Home Interviews THMG131 – Hydrogen Vehicles and Filling Stations with Jen Hamilton

THMG131 – Hydrogen Vehicles and Filling Stations with Jen Hamilton


In this episode, Bob and Mike talk to Jen Hamilton from the California Fuel Cell Partnership about hydrogen gas, cars, and filling stations.

Complete Show Notes

1:05 Introduction to Jen Hamilton

  • Expert in safety education and codes and standards management
  • Works at the California Fuel Cell Partnership

2:30 Adding Hydrogen Dispensing to Existing Gas Stations

  • Dispenser is a good distance away from the equipment itself, which can be costly
  • Underground tubing brings hydrogen out from storage and through the nozzle into the car
  • Interface is very similar to what we normally see when fueling at a gas station
  • California has been using this technology for 15-20 years
  • Getting to commercialization because real customers are leasing or buying hydrogen-powered vehicles
  • 12 stations coming to the East Coast between Boston & New York City
  • Toyota is already manufacturing hydrogen-powered vehicles and other brands are in the mix, too

5:05 Why Use Hydrogen Fuel Cell Vehicles?

  • Overall goal of the industry is reducing vehicle emissions – fuel cell vehicles are all zero emission
  • Advantages include:
    • Short refueling time – only takes a few minutes to fuel at the dispenser
    • Range is similar to what you get with a gasoline engine
    • Fuel cells can also be put into transit busses, which they’re already doing in California
    • Also used frequently in forklifts – power output is consistent from full to empty
    • Can also be small enough to power a laptop or cell phone or large enough to provide backup or emergency power – saved the day during Hurricane Katrina as a result

8:45 Hydrogen Fuel Cell Composition

  • Anode and cathode with a carbon-based membrane between them
  • Platinum is embedded in the membrane to catalyze the hydrogen molecule, which breaks down into protons and electrons
  • Electrons have to be routed to an external circuit to provide the electricity that powers the car
  • Protons pass through the membrane (proton exchange membrane) – on the other side of that reaction, the protons and electrons come together with oxygen from the air to create water (the tailpipe byproduct)
  • Very efficient system – heat is much lower than internal combustion engines
  • Solid state unit – vehicles use a non-conductive coolant to manage the temperature of the overall system
  • All of these vehicles also use a hybrid battery (i.e. lithium ion)
  • Energy is stored in the vehicle in the form of a compressed gas – can be stored indefinitely at pressure in Type 3 or Type 4 cylinders
  • Units are tested – virtually impenetrable and will not explode under any circumstances

12:10 At the Filling Station

  • Stations can have it shipped to them as gasses or liquids
  • Liquids have to be vaporized into gasses, compressed, and stored at pressure for cascade filling
  • Composite tanks are a must since it’s high-pressure ground storage

14:00 Hazards Associated with Storing and Transporting Hydrogen

  • Hydrogen is already being made and stored for other industrial purposes – NFPA 704 placarding used for storage and DOT placards used for trailers and tankers
  • Hydrogen is a cryogen, but it vaporizes quickly to a gas and wants to rise
  • It’s not the gas that’s a concern – it’s the pressure in the containers
  • However, there’s no liquid phase in gaseous storage like you have with a propane tank and no risk of BLEVE
  • All transport vehicles are equipped with venting and pressure relief – hydrogen can be vented to the atmosphere because it’s non-toxic

16:15 Things to Look for at Filling Stations

  • Orange high voltage cables – hybrid vehicle
  • Cylinders – pressurized gas
  • The letter “G” – could be hydrogen
  • Vehicles are badged with the make and model like any other commercial vehicle – most say “Fuel Cell,” which indicates they only use hydrogen

17:30 Handling Hydrogen Fires

  • Pressure relief devices aren’t standardized across different vehicles or identified on the car
  • Leaking hydrogen can’t go anywhere into the passenger compartment or where it might be trapped – up to automakers to figure out how to engineer this
  • TPRD (thermally-activated pressure relief device) is integrated into the steel end of the tank that regulates temperature and pressure
    • This is a diffusible metal plug that opens to release pressure – once it’s opened, you can’t close it
  • Car itself is highly unlikely to just catch on fire – any fire would probably be the result of an adjacent gasoline fire
  • Any venting will go towards the tanks themselves or towards the ground at a slight angle – you’ll find this at the rear of the car
  • Venting will be very loud since it’s a high-pressure vent – you’ll hear a loud pop or bang
  • You’ll see a pretty impressive hydrogen flame initially – this will hit the ground and spread out some distance from the car before going up
  • Flame gets smaller and smaller as it continues burning since the hydrogen is escaping and the tank is relatively small
  • Carbon-based flame remains since that’s what caused the venting in the first place – this packs a lot more heat due to the internal flame temperature
  • No way to know whether this has happened other than with eye witnesses since it usually happens before firefighters arrive at the scene
  • Understand that any fire will be coming from the rear of the car or the fuel door
  • In many cases, it’s smart to just let the hydrogen burn itself out and not try to cool off the tanks – in some cases, cooling causes the TPRD not to activate
  • If the leak is large enough, the vehicle shuts off the solenoids and goes to battery power so you can safely get off the road – won’t re-start after that so you can get it serviced
  • Car is constantly monitoring itself to keep these things from happening in the first place
  • Fueling stations can shut off hydrogen pumps if there’s any kind of issue

28:55 Contacting Jen and Learning More

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