Bio-plastics are a form of plastics made entirely or almost entirely from renewable raw materials such as vegetable oil, corn starch, biomass or microbiota, whereas fossil-fuel plastics are made from petroleum (oil or gas). Several types of bio-plastics have exactly the same physical properties as petroleum-based plastics, as the molecular structures of both are identical. Other types have very different properties, one of which is the hot topic issue of biodegradability. Since bio-plastics are made from renewable sources, they can reduce our dependence on oil and gas – which are non-renewable – to make plastics. They can also be produced in ways that allow the material to degrade. At the moment however bio-plastics cost too much to produce, and the amount of renewable raw materials is relatively limited, so they represent a small part of the plastics industry.
Are bio-plastics greener?
Many people think that bio-plastics are more sustainable than plastics made from oil or gas because they rely less on fossil fuel. However, converting renewable raw materials into useful plastics is a complex and energy-intensive process, especially if you compare it with the efficient way that conventional plastics are made today. Also, to make bio-plastics, you still need petroleum as an energy and materials source. How? Well, you need petroleum-based energy to power farm machinery and irrigate and transport the crops to the processing plants. You need energy to make fertilisers and pesticides to grow and protect the crops. And you need energy to process the raw materials and produce the bio-plastic. There is also an ethical issue here: should valuable farmland be used to make bio-plastics instead of growing crops to feed people and animals? So, it is not so easy these days to simply say that bio-based plastics are better for the environment or not. Many companies however are investigating ways to manufacture bio-based plastics in the most efficient way possible. With global oil reserves running out and oil prices increasing, it makes sense to find alternatives to fossil fuel as soon as possible.
Making plastics biodegrade
Many people associate bio-plastics with materials that you can just discard in the green waste container or (even worse) just throw away. But this is simply not true! When plastics 'bio-degrade', it means that a part of the plastic degrades (or decays) through natural means. In many cases, this means that the bio-plastic can be put into a compost heap where it degrades. This does not apply to compostable plastic. Compostable plastics require much more heat and humidity to break down than that generated in your average backyard compost bin, so they have to be processed through industrial composters or incinerators. If there aren’t suitable recycling bins for your compostable plastic, it is sometimes even better to put it in your regular rubbish bin.
A growing family in a world market
Biodegradable bio-plastics are used for disposable items such as packaging, and catering items (crockery, cutlery, pots, bowls, and straws). They are also often used for organic waste bags, where they can be composted together with the food or green waste. Some trays and containers for fruit, vegetables, eggs and meat, bottles for soft drinks and dairy products, and blister foils for fruit and vegetables are manufactured from bio-plastics. In the years 2000 to 2008, worldwide consumption of biodegradable plastics based on starch, sugar, and cellulose - so far the three most important raw materials - has increased by 600%. Even so, bio-plastics still represents a very small part of the overall plastic market.
Cost-effective in healthcare
With the exception of cellulose, most bio-plastic technology is relatively new and is currently not cost-competitive with petroleum-based plastics. However, in certain, special applications bio-plastics are already unbeatable because of their special added value. For example, medical implants made of biodegradable plastic that dissolve in the body can save patients from having to undergo a second operation.
Bio-plastics – a sustainable option
Bio-plastics should be viewed as one viable option to improving environmental sustainability. There’s no doubt that the bio-plastics market is growing, and strategies such as blending bio-plastics with other plastics could be the best way to reducing costs and improving performance in the short term. In the long term, what’s needed is investment from major players in the plastics market to provide the resources and application knowledge needed to increase market penetration. There is also a need for national Government to develop an infrastructure for recycling bio-plastics, and to educate everyone on the importance of recycling. If we can get more of our processing energy from renewable resources, produce the raw material sustainably, and recycle the final product as much as possible, bio-plastics could certainly have a secure and sustainable future.