SK Energy, a leading oil company under SK Innovation, said Sunday it has opened the country's first hydrogen charging station for large cargo trucks in Ulsan, an industrial city on the southern coast.

With the charging capacity of 80 kilograms per hour, the hydrogen fueling station can charge 16 passenger cars per hour or 40 large trucks a day.

Of the 7 billion won ($5.3 million) joint investment with the Korean government and Ulsan city, SK Energy shelled out 1.3 billion won to build a 1.5-kilometer underground pipe that connects the charging station and the hydrogen plant.

The station, located 7 kilometers from Ulsan Interchange and 3 kilometers from Cheongnyang Interchange, is in proximity of driving routes frequented by truck drivers.

The hydrogen charging station helps fill a gap as most large diesel-powered trucks have shown little progress in electrification because EV batteries do not have enough energy density, the company said.

“Instead of electricity, hydrogen was considered as the alternative choice of energy. But there was no hydrogen station suited to charge big-sized cargo trucks until the Ulsan charging point,” it added.

“Unlike the existing hydrogen delivery system via tankers, we are supplying it through an underground pipe to improve stability.”

As a promotional event, the company will provide the hydrogen charging service free of charge for 10 vehicles per day until Friday.

In a move to accelerate its green energy business, SK Energy announced it will set up fuel cell and EV chargers with renewable energy companies last year. In January, it vowed to build an energy station that can produce hydrogen, electricity and heat.