How Braskem Is Reimagining Carbon Accounting for Bio-Based Plastics

Braskem is working to improve Scope 3 accounting through life cycle assessments, addressing gaps in today’s GHG Protocol and advocating for a shift to the -1/+1 model — an approach it says could better reflect the climate value of biogenic materials.

Sponsored Content | This article is sponsored by Braskem | By Braskem | Published 12 hours ago | About a 6 minute read

The Scope 3 problem

Imagine investing in sustainable materials, only to be told you can’t fully count the climate benefits. That’s the reality facing many brands that use renewable, plant-based plastics — and it largely comes down to how carbon is accounted for.

As the world works to cut emissions and meet net-zero targets, one area continues to lag: Scope 3 emissions. These indirect emissions, which come from a company’s value chain, are difficult to track and even harder to reduce. Yet for many industries, including plastics, Scope 3 is where the majority of climate impact resides.

Braskem, one of the world’s largest producers of thermoplastics, has been investing in bio-based materials for more than 15 years. In 2010, it launched I’m green™ bio-based polyethylene, made from sugarcane, offering a renewable alternative to fossil-based plastics. The material is chemically identical to its fossil-based counterpart.

BraskemSugarCane Image credit: Braskem. Braskem's I’m green™ bio-based polyethylene is made from sugar cane.

While it performs the same function, it has a significantly lower carbon footprint — a benefit that current emissions accounting systems often fail to fully reflect.

“We are selling exactly the same molecules that already exist in the market, but instead of coming from fossil fuels, ours are made from renewable, bio-based sources,” says Yuki Kabe, Braskem’s Technical Advocacy Specialist. “The added value we offer our partners is sustainability. But that only works if people understand the difference and if it can be properly accounted for.”

Kabe has worked in life cycle assessment (LCA) for more than two decades and joined Braskem in 2013. Today, he sits within the company’s External Affairs team, serving as a link between Braskem’s technical data and policymakers, standards bodies, and global brands. His role is to help ensure the sustainability attributes of Braskem’s bio-based products are accurately understood.

“Our role is to translate complex sustainability information into clear messages that stakeholders can act on,” he explains. One of the biggest barriers, he adds, is that current carbon accounting frameworks make it difficult to clearly communicate the benefits of renewable materials.

Why the current model falls short

To assess the environmental performance of its bio-based materials, Braskem relies on life cycle assessments. LCAs are designed to provide a comprehensive view of a product’s environmental impact, from resource extraction to end of life, by measuring carbon and other resource flows across the value chain.

“Life cycle assessment is about measuring flows,” says Kabe. “From nature to product, and from product back to nature.”

However, when it comes to corporate emissions reporting — particularly under the current GHG Protocol — much of that detail is lost. The central issue lies in how the protocol treats biogenic carbon: carbon derived from renewable sources such as plants.

“The GHG Protocol uses what’s called the 0/0 approach,” Kabe explains. “It doesn’t account for the CO₂ absorbed by plants during growth, and it also doesn’t count the emissions when that carbon is released later. It simplifies things, but it obscures important information.”

This model assumes that biogenic carbon is always released at the end of life. That assumption does not align with how fossil carbon is treated, particularly in cases where materials are recycled and emissions are delayed or avoided.

“On paper, 0/0 and -1/+1 look the same. They both net to zero,” Kabe says. “But in practice, 0/0 ignores timing and transparency. It ends up favoring fossil materials because the same logic isn’t applied consistently.”

According to Braskem’s LCA, its sugarcane-based polyethylene has a cradle-to-gate carbon footprint of -2.12 kg CO₂e per kilogram, compared to +3.1 kg CO₂e per kilogram for fossil-based polyethylene. Under current reporting rules, however, only a portion of that difference can be reflected in Scope 3 reporting.

“Brands may pay a premium for sustainability, expecting a significant reduction,” Kabe says. “But if they can only report part of that benefit, the business case becomes harder to justify.”

The -1/+1 approach

Braskem’s proposed alternative is to replace the 0/0 model with a -1/+1 approach. Rather than ignoring both carbon uptake and release, this method accounts for each. Carbon removed from the atmosphere during plant growth is recorded as -1. When that carbon is released at end of life — for example, through incineration — it is recorded as +1.

“With -1/+1, we can map the entire cycle,” says Kabe. “It improves transparency. We can see where removals occur and where emissions occur, and it allows circularity and decarbonisation strategies to work together.”

The approach more closely mirrors how carbon moves through natural systems. “Carbon flows in cycles — from atmosphere to plant, to soil, and back again,” he explains. “The goal is to reflect that same logic in product systems: take carbon from the air, store it in materials, keep it in use for as long as possible, and delay its return to the atmosphere.”

It also aligns more closely with circularity principles. “If I recycle fossil-based plastic, I’m allowed to say that carbon carries over into the next product,” Kabe notes. “But with bio-based plastics, the current method requires emissions to be counted immediately, even if they haven’t occurred yet. That inconsistency matters.”

Where the industry goes from here

Braskem has begun sharing its proposed model with industry stakeholders. Recently, the company presented the approach to a group of global brands representing a combined turnover of $460 billion.

“They stayed for four hours,” Kabe recalls. “There was broad agreement that this is a change worth pursuing.”

For Braskem, the issue goes beyond accounting mechanics. It’s about enabling more informed decisions — ones that better reflect a product’s climate impact and support the transition to a lower-carbon economy.

“We can’t remove carbon from plastics entirely,” Kabe says. “They are made of carbon. But we can choose where that carbon comes from. If we combine bio-based feedstocks with circular strategies, we can build a carbon pool that keeps carbon in use and out of the atmosphere for longer.”

The company has been investing in bio-based plastics for more than 15 years. As interest in these materials grows, Braskem is positioning itself to contribute to broader discussions around carbon accounting frameworks.

“We’ve been thinking about these challenges for a long time,” Kabe says. “That comes with a responsibility to contribute data, science, and practical insights that others can build on.”

The science and tools already exist. What’s needed now is greater alignment across policy, reporting standards, and supply chains. Without that alignment, progress on Scope 3 emissions will remain difficult.

“We need fairer accounting practices,” Kabe says. “Only then can brands fully understand the impact of their choices — and only then can we accelerate progress on Scope 3.”

Learn more about Braskem in this video from the SB'25 San Diego conference, [Innovating with nature: Harnessing bio-based materials for measurable carbon impact].(https://sustainablebrands.com/view/innovating-with-nature).