Fuel Cells & Batteries As Energy Sources For Transport

[gl556tr]

I am in favour of alternative energy for the current CO2 and NOx stinkers. Whereas the much-vaunted eTransport uses Batteries, I cannot appreciate where their advantage, if any, over Fuel Cells lies.
__eVehicles use the former, which are heavy, need Li and associated dodgy technology, and require hours for a "refuel". