A micro-thread about where we are on hydrogen: in the 1990s, the Clinton admin wanted to raise car mpg standards, but the automakers were against it, and congress prevented action. Their counter proposal: don’t raise mpg standards, we’ll make hydrogen cars pewtrusts.org/~/media/assets… 
Then, even through the 2000s, even a little bit now, folks were basing the whole hydrogen proposal around making hydrogen from natural gas, which, for an entire economy, would not only be not great for emissions, it would be inefficient. The focus was on making a H2 car work.
2000 came and went, then the mid 2000s, and still no viable hydrogen car. The value proposition was initially that batteries weren’t good enough to go 300 miles on a single charge. They were right, batteries weren’t ready. But then, batteries got better while hydrogen sputtered.
Then finally, interest in green hydrogen started advancing. In reality, it was 15 years too late to start, but better late than never. We should still research H2 for some transport, but we should also have a big green hydrogen program for heat, industry, & stationary power.
So we spent a bunch of time on hydrogen cars, & learned a bunch, but batteries were the tortoise to hydrogen’s hare & caught up. Now, we’re realizing we need clean hydrogen not for cars, but for lots of other stuff. Enter from stage left, @jtemple: technologyreview.com/2020/08/07/100…
Another globally significant impact of not raising fuel economy standards in the 90s: the rise of the Ford Explorer & other SUVs, which quickly took over the car market, & the trend of automakers putting innovation efforts into horsepower instead of mpg. We live with that now.
There’s also a clean energy R&D lesson learned here: the govt hydrogen R&D program, was running about $100 million a year. Now, that sounds big, but it isn’t. Total federal R&D is like $140,000,000,000. They were trying to disrupt the gasoline engine with 0.07% of the R&D budget
