It doesn't really say what the hydrogen storage scheme is for these trucks. It's my understanding that highly pressurized tanks are bad for applications like this because they leak (hydrogen is the smallest atom/molecule) and they are a explosion risk in the case of an accident or leak. It's been a while since I've looked into this but there was work being done to "charge" a carbon container with hydrogen than could then be released in a manner similar to a battery but without as much of a leak or explosion risk. Since nothing was made of it in this press release I am guessing they were using standard pressurized hydrogen gas tanks.