Imagine removing billions of tons of plastics made from petroleum products from both over-taxed waste streams and costly recycling processes. What if the plastic shopping bags we use or plastic tops covering drinks were biodegradable? Dr. James Nakas and his colleagues, Dr. Stuart Tanenbaum and Dr. Thomas Keenan at the State University of New York College of Environmental Science and Forestry, in Syracuse New York are actively researching this question. Their new generation of biopolymer plastics represents an attractive alternative to plastics derived from fossil fuels during a time of rising crude oil prices, waste management problems and continued global pollution.

Growing environmental awareness and the emerging global concern over limited fossil fuel reserves, has prompted the search for novel plastic materials and production processes that draw from sustainable, renewable stocks and enhance the environmental quality of the products produced.

Whilst most plastics can take hundreds of years to break down in landfills, Dr. Nakas is working on a new type of plastic which breaks down in six to ten weeks. Conventional plastics are made from oil-based chemicals and their molecules are bonded too tightly to be easily broken down by the bacteria found in landfills.

Rather than using petro-chemicals, Dr. Nakas has turned to wood, which is a renewable resource. Polymers or plastics, made from these wood-based materials can be easily broken down by bacteria and leave behind only carbon dioxide and water. Furthermore, these plastics can be manufactured to be quite rigid or very flexible, yet still have the shelf life of the plastics we are familiar with.

One source for these bio-plastics is the wood-based waste material left over from the paper-making process. Paper mills produce tons of the waste every day, so it is readily available and relatively inexpensive, according to Dr. Nakas.

Another source for bio-plastics is dedicated woody crops such as willow shrubs (Salix spp.). Fast-growing willows can be grown in numerous locations and yield a large amount of biomass on a small plot.

Biodegradable plastics are not new. Other materials used to make bioplastics from plant materials include wheat or cornstarch. The development and use of woody biomass resources have advantages over agricultural sources in that they are available year round and, in the case of willow biomass, provide high yields that can be obtained in only three to four years.

Unfortunately at present, the cost of making bioplastics from these materials is currently more expensive than making them with petroleum. However, Dr. Nakas believes that the wood-based plastics being developed in his lab could be very cost-competitive with oil-based products in the near future.

This promising research could lead to replacing conventional, oil-based plastic products with environmentally-friendly plastics.

Forest biomass represents an enormous reservoir of renewable carbon-rich material. It also has the potential to be used as stock for the production of a wide variety of industrial and commodity products, ranging from paper, lumber and platform chemicals to a variety of fuels and speciality chemicals including biodegradable polymers. The total amount of plant biomass accumulated globally amounts to approximately 182 trillion kg, while only 5 trillion kg are utilized (primarily for cereal/oil, sugar and wood). Lignocellulosic biomass comprises approximately 50% of the global biomass and is by far the most abundant renewable organic resource on earth.

The rapid growth of oil-based plastics production has been a Twentieth Century phenomenon, obviously due to the extraordinary versatility and until recently, relatively low cost of conventional petroleum-based stocks. Built for the long haul, these environmentally recalcitrant plastics are being produced at alarming annual rates of production, estimated at over 91 billion kg in 2000, with over 36 billion kg being produced in the United States alone.

The packaging industry represents one of the largest areas of plastics’ growth, utilizing the four major commodity resins, polyethylene, polypropylene, polystyrene and polyvinyl chloride in a variety of applications including films, flexible bags and rigid containers. These conventional plastic materials have the advantages of reasonable cost, strength and durability. However, these same qualities contribute to their accumulation and considerable ecological and environmental concerns.

Although recycling efforts have evolved, daunting quantities of single-use non-recyclable plastic material continues to fill landfills and incinerators throughout the United States and the World. Each year, over 10 million tons of plastics are discarded as waste in the United States and Europe. Ignoring the obvious associated problems of waste-disposal, incineration of plastic waste brings about secondary environmental pollution with the production of potentially harmful toxins.

Recent heightened interest in the area of biodegradable polymers is indicated by the increase in worldwide consumption of biodegradable polymers from 14 million kg in 1996 to 68 million kg in 2001. However, when compared to over 70 years of research and development devoted to improving the production and performance of synthetic oil-based plastics, scientific progress regarding bio-based and biodegradable polymers is clearly in its early stages with current production costs. There is also a lacklustre consumer acceptance for the more expensive ‘Green’ generation of products which has hindered their advancement.

There have been other important factors that have discouraged commercialization of degradable polymers during their initial appearance in the late 1980s and early 1990s. There were no clear, well-defined standards for industries and governmental agencies to evaluate and confirm degradability claims, leading to ‘confusion and misunderstandings.’ Now, unambiguous and scientifically credible standards have been established to prove the products’ degradability and the relatively recent advances in polymer chemistry and biotechnology have helped to establish a growing degradable-plastics industry.

Clearly, use of renewable resources, such as those derived from forest biomass and willow could contribute to substantial reductions in use of non-renewable oil-based plastics. The commercialization of biodegradable polymers should continue to increase, especially in markets where plastics products have very short, single-use applications.