environmentally friendly plastics into their products. Procter and Gamble now use renewable sugarcane plastics for packaging in Covergirl, Max Factor and Pantene beauty products. And, surprisingly, Ford has developed an innovative research program in partnership with Heinz, investigating a way to make sustainable plastics from tomato skins.

Clearly, developing a useful and sustainable plastic isn’t an easy task. We may have a breakthrough tomorrow, or it might be many years before we’re able to make the switch with all of the plastic products we use. But who knows? Maybe the only thing we need to do to find the perfect plastic, is to eat more tomato sauce.