Bioplastics
We estimate the total production of plastics to grow from 311 million tons in 2014 to at least 792 million tons by 2050. This is conservative, with other sources estimating over 1 billion tons if trends continue. We model the growth of bioplastics to capture 12-46 percent of the market by 2050, avoiding 0.96-3.8 gigatons of emissions. The cost to produce bioplastics in this scenario is $25-88 billion over thirty years.
Summary
Globally, we produce roughly 310 million tons of plastic each year. Almost all of it is petro-plastic, made from fossil fuels. Experts, however, estimate that 90 percent of current plastics could be derived from plants instead. Bio-based plastics come from the earth, and those that are biodegradable can return to it—often with lower carbon emissions.
What affords plastics their malleability are chainlike polymers, comprised of many atoms or molecules bound to one another. Cellulose, the most abundant organic material on earth, is a polymer in the cell walls of plants. Chitin is another abundant polymer, found in the shells and exoskeletons of crustaceans and insects. Potatoes, sugarcane, tree bark, algae, and shrimp all contain natural polymers that can be converted to plastic.
Most bioplastics are used in packaging, but they are finding their way into everything from textiles to pharmaceuticals to electronics. Research continues to push the bounds of feedstocks, formulations, and applications. Bioplastics can sequester carbon, especially when made from waste biomass. The big challenge for bioplastics is separation from other waste and appropriate processing. Otherwise, they do not fulfill their promise as more sustainable materials.
Bioplastics
Project Drawdown defines bioplastic as: replacing petroleum-based plastics with biomass feedstock-based plastic materials (also referred to as biopolymers). This solution replaces traditional plastics made from petroleum.
The fossil-based system of plastics manufacturing is characterized by the extraction of hydrocarbons from the Earth and the use of this fossil resource as a raw material to create different plastic products. The agricultural process uses carbon dioxide taken in by plants through photosynthesis, which are then harvested and used to create bioplastic. The carbon in these materials is known as biogenic carbon. Climate emissions reductions from bioplastic are achieved through the atmospheric origin of the carbon within the materials themselves, and through keeping production impacts low enough to realize the benefits of the biogenic carbon.
Methodology
To arrive at the results for mitigation impact and financial considerations for bioplastic, several steps were taken. 1) A forecast was calculated for the total million metric tons of plastics production from 2014-2050; 2) current adoption[1] of bioplastic was determined; 3) future adoption scenarios of bioplastic were forecast for that period; 4) an emissions mitigation value was derived per million metric tons of bioplastic produced; 5) the emissions mitigated and costs were calculated in comparison to a Reference Scenario that keeps bioplastic adoption at its current percentage of global plastics adoption.
- Total Addressable Market
The total addressable market for plastics was measured by finding a best fit trend line (using a third-order polynomial expression) among four different data-sets of forecasted plastics adoption from 2020-2050. The four data sets were derived primarily from PlasticsEurope (2019) and the World Economic Forum (2016), using different growth rates and benchmarks to inform extrapolation.
- Adoption Scenarios
Impacts of increased adoption of bioplastic from 2020-2050 were generated based on two growth scenarios, which were assessed in comparison to the Reference Scenario mentioned above.
Custom adoption scenarios for bioplastic were created by: using Drawdown’s land use models to set plausible land use for generating bioplastic feedstock; considering the municipal solid waste fractions that could plausibly be attributed to recyclable or compostable plastics; and taking existing prognostications from European Bioplastics (2018) that could be extrapolated. Scenarios were generated using third-order polynomial extrapolations, and a ceiling was fixed on adoption based on the other factors described.
For bioplastic, two scenarios were developed:
Scenario 1: The bioplastics market grows to 92 million metric tons, or 12% of the total plastics market of 782 million metric tons in 2050.
Scenario 2: Bioplastics grows to 357 million metric tons, or 46% of the market in 2050.
- Emissions Model
Using values from over 25 studies, an average difference in carbon dioxide-equivalent emissions between traditional plastics and bioplastic was generated. A weighted average based on type of plastic and market share results in approximately 0.933 units of carbon dioxide-equivalent emissions per unit of bioplastic produced, compared to traditional plastics, which have direct emission of approximately 2.4. Despite the large potential for improvement in bioplastic technologies in the coming years, this emissions reduction value is assumed to stay constant over the 30-year time frame that was modeled.
- Financial Model
Production costs used for this solution for both traditional plastics and bioplastic are based on the most currently available price data and a projection for prices in 2020 from the literature (Shen, 2009, Biron, 2015, Rorrer 2017, Ashok 2018). The data found within the literature, via email, and in online market reports from 2011-2015 was averaged to estimate current market prices, and was combined with future estimates for polypropylene and bioplastic in an attempt to accommodate both historical prices and future trends within the model. Rather than try to predict undulations in the market, a static price was assigned over the next 30 years, which is assumed to be an approximation of the average price in that timeframe.
- Integration
As already noted, integration with other Drawdown solutions has limited the adoption of bioplastic by cropland available to be allocated to the production of bioplastic feedstocks. Assumptions are also made as to what portion of bioplastic is compostable and what is recyclable, in order to adjust the market for composting and recycling as well as to adjust the fraction of waste, low heat value, and degradable carbon remaining to be used in waste-to-energy and landfill methane capture solutions.
Results
The total carbon dioxide-equivalent reductions that can be achieved from 2020-2050 in the Scenario 1 are 0.96 gigatons, with a cumulative first cost of production of US$2,065 billion. The Scenario 2 shows a mitigation of 3.8 gigatons from 2020-2050.
Discussion
Bioplastics are nascent technologies and will continue to develop. As such, there are some areas of uncertainty regarding the model and there is room for improvement in future iterations. While there was quite a bit of literature dedicated to measuring the climate impacts of fossil plastics and bioplastics, there are many different types of bioplastics, each with different feedstocks and production techniques. The current model aggregates all plastics and biopolymers into two generalized groups, but future versions should consider each different polymer type and production method. The same holds true for prices that were aggregated in the same manner.
Additional work could also be done on a robust financial breakdown of plastic commodities and feedstock availability, including a techno-economic analysis of bioplastics. Production models could also include more nuanced data regarding geographical production rates, recycling rates, and source reductions, even if they are already accounted for in the aggregate in this version of the model. In conclusion, this analysis suggests that the bioplastics market can grow to replace a significant portion of traditional plastics, while reducing climate emissions.
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REFS
Published on drawdown.org