Allbirds says its net-zero carbon shoe is here

“We could spend decades debating the finer points of carbon sequestration, or we can innovate today with a common sense approach,” says Allbirds’s Kajimura.

Allbirds is planning to make its formula for net-zero carbon shoes open-source, as it did with its sugarcane EVA SweetFoam in 2018, the life cycle assessment tool it uses to calculate product-level carbon footprints in 2021, and its Plant Leather in 2022. The brand says SweetFoam has since been adopted by over 100 brands, including Puma, Reebok, Ugg and Timberland. Allbirds will also be pursuing brand partnerships to turn the M0.0nshot materials and tools into other products that appeal to more fashion-forward consumers, but Brown is tight-lipped about the contenders. 

Carbon tunnel vision

Such a tight focus on carbon inevitably means trade-offs in other sustainability and design metrics.

The SuperLight midsole uses a similar process to Allbirds’s sugarcane-based SweetFoam, but builds in more of its carbon-negative resin input. The new method is similar to a Sodastream, explains vice president of innovation and sustainability Jad Finck, applying heat and pressure to infuse the material with bubbles through a supercritical process. The resulting foam is lighter than its predecessor, which also saves on transportation emissions. “There is certainly energy used in this process,” says Finck. “The main thing we need to do is use renewable energy to get the carbon intensity down.” 

When it comes to transportation, Allbirds will be using biofuel powered ocean shipping, and electric trucking from port to warehouse. This is a significant stepchange from traditional transportation, but there could still be improvements, says Chow. “There can be destructive practices in the production of biofuel, and the only truly net-zero form of shipment is wind sailing,” she explains. “A few companies offer this now but it’s still very novel.” Allbirds says its biofuel is derived from waste or residue feedstocks, and it will roll out additional low-carbon transportation options as they become available at scale. 

There are other limitations, says Kajimura. “We’ve managed to make a shoe with a net-zero carbon footprint, but there’s still a cost at the end of life. In the early phases, we discussed making this product fully circular, but the limitations on construction and materials made that very difficult — you would likely need to use just one material.” 

Still, the design has been streamlined to reduce additional emissions, says Finck. The three materials outlined above make up around 90 per cent of the shoe, but other inputs were unavoidable at this stage, such as recycled synthetics for smaller pieces that enable structuring and durability. “We were able to make the foam suitable for ground contact, as well as being comfortable for the cushioning, and we used the knitting arrangement to add structure where you would otherwise need additional parts to reinforce it, so we could cut down on extra components there,” he explains. “It’s one thing to get the carbon footprint down on a part, but another thing to be able to remove it entirely.”