[Ram Jet]

Originally Posted by adouglas

Doesn't mean it's not a workable solution long-term.

Think big-picture energy flow. Ultimately, the source of all energy is the sun. When we burn dino juice, in effect we're converting solar energy that was stored millions of years ago, right?

The big problem with producing hydrogen is that it simply transfers the energy production from the vehicle to a power plant. Inefficiencies in generation and transmission plus thermodynamics mean it's not a net gain in energy efficiency.

So let's posit a fictional solar-powered hydrogen infrastructure. You use solar energy (captured however you like) to power electrolysis. You burn the resulting hydrogen and oxygen to power your vehicle. Net output is usable energy plus heat (second law...).

Thermodynamics works in that case. Solar energy in is always going to be greater than usable energy out... the remainder ultimately becomes waste heat. You're still using more energy to electrolyze the water than you get from burning the resulting gas. BUT it's free energy... sunshine. So you can put up with the losses to gain the benefits.

The question to ask is what you're solving for. In this case, it's zero carbon emissions, zero reliance on fossil fuels and less impactful technologies (a gas-burning engine does not require rare-earth metals the way batteries do). Plus you get a source of clean water, if you want to capture it. Those are worthwhile goals.

Downsides.... lack of fueling/storage infrastructure and low energy density, which means low power output and short range.

Great synopsis, thanks. I guess we'll just have to rely on good ol' Dino Poop for a while longer.

Bill