trellisresin lca

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Life Cycle Assessment (LCA)

of Trellis Earth® Bioplastic

Relative to Conventional Polymers

www.TrellisEarth.com

*not for public domain release*

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Sources:

Environmental assessment of bio‐based polymers and natural fibers Dr. Martin Patel, Dr. Catia Bastioli, Dr. Luigi Marini, Dipl.‐Geoökol. Eduard Würdinger Utrecht University, Department of Science, Technology and Society (STS), Copernicus Institute, Padualaan 14, NL‐3584 CH Utrecht, Netherland. This definitive study defines many of the methodologies adopted by the industry in subsequent LCA studies performed on behalf of various commercial clients in the bioplastics industry. http://en.european‐bioplastics.org/

European Bioplastics e.V. published a 2008 Position Paper entitled "Lifecycle Assessment of Bioplastics" in which it outlines methodologies and issues related to bioplastics LCA studies. http://www.altumetrics.com/ Much of the material in this document is taken from the Altumetrics comparison of biopolymers to conventional polymers published in 2011. This report, which focuses on starch based resins (bio‐propylene, chemically equivalent to Trellis Earth(R) bioplastic) in comparison to conventional polypropylene (PP), Polyethylene terephthalate (PET), high impact polystyrene (HIPS) and low density polyethylene (LDPE), the most common alternative materials for food packaging including cutlery.

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Executive Summary Environmental considerations have been and will continue to be an important motivation to

develop and introduce bio‐based polymers and natural fiber composites. This calls for a comparison

of their environmental performance with their petrochemical counterparts. To this end, life cycle

assessment (LCA) can be applied, which is a standardized method to quantify environmental

impacts (ISO, 1997‐1999).

A Life Cycle Assessment (LCA) of the bio‐propylene that is chemically equivalent to the Trellis Earth

(R) brand bio‐resin and four conventional plastic resins was conducted by Altumetrics. The study

compared the pound‐for‐pound impact of bio‐propylene (a trade term for the Trellis Earth(R) brand

of bioresin) against conventional polypropylene (PP), polyethylene terephthalate (PET), high

impact polystyrene (HIPS) and low density polyethylene (LDPE).

This purpose of the study was to potentially to help customers understand the environmental

ramifications of their polymer choices. The boundaries of the study were from cradle to

customer, those that are using the Trellis Earth(R) brand products (up to the point of departure

from the Trellis Earth factory gate).

The plastics were compared by carbon footprint (global warming potential, GWP), resource

depletion, and an environmental score called ReCiPe, which combines environmental impacts into

a single value.

The study found that:

Trellis Earth bioresin had the best overall environmental performance. It had the

lowest carbon footprint (GWP) of any of the plastics. Its carbon footprint was 8% lower

than the best conventional plastic, which was PP, and 76% lower than the worst

conventional plastic, which was HIPS. This was when no credit was given for

plant carbon dioxide absorption. When credit was given, the benefit of Trellis Earth

bioresin was even greater: its carbon footprint was 32% lower than even the best

conventional plastic (PP).

In terms of the ReCiPe single score (which amalgamates environmental impacts into a

single value) Trellis Earth bioresin was found to be superior to all conventional plastics:

it was 23% better than the best conventional plastic, which was again PP.

The Trellis Earth bio‐resin also performed well against conventional plastics in terms of

abiotic depletion, where it was better than all conventional alternatives.

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Contents Executive Summary ....................................................................................................................... 3

Contents ........................................................................................................................................ 4

1 Introduction ............................................................................................................................. 5

2 Life Cycle Assessment............................................................................................................... 5

3 Goal and scope ........................................................................................................................ 7

3.1 Scope ................................................................................................................................ 8

3.2 Inventory Analysis............................................................................................................. 10

3.3 Impact assessment ......................................................................................................... 11

4 Inventory analysis.................................................................................................................. 12

4.1 Trellis Earth bioresin ........................................................................................................ 13

4.3 Conventional plastics ..................................................................................................... 14

5 Impact assessment ................................................................................................................ 1 9

5.1 Global Warming Potential .............................................................................................. 19

5.2 Abiotic Resource Depletion ............................................................................................ 23

5.3 Single environmental score ............................................................................................ 25

6 Sensitivity Analysis ................................................................................................................ 2 6

6.1 A change to the starch and PP content of Trellis Earth bioresin ...................................... 27

7 Conclusion ............................................................................................................................. 29 Appendix A: Description of Impact Categories ............................................................................ 31

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Introduction Life cycle assessment provides a standardized method for measuring and comparing the

environmental impacts associated with the manufacturing, use and disposal of a product. This

study considers the production of each plastic to Trellis Earth’s factory outbound shipping gate. The

environmental impacts of each of the plastics have been assessed from raw material extraction

through to the production of finished goods.

