Japan’s ex-coal town makes circular shift with recycled cooking oil

Omuta City, a historic centre of Japan’s coal industry, aims to make its mark with circular energy by paving its roads with asphalt made using recycled cooking oil.

The “Roa(d)cal SDGs Project,” initiated by the Saga-based Tanaka Iron Works Co., Ltd., creates a local circular economy by collecting waste cooking oil from homes and restaurants and using it as a substitute fuel in asphalt production. This low-carbon asphalt is then used to surface roads within Omuta itself.

Omuta is home to the Miike Coal Mine, a UNESCO World Heritage site that fuelled Japan’s modernisation. Today, the city has declared its ambition to become a “Zero Carbon City” and achieve net-zero carbon dioxide emissions by 2050.

Under the scheme, residents can deposit used cooking oil at collection points in local supermarkets, including Marumiya Store, Green Coop Fukuoka, and Aeon malls. The collected oil is then transported to an asphalt plant operated by Mitsui Road Co., Ltd., where it replaces heavy oil as a fuel for the manufacturing process. This directly reduces emissions of carbon dioxide, sulphur oxides and nitrogen oxides.

Since collections began in February, approximately 220 litres of oil had been recovered from households by the end of July. Shipments of the resulting asphalt mixture have already started for use in local roadworks.

For Omuta, it is a discovered opportunity, as they an estimated 96% of household waste cooking oil in Japan is currently discarded as waste. The Roa(d)cal project provides an avenue for this resource to be used effectively within the community where it is generated.

To foster community engagement, the project also includes educational outreach. In July, an environmental learning programme was held at the Omuta City Eco Sanku Centre, where children learned about recycling by making candles from waste cooking oil.

The project in Omuta is the third of its kind in Japan, following successful launches in Omura, Nagasaki Prefecture, and Otaru, Hokkaido.