The world today has an insatiable demand for plastics, in everything from shopping bags and soda bottles to fast-food and supermarket packaging. While common fossil-fuel plastics derived from petrochemicals (petroleum or natural gas) take hundreds of years to create and release significant amounts of greenhouse gases in their production, they are quickly consumed, adding to landfill or ending up in our oceans. However, there is hope for sustainable plastic with the emergence of bioplastic.
But bioplastic made from renewable resources provide one solution, with many being completely biodegradable, enabling them to be composted naturally and locally, reducing our environmental impact. While they’ve been dabbled with in the past (Henry Ford made a prototype plastic car made from soybeans in 1941), it has only been in recent decades as awareness of our global environmental impact has increased (together with our demand for plastics), that research into bioplastics has soared. So what are bioplastics, what do they mean for our environment, and how can they be applied as a sustainable building material?
What is bioplastic?
Bioplastic is a plastic which is completely derived from renewable biomass sources, including vegetable fats and oils, as well as corn starch and microbiota. Natural feedstocks including corn, potatoes, rice, wood cellulose, wheat and palm fibers are all commonly used to create bioplastics, and transformed into plates, cutlery, bottles, bags, textiles and packaging materials. In the United States, the required percentage of biobased ingredients in a product before it can be labelled ‘biobased’ varies widely on a product-by-product basis, and is determined by the United States Department of Agriculture (USDA).
While some biobased material will biodegrade in commercial or home-based composting facilities, as well as aquatic and roadside environments, others require very specific environments before they will biodegrade and others won’t biodegrade at all. Before a product receives a Biodegradable Products Institute (BPI) compostable logo in the United States is must:
- Disintegrate rapidly during the composting process
- Biodegrade quickly under the composting conditions
- Not reduce the value or utility of the finished compost, with the humus manufactured still being able to support plant life
- Not contain high amounts of regulated metals
Why do we need bioplastic?
Bioplastic can not only be used to eliminate the waste created by petroleum-based plastic packaging, but also used in non-disposable applications to create sustainably resourced products. This includes mobile phone casings, plastic piping and fuel lines which are designed to be long-lasting and resilient, without the negative environmental consequences of their traditional plastic counterparts.
Bioplastics are also promising in the medical field, with implants made from polylactic acid able to be dissolved within the body, preventing patients from needing a second operation to remove them at a later date. In agriculture they can also be used in compostable mulch films produced from starch polymers, which don’t need to be removed and disposed of in rural communities.
The environmental benefits and challenges of bioplastic
Because so many different types of bioplastic exist, each with their own environmental benefits and challenges, the overall impact of bioplastic is still hotly debated. They generally require less fossil fuel for their production and release fewer greenhouse gas emissions, as well as resulting in less hazardous waste than petro-plastics which can remain in their solid state for hundreds of years.
In many cases, fossil fuels are still used in substantial quantities to produce bioplastics in the form of energy required to power farm machinery, as well as produce fertilizers and pesticides. Fossil fuels may also be used to transport crops to processing plants where bioplastics are created. But in some cases, renewable energy sources are implemented instead and petroleum can be avoided all together.
Genetic modification is another challenge facing the industry, with many bioplastic factories using genetically modified crops or bacteria to optimize efficiency. Understandably, this raises concerns and requires careful management to ensure that non-GM crops aren’t affected.
While petroleum-based plastics have long been a more affordable option, the increasing cost of crude oil in recent years has made them less lucrative. This, in turn, has seen the worldwide consumption of bioplastics increase exponentially. There are concerns that the large-scale production of bioplastics could lead to accelerated deforestation and soil erosion, as well as having detrimental effects on water supplies if not managed adequately. Sustainably grown biomass is essential if bioplastics are going to be the environmental savior that they have the potential to. Effective composting programs and infrastructure also need to be developed to help support their biodegradation on a large scale.
Can bioplastics be used as a building material?
In recent years, bioplastic technology has been applied to building construction, with an ultra-modern pavilion made from bioplastic constructed in Stuttgart, Germany. Its freeform facade was developed as part of a collaborative project bringing together scientists, architects, manufacturing technicians and environmental experts, resulting in a thermoformable facade cladding made from more than 90% renewable resources. Dubbed Arboblend, this material is made from bioplastic granules which are shaped into sheets and can be further adapted to achieve different surface qualities and forms.
The bioplastic granules are made primarily from lignin which is an abundant natural material and byproduct of the paper industry, responsible for the compressive strength in natural wood. The majority of lignin is currently burned for thermal energy, but when mixed with natural fibers such as cellulose, flax and hemp, results in the bioplastic granules of Arboblend.
While Arboblend bioplastics have been used to make furniture, garden supplies and even children’s toys, this is its first application as a building construction material. Its composition can be adjusted to create different strength and rigidity properties and has the ability to withstand combined tensile and compressive loads, just like natural wood. Arboblend cladding sheets meet the high durability and inflammability standards required of building materials, while keeping petroleum-based additives to an absolute minimum.
There’s also ongoing research into bioplastics that would effectively sequester carbon and their application in areas traditionally left to concrete, steel and wood. The construction of large-scale infrastructure, such as bridges, piers, sidewalks and water pipes, using bioplastics could have a huge impact on global carbon sequestration, as well as reducing the amount of CO2 commonly released during the manufacture of petroleum-based building products.
While it may be early days for bioplastic as a building material, the Stuttgart pavilion and research currently being conducted into its feasible application indicates a promising future.