Life Cycle Assessment Life Cycle Assessment (LCA) is defined by ISO (International Standards Organization) as the

“compilation and evaluation of the inputs, outputs and the potential environmental impacts of a

product system throughout its life cycle” (ISO 14040). In other words, an LCA identifies the material

and energy usage, emissions and waste flows of a product, process or service over its entire life cycle

in order for its environmental impacts to be determined.

Figure 1 illustrates the life cycle system concept of natural resources and energy entering the system

and product, emissions and waste leaving the system.

Figure 1, Typical categories of data collected to describe processes in LCA terms

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Companies undertake an LCA to understand the environmental performance of their product for

a variety of reasons including legislative pressures and supply chain issues. Another reason is the

increasing number of environmentally conscious customers who are demanding products that

combine the benefits of good functionality and low cost with high environmental performance. While

an LCA is a valuable tool, it should be emphasized that it is one of many factors, such as costs,

consumer acceptance and production feasibility, which companies must take into account during

the decision‐‐‐making process.

The technical framework for a life cycle assessment consists of four inter‐‐‐related stages: goal

and scope definition, inventory analysis, impact assessment and interpretation as shown in

Figure 2.

Figure 2, Stages of an LCA (ISO 14040)

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The ISO standards set out the requirements associated with each stage.

The goal and scope definition involves identifying the purpose of the study and the systems to

be studied, including setting the system boundaries and determining the level of detail

included.

In the inventory analysis all materials, substances and energy used and all emissions and waste

released to the environment are identified and quantified over the whole life cycle of the

product (from raw material extraction and processing, through manufacture).

The impact assessment is a technical, quantitative method used to assess the environmental

significance of the inputs and outputs identified in the inventory analysis. The impacts

considered can be divided into subject areas such as resource use, human health, and

ecological consequences.

In the interpretation stage, results are analyzed, limitations explained, conclusions are made

and recommendations are provided.

The following sections outline each of these stages for this project in detail.

Goal and scope The goal and scope of an LCA involves identifying the purpose of the study and information

relating to the systems being studied such as the system boundaries (i.e. what is

included/excluded from the study).

The purpose of this study was to evaluate the environmental impacts associated with Trellis Earth

bioplastic and four conventional plastics prior to their delivery to the customer.

Trellis Earth intends to use the results internally to help develop more environmentally

responsible polymer blends as well as use the results to help buyers evaluate its products with

environmental impacts considered when choosing between bioresin and conventional plastics.

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3.1 Scope

3.1.1 Functional unit Any comparison of life cycle impacts must be based on a comparable function (or “functional

unit”) in order to allow clear interpretation. The functional unit for the study was:

“The production of 1lb of plastic pellets”

All results contained within this report therefore represent the environmental impact

generated by the production of this unit. The pellets are designed to be functionally equivalent.

For example, 1lb of Trellis Earth bioresin is equivalent to 1lb of polypropylene when formed

into a product such as cutlery or deliware. However it is possible that in rare instances unknown

to Trellis Earth some applications may require different amounts of polymer to achieve

equivalent product performance. The discussion within the impact assessment (section 5)

directly compares the products considered on a pound for pound basis since this is the most

common situation when the resins are formed by a customer through extrusion, mo l d i n g

o r f o rm i n g a p p l i c a t i o n s . If a customer uses different amounts of material the results

of this study would need to be adjusted to reflect that situation.

3.1.2 Product systems and system boundaries The system boundaries define the life cycle stages and unit processes included in the systems

to be studied. This study considered one blend of bioplastic:

• Trellis Earth bioresin – containing a blend of polypropylene and starch (and additives).

The following conventional plastics were also considered in the study:

• Polypropylene (PP) – pellets containing conventional PP.

