Mass balance allocation rules again - if you have heard me speak at one of our AMI conferences you will know that I regularly say "details matter" - in this world of information overload there is unfortunately a tendency towards "black versus white" thinking that does not tend to be particularly supportive of resolving complex issues.

In my post on the subject of mass balance accounting earlier this week I said that the recycled content targets formulated by the European Commission, in order to be achieved, require the adoption of the fuel-exempt model of mass balance allocation. At this stage, this is a sheer numbers game, not a matter of sentiment or opinion - a legislator sets a target and, in consequence, should establish the framework conditions that allows an industry to achieve this target. Yes, there are concerns about potential greenwashing but again, it is up to the legislator to put in place the necessary checks, balances, and sanctions to stop this from happening. In addition, any hint of greenwashing would create a backlash against the industry, self-harm in the extreme.

It should also be self-evident that mechanical recycling needs to be the recycling pathway of choice whenever possible and that, within the waste hierarchy, 'reduce' and 'reuse' come before recycling - an often neglected aspect (regrettable here in particular the intense lobbying against reuse models as part of the negotiations surrounding the new Packaging and Packaging Waste Regulation).

But getting back to my earlier point about the importance of details - mass balance/chain of custody models are about more than just a choice of allocation method. Decisions have also to be made on system boundaries - this can be a batch, a site or multi-sites, with batch allowing for the highest level of traceability. There appears to be consent within the industry that system boundaries either need to have ‘physical connectivity’ in the form of co-located facilities or facilities connected by pipelines and other transportation systems, or ‘chemical connectivity’ in that facilities in different locations produce the same outputs.

In addition, the physical properties of the material to be measured have to be established as well as the time period over which the amount of recycled feedstock that, for example, enters a steam cracker needs to equal the amount exiting it (accounting period). There are thus opportunities to fine-tune the requirements for mass balance accounting that go beyond a choice of the allocation model.

More information on mass balance is available on Silke's LinkedIn profile