SEOUL, Jan. 17 (Xinhua) -- South Korean President Moon Jae-in vowed on Thursday to foster a so-called "hydrogen economy" as new growth engine.

"Our government's determination is firm toward a hydrogen economy. It is a golden opportunity to fundamentally change our national energy system and foster new growth engine," Moon said during an occasion with businessmen from hydrogen-related companies, including Hyundai Motor.

The hydrogen economy would become a "revolutionary" change to turn the country's energy source from coal and oil into hydrogen, Moon said in Ulsan, about 410 km southeast of Seoul, which houses hydrogen-relevant businesses such as a Hyundai Motor facility.

The industrial city of Ulsan was the fourth leg of Moon's sporadic industry-bolstering tours, which began in October, to help reinvigorate regional economies.

Hyundai Motor, the country's largest automaker, unveiled a long-term roadmap in December to expand its hydrogen business, planning to increase its annual fuel-cell systems production capacity to 700,000 units by 2030 that includes 500,000 units for fuel-cell electric vehicles (FCEVs).

Hyundai's fuel-cell systems, which combine hydrogen fuel with oxygen taken from the air to produce electricity, are known to emit only water as a by-product and help purify polluted air. The fuel-cell system involves fuel-cell stack and relevant components.

Hyundai aimed to expand its hydrogen business beyond the automotive sector by supplying its fuel-cell system to other manufacturers of drones, vessels, rolling stocks and forklifts as well as automobiles.