• Polyethylene terephthalate (PET) – pellets containing conventional PET.

• High Impact Polystyrene (HIPS) – pellets containing conventional HIPS.

• Low Density Polyethylene (LDPE) – pellets containing conventional LDPE.

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Each of the plastics considered have been evaluated from “cradle to gate”. Cradle to gate

means that the systems include the extraction of raw materials, the production and

transportation of input materials, and the production of products in Trellis Earth’s

facilities.

However, the system boundary of this study does not include the distribution of the product to

the customer or the disposal of products after use. Therefore, the differing impacts of these

plastics at end of life, such as composting and recycling, are not considered within this

study. Where a customer wishes to carry out an life cycle assessment of its product this study

may be used to contribute to that study to achieve a “cradle to grave” study.

3.1.3 Excluded processes Processes outside the system boundary are not included in the study. In particular these stages

of the life cycle are not included:

• Transport of products from Trellis Earth’s facilities to the customer (this

transportation would be the same for all polymers and so would not change the

results).

• Use of the customer’s product (products are various and not always known to

Trellis Earth, after delivery. In some instances, such as disposal methods, carbon

sequestration would vary, hence this study shows the two carbon extremes so that a

customer can see the range of results within which their product’s results would fall).

• Waste treatment (which would vary depending on the customer’s product).

The exclusion of these aspects is in line with the purpose of this study, which is to help

Trellis Earth R&D and introduce the issues to customers. A customer could build on this study

by including product stages in a life cycle assessment of its own particular product.

In addition to the processes excluded by the system boundaries, a number of other processes

have been excluded from the study. All excluded processes are outlined below:

• The construction, maintenance and demolition of industrial buildings and the

manufacture of machines and equipment was excluded from the study as these

impacts should be absorbed over the whole of the period of use. Experience shows that

these impacts are negligible compared with those linked to their operation.

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• Packaging used to transport materials between the supplier and the producer was

excluded as this impact was found to be negligible when compared to the impact of the

materials contained within them.

3.1.4 Key Assumptions and Limitations

Within any LCA some assumptions are required due to data constraints. The key assumptions

made within this study are outlined below:

• The transportation of all conventional plastics from the supplier to the producer was

based on distances provided by Trellis Earth.

• All road transportation was assumed to be via a 16‐‐‐32 metric ton truck.

• The use of natural gas during plastic product manufacture was assumed to be in a

>100kW modulating boiler.

• The production of conventional plastics was based on Ecoinvent data on polymer

production in Europe.

3.2 Inventory analysis Inventory analysis is the identification, collection and calculation of inputs and outputs of

environmental flows across the system boundaries. The inputs and outputs are scaled to the

functional unit and include both elementary and non‐‐‐elementary flows. Elementary flows are

materials or energy entering the system being studied, which have been drawn from the

environment without previous human transformation, or materials and energy leaving the

system, which are discarded into the environment without subsequent human transformation.

The software tool SimaPro was used to model the systems and calculate the environmental

impacts of the life cycle scenarios studied. SimaPro has been specifically developed by PRé

Consultants in the Netherlands for the calculation of life cycle impacts and is one of the world’s

leading LCA tools.

Life cycle Inventories generally contain hundreds of environmental flows for a single product

system. Life cycle impact assessment (LCIA) translates these flows into potential impacts on the

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environment enabling the evaluation of the systems through a number of impact categories

such as global warming and abiotic depletion.

Where generic average data has been used, data specific to United States was used in the

modeling where possible. However, in some cases the data represents a European average.

Primarily this data was obtained from the Ecoinvent database which contains the elementary

and non‐‐‐elementary flows for over 4000 industrial materials and processes.

3.3 Impact assessment The impact assessment phase of an LCA assigns the results of the inventory analysis to different

impact categories. The impact categories considered in this study were:

• Global Warming Potential (GWP or carbon footprint)

• Abiotic resource depletion

Global warming potential is a measure of how much of a given mass of a greenhouse gas (for

example, CO2, methane, nitrous oxide) is estimated to contribute to global warming. Global

warming occurs due to an increase in the atmospheric concentration of greenhouse gases

which changes the absorption of infra‐‐‐red radiation in the atmosphere, known as radiative

forcing leading to changes in climatic patterns and higher global average temperatures. Global

warming potential is measured in terms of CO2 equivalents.

