BIODEGRADABLE CARRY BAGS

Bio-plastics can be defined as plastics where part or all of the material is derived from renewable biomass resources. For the purposes of clarity we will refer to bio-based plastics as those made from plant-based molecular sources. The term ‘bio-based’ must not be confused with the term ‘biodegradable’ which refers to the natural breakdown of a material at the end of life disposal phase. Not all bio-based polymers are biodegradable and not all biodegradable polymers are bio-based; some biodegradable polymers only biodegrade under specific circumstances.

With the introduction of plant-based bio-PE as a ‘drop-in’ alternative to fossil-derived PE (offering a direct replacement to its fossil based equivalent), coupled with an increase in the production capacity of these bio-polymers, it is becoming increasingly difficult to ignore the potential that bioplastics offer to improving the sustainability of plastic products. They are making an impact on the wider plastics market, in part because:

• As a result of increased demand and finite supply there is a long term upward trend in the cost of fossil based resources. As a result demand for bio-plastics is rising strongly year on year at a rate of 20-100%.

• The resources used to make bio-polymers are predominantly annual crops (such as corn and sugar beet) or perennial cultures (such as cassava and sugarcane) and as such are considered renewable.

• Bio-based plastics present a unique opportunity to reduce greenhouse gas (GHG) emissions or even become carbon neutral.

The production costs of sugarcane bio-ethylene across the globe are summarised in Table. Overall the current production cost of bio-ethylene is between 1.1-2.3 times higher than the global average petrochemical ethylene, but ligno-cellulosic bio-ethylene is expected to reduce the gap in the near future to the point where bio-ethylene could be less expensive than fossil-based ethylene.

Table Average production cost of bio-ethylene

With regards to the cost of feedstock’s used to produce polymers the market conditions are quite variable. Currently according to the Market Price Information and Comparison of Price Indexes and IMF Commodity Price Forecasts for crude oil, sugar, and cereals, the trend in the price of oil is stable to falling, based on a growing supply of shale oil in the USA. The price of cereals is also not trending up and the price of sugar is projected to strengthen slightly. On this basis, the trend in the short term cost of oil-based ethylene is likely to be stable to falling, and the trend for bio-based ethylene from sugarcane ethanol is likely to be stable to rising.

However, large scale production of ligno-cellulosic ethanol will enable a significant fall in the cost of bio-ethylene, but as it will take at least five years to develop and construct such a plant, it must be considered that few will start up before 2020. The longer term trend (10 – 20 years) is expected to see renewable sources of bio-ethylene remain more stable and exhaustible sources of oil-ethylene follow a rising trend as supplies dwindle. However, there is no guarantee on the predicted costs into the future as has been shown with the impact of shale gas in recent years.

Total world petroleum-based ethylene production capacity (including oil-based naphtha and ethane, propane and butane (natural gas liquids (NGLs)) reached 138 million tons per year (Mtpa) in 2011. The global demand for ethylene is expected to increase at a higher rate than the gross domestic product (GDP) rate of 3.9% through to 2020.