Tanker Transport Explosions involving Ammonium Nitrate Emulsions

Ken Price, Expert Panel

We in Australia have had two transport explosions of ANE tankers in the past two years. The first, in Western Australia was a single vehicle event. The second, in Queensland, involved two vehicles – a light vehicle crashed into the ANE tanker. To my knowledge, nowhere else in the world has had a deflagration-detonation transition (DDT) where ANE is the only chemical involved.

Both explosions occurred after extensive fires and neither of the explosions caused any injury or death. (The driver of the light vehicle in the Queensland crash was killed in the crash.) It took two hours for the truck in Western Australia to explode and four hours for the Queensland truck. After such prolonged fire/heating and melting/rupture of the tank, the involved product was no longer ANE, but rather, molten AN residue, potentially mixed with Aluminium.

Like several of my previous articles, I have a bunch of questions and no answers.

If trucks of Ammonium Nitrate Emulsion are going to explode (only after such prolonged burning) what is the value of any tests to classify the original ANE product? The Western Australian emulsion passed all the Series 8 tests and am sure the Queensland emulsion did too.

If the Queensland truck had been carrying only ammonium nitrate, how much faster would it have transitioned to detonation? There is no water in ammonium nitrate to phlegmatize the reaction. On the other hand, there is minimal fuel in a load of ammonium nitrate. (This only works if you say it fast and don’t think too hard.)
In fact, there is plenty of fuel for a fire on a truck transporting ammonium nitrate. The tyres, the fuel tank, the plastics bags holding the ammonium nitrate, possibly pallets. And ammonium nitrate won’t pass the series 8 tests.

What might have been the reaction if the accident happened in a town? Sure, a big town could get water pumped onto the fires pretty quickly, but most small towns will have only a volunteer fire brigade with minimal water pumping ability.

How much safer are our roads because we are moving ANE and not blasting explosives? Every truckload of ANE removes two or three trucks transporting explosives. (ANE can move on road trains, blasting explosives may only be transported on rigid vehicles or semi-trailers.)

How come Australia is winning in the ANE transport fires? It’s not a place I am happy to be, but it does deserve some analysis. Mining is a big industry in Australia and we move a lot of emulsion. But it is also a major industry in Canada, USA, Russia, China, Africa.

Changing the labelling or classification isn’t going to change the nature or behaviour of the product. The emergency response is the same for ammonium nitrate, ANE, and Hazard Division 1.5 explosives.

How might things have been different if the truck had been powered by electricity? The battery electrolytes may have added to the fuel load, but so what? There was plenty of other fuel available and the emergency response teams did the right thing: evacuated the area until it was safe.

Speaking of electric powered vehicles… an informal Working Group has been set up to review the requirements for e-vehicles and consider their potential to transport explosives and precursors such as ammonium nitrate and Ammonium Nitrate Emulsion.

The Working Group is part of the World Forum for Harmonization of Vehicle Regulations (WP.29). This World Forum convenes as Committee WP.29 and it drafts and manages a wide variety of regulations relating to road vehicles, such as lights, brakes, construction etc. These regulations are generally picked up and applied by nations or regions. Among those regulations are Regulations 100 and 134:

• R100: Uniform provisions concerning the approval of vehicles with regard to specific requirements for the electric power train;
• R134: Uniform provisions concerning the approval of motor vehicles and their components with regard to the safety-related performance of hydrogen-fuelled vehicles (HFCV) [2019/795]

Within Europe, the principles in R100 have been adapted to enable flammable liquids and other flammable materials to be transported in e-vehicles. Europe is also likely to be an early adopter of any recommendations that may permit the transport of explosives in e-vehicles.

What about all those e-vehicle fires?

Have you seen the Tesla fire of the week? Next time you see a good e-vehicle fire report, don’t just accept it. Chase it down and look for the facts. Almost all the reports I have seen include one or more of the following:

• It wasn’t an e-vehicle at all;
• It was a liquid fuelled vehicle that ran over an e-scooter/e-bike/e-whatever and there was a fire;
• Some turkey ran into the e-vehicle and destroyed it and there was a fire;
• There was a fire from another cause and the e-vehicle was incidental;
• A building went on fire and there was an e-vehicle in it.
• A bus went on fire and there was an e-vehicle nearby that also caught fire.
• The same e-vehicle is reported as a battery fire in numerous jurisdictions.

In contrast to modern journalism, let me give you a few facts.

• Professor H Dia, Swinburne University of Technology published a report in 2023 which referred to Australian firm EV FireSafe , which tracks passenger electric vehicle battery fires worldwide. From 2010 to June 2023, its database records only 393 verified fires globally, out of some 30 million electric vehicles on the road.
• A May 2023 report by the Swedish Civil Contingencies Agency found vehicles powered by internal combustion engines were 20 times more likely to catch fire than electric vehicles in Sweden.
• Sweden recorded 106 fires in various electrified modes of transport in 2022. More than half were in e-scooters (38) and e-bikes (20). Out of Sweden’s 611,000 electric vehicles, 23 fires (0.004%) were reported. The fleet of 4.4 million petrol and diesel vehicles recorded 3,400 fires (0.08%).
• A 2020 Tesla internal report (not verified independently) suggested there was one Tesla fire for every 205 million miles (330 million kilometres) travelled. The Tesla report notes National Fire Protection Association data for the United States showed a much higher rate of one fire for every 19 million miles (30.6 million kilometres).

So what

E-vehicles are definitely not perfect and they have their problems, however, like we do with liquid fuelled vehicles, the problems can be managed.

Most fires occur soon after charging. Allowing a rest time after charging could minimise this risk.
Australia’s National Science Agency (CSIRO) has produced a report on lithium-ion battery safety that has a range of protective measures that can be applied to lithium batteries. It is a great reference if any mining or explosives company is contemplating use e-vehicles.

References:

Swinburne University of Technology: https://www.swinburne.edu.au/news/2023/09/electric-vehicle-fires-are-very-rare-the-risk-for-petrol-and-diesel-vehicles-is-at-least-20-times-higher/

Swedish report: Document Title: Sammanställning av bränder i elfordon och eltransportmedel år 2018–2023
Published by: Myndigheten för samhällsskydd och beredskap Contace email: registrator@msb.se

Best, A, Cavanagh K, Preston C, Webb A, and Howell S (2023) Lithium-ion battery safety: A report for the Australian Competition and Consumer Commission (ACCC). CSIRO, Australia

Acknowledgements

Thanks to Hussein Dia PhD FIEAust FASCE FITE, Professor of Future Urban Mobility
Swinburne University of Technology, Melbourne VIC 3122 Australia, for the 2023 report
Thanks to Dr Shulin Nie, Swedish Civil Contingencies Agency (MSB) S-651 81 Karlstad, Sweden for providing the original MSB research paper and translating the tables.
Thanks To Bob Sheridan and Noel Hsu for their considered comments on the draft.

All of these people helped with information and guidance in preparing this paper. Unfortunately, I have to take full responsibility for the result and any opinions or conclusions expressed therein.