For GWP, the IPCC 2007 characterization factors were used to translate the greenhouse gas

emissions generated by the life cycle scenarios into a single carbon footprint. These

characterizations factors do not included the absorption of biogenic CO2 from the atmosphere

during biomass growth and the release of biogenic carbon as carbon dioxide and methane

emissions during product degradation. This is a significant issue for polymers that contain

biomass, such as the bioplastics produced by Trellis Earth, since the exclusion of the absorption

of biogenic CO2 from the atmosphere during plant growth eliminates one of the key benefits

of the bioplastics. Therefore, to understand the relevance of this issue, these biogenic

impacts have been included as a sub category within the global warming results. This sub

includes the amount of biogenic carbon dioxide sequestered during production. However,

it does not consider the implications of product degradation and the potential release of

this biogenic carbon as carbon dioxide and methane as this degradation is outside the cradle

to gate scope of the project.

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For abiotic resource depletion, the CML 2 baseline 2000 method, a problem‐‐‐oriented approach

developed by the Center for Environmental Science (CML), Leiden University, the Netherlands,

was used. A description of each of these impact categories is given in appendix A.

To provide a greater understanding of the relevance of certain impact categories, the ReCiPe

method was also used to generate a single environmental score for each scenario. This method

normalizes and weights environmental impact categories and then combines them into a single

score in terms of eco‐‐‐points where 1,000 eco‐‐‐points is the equivalent of an average person’s

annual environmental load. ReCiPe was developed by panels of experts agreeing weightings of

different environmental issues. Any weighting is potentially controversial. For example, some

experts feel that ReCiPe assigns too much importance to GWP, whereas other experts feel this

appropriately reflects the importance of the global warming issue. Some experts even feel that

no weightings should ever be used, meaning no single score methodology should ever be used.

In recognition of this range of views, ReCipe results should be seen as “rule of thumb”

management summary indications rather than as “hard and fast” scientific fact.

The impact assessment reflects potential and not actual impacts and takes no account of the

local receiving environment. In addition, the underlying scientific knowledge, especially for fate

and exposure assessment, is still under development.

Included in the assessment is an evaluation of the GHG impacts both with and without biogenic

carbon. This is the approach recommended in the most recent GHG Protocol adopted by the

Sustainability Consortium. This approach is recommended by the Consortium because it

provides transparency: a reader who feels biogenic carbon should not be included can see

those results, while a reader who feels that it should be included can see those results. In

addition, in the case of Trellis Earth the approach makes sense because it shows the range of

potential results achieved by different Trellis Earth customers.

4 Inventory analysis This section describes the data used to model the life cycles of the five plastics considered

during the inventory analysis stage. The following sections describe the primary data (data

collected from the customer and suppliers) and secondary data (data provided by existing

datasets or assumptions) used to model the production of the bioplastics and conventional

plastics considered from cradle to gate.

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4.1 Trellis Earth bioresin

The diagrams in figure 3 show the cradle to gate life cycle of 1 lb of Trellis Earth bioplastic

pellets produced by Trellis Earth Products, Inc. The following sections outline the data used to

model the life cycle of this product based on the life cycle stages identified in this figure.

Figure 3, The cradle to gate life cycle of 1lb of Trellis Earth bioresin bioplastic pellets.

4.2 Additives The quantity of all additives required to produce 1 lb of bioplastic resin was supplied by Trellis

Earth. All input materials were assessed and modeled using the most appropriate

secondary data available.

4.2.4 Production energy

The production of grid electricity was based on the delivery of medium voltage electricity from

the US grid. The use of natural gas was modeled using European data on the delivery and

burning of natural gas for heat in a >100kW modulating boiler.

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4.2.5 Transport The transportation of materials from material supplier to Trellis Earth was based on

a combination of estimates and primary data provided by Trellis Earth. All distances from

the material supplier to Trellis Earth were provided by Trellis Earth.

4.2.6 Production waste

The disposal of the pellet production waste was based on wastage rates provided by Trellis

Earth. The landfill of pellet production waste was modeled using Ecoinvent data on the

disposal of mixed plastic to landfill and is representative of a Swiss municipal sanitary landfill.

