The Promise of Return to the Sea: Biodegradable Plastics Today and 2025

The Promise of Return to the Sea: Biodegradable Plastics Today and 2025
In 2025, biodegradable plastics are entering a new phase. The global market is estimated to be worth approximately US$5.5 billion in 2023, and is expected to nearly double by 2030. In particular, demand is growing in the food packaging and disposable container sectors, and expectations for the realization of a recycling-oriented society have never been higher. However, high cost, stability of raw material supply, and reliability of degradation performance remain challenges, and the gap between material development and processing infrastructure has not been completely closed.

On the research front, Japanese scientists have attracted a great deal of attention with the announcement of a new plastic material that dissolves within hours in seawater. This is an innovative achievement that goes beyond conventional biodegradable materials and aims to make them less likely to remain in the marine environment. Kobe University has also produced a polyester-like substance using Escherichia coli bacteria, creating a new biodegradable plastic that is stronger than conventional PET. These are not merely substitutes for petroleum, but attempts to reconstruct the design of materials themselves, symbolizing the challenge of science toward the future.

Looking at the domestic situation, many biodegradable plastics are shifting to bio-based, i.e., derived from renewable resources. Nevertheless, being bio-based does not necessarily equate to being biodegradable or compostable, and careful selection is required for each application. The government and local governments are rushing to expand social infrastructure to enable proper disposal while reinforcing the institutional framework centered on the Containers and Packaging Recycling Law. Meanwhile, worldwide negotiations on the "Convention on the Prevention of Plastic Pollution" are continuing, and although no agreement has been reached, they are shaping a major trend in environmental policy.

However, it is also becoming clear that the term "biodegradable" is not a universal exoneration. In marine and low-temperature environments, degradation is slow, and as a result, microplastics may be left behind. In addition, research has pointed out that starch-based bioplastics may be as toxic as or more toxic than conventional petroleum-based resins, highlighting the issues that lie between the ideal of "returning to the soil" and the reality of the situation.

Nevertheless, the dream that began in the 1990s is steadily evolving. As of 2025, it is still a work in progress. But the idea of a "vessel that returns to the sea" continues to shine as a guiding light for the challenges of science and society.