By Dr John R Williams, NNFCC, York

Introduction
Bio-based polymers have been used in many applications for thousands of years, and there was resurgence in the development of artificial bio-based plastics from the mid 19th century until the early 1940’s. The main reason for the lack of commercial production was the discovery of crude oil and its large-scale use for plastics since the late 1940’s. It is now often taken for granted that plastics are made from fossil derived oil.  The rising cost of oil, regulation and mounting concern over climate change has necessitated a move towards renewable sources of polymer feedstock.

Production of plastics from plant products and biomass offers the potential to replace non-renewable materials derived from petroleum with renewable resources, resulting in reliable supply, jobs in rural communities, sustainable production, lower greenhouse gas emissions, and competitive prices. The increasing pressure on fossil derived resources because of concerns over climate change and supply security has led to an increase over the past two decades in the developments and industrial scale-up of bio-based plastics.

Bio-based plastics
The early stage developments were improvements in starch and cellulose derived materials but over the last 5 years there has been a huge expansion in the portfolio of products available. Examples include PLA from lactic acid, PHA’s from fermentation platforms and polyethylene from bioethanol. Moreover, recent technology breakthroughs have made substantial improvements to the properties of bio-based plastics enabling their expansion into the mainstream market. In many cases it is only the current relatively small scale of production which prevents wider uptake. Polymers derived from renewable resources offer the opportunity to benefit society and the environment by reducing demands on fossil resources. Sugars, oils and other compounds in renewable feed-stocks can be converted into platform chemicals and polymers using conversion processes similar to those employed by the petrochemical industry today.

Recent reports have identified several building block chemicals produced from sugars via biological or chemical conversions. These building block chemicals together with starch derived directly from plants enable the synthesis of biopolymers. The use of biomass-derived chemicals represents an area with extensive potential for the development of renewable feedstock-based technology platforms. Improvements and innovations to existing biological and chemical processing of cellulose, sugars and starches, often made possible through advances in catalysis, will provide the opportunity for the production of high-value chemicals and polymers from biomass and reduce reliance on petrochemical-derived products.

Bio-based plastics compete with petrochemical-based equivalents, the production of which has been optimized over the last decades. Optimization of these production methods according to green or sustainable chemistry principles may still significantly reduce costs, waste production, energy and raw materials use for petroleum-based polymers. However, many chemical processes are mature and have little room for optimization, while biotechnological processes are in their infancy; there is great potential for streamlining and improved process integration. In petrochemical refineries, the raw materials cost are critical as processing costs have gradually decreased, more products are developed, and less waste is produced.

White biotechnology provides new routes to renewable polymers; biomass can be converted to glucose, fatty acids, or other small compounds, either as the main product or as a waste stream from other production processes. These small compounds serve to produce plastics by microbial fermentation or chemical polymerization. For example, poly-ß-hydroxyalkanoates, biocellulose, xanthan, silk, and polythioesters, can be produced by fermentation processes, while polylactic acid (PLA), poly-caprolactone, and other (partially renewable) polyesters such as Sorona (Dupont), and Bionolle (Showa) are produced using chemical polymerization of substrates that are at least in part produced by bacterial fermentation. It is likely that these processes will be part of future biorefineries, which are now in a very early stage of development, with the exception of starch and paper mills. This implies that in biorefineries, the processing costs still determine the economic viability of bio-products. As biorefineries mature, the focus will also shift to the cost of producing the raw materials.

The cheapest and easiest to handle biopolymer is starch. Due to its abundance and low price it has found numerous applications in the non-food sector, which includes its use in renewable plastics. The current rise of the oil and natural gas prices is reflected in the plastics market, and is making renewable plastics more competitive.

As a consequence of the development of new markets energy consumption and waste production are increasing at a fast rate. Emerging countries are requiring more and more fossil resources whilst the developed countries are hesitant in introducing energy saving programmes and controlling the release of greenhouse gases. The amount of goods produced and packed is also growing, making waste disposal a big issue. These problems represent a powerful driving force stimulating the growth of renewable plastics.

The continuing market development of renewable plastics gives far more opportunities to close the loop from raw material to end of life disposal than is possible with fossil derived materials. It should also not be forgotten that reuse and recycle equally applies to renewable plastics as it does to fossil derived polymers, it is just a question of scale.

Summary
An industry that produced just 200,000 tons in 2006 and is set to grow to about five million tons by 2015, bioplastics is fast gaining prominence, observes the Germany-based Helmut Kaiser Consultancy. Currently, bioplastics production is concentrated in the U.S., Europe and Japan, with the largest market being Western Europe, which accounts for about 40% of the world’s demand for bioplastics. This region covers approximately 10% to 15% of the total plastics market and has recorded a fast-paced growth of about 8% to 10% per year. But a report by the market research group Freedonia, estimates that there will be a paradigm shift by 2013 when Asia will become the world leader in bioplastics production, clocking an annual growth rate of 39.1%. In the next decade, the global bioplastics market share is expected to jump up to 25% to 30%.

The renewable polymers market will increase rapidly in the next 10-20 years as the fossil feedstock costs rise and the drive for carbon savings is established. Research and the enhancement/refinement of industrial scale-up processes will introduce a wider array of products into the marketplace at competitive prices. The feedstock for these renewable polymers will be either directly (crop) or indirectly (biomass) derived from agriculture.

JOHN WILLIAMS
National Non Food Crops Centre
Tel: +44 (0)1904 435182
Fax: +44 (0)1904 435345
Web: www.nnfcc.co.uk
Email: j.williams@nnfcc.co.uk