4.3 Conventional plastics The following sections outline the data used to model the life cycles of the conventional

plastics considered in this study.

4.3.1.1 Polypropylene

The diagram in figure 7 shows the cradle to gate life cycle of 1 lb of polypropylene pellets

(as though) produced by Trellis Earth (for normalization purposes). The following section

outlines the data used to model the life cycle of this plastic.

Figure 7, The cradle to gate life cycle of 1lb of conventional polypropylene (PP) pellets.

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The production of polypropylene resin used in the conventional PP pellets was modeled using

Ecoinvent data representing the average of 28 production sites producing a total of 7.2 Mt in

Europe during 1999.

The transportation of polypropylene resin from the material supplier to Trellis Earth was based

on a distance of 940 miles by train provided by Trellis Earth. Rail transport was modeled

using Ecoinvent data representing the use of diesel rail freight in the United States.

The production of the plastic pellets was modeled using primary data on the use of grid

electricity and natural gas and was provided by Trellis Earth. A detailed site assessment was

undertaken and this showed that all the plastics were processed in the same way with the

same energy requirements (mixing, heating and pelletization were the same in each case). This

data was combined with secondary data from the Ecoinvent database on the impact of grid

electricity production and natural gas extraction and use. The production of grid electricity was

based on the delivery of medium voltage electricity from grid in the United States. The use of

natural gas was modeled using European data on the delivery and burning of natural gas for

heat in a >100kW modulating boiler.


Earth. The landfill of production waste was modeled using Ecoinvent data on the disposal of

mixed plastic to landfill and is representative of a Swiss municipal sanitary landfill.

4.3.1.2 Polyethylene terephthalate

The diagrams in figure 8 show the cradle to gate life cycle of 1 lb of the polyethylene

terephthalate pellets ( a s t h o u g h ) produced by Trellis Earth. The following section

outlines the data used to model the life cycle of these pellets.

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Figure 8, The cradle to gate life cycle of 1lb of conventional polyethylene terephthalate (PET)

pellets.

The production of polyethylene terephthalate resin used in the conventional PET pellets was

modeled using Ecoinvent data representing the production of a total of 569,000 t of

amorphous polyethylene terephthalate from ethylene glycol and PTA in Europe during 2000.

The transportation of polyethylene terephthalate resin from the material supplier to Trellis

Earth was based on a distance of 940 miles by train provided by Trellis Earth. Rail

transport was modeled using Ecoinvent data representing the use of diesel rail freight in the

United States.


electricity and natural gas and was provided by Trellis Earth. This data was combined

with secondary data from the Ecoinvent database on the impact of grid electricity production and

natural gas extraction and use. The production of grid electricity was based on the delivery of

medium voltage electricity from the US grid. The use of natural gas was modeled using

European data on the delivery and burning of natural gas for heat in a >100kW modulating

boiler.



disposal of mixed plastic to landfill and is representative of Swiss municipal sanitary landfill.

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4.3.1.3 High Impact Polystyrene

The diagrams in figure 9 show the cradle to gate life cycle of 1 lb of the high impact polystyrene

pellets ( a s t h o u g h ) produced by Trellis Earth. The following section outlines the data used

to model the life cycle of these pellets.

Figure 9, The cradle to gate life cycle of 1lb of conventional high impact polystyrene (HIPS)

pellets

The production of the high impact polystyrene resin used in the conventional HIPS pellets was

modeled using Ecoinvent data representing the average production of 15 sites of high impact

polystyrene from ethylene and benzene by free radical processes.

The transportation of high impact polystyrene resin from the material supplier to Trellis Earth

was based on a distance of 940 miles by train provided by Trellis Earth. Rail transport was

modeled using Ecoinvent data representing the use of diesel rail freight in the United States.







boiler.

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4.3.1.4 Low Density Polyethylene

The diagrams in figure 10 show the cradle to gate life cycle of 1 lb of the low density

polyethylene pellets (as though) produced by Trellis Earth. The following section outlines the

data used to model the life cycle of these pellets.

Figure 10, The cradle to gate life cycle of 1lb of conventional Low Density Polyethylene (LDPE)

pellets.

