SAGA CITY, Japan — The capital of Japan’s Saga Prefecture is using the carbon dioxide  and heat emitted by its waste disposal plant to cultivate crops and grow algae.

The Saga City Waste Incineration Plant uses technology developed by Toshiba Energy Systems and Solutions to burn household waste.

The plant then sells the resulting carbon dioxide and heat to farming operations, sending them to greenhouses via pipelines.

Alvita Corp., a joint venture between Sincere Corp. of Japan and Heliae Corp. of Gilbert, Ariz., grows haematococcus, an algae found in nature throughout the world, is one recipient of the carbon dioxide.

Growing algae requires water, sunlight and carbon dioxide for photosynthesis, said Yasunobu Katsuki, Alvita manufacturing department director and engineering section chief.

The company extracts from the algae the chemical astaxanthin, an antioxidant used as an ingredient in health food and cosmetics, which it sells.

The algae, each one-tenth of a micron, is first cultivated two to three weeks in cylindrical plastic bags in the company’s “bag room,” where it is fed carbon dioxide.

“In the room, there is less danger of contamination from mold, dust, et cetera,” Katsuki said.

In the next growing phase, the algae is transferred to pools in greenhouses, where it is fed more carbon dioxide.

“The algae grows in freshwater,” Katsuki said.

Originally green, the algae becomes red after 14 to 23 days from exposure to the sun’s ultraviolet rays, and its astaxanthin content becomes high, Katsuki said.

Alvita currently produces about 1,100 pounds of astaxanthin in oil form a year.

“We plan to expand production 10 times by buying land from Saga City,” Katsuki said.

Alvita started operations in 2016.

“We already had the idea to do this business, but we needed carbon dioxide. We checked online and saw what Saga City was doing,” Katsuki said.

The National Federation of Agricultural Co-operative Associations — known by the acronym ZEN-NOH — set up an experimental cucumber farm in Saga City last year specifically to use the carbon dioxide and heat for its greenhouses.

ZEN-NOH is in charge of Japan Agricultural Cooperatives, the group of regional co-ops that supplies members with inputs for production, packaging, transportation, financing and marketing of agricultural products.

Hiroaki Nishimura of ZEN-NOH’s agribusiness general planning division said at 2.25 acres, including both greenhouse and field growing, Yume Farm — “yume” means “dream” in Japanese — is the biggest cucumber farm in the country.

In a closed environment, the concentration of carbon dioxide is higher, Nishimura said. “We hope to have a faster yield this way,” he said.

Nishimura said speed of growth depends on factors such as the season and weather, but should be 120% to 140% faster than field growing.

Yume Farm started its greenhouse cultivation Dec. 12 and had its first harvest Jan. 28, selling the cucumbers at the JA store in Saga.

“They tasted good,” Nishimura said.