Zero energy tunnel: renewable energy generation and reduction of energy consumption

Creating a zero energy environments is a hot topic. The developments in this field are based on the concept of the 'Trias Energetica': reducing energy consumption, using of renewable energy, and efficient using of fossil fuels. Zero energy environment concepts can be also applied to road tunnels to improve the energy performance by means of reducing energy consumption, introducing of renewable energy generation and by this way lowering energy bills. Nowadays the energy consumption in the road tunnel is high, up to 6.6 MWh/km per year during normal operation conditions. Thus, the reduction of energy consumption even by 5-10 per cent could bring greatly benefit to tunnel owners. This paper presents the framework of zero energy tunnels and highlights the major innovative aspects. These aspects include various technological approaches to reduce energy consumption, to extract thermal energy from the tunnel and to improve air quality inside and outside the tunnel. Furthermore, it discusses the introduction of renewable energy generation for tunnel constructions.