Impact matters more than content when using non-fossil feedstocks

The lines have been drawn in the ongoing discussion about the role of mass balance in the transition towards a circular economy for chemicals and plastics. Supporters of the mass balance approach highlight its benefits for a fast transition away from fossil resources as well as its potential for satisfying consumer demand for more sustainable value chains and products. Skeptics criticize its bias for large and asset-heavy production setups whilst questioning the impact on sustainability. Dr. Christian Krüger, head of Global Sustainability and Chemical Recycling Advocacy at BASF, answered some questions from Sustainable Plastics about the mass balance debate.

Thank you for your time, Dr. Krüger, and perhaps you could start by explaining what exactly is meant by mass balance?
Mass balance is a chain of custody with defined rules for the attribution of non-fossil feedstocks within a production system to intermediate and customer products. Driven by consumer demand, customers today are asking for circular or low-carbon footprint solutions that still provide the high quality and performance of their conventional equivalent. Mass-balanced products can contribute to the substitution of fossil resources in the chemical production process by using alternative recycled feedstock from post-consumer plastic waste or end-of-life tires as well as bio-based feedstock. These raw materials are then attributed to the downstream products according to a set of transparent rules of the third-party certified approach. The most common certification schemes in the chemical sector are REDcert2 and ISCC PLUS. The certified mass-balanced products can be marketed with the respective sustainability claim.

The mass balance concept looks complex and cumbersome at first sight. You may ask, why did the chemical industry choose to adopt this chain-of-custody model to its complex production environment? What is the benefit of applying this model to a production environment which is designed to create thousands of different products, from polymers to coatings or crop-protection agents or vitamins? Isn’t the chemical production system with multi-input, multi-output and in-between processes too complex to account for a range of non-fossil drop-in feedstocks? Obviously, the chemical industry opted for mass balance for the same reasons other value chains like FSC certified timber or fair trade cocoa did: mass balance enables the introduction of more sustainable practices and materials into a system while providing a transfer mechanism of the sustainability benefit to the customer. It is a powerful transmission belt for sustainability contributions in the value chain. In the initial phase of the transition away from fossil resources, it offers the opportunity to differentiate more sustainable products on the market and return the higher costs of alternative processes and materials using the existing infrastructure. 

Why is it such an intensely debated topic when it comes to plastic recycling and circularity issue?
Mass balance is an abstract and rational model and not as intuitively grasped as the type of physical content created by mechanical recycling or 14C-biobased routes. It may seem counter-intuitive that this accounting method can attribute up to 100 percent of the alternative feedstock to certified plastics, even though they may incorporate no measurable content, while, in the case of bio-based feedstock resulting in a lower product carbon footprint.
But, on the other hand, we need a model that can cope with the complex value chains with various feed-in points for circular feedstocks from e.g. biogas to pyrolysis oil. Offering customers a tailor-made portfolio of sustainable and affordable products requires flexibility in terms of feedstock choice, entry points and value chains. And beyond recycling and bio-based feedstocks, new carbon capturing and utilisation technologies are on the horizon. With these emerging technologies, the range of alternative carbon sources continues to expand.
You may ask, doesn’t mass balance become arbitrary, given this extensive flexibility? Not really, because input and output of the production systems are calculated and accounted in digital applications, just like cash flow. The certification ensures correct calculation of feedstock input, bookkeeping of the alternative feedstock and compliance with all criteria of the mass balance approach. As alternative feedstock can be attributed independent of its origin, mass balance allows for a variety of options and maximum speed in the raw material transition.

What’s the difference between mass balance and other accounting and attribution methods?
There are different chain-of-custody models, from physical content of material like segregated production or controlled blending, to attributional models like mass balance and book and claim. The attribution models focus on attributed, not on measurable content, together with asset connectivity. What all models have in common is that they create a link between input and output which requires third-party certification for transparency and credibility, and that they have an environmental impact independent of the degree of physical or chemical connectivity. Each of these chain-of-custody models is suitable for certain supply-chain and production settings. For example, segregated material flows or controlled blending can be applied to dedicated, linear value chains. In a complex production environment, mass balance will be preferred. Book and claim may be an option for sharing sustainability attributes between companies without physical transport of products.  

Why did BASF opt for the mass balance method?
At BASF, we adopted a pragmatic approach: The essence of mass balance is the sustainability impact, not measurable content in a product. The substitution of hydrocarbons from fossil sources with hydrocarbons from non-fossil sources at the beginning of petrochemical value chains is audited and the attribution to products is certified according to well-recognised schemes. This flexibility makes it possible to choose the appropriate feedstock to fulfill customer demands. In our view, it is important for the feedstock transformation to introduce a range of circular feedstocks into the production system, including renewable, recycled (mixed plastic waste), and depolymerised feedstocks. The corresponding sustainability attributes can be transferred to the products via mass balance, enabling societal and customer demand for circular and low-carbon footprint solutions to be met. In other words, customers choose their preferred sustainability impact, which can be delivered via the flexible and pragmatic mass balance approach. Driven by market demand, a supplier like BASF purchases the appropriate amount of circular feedstock, which drives the green transformation. The benefits of such a flexible approach are first and foremost the reduction of fossil resource consumption, the establishment of recycling routes, and the potential for greenhouse gas emission reduction.

