Bacardi recently announced that it will be packaging its products in a new, compostable bottle starting in 2023—part of the brand’s long-term goal to becoming fully plastic-free by 2030. The bottle’s made with PHA, a 100% compostable biopolymer that’s created using natural seed oils instead of petroleum and breaks down naturally in 18 months.

But while the spirits brand is calling this innovation a “silver bullet” solution to the plastic pollution problem, experts have urged caution. PHA represents an exciting technological development in biodegradable packaging, experts say, but it also requires a composting infrastructure that is not yet widely available. And unless consumers fully understand the difference between these different plastics and how to dispose of each, it could result in contamination at recycling plants.

The new bottle will replace the 80 million plastic bottles—3,000 tons of plastic—that Bacardi produces across its portfolio of brands every year. To develop this solution, the spirits company partnered with biotech company Danimer Scientific. The resulting Nodax PHA biopolymer biodegrades in compost, soil, freshwater or seawater in 18 months—a significant improvement from the roughly 400 years it takes for petroleum-based plastics to decompose.

“Over our 158-year history, Bacardi has always believed in respecting the world’s natural resources and acting responsibly, from the sustainable sourcing of our sugarcane to the water and energy used to make our rum,” said Ned Duggan, svp of Bacardi. “We’re now excited to be pioneering this new biopolymer technology for the benefit of all Bacardi brands and the entire spirits industry.”

Bacardi’s not the only CPG company looking to incorporate PHA into its packaging—PepsiCo’s working on a chip bag made of the biodegradable plastic and Nestlé has a PHA water bottle in the works.

But making a large-scale switch from a highly recyclable petroleum-based plastic to a biodegradable PHA biopolymer will require widespread access to composting infrastructure and clear consumer messaging, said Bridget Croke of Closed Loop Partners, a sustainability-focused investment firm. While PHA is a “promising material,” Croke said, “the question is: what is the appropriate use case?”

According to a 2019 report from the U.S. PIRG Education Fund, only 326 towns and cities out of more than 19,000 nationwide have curbside compost pickup. Unless these efforts are significantly scaled over the next two years, flooding the system with biodegradable plastics come 2023 could serve as a “bulking agent” rather than adding nutrients to the compost, said Croke. PHA bottles also run the risk of ending up in the recycling bin along with traditional plastics, where they could contaminate an otherwise highly recyclable batch of materials.

For companies looking to switch to compostable materials, Croke said she hopes that they’re “willing to invest in the infrastructure to actually recover that material, because it’s far more nascent than recycling infrastructure.”

Still, with heavy investments in educational messaging, composting infrastructure and a movement toward more home composting systems, PHA offers an opportunity to cut back on the pollution created by single-use plastics in the CPG industry without really giving up plastic.

Nodax PHA “delivers the biodegradability that consumers demand without losing the quality feel they receive from traditional plastic,” said Danimer Scientific’s chief marketing and sustainability officer Scott Tuten in a statement. “The material provides the best of both worlds.”