The Challenges and Opportunities of New Energy Vehicles in Tunnels

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1 The Challenges and Opportunities of New Energy Vehicles in Tunnels Yajue Wu Department of Chemical and Biological Engineering Sheffield University, UK

2 Background European Union has committed to become a highly energy-efficient and low carbon economy and move towards the decarbonisation of the EU s transport sector by 2050 To meet the EU targets a range of new generation of vehicles are developed to utilize new energy powering methods such as electric/hybrid and fuel cells or alternative fuels such as carbon neutral natural gas, or liquefied propane gas

3 Current Status In UK, the new energy vehicles count 2% of the road vehicles. Across European countries, the percentage of new energy vehicles is in the similar order. The volume of the new energy vehicles is increasing. The hybrid/electric vehicles market share of total new car sale increased between 2013 and The plug-in electric passenger car is leading the emerging new energy vehicles. PEV market share of total new car sales in Norway is 22.39%.

4 Fire and Explosion Hazards The new energy vehicles are still in relatively low volume, but demonstrated diversity in fuelling and powering methods The some of the fuelling and powering systems are more hazardous in terms of fire and explosion safety The different fire and explosion behaviours of new energy carriers will have implications on the tunnel safety, as the vehicles become more diverse and the volume increases.

5 New Fuelling and Powering Systems IC engine alternative fuels such as more carbon neutral natural gas, or liquefied propane gas and carried on board as LNG, CNG or LPG (Autogas) Electric/hybrid Battery/ battery & petrol Fuel cells Hydrogen fuel in compressed gas or liquid

6 CNG LPG IC engine Engine technology is almost ready made and the fuel supply system can be easily implemented using existing fuelling infrastructure. It represents 3% of total market value. Developed for both passenger cars and buses Pressure relief valve is used to limit the pressure in the liquid fuel tank and prevent tank explosion in accidental situations. The fire and explosion behaviour of CNG, LPG is well understood in chemical process industry in terms of quantitative risk analysis.

7 Jet flame hazard with the pressure relief Explosion without pressure relief system Jet flames during the pressure relief

8 Electric/hybrid Plug-in electric passenger cars passed one million unit milestone in Sale of plug-in electric cars is almost twice fast as the hybrid electric vehicles 22% of newly registered cars in Norway in 2013 to 2015 is PEV Battery hazard is still not well understood in terms of risk analysis for fire and explosion behaviour of PEV and HEV.

9 The Hazard of Eclectic Vehicles Thermal management of the battery system is a key issue for battery safety The break down rate of PEV is expected high Battery induced fire incidents are more frequent. Overall HRR is similar or less due to simpler structure

10 Cutting Edge IT Technologies 360 Panorama image GPS voice navigation Remote diagnosis Mobile power station

11 Fuel cells Fuel cells cars produce zero emission and require hydrogen fuel in compressed gas or liquid A completely new supply and fuelling infrastructure is required to support hydrogen cars Demonstration fleets of hydrogen fuel cell vehicles are supported by EU and regional government. Hydrogen safety is one of the key research issues in the development of fuel cell vehicles.

12 The Safety Implication of New Energy Vehicles in Tunnels The new energy vehicles use new fuelling and powering systems and produce different fire, toxic and explosion behaviours during accidents from traditional vehicles powered by petrol or diesel. Currently, the risk levels that will be induced by these behaviours to underground structures and their users are unknown.

13 The Safety Implication of New Energy Vehicles in Tunnels NEV behaviour deviations will definitely cause safety implications in urban tunnels and underground space, both to users and the structures themselves, a concerted approach based on our already EU-wide implemented risk assessment methodology is mandatory. There is an urgent need to study the impact of the deviations of the fire, toxic and explosion behaviour on the current safety level implemented in road transportation tunnels and underground space, and assess the evacuation, fire-fighting strategy, the emergency response, structural safety as well as the overall operation of the facility with an increasing number of NEVs in mind.

14 Risk Analysis Based on the current status of NEVs, is it sufficient to develop a comparative risk analysis methodology the NECs comparable and deviation hazards from the conventional vehicles?

15 The Source Terms The root of all the deviations is the fuel system in the NEVs. Understanding the fuelling system and their safety features is important. For gaseous based fuel systems, such hydrogen, CNG, LPG, the pressure relief systems could caused fast fuel release rate. Electric and hybrid based NEVs, the behaviour of the electric battery during the fire is major concern.

16 The Fire Scenarios Fire scenario based on real traffic volume Risk assessment for operability The deviations of the subsequent events can be assessed in systematic fashion. Worst case fire scenario Major hazard analysis

17 The Opportunity How the tunnel community to interact with new technology in automobile GPS navigation Smart cars with artificial intelligence Platoons Automated highway system for driverless cars What do we need to develop a smart tunnel?

18 Conclusions The un-quantified hazards associated with new energy vehicles bring challenges to the current tunnel operation. Comparative risk analysis could be an effective way to highlight the deviations of NECs hazardous consequences. Quantitative modelling of the deviations would provide valuable information to assess the impacts on the tunnel s traffic management system, the ventilation, tunnel fixed fire fighting systems and tunnel structure. The new energy vehicles could also bring opportunity for the development of future tunnel systems.

19 Faculty Of Engineering.