The starting point of our project was a look at the world as it is. We have marvelous technologies which make our lives better, things that were problems 100 years ago we can't think of anymore and all information can be shared faster than ever. However, there is also something terribly wrong with this world. Temperature is rising, animals go extinct and the price of our advancement is pulling fossil fuels out of the earth that have been there for millions of years.

We love all these advancements. We would lie if we say we didn't. But we do want to solve the downside of our development. Therefore we looked into a surprising polluter: plastic. Plastic is a wonderful product and these days it is impossible to live without it. Therefore we looked into the production of plastic. Can we make clean plastic, which does not pollute the earth? And what should we do with this plastic? On the Human Practices pages you'll found where our journey brought us; from schools to festivals; from start-ups to multinationals. We started off by calculating the Carbon Footprint of styrene.

Carbon Footprint Analysis

We are facing an huge increase in global population, from the current world population of f 7.6 billion to an expected 9.8 billion in 2050[1]. This projected increase in global population leads to an increase in both increased food and energy consumption, which in turn in is associated with the release of larger amounts of greenhouse gasses the atmosphere. Right now, we live in a plastic generation. The global production and consumption of plastics have been on the rise for over 50 years now, reaching a plastic consumption of 297.5 million tons by the end of 2015[2]. Plastic products from the petrochemical industries have a high carbon footprint (Boonniteewanich et al,. 2014). The combination of global population increase and a mass consumed non-eco-friendly product, in the form of petroleum-based plastics, could be disastrous. This is one of the reasons that the Groningen iGEM team’s project attempts to produce (bio)styrene, a building block for many plastics, from cellulose as an alternative to substitute the petroleum-based styrene. In this section we have carried out a partial Life Cycle Assessment (LCA) analysis to identify the environmental impact of both alternatives of petroleum-based styrene and bio-based styrene. The main purpose is to provide an insight of environmental burden that is caused by the worldwide styrene industry in terms of carbon dioxide equivalent emissions (CO2-e) and to showcase our greener alternative.

Analysis

For our LCA analysis , we have set the study boundary to what is called the ‘cradle to gate’ analysis instead of a full LCA which is called the ‘cradle to grave’ analysis (see figure 1). The reason for this is twofold. First of all, we discovered the LCA analysis in a late phase of the project. Therefore, so we did not have enough time to do the complete quantitative analysis because, in that case you have to look at all the inputs and outputs of equivalent CO2 of feedstock and energy, for each stage of our process, which is a complex task and in some cases that information is not even freely available. However, the main reason we choose to use the cradle to gate analysis over the cradle to grave is that fact that it is the only part that matters, since we will produce the exact same product, namely styrene. The second part of the life-cycle will be exactly the same. Therefore, the only part that matters is from the feedstock you use and the energy required to the product, in our case styrene.

Figure 1. Figure retrieved from: http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-20192013000200001

Contacts

In order to evaluate the environmental impact of the two ways of producing styrene, we met with multiple experts from the University of Groningen, and with experts from various start-ups and companies. First of all, Tjerk Douma, a master student whose specialized in sustainability and did a major part of the analysis. We also met with prof. dr. F. Francesco Picchioni, of the University of Groningen, head of the Product technology department - Engineering and Technology Institute Groningen. Moreover, we met with the start-up companies BioBTX and Zernike Advanced Processing and the companies CE Delft and Avantium.

Analysis

For our analysis, we compared the process of producing styrene from a bio-based feedstock to the process of producing styrene with petroleum as a feedstock. The defined cradle to gate emission of petroleum based in our analysis is 4.7 CO2-eq per kilogram styrene, this is based on the official GER report of CE Delft who elucidated the whole life-cycle of styrene and the emission for each step along this cycle (Croezen & Lieshout, 2015). To use this data, Tjerk Douma got into contact with the makers of the data and found out how the styrene values were derived. The first step in defining the amount of CO2-eq per kilogram StyGreen is, defining the feedstock that is going to be used. We explored many different options (link https://2018.igem.org/Team:Groningen/Applied_Design#source), in the end we decided to use recycled toilet paper. The main reason for this choice was the sustainability aspect, toilet paper is product that is not used for anything at this moment. Therefore, it does not hold much value at all, or negative value, which means that we can potentially add value to the life-cycle of toilet paper. Another reason for choosing toilet paper is that we do not want to compete with the food industry. It might be feasible to use sugar, or 1G resources to produce styrene, but this does not fit into our view of a better world (link Human Practices).

The second step was to calculate the Carbon Footprint of recycled toilet paper. For this, we looked into the value of recycled toilet paper in combination to the resource, in our case paper. After this we looked at the price of the toilet paper, and compared to the price of wood. This way, we could make a parallel to the toilet paper CO2-eq. We found the paper CO2-eq to be 0,9, and the costs to be 150 euro per ton. Due to the fact that toilet paper recycling is still in its kindershoes, it was hard to find a good price for the resource. However, after talking to several experts, we came to a rough price around 15 euro’s per ton. As this is a factor ten difference, we needed to divide the CO2-eq by 10 as well, coming to a CO2-eq of 0.09.

This is a lot better than 4.7, but our yields are not 100%. For each kilo of styrene, we need right now 263 kilos of cellulose[link flux model]. This would result in 23.67 CO2-eq, which is way worse than regular styrene. But how is this possible? How could it be that StyGreen has a higher CO2-eq output than the regular styrene? This is because the CO2 depletion of the trees are not in calculated in the GER values. Therefore we calculated the difference, when we would switch from styrene to StyGreen. To do this, we compared the production costs of both styrene and StyGreen, i.e. we did not take into account the CO2-eq of toilet paper, as it was thrown away now anyway. When we looked at these numbers we found a CO2-eq of 1.23 for StyGreen compared to the 4.7 of styrene. This is a 71% decrease in CO2 emissions when we switch from styrene to StyGreen! Please remind that we assume here that toilet paper has no competitors CO2 wise. At the time more people are interested in using toiletpaper, we have to caluclate in these losses as well. However, right now toilet paper is just rotting away.

Conclusions

1. Toilet paper waste is used as the primary raw material in the biorefinery to produce styrene.
2. Is it possible to take that percentage and use it in the biorefinery? The composition of cellulose is the determining factor which would need to be examined. If the raw materials were made up of pure biomass then the implications to the environment would be proportionally greater. Therefore locally sourced biomass, which does not impact on agricultural land, is the preferred option.
3. Currently the biorefinery is an energy and chemically intensive process. The amounts needed to convert x kg/h of raw materials into glucose is substantial.

Safety should be a cornerstone of every project, taken into account during every phase. For this reason the Dutch Governmental Institute for Public Health and Environment (RIVM) has challenged us to participate in their Safe-by-Design assignment. The goal of this assignment is to demonstrate how our team has taken safety into account throughout our project, in every aspect. Of particular importance is the human practices part, where our ideas get taken outside the lab and into the world surrounding us. Of special interest is the iterative process, where the direction of the project is adjusted based on input from stakeholders and experts in relevant fields, safety and ethical guidelines, and considerations regarding the upscaling of our project. We have had 2 Skype meetings with staff members of the RIVM, and using their tips and guidance we made some more adjustment. The final product, an infographical timeline describing the iterative process of our project, is pictured below.