Trinseo
Mass-balancing is an approach to supply chain management that has been adopted across sectors like forestry and cotton as part of the drive towards greater sustainability.
Dr. Julien Renvoise, Global Circularity Manager Plastics at US-headquartered plastics manufacturer Trinseo, spoke to S&P Global Platts to explain the mass-balance approach in petrochemicals and how it is being used by Trinseo.
Trinseo received mass-balance certification from International Sustainability and Carbon Certification (ISCC) last year. What does this mean?
Essentially it means that we’re able to provide evidence of sustainable content in a final product throughout a complex value chain, in cases where it’s not possible to segregate inputs. It is not a simple concept to digest for sure. If you look to a simple analogy like green electricity, it becomes easier for people to understand. But you notice when you are pushing the [idea of] mass-balance to the market, it takes some time for customers to understand the concept. There is quite a lot to it, with logistics, inventory management, and tracking. Even the financials of the product you need to have coded into your system.
Can you talk us through the mass-balance concept?
To explain the mass-balance process, it’s helpful to compare it with the segregation model.
In an ideal world, if you want to include a sustainable feedstock in your product, you will keep separate streams of bio- and fossil-based material, with dedicated production lines, silos, etc. The situation now in the marketplace is that there isn’t enough sustainable material available yet. Assets are not purely dedicated to bio-material as it doesn’t make economic sense for all parties along the value chain to invest, and so we have to blend sustainable streams with fossil-based streams for the moment.
If you blend these two streams in a continuous process you can lose track of the precise sustainable portion at the end of the process. Hence, from segregation you move to the mass-balance principle. Mass-balance allows you to allocate the quantity of sustainable material you’ve added along a value chain to the final product in a virtual fashion.
The analogy is with green electricity. You buy electricity from a green supplier, which uses a renewable type of energy such as wind or solar – and once you use the electricity or switch on the button you don’t know if the electricity you are using comes from wind, solar or coal. But you know when you buy from the supplier that there is a certain quantity of renewable energy being used and the more you buy from the supplier the greater the chance that the renewable energy will get developed. This is exactly the same principle in mass-balance.
What do you have to do as a company to gain the mass-balance certification?
First, a company needs to be audited by a third-party certification body, which is done once per year. You have to show that your suppliers of sustainable feedstocks are certified and the sustainable material is managed according to best practice tracking processes in order to allocate sustainable credits, which is done once per month and done per site. The process for certification, actually, is not that long, and we are trained to deal with the manufacturing, tracking and traceability process. It can take four months to be certified but it depends on how well your system is already developed and managed.
If you are certified and you aren’t able to sell a certified product in the year, then normally you lose the certification. If you can explain why you were not able to sell, then it may be flexible, but there are certain rules to respect. For example, you have to have a positive balance of sustainable credits over the quarter.
Is it compulsory to have the certification in order to sell material as being mass-balanced?
Actually no, but it really is in everyone’s interest to not want to break the certification chain in the sense that I, as a manufacturer, want to be certified and pass this certification along to my customers — and this means my suppliers need to be certified. I wouldn’t be able to put the ISCC logo on my product if my suppliers aren’t certified and my customers would be restricted in making certain claims when selling their end products or applications. Nothing prevents me from selling certified products to a non-certified customer.
To be honest, I recommend to customers to get certification as it provides them with the right level of transparency, traceability and credibility that is required for this concept and for the value chain to get familiar with.
Mass-balance still needs the value chain to become familiar with [it]. It provides a certain level of objectivity and transparency about the work that you are doing as it is the methodology required by an official external auditing body and a third-party certification and audit. There is a list of auditors you can solicit. It is quite objective as a process.
Do you see the mass-balance concept as being in competition with recycling, or is it complementary to it?
They are two different things really; mass-balance is a tracking methodology which can apply to recycled or to bio-sourced material.
For me, mass-balance competes with a segregation model. So, you have either the segregation model tracking methodology or the mass-balance tracking methodology.
Today, chemical recycling cannot happen without mass-balance. You need mass-balance to be embraced by the European Commission to support chemical recycling to achieve the ambitious 2025 [recycling] targets. It is a necessity to move on and support the circular economy.
Ideally, we will, in the future, go to a segregation model where players will invest in dedicated assets and sustainable streams can be separated from the fossil-based streams.
Bio-material is a complementary element to recycling. Recycling has a yield of recycled content and you lose material during the recycling process. You then have to compensate with virgin material, and if you don’t want fossil-based virgin content added, because of sustainability goals, then you will have to add bio-sourced virgin material.
