Thank you for the assist! I should have clarified point 1.2 (thermally excited iron). The basic idea for that one is forcing a piece of iron to get rusty very very quickly. The iron will grab the oxygen, leaving the hydrogen free for the taking. While the overall efficiency isn't the world's best, the process is pretty much idiot-proof to the point that froggles could probably handle a home unit. Assuming the numbers are right in the books I've read, then about 14 KWH will produce one lb of hydrogen. Using only bargain basement solar cells, I can get 10 watts per square foot. that works out to some 1400 square feet, using I want 1 lb/hr of hydrogen. with a standard tank using about 12 gallons per week, after working out the conversion factors, and assuming that New England only gets 4 hours a day of sunlight, I need something like 4300 square feet of cheap PV panels per car. Harsh, but doable That means that 1 acre can support 10 car/weeks of drivers, assuming such hideously low efficiency PV panels. This scales up to some 3,000 cars per square mile, assuming only half of the square mile is covered with panels. Assuming we decided to build one big PV industrial plant dedicated to making hydrogen to power the cars, and we gave every American a car...

We'd need something like an area 100 miles by 100 miles.
Boston's GMA of 3 million people (using they went apostate from the T and Bus system) would need something like 33 miles by 33 miles. Not that big an area, when you think of it.
( I think that collector could be placed in the Bay, and few would notice.)

The biggest problem with talking about this stuff to the public is that they forget that oil is also just an energy currency.

Seeing as I can be a cheap bastard at times, I would prefer to use a few PV panels, and a whole lot of concentrator mirrors. Place a large water filled heat exchanger between the incoming concentrated light and the PV panel, and you can capture the concentrated IR, and let most of the visible light through to the panel. You can use trapped heat for a steam engine, allowing a little bit more generated power (and it gives the whole facility that added stylish Steampunk motif.)

I could see using scrubbers to store the CO2 until collected at some station, maybe an add-on to regular gas stations? The collected CO2 could then be used to help grow more plants/crops. With a touch of creative tinkering, we could use this process to create larger farms in New England.

give me lever, and a place to stand...