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The production of the low density polyethylene resin used in the conventional LDPE pellets was

modeled using Ecoinvent data representing the average production of 4.79Mt of LDPE during

1999. The transportation of low density polyethylene resin from the material supplier to

Trellis Earth was based on a distance of 940 miles by train provided by Trellis Earth. Rail

transport was modeled using Ecoinvent data representing the use of diesel rail freight in

the United States.







boiler.




5 Impact assessment The following sections outline the results of the impact assessment of the Trellis Earth

bioplastics and conventional plastics identified in section 3.1. The first section (5.1) provides an

overview of the carbon footprint results (Global Warming Potential, GWP). The second

section (5.2) outlines the results for abiotic resource depletion. The third section (5.3)

provides an analysis of the ReCiPe single environmental score results.

5.1 Global Warming Potential The results for the carbon footprint (Global Warming Potential, GWP) of all the plastics are

shown in table 1 and figures 11 and 12. The table and figures show the results excluding and

including the effect of biogenic carbon dioxide absorption during biomass growth. All results

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represent the functional unit (the production of 1lb of plastic pellets). The table shows the

results along with the best and worst option marked either red (worst) or green (best). The

figures show a breakdown of each plastic based on the life cycle stages identified in the

inventory analysis (section 4). The results can be summarized as follows:

• The Trellis Earth bioresin bioplastic had the lowest GWP per lb of any of the plastics

considered (both when the absorption of biogenic carbon dioxide was included and

excluded). It was found to be 8.1% lower than the nearest conventional plastic (PP) when

biogenic carbon dioxide was excluded. This difference rose to 31.7% when biogenic

carbon was included.

Table 1, The Global Warming Potential (GWP) of each plastic with and without the inclusion of biogenic carbon.

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Figure 11, The Global Warming Potential (GWP) of each plastic without the inclusion of biogenic

carbon based on life cycle stage.

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Figure 12, The Global Warming Potential (GWP) of each plastic with the inclusion of biogenic

carbon based on life cycle stage.

The results show that, when biogenic carbon was excluded, the plastic with the lowest GWP

per lb was the Trellis Earth bioresin while the plastic with the highest GWP per lb was HIPS.

In some cases the Trellis Earth bioresin bioplastic was very significantly better (76% lower than

HIPS) and in other cases it was significantly better but by a smaller amount (8% lower than PP).

The compostable bioplastics were all found to be superior to HIPS and competitive with APET.

However, they were found to be inferior to all other conventional plastics. This was due to a

number of factors including the greater transport distances involved (particularly for Ecoflex

from Germany) and the impact of material production. The split of impact between Ecoflex and

PLA was fairly even despite the use of a larger quantity of Ecoflex within each compostable

bioplastic. Therefore the PLA had the largest material contribution, almost entirely due to the

consumption of energy, from grid electricity and natural gas, used to produce it.

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When biogenic carbon was included in the impact assessment of GWP, the Trellis Earth

bioplastic was found to be superior to all other alternatives. The inclusion of the absorption of

carbon dioxide reduced the impact of the Trellis Earth bioresin by over 25% compared to the

original results due to the uptake of CO2 from the air. So the benefit of Trellis Earth bioresin

became even greater. The impact of the conventional plastics remained largely unchanged as

they did not include any renewable material in their composition.

5.2 Abiotic Resource Depletion The results for abiotic resource depletion using the CML impact assessment method for all

plastic pellets are shown in table 2. The table shows the results along with the best and worst

option in each category marked either red (worst) or green (best). All results represent the

functional unit (the production of 1lb of plastic pellets).

Table 2, The impact on resource depletion for each plastic.

Plastic products

Abiotic depletion

(lbs Sb eq/lb)

Trellis Earth bioresin 0.0283

Compostable 3000 0.0320



Polypropylene 0.0369

Amorphous Polyethylene Terephthalate 0.0386

High Impact Polystyrene 0.0443

Low Density Polyethylene 0.0377

The Trellis Earth bioresin was found to have the lowest abiotic resource depletion and was 23%

lower than the nearest conventional plastic (PP). Both the Trellis Earth bioresin and compostable

bioplastics were found to be superior to their conventional alternatives due to the reduced

quantity of fossil based plastic used to produce them. This is particularly clear in figure 13

which shows the results based on their life cycle stage. This shows that the impact of starch on the

Trellis Earth bioresin and PLA on the compostable bioplastics was relatively low compared to the

impact of the materials used in the conventional alternatives.

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Figure 13, The abiotic resource depletion of each plastic based on life cycle stage.

5.3 Single environmental score The ReCiPe impact assessment method was used to provide a single environmental score. The

Recipe method normalizes and weights a number of categories based on their relative

importance to provide a single score in eco‐‐‐points where 1,000 eco‐‐‐points is the equivalent of

an average citizen’s annual environmental load. This presents an understanding of the relative

importance of the impact categories considered in the previous section. However any

weighting method is potentially controversial since value judgments are involved (the

importance of one environmental issue compared to another is a human judgment). This

means that ReCipe results should be taken as an interesting management perspective rather

than hard science agreed by all stakeholders. The results were based on a Hierarchist

(balanced) perspective using world normalization factors and are shown in table 3 and figure

14.

The results show that Trellis Earth bioresin bioplastic was superior to all conventional

alternatives. The Trellis Earth bioresin was found to have a 16% lower score than the best

performing conventional plastic (PP). The best performing compostable plastic (Compostable

3000) had an impact only 1% greater than conventional PP, but 9% lower than APET, 24% lower

than HIPS and 1.3% lower than LDPE. For the Compostable bioplastics, the slight advantage

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gained through the use of renewable materials was balanced by the additional transportation

impacts required. However, the use of starch and other materials within the Trellis Earth

bioplastic gave it a clear advantage over conventional polymers.

Table 3, The ReCiPe single score results for each plastic.

Plastic products

ReCiPe World H/A Single Score

(Eco‐‐‐points/lb)

Trellis Earth bioresin 0.1568




Polypropylene 0.1869

Amorphous Polyethylene Terephthalate 0.2082

High Impact Polystyrene 0.2479

Low Density Polyethylene 0.1916

Figure 14, The ReCiPe single score of each plastic based on life cycle stage.

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6 Sensitivity Analysis To provide a greater understanding of the influence of individual materials on Carbon Footprint

(Global Warming Potential, GWP), a range of sensitivity analyses were conducted.

Figure 15 shows the impact per lb of each of the major component materials utilized within all

of the bioplastics (including transportation to Trellis Earth). This shows that when biogenic

carbon dioxide absorption is excluded from the results, PLA and Ecoflex have the highest impact

per lb of the major materials, while starch has the lowest. When biogenic carbon dioxide

absorption is included, the PLA becomes superior to the conventional plastics (HDPE and

PP) dropping 61.5%, but the impact of Ecoflex only drops by 5.3%, making it the worst

option. In addition, the starch provides a negative GWP value meaning it provides a net

benefit to GWP through the absorption of carbon dioxide during growth.

Figure 15, The GWP per lb of each major input material including transportation to site.

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Figure 15 emphasizes that:

• Starch always has the best carbon footprint result, whether or not biogenic carbon is

credited.

• PLA shows very different results depending on whether biogenic carbon is credited: it

has the worst carbon footprint of any of the materials when not given credit for plant

carbon dioxide absorption, but the second best when given this credit.

• Ecoflex only improves slightly if given credit for carbon absorbed (which is to be

expected since it is not a plant based material), and in all cases Ecoflex has a worse

carbon footprint than conventional polymers (because it is derived mainly from the

same conventional monomers as PET, which is one of the higher‐‐‐impact conventional

polymers).

• HDPE and PP have very similar carbon footprints: they have a higher impact than starch

if carbon is not credited, and a higher impact than PLA and starch if carbon is credited.

6.1 A change to the starch and PP content of Trellis Earth bioresin Since starch has the lowest carbon footprint, it means that the environmental performance of

Trellis Earth bioresin improves if starch content is raised. However in reality the product would

become too weak if the starch content was too high.

A sensitivity analysis was carried out to show the benefit of an increase in starch content on

Trellis Earth bioresin (Figure 16). This figure shows that if no starch is included in Trellis Earth

bioresin and the proportions of the other materials remains the same (meaning it is made

up of PP and additives), the carbon footprint is 2.529 lbs CO2 (e)/lb (biogenic carbon included

and excluded). This would mean that Trellis Earth bioresin would still be marginally superior

to conventional PP (the reason it is not identical to PP is that it has additives). However, as the

content of starch begins to increase, the GWP falls (with and without biogenic carbon). The

result excluding biogenic carbon falls at a rate of 0.012 lbs CO2 for every 1% increase in starch

content while the result including biogenic carbon falls at a greater rate of 0.029 lbs CO2

for every 1% increase. Although a 100% starch content does not result in a negative value

like the starch material shown in figure 15, the GWP result including biogenic carbon drops

by 95% to just 0.139 lbs CO2/lb.

28

Figure 16, The GWP per lb of Trellis Earth bioresin with increased/decreased starch content.

Conversely, figure 17 shows the implications of increasing the polypropylene (PP) content when

the proportion of the other materials remains the same. This shows that the impact of Trellis

Earth bioresin increases as the PP content increases at a rate of 0.006 lbs CO2 per 1%

increase when biogenic carbon dioxide is excluded. This again shows that as the content of

starch drops, the impact of Trellis Earth bioresin increases. However, even at 100% PP content,

the Trellis Earth bioresin is superior to all other alternatives and identical to conventional PP.

29

Figure 17, The GWP per lb of Trellis Earth bioresin with increased/decreased PP content.

7 Conclusion The study found that the Trellis Earth bioresin was better than conventional plastics in terms of

global warming potential, abiotic resource depletion and ReCiPe single score.

The performances of the Trellis Earth bioresin was further found to be aided by the inclusion

of absorbed biogenic carbon dioxide in the measurement of global warming. T h e b ioresin

saw a 21‐‐‐25% drop in its impact when the absorption of CO2 during plant growth was included.

Carbon footprint results need to be taken in context with the use and disposal of the product

produced from the plastic. If the product is used for a significant period of time or does not

degrade, the carbon will remain sequestered within the material, therefore removing it from

the atmosphere for a significant period. Alternately, this benefit may be lost if the

30

material is used in short term product and is either incinerated or entirely degrades within a

relatively short period.

The sensitivity analysis found that Starch had the lowest GWP of any of the materials used both

when biogenic carbon was included and excluded. However, even without a starch content, the

Trellis Earth bioresin bioplastic was found to be superior to conventional plastics (because in

this case it is made up of the best of the conventional plastics, PP, plus additives that have a

lower carbon footprint than PP).

To conclude, the results of this study found that:

• Trellis Earth bioresin had the best overall environmental performance. It had the

lowest carbon footprint (GWP) of any of the plastic pellets. Its carbon footprint was 8%

lower than the best conventional plastic, which was PP, and 76% lower than the worst

conventional plastic, which was HIPS. This was when no credit was given for plant carbon

dioxide absorption. When credit was given, the benefit of Trellis Earth bioresin was

even greater: its carbon footprint was 32% lower than even the best conventional

plastic (PP).

• In terms of the ReCiPe single score (which amalgamates environmental impacts into a

single value) Trellis Earth bioresin was found to be superior to all conventional

plastics: it was 23% better than the best conventional plastic, which was again PP.

Appendix A: Description of Impact Categories Abiotic depletion

What is it? This impact category refers to the depletion of non living (abiotic) resources such as fossil

fuels, minerals, clay and peat.

Why is it an issue? In 2006, WWF International reported that mans impact on global resources has

tripled since 1961 and is now 25% above the planets ability to regenerate itself. If the world’s

population shared a western lifestyle, three planets would be required to meet their needs.

How is it measured? Abiotic depletion is measured in kilograms of Antimony (Sb) equivalents.

Global warming

What is it? Global warming potential is a measure of how much of a given mass of a green

house gas (for example, CO2, methane, nitrous oxide) is estimated to contribute to global

warming. Global warming occurs due to an increase in the atmospheric concentration of greenhouse

gases which changes the absorption of infrared radiation in the atmosphere, known as radiative

forcing leading to changes in climatic patterns and higher global average temperatures.

Why is it an issue? If no action is taken to reduce global carbon emissions, average

temperatures are likely to rise by more than 2 degrees Celsius. This change will increase severe

weather such as tropical storms, droughts and extreme heat waves and heavy precipitation.

Stabilization would require emissions to be at least 25% below current levels by 2050.

How is it measured? Global warming potential is measured in terms of CO2 equivalents.

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