ALLOCATION
Understanding mass balance as used in chemical recycling
Tracking use of mechanically recycled material is straightforward — the recycled resin is simply used as supplied or blended in with virgin. It is not so easy in chemical recycling, where recycled content takes the form of basic hydrocarbons fed into complex cracking and polymerisation processes. Individual molecules cannot be tracked but have to be accounted using the principles of mass balance. The idea behind mass balance is to measure the
input of an individual component in a much larger manufacturing process and allocate its contribution to each unit of end product. In the case of chemical recycling, it aims to ensure that the amount of recycled feedstock entering a production plant equates to any claims made about the recycled content of products leaving it. It is not a new con- cept; the idea is already applied in sectors as varied as electricity marketing and Fair Trade agriculture. As with many ideas, however, the challenge is in implementation. Different approaches can be taken with regard to what to allocate and where to allocate it. For instance, the entire output of a chemical recycling process — including both fuels and feedstocks — could be allocated as a contribu- tor to any polymer or chemical production process, whether or not there is any direct link. This is called free-attribution. Alternatively, it may be decided to allocate only non-fuel components. Or, at its strictest, only those components used as a non-fuel contributor to production of a polymer.
Chemical Recycling – Global Insight 2024
Plastics Europe has emphasised the importance
of the European Commission’s pending decision on mass balance. The polymer producer organisation has published its Plastics Transition roadmap which includes chemical recycling as part of the mix in the industry’s move to circularity. Plastics Europe’s position accepts that fuel products cannot be included in mass balance allocation but it warns that some options would lead to lower yields that would make chemical recycling uncompetitive in Europe. The organisation also calls for clarity about the claims made about the presence of recycled or bio-based content in the end product. It recom- mends that products/plastics resulting from a mass-balance approach use terminology such as recycled-attributed and bio-attributed. Mass balance will be essential in the develop-
ment of chemical recycling as an industrial process and to that end it is important it is seen to be transparent and trusted — consumers, for example, must understand the claims made and, more importantly, have confidence in them. A number of organisations are already running certification programmes, of which the best known are Interna- tional Sustainability and Carbon Certification (ISCC) and RedCert (both headquartered in Germany). In addition, the International Organisation for Stand- ardisation (ISO) is working on a global mass balance standard — ISO/AWA 13662 Chain of Custody-Mass Balance-Requirement and Guidelines.
17
Main image: How are inputs and outputs treated in a chemical recycling process?
IMAGE: SHUTTERSTOCK
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64
