Hazards and Associated Risks of Hydrogen Vehicles in Underground Traffic Infrastructure

Abstract

This paper overviews some findings of the HyTunnel-CS project (www.hytunnel.net) on inherently safer use of hydrogen-powered vehicles in underground traffic infrastructure. The focus is on mitigation and prevention of hazards from blast wave and fireball following hydrogen tank rupture in a fire. It is demonstrated that hydrogen tank rupture in a fire is unacceptable and must be excluded. The criticism of the fire test protocol of GTR#13 is presented. It is underlined that hydrogen storage systems protected by thermally activated pressure relieve device (TPRD) do not exclude risk of tank rupture in a localised fire. The safety strategy for underground parking of hydrogen cars is described. The concept of explosion free in a fire self-venting (TPRD-less) tank is explained. The hydrogen safety engineering tools and QRA methodology developed in HyTunnel-CS are used for assessment of risk for incident scenarios of an onboard hydrogen storage tank rupture in Dublin tunnel fire. The risk is assessed in terms of fatalities per car per year, and cost per event. It is concluded that the fire-resistance rating (FRR) of the hydrogen storage tank should exceed 91 min to reduce the risk of a hydrogen-powered car in a tunnel fire to the acceptable level of 10-5 fatalities/vehicle/year. The ultimate safety solution to eliminate hazards and associated risks of hydrogen vehicles use in confined spaces is the application of the breakthrough safety technology of explosion free in a fire self-venting (TPRD-less) tank that was experimentally validated.