Based on the increasing need of energy for the future and the related risks to the environmentsdue to burning of fossils fuels, hydrogen is seen as an efficient and application related cleanenergy carrier that may be derived from renewable energy sources. A variety of applicationsconnected with production and use of hydrogen and the related risks have been identified, anda survey has been conducted among a number of experts as an internet exercise for unveilingthe potential lack of necessary knowledge in order to handle hydrogen in a safe wayconcerning the various applications.The main results concern hazardous situations related to release and explosions of hydrogenin confined and semi-confined areas, tunnels and garages, and mitigation of hazardoussituations, i.e. preventions of accidents and reduction of consequences from accidentshappening anyway.