Hydrogen ICE can still make those beautiful exhaust sounds
 

Toyota has teaser videos of its modified Corolla Sport in a hydrogen-propulsion race project. It will be running on compressed hydrogen gas rather than liquid gasoline. Many internal-combustion engines are capable of running on gaseous hydrogen with some modifications. Toyota claims the hydrogen combustion occurs at a faster rate and improves responsiveness. Many race teams have used hydrogen fuel cells but on hybrid and battery-electric powertrains. Toyota uses compressed hydrogen gas direct-injection into its turbocharged inline-3 engine. More impressive it will be entered in the Japanese Super Taikyu Series' 24-hour endurance event at Fuji Speedway, from May 21-23, 2021.

https://www.youtube.com/watch?v=2dgzKW8EKMc

https://www.youtube.com/watch?v=O0yM5RlD7Zo

This is relevant: Sandy Munro On Next-Generation EV Technology: 25:45

Light Activated Hydrogen for storage. Lighter, more economical, recyclable, no pressure/non-flammable. They show something like a big 8-track tape that weighs 18lb and contains 5.5kWh.

Very interesting! What is the efficiency of ICE hydrogen vs. fuel-cell?

I wonder what would be any advantage compared to using methane (CNG), which is safer (and thus more affordable and less energy-intensive) to handle than hydrogen.

CNG is not carbon-neutral. I think, this is the main driver.

Even if hydrogen can be obtained from carbon-neutral sources, it's excessively energy-intensive and more dangerous to justify. It's more sensible to resort to biomethane which is useful to close the carbon loop, is safer to handle and can be sourced from whatever organic matter is available.

Go back to Permalink #2 and click the link. The material from Plasma Kinetics suggests other sources than industrial hydrogen, municipal waste water and incinerators (and potable water hydrolysis, however that works) using Laser Activated Hydrogen.*

The advantage of ICE over fuel cells is you can tune the exhaust note with different numbers of cylinders.

*Seriously, click the link.

It may work, mostly for industrial purposes requiring pure hydrogen, but it's not suitable as a motor fuel. The energy required to perform the hydrolisis, even resorting to catalyzers, is higher than what is delivered by the hydrogen released.

I was thinking any process that produces potable water wouldn't have an excess of hydrogen.

Were long over practical questions and sceptical calculations.... Clean Energy now, electrical power is coming from the socket, the money to pay it we just print.