Hydrogen fuel for cars? Just why?

Could someone please explain to me why hydrogen is the 'fuel' of the future?

I don't understand how hydrogen is a better alternative to electricity, (for cars I'm talking)...
As far as I get it, for hydrogen fuelled cars:
- use electricity in electrolysis to form hydrogen
- use hydrogen as a fuel to generate electricity
- the electricity powers the car

Now why not just use the electricity you already had, to power the car? What's the point in converting electrical energy to hydrogen, then back to electricity?!

Will be so grateful if someone can actually explain this to me :smile:

I'm obviously missing something ridiculously obvious...

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Reply 1

Sammy Lanka

Original post by Nice.Guy

I'm obviously missing something ridiculously obvious...

It is cleaner. More electricity is created then used so you are not dependent on external power sources. Hydrogen fuel is clean whereas coal is not

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Reply 2

Nice.Guy

Original post by Sammy Lanka

It is cleaner. More electricity is created then used so you are not dependent on external power sources. Hydrogen fuel is clean whereas coal is not

Posted from TSR Mobile

But you need electricity to form hydrogen, right? So technically they're as clean (or unclean) as each other??

Also could you explain more about how 'more electricity is created than used' part please? :smile:

Reply 3

Cerdic

I always thought it was a range thing. People first started talking about hydrogen cars in a big way when electric cars were awful. So you could fill up a hydrogen fuel cell (or replace it), but with electric cars you'd have to recharge them which can take hours and so isn't very practical on long journeys. You can see why for health and safety reasons swapping an electric car's battery out all the time wouldn't be favourable.
I think the reason most people don't want an electric car, apart from any pricing issues, is a few times a year they go see the relatives 400 miles away for special events and don't want to risk having to recharge their batteries. Once cars get so they can travel from John O'Groats to Land's End and the price comes down to just above the level of a normal car, then I could see electric cars becoming wildly popular here. Alternatively if the government introduces free wireless charging on motorways, but I don't see this happening any time soon.

Reply 4

Sammy Lanka

Original post by Nice.Guy

The electricity used for electrolysis is negligible but using hydrogen as fuel creates alot of energy

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Reply 5

BlueSam3

Also, because batteries weigh a lot and take forever to recharge, whereas hydrogen is light and quick and easy to refuel with.

Reply 6

Timikji

Original post by adi19956

I saw a video on TED I think (I can't remember the title though) that was saying that they would store batteries at petrol stations and have a mechanism to swap out the batteries automatically so instead of filling up at the pump you're swapping out at the 'pump'. They could charge the batteries there and cycle through, disposing of them at the end of its lifetime. Of course there is still the problem of getting clean energy but this was more a case of infrastructure. I thought that it was interesting anyway :smile:

Reply 7

Bradshaw

I seriously doubt that hydrogen will be the future. It's a pain to store, has many safety implications and as previous posters have said, electric cars are likely to be better. The limitation with electric cars are:
1) Quality of the battery
2) How long it takes the battery to recharge

However it's arguable that neither of them are a particular clean, as of course it's been pointed out you still need a fair amount of electricity, a large proportion of which is still created by coal (and thereby dirtier than petrol).

Reply 8

WGR

It's because electricity is hard to store. Batteries aren't great so hydrogen is used sometimes. Think of the hydrogen as an electricity store. Hydrogen is much misunderstood for this reason because people think it is the raw energy source. It isn't it is merely the means to "store the electricity" and that energy ultimately comes from fossil fuels so at the end of the day you may as well just stick with the internal combustion engine.

Reply 9

Helloworld_95

It's more to do with energy density, batteries are not dense at all. However H2 is also a pretty poor storage medium overall due to issues with volatility and leaking. So to use hydrogen as a fuel we'd need to store it in something else, either by adsorption, preferably absorption, which comes with density issues or as part of another molecule, such as ammonia, with it being released by equilibrium shifts which would be very complex and has issues with loss of product and energy. Another option is methanol which solves the storage and some production problems.

Reply 10

username913907

Original post by Nice.Guy

I'm obviously missing something ridiculously obvious...

The reason why Hydrogen is (currently) a potentially better fuel source is due to one simple factor.... energy density!

It requires a gigantic weight in batteries to achieve a reasonable lifetime for a charge, and this makes it inefficient due to the huge weights being lugged around. Liquid fuels such as Oil and liquid H2 have a much better energy density than a battery allowing you to go much further on a single fuel load.
Another factor is the recharging time. For a liquid fuel this takes a matter of seconds but it takes many hours with a battery!

A lot of research has gone into storing hydrogen safely as pressurised H2 has the unfortunate property of being highly explosive!!! My tutor has infact developed a full scale system using ammonia as a hydrogen source! So in the long term the major barriers to making Hydrogen powered cars the norm are disappearing.
The biggest obstacle to battery powered cars in packing more energy into a smaller mass and size. The current battery technology (Li-ion) limits this to energy densities close to the current values, so a major advance in battery technology is required to really get this system popular.

Reply 11

Nice.Guy

Original post by adi19956

Original post by BlueSam3

Original post by WGR

Original post by Helloworld_95

Original post by JMaydom

Thanks very much for all the replies!! :smile:

I think I finally understand it - I never realised the hydrogen was essentially an energy 'store'... I always thought people regarded it as an energy source (which didn't make sense to me).
So, if batteries had a similar energy density to hydrogen fuel cells... we'd all be using batteries instead of hydrogen fuel cells?
Also, why aren't supercapacitors used in electric cars? They seem like a fantastic way to store electricity - or do they have a similar problem of being too heavy/short range?? :smile:

Reply 12

Nice.Guy

Original post by Sammy Lanka

The electricity used for electrolysis is negligible but using hydrogen as fuel creates alot of energy

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Have you got a link which backs this up please? For some reason, I don't think it's true...

Reply 13

Rainingshame

Original post by Nice.Guy

I'm obviously missing something ridiculously obvious...

Normally because once we figure out how to effectively transfer hydrogen it will be easier to store energy in that form. Additionally because the energy has already been transferred to the store (In battery powered cars it's a lithium ion cell) the recharging process is much quicker and so you can be more flexible. I'm not sure about the last one but I'm guessing building fuel cells and producing hydrogen is more environmentally friendly than constantly producing lithium ion cells for cars.