Risks Associated with Alternative Fuels in Road Tunnels and Underground Garages

In the future, a large number of road vehicles will not be powered by fossil fuels and due to environmental considerations, much current transportation policy development is aimed at increasing usage of renewable energy sources. These include gaseous fuels such as liquefied petroleum gas (LPG), methane and hydrogen, along with electricity. In order to prevent incidents in connection with such a change in the transportation sector, regulations and practices should stay one step ahead.

RISE Research Institutes of Sweden (former SP Fire Research) has conducted a research project funded by the Nordic Road Association (NVF), which was intended to review and update current knowledge regarding alternative fuels, provide guidelines for the operations of rescue services, and offer recommendations for the creation of regulations. Road tunnels and underground garages constitute particularly high-risk environments with regard to fires and explosions. The project focused on commercial gaseous fuels (LPG, DME (dimethyl ether), methane and hydrogen gas) and electric vehicles.

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Gaseous fuels and electric vehicles pose new risks that we, due to our greater familiarity with liquid fuels, are unused to. The greatest of these relate to gaseous fuels and pressure-vessel explosions, and the release of toxic gases such as hydrogen fluoride from Li-ion batteries undergoing thermal runaway. One of the greatest dangers posed by electric vehicles at present is arguably not the technologies that constitute them and the possible adverse consequences of their use, but uncertainty regarding how to handle them. The technology is relatively new, and differs significantly from conventional fuels. This may lead to uncertainty during a rescue operation, and thus a greater degree of risk.

Two workshops were organized to obtain feedback from stakeholders and initiate discussion regarding the issue. Future research, risk-reducing measures, rescue service guidance, and changes to regulations and guidelines are discussed and proposed in SP report 2017:14.

The SP Report 2017:14 written by Jonatan Gehandler, Peter Karlsson, Lotta Vylund can be downloaded here.

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