NAGOYA (Kyodo) -- Just as with wine, aging a sake can produce a smoother drink, but there is a cost in maintaining the right conditions for storage. A group of brewers in central Japan, however, has found a virtually free alternative -- storing the drink inside tunnels in dams.

Thirteen brewers are storing products in the Maruyama, Agigawa and Origawa dams in Gifu Prefecture and the Yahagi Dam that straddles it and neighboring Aichi Prefecture at no cost from the operators.

While Japanese sake typically matures over a year, some benefit from longer storage. Usually, investment is required in facilities that can prevent changes in temperature and exposure to ultraviolet rays.

Tunnels within the dams, however, can be maintained at an ideal temperature of around 15 C, eliminating the need for refrigeration. They are also dark.

The ability to save on costs may help the brewers take advantage of growing international appreciation of sake products.

Japanese exports of the rice-based drink soared to around 47.5 billion yen ($307 million) in 2022 from 8.9 billion yen in 2012.

Meanwhile, the knowledge and skills for making it and "shochu" distilled spirits are expected to be formally endorsed for inclusion on the U.N. Educational, Scientific and Cultural Organization's Intangible Cultural Heritage list later this year.

For local consumers, events are being held to publicize the initiative, but according to the Nagoya Regional Taxation Bureau, which is among the dam project backers, awareness is still low.

Mitsuteru Watarai, who heads the project's executive committee and runs Iwamura Brewery Inc. in Gifu Prefecture, said he hopes the initiative can produce new sake fans. "By continuing to hold events in future, we hope to show people how the flavors have changed each year," he said.