Bioplastics: the sustainable pack material that could help the UK hit emissions targets

With the UK government poised to implement a greenhouse gas reduction target of 80% from 1995 levels by 2050, it is becoming increasingly important to source materials and fuels from renewable resources to reduce our environmental impact. Bioplastics offer the packaging industry a renewable, sustainable and biodegradable alternative to oil-based plastics (petroplastics). With the advent of corporate social responsibility (CSR) reporting, packaging companies have the opportunity to raise their environmental profile by using materials with a low carbon footprint, such as bioplastics.

Interestingly, bioplastics have been used in medicine for years and were also considered for automotive parts in the days of Henry Ford. However, with climate change on the minds of manufacturers, retailers and consumers alike, there is renewed interest in the materials.

Benefits of PLA
In the UK, bioplastics are already on shelves in the form of compostable waste bags and some food and consumer goods packaging. Currently, most bioplastics (around 80%) are derived from maize, wheat, potato or cassava starch. Of these, polylactic acid (PLA, a polymer currently produced by fermentation of maize-starch sugars) presents desirable functional properties for packaging:

• It can be used for film, clamshell, bubble-pack, bottle and foam packaging
• It runs on existing processing equipment
• It has better structural properties than some petroplastics, allowing 10-15% reduction in packaging weight
• It has a melting point of up to 240°C
• A wide range of additives are available for resin property modification
• It can be blown with carbon dioxide providing volatile organic compound-free expanded PLA

In the past, use of PLA has been limited by a low melting temperature. However, recent technological advances, allowing the control of the molecular orientation and crystallisation of PLA, offer the promise of so-called ‘second-generation PLA’ with a higher melting temperature (up to 240°C) and an extended application range.

Currently, the bioplastics market in Europe is small, with only around 60,000-100,000 tonnes per annum (ktpa). This equates to 0.1% of the total European plastics market (around 53m tonnes per annum). The current UK PLA market is tiny, at 0.0004% (around £1.5m) of total UK polymer imports. Considering this, there is potential for growth of PLA in the UK market if local production and economies of scale can make the price of PLA competitive with other petroplastic resins.

Maximising the environmental benefits of bioplastics in the UK requires an appropriate labelling and disposal route for them. Currently, there is no unified labelling, national collection system or developed disposal infrastructure for compostable wastes in the UK. However, research undertaken by the Waste and Resources Action Programme (Wrap), the National Non-Food Crops Centre (NNFCC) and others is helping to pave the way.

After use
In terms of disposal, PLA is versatile and can be composted, recycled, burned for heat and power production or sent to landfill. However, landfill is not a preferred option due to its global warming potential through the release of methane (a greenhouse gas 23 times worse than carbon dioxide). In addition, European landfill legislation is placing an obligatory tourniquet on the landfill of biodegradable wastes.

Recently, an NNFCC-sponsored feasibility assessment for the production of PLA from UK wheat feedstock has been produced. This study identified that European demand could support the production of 650ktpa of PLA by 2025. It also indicated that a UK facility capable of producing 132ktpa of ‘second-generation’ PLA from wheat was feasible. Wheat is a preferred UK feedstock option (over crops such as maize) because it is widely available in the UK. In fact, wheat accounted for more than 70% of the 2008 UK cereal crop, at 17.2m tonnes (3.9m tonnes for export). In addition, wheat starch is more easily converted than maize starch into sugars for fermentation and there are several valuable co-products of wheat starch extraction. Other benefits of utilising home-grown wheat for PLA manufacture include lower transport costs and GHG emissions.

Recently, concerns have been raised over the availability of land for growing crops for bioplastics and biofuels. This land-use issue relates to the increased crop demand that may result in the conversion of non-agricultural land to crop land to meet demands, resulting in additional greenhouse gas emissions. A 132ktpa PLA plant would require a feedstock supply occupying around 3% of the current UK wheat growing area. This demand could be met through utilising some of our exportable wheat surplus and through increasing planting on former set-aside and fallow land.

HGCA, formerly the Home-Grown Cereals Authority, is a subsidiary of the Agriculture and Horticulture Development Board supporting the cereal and oilseeds industry in the UK and overseas markets. HGCA sponsors the marketing and R&D of cereals and oilseeds for industrial uses. Visit www.hgca.com

BIOPLASTICS AT A GLANCE
• Around 80% of bioplastics are currently made from maize, wheat, potato or cassava starch
• Polylactic acid (PLA) is produced from fermented maize-starch sugars
• Use of PLA has been limited by a low melting temperature. Recent technological advances allowing the control of the molecular orientation and crystallisation of PLA can produce ‘second-generation’ PLA with a melting temperature up to 240°C
• The bioplastics market in Europe is small, at present: around 60,000-100,000 tonnes per year – about 0.1% of the total European plastics market
• The UK PLA market is currently only 0.0004% (£1.5m) of total polymer imports
• A feasibility assessment by the National Non-Food Crops Centre identified that European demand could support the production of 650,000 tonnes a year of PLA by 2025. It also indicated that a UK facility capable of producing 132,000 tonnes a year of ‘second-generation’ PLA from wheat was feasible
• Wheat is a preferred UK feedstock because it is widely available
• Concerns have been raised about the availability of land for crops for bioplastics. A 132,000 tonnes per year PLA plant would require a feedstock supply occupying around 3% of the current UK wheat growing area

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