The Hydrogenperoxide needed for this type of proplusion system was very ,very expensive to make and very dangerous to store and use. If this stuff came into any organic matter it would explode, it could only be stored in a ceramic container ( not very practical for use on a combat U-boat ) or a rubber bladder type of container ( rubber of any type was in very short supply in Germany at that time . This system was not very fuel efficient ( high fuel consumption,low radius of action). This fuel was very caustic and the turbine and pumps had a short life span. This system looks good on paper but in the real world the dangers and expense was not worth it. The British tried it after the war and one boat was nicknamed" HMS exploder "instead of explorer by it's crew. The USA worked with this stuff in the early 1930's ( Walter was not the only person working with this stuff ! ) but it was found that it was so dangerous to work with the Federal tranportation Department banned it from being transported on the roads or railway at the time. The US navy built a plant to make it in upsate NY so navy ships could transport it down the ST.Lawrence seaway. I believe it was called NAVOL or something to that effect.