The outbreak of three explosions worldwide in the recent one month has caused concern over the safety of hydrogen energy, overshadowing the prospects of its development.

On March 23, hydrogen cans at a hydrogen plant in Gangneung City of South Korea exploded, causing two deaths and six injuries, due to a mistake in operation during the experiment for the production of hydrogen via water electrolysis with the use of solar energy. On June 1, in the County of Santa Clara, California, several hydrogen transport trucks caught fire, leading to a series of explosions, due to the leakage of high-pressured hydrogen, which luckily caused no casualties.

Last week, a major explosion erupted at a hydrogen-fuel station in Norway, with the shock wave activating the safety airbags of some vehicles nearby, leading to injuries of two drivers. The culprit was leakage of hydrogen.

The accidents have refueled concern over the safety of hydrogen energy, given its high flammability, as it can catch fire at a wide-ranging density of 4-75% in air, compared with 5-15% for natural gas.

Caused mainly by hydrogen leakage, the successive accidents have cast doubt on the safety of the transport and storage of hydrogen fuel, clouding the prospects of hydrogen-fueled cars.

Michela Bortolotti, media manager of Hydrogen Europe, however, discounted the safety concern, noting that hydrogen has been extensively applied in industries over the past 40 years. He pointed out that the issue is how to handle hydrogen safely, similar to gasoline, diesel oil, and natural gas, whose safety risk is similar to hydrogen, adding that it's not easy for hydrogen density in lower-layer air to reach flammable level, due to fast diffusion of the gas.

In fact, many precautions have been adopted to assure the safety of the operation of hydrogen-fueled cars, such as leakage-prevention treatment, requirement of anti-explosion and static electricity for electric apparatuses, and gas-discharge equipment and hydrogen-density detection devices at hydrogen-fuel stations.

Meanwhile, fuel-cell cars have to undergo a series of safety checks before leaving auto plants, including leakage check in collision test, as well as rigorous safety test for hydrogen-storage systems of the cars.