What is the criticism of those opposing the mass balance approach?
As indicated before, skeptics of mass balance argue in favour of content and connectivity. They rate content in the product higher than attributed feedstock. In their view, and supported by functioning routes like mechanical recycling, credibility depends on measurable content. If there is no measurable content, they demand at least a strict chemical connectivity through the value chain. Let’s take a look at this concept.

The corresponding rules currently being discussed in standardisation and industry guidelines (like ISO, TfS) are affecting how feedstock is linked to the final product. The stricter versions of these rules are mainly trying to limit the options for using alternative raw materials that replace fossil feedstock, and how these materials need to be connected in the production process in the creation of a mass balanced product. Restrictive mass balance rules could force unnecessary investments in redundant assets by requiring feedstock-to-product connectivity, discouraging and slowing down the feedstock transformation. The creation of additional production lines and process steps will unnecessarily increase CO2 emissions as well as hamper and delay the transition. Such rules would limit availability, price and choice of alternative feedstock. We should keep in mind that they would neither enable content claims, nor would they increase the sustainability impact in the value chains. Considering the costs associated for companies and society in the material transformation, the investments should focus on those areas that create additional impact instead of satisfying arbitrary connectivity needs to a chain of custody.

What is BASF’s position?
BASF's biomass balance (BMB) and ChemCycling approach were born out of a simple question: How can we replace fossil raw materials for thousands of products manufactured in BASF's vast, complex production network? Which chain-of-custody approach enables us to keep fossil resources in the ground and has the potential for a swift scale-up? The solution is to feed alternative raw materials into the production chain alongside fossil raw materials at such an early stage that the end products remain chemically unchanged. Products that are certified as biomass balanced (attributed bio-based feedstock) or Ccycled (attributed recycled feedstock) thus offer the same performance and quality as conventional products, with the additional benefit of a smaller product carbon footprint (BMB) and a contribution to plastic waste recycling (Ccycled).

The mass balance approach provides the necessary transparency about the use of circular feedstocks so that consumers can make informed purchasing decisions. Manufacturers can continuously increase the availability of products with an improved environmental footprint in response to rising market demand.

In the current transformation process, we have no time to lose. This again means we must work with feedstocks that are available and affordable today and use all possible ways to introduce them into our production systems. Flexible attribution enables pushing the full sustainability impact down the value chain without dilution. Again, pragmatic rules will be needed to link these feedstocks to our customers’ demand for circular products in their industries.  

How does BASF see the topic developing midterm? Which model is the best and why?
Although no single solution is a “silver bullet”, we see attribution models including mass balance as an effective and powerful approach to enable a faster transition to alternative feedstocks and a circular economy. We should not expect a complete switch within the next two decades, but a significant increase in recycle-based and bio-based feedstocks. Mass balance complements routes which deliver renewable or recycled content in the product or contribute to carbon footprint reduction. A pragmatic and flexible mass balance approach is needed to leverage the maximum possible number of feedstock entry points reflecting availability, readiness of technologies and costs that the value chain can absorb. In such a flexible approach, the recycled and renewable feedstock demand is calculated back to the primary carbon sources like naphtha and natural gas which can be replaced with adequate volumes of e.g. bio-gas, bio-naphtha or pyrolysis oil. With mass balance, the focus is on substituting the overall fossil carbon demand for a customer product instead of every dedicated input in a single product value chain one by one. This provides the flexibility to substitute more fossil carbon than more restricted MB approaches that imply tracing carbon of one feedstock.

Is the industry in Europe ready to endorse the transformation into a more circular economy for chemical and plastics?
European chemicals and plastics producers are ready to transition to a circular economy and to use alternative feedstocks, despite a declining share of European plastics production (see “A Circular Economy for Plastics. A European Analysis” by Plastics Europe, March 2024). Highlighting the potential industrial decline of Europe, more than 750 companies and more than 280 associations have signed the “Antwerp Declaration” in support of a European Industrial Deal to complement the Green Deal and to keep high quality jobs for European workers in Europe. Calling for improvements to competitiveness and infrastructure to advance energy supply, digitalisation, CCUS and recycling, the Antwerp Declaration also points to the need for increasing the EU’s raw materials security and boosting demand for net-zero, low-carbon and circular products. One aspect of raw materials security is the scale-up of renewable carbon and circular carbon feedstocks, including the expansion and fast-permitting of advanced chemical recycling technologies. Demand for more sustainable products may be driven by consumers’ choice of net-zero and circular products, based on transparent product and environmental carbon footprints. In our view, a pragmatic and flexible mass balance approach with independent certification and transparent and credibly product claims can contribute to a competitive, low-carbon emitting and circular economy. It has the potential to reconcile a green transformation with a prolific industry landscape that keeps investing and creates jobs.

This article first appeared in the May/June issue of Sustainable Plastics.