The composition of their "hydrogen-rich gas" is behind a paywall...but from a quick peek at Wikipedia - > Hydrogen poses a number of hazards to human safety, f

The composition of their "hydrogen-rich gas" is behind a paywall...but from a quick peek at Wikipedia - > Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form. [...] Hydrogen dissolves in many metals and in addition to leaking out, may have adverse effects on them, such as hydrogen embrittlement,[167] leading to cracks and explosions.[168] Hydrogen gas leaking into external air may spontaneously ignite. Moreover, hydrogen fire, while being extremely hot, is almost invisible, and thus can lead to accidental burns. > Hydrogen has one of the widest explosive/ignition mix range with air of all the gases with few exceptions such as acetylene, silane, and ethylene oxide, and in terms of minimum necessary ignition energy and mixture ratios has extremely low requirements for an explosion to occur. This means that whatever the mix proportion between air and hydrogen, when ignited in an enclosed space a hydrogen leak will most likely lead to an explosion, not a mere flame. - this really doesn't sound like good news.