Solar panels make hydrogen

You probably worked with liquid helium then if you were cooling magnets, and helium has the peculiar habit of creeping up the inside of its containment vessel and over the top and out. So that's different.

Meanwhile, even helium is successfully contained in large 2200 LB/Sq.In. tanks for inflating toy balloons. You've seen them.

 

The problem is that the molecules on the order of the size of the pores in the metal containing them.

And we were working with closed, pressurized systems.

 

I noticed from Consumer Reports that when you buy a Toyota Mirai you get 3 years of free hydrogen, not to exceed $15,000.

Also, they say a fill-up will get you almost 275 miles on a 5kg tank full. And, a fillup can be done in a few minutes.

Of course, one catch is that you need to find a station, which means you're tethered to areas near SF and LA in California.

Also, CR says the car is about the size of a Camry and is sluggish at 153 hp.

 

The relevant figure is the energy density. Hydrogen gas has an energy density of around 9 MJ/L (at 700 bar (10,000 PSI)). Natural gas has an energy density of 22.2 MJ/L. Gasoline has an energy density of around 34 MJ/L. Yes, hydrogen gas is compressible, but there is not nearly as much energy available, so it has to be compressed higher than natural gas to be practical.

 

How much leaks in practice? And just the tanks aren't the problem so much as fittings, pumps, and valves.

 

or refill more often. I guess the point is that regarding utilization of the solar panels in question, the bottom line is cost, and that will improve over time with any new technology.

 

Tanks are commonly stored successfully. If you can find data on "difficulties" as you've mentioned with helium tanks, go ahear and post it (although it's off topic).

 

The Toyota Mirai exists and has been tested. So we have an example of real world performance.

Consumer Reports says it takes "a few minutes" to fill the 5kg hydrogen tank and has a 275 mile range - 55 m/kg. CR then says that's about the energy equivalent of 6 gallons of gas, but I think if you get 275 miles out of 6 gallons that's 45mpg! It says the car is roughly equivalent to a Camry - which has a longer range and well established refueling infrastructure to draw on, of course.

It's perfectly valid to compare energy density of hydrogen and gas, of course. But, for performance in a car I think one has to compare the full meal deal. Hydrogen cars will be electric, so one has to consider the efficiency difference in getting electricity out of a battery and getting it by fuel cell production.

There certainly will be a huge barrier centered around filling stations. These stations require real estate and safety measures consistent with handling fuel. This represents a gigantic investment while would need to get paid off by fuel price.

Tesla has electric cars rated at 310 miles. You can drive your car home at night and plug it in - no service station trips! Electric service for charging cars is relatively cheap to install, so businesses are installing such service for employees (to charge while working) and customers (while they shop/whatever). Charging is getting faster, but a full charge still takes 6 hours if you install the 220 volt service - like your electric clothes dryer uses. Of course, you can just plug it into any socket, but that takes a lot longer.

I think hydrogen is going to have to win on some other dimension. For example, maybe hydrogen is a cheaper way to deliver energy. Electric transmission lines lose energy, adding to the cost of electricity. (I doubt this one, as someone has to pay for all those service stations.)

Home production of hydrogen just gets you hydrogen, which requires special equipment if you want to use it in your hydrogen car, while solar electric energy can be used anywhere and can be sold back to the grid.

Overall, I think hydrogen cars have a tough road ahead. If I lived next door to a hydrogen fuel station I'd still have to get over that range limit and the $60,000 Mirai price tag.

 

It certainly would be advantageous to have one on every house to power their cars.

 

Toyota has put their eggs in this basket. But they’ll have to share the technology to be used by others if anyone can benefit. Theoretically, your rooftop could be the fuel station. Scary thought.

 

I agree with both your comments here. Also, right now there ARE other car manufacturers who have hydrogen cars - Toyota is the leader, but not the only entrant.

My problem with hydrogen cars is that Toyota and others see it as requiring a network of hydrogen stations that would approximate the network of gas stations we have today. Recharging electric cars doesn't really have to use such a network, as installing charging at places of business is cheap and does not require safety infrastructure for large pressurized fuel tanks.

I will say that if you run out of hydrogen on the road, you can't just phone a friend to bring you some hydrogen!

My problem with home hydrogen is that it requires significant new equipment such as a tank(!) and pressurization equipment and it requires equipment for using the hydrogen (car refueling equipment?, a hydrogen generator for electricity?) I just don't see it as likely competition for home solar electricity, as with home solar one can use it in all current appliances including cars and it can be sold back to the grid for use by others. It just seems like a far smaller and probably less dangerous footprint.


I'm sure there are uses for hydrogen. I'm all in favor of including hydrogen production as an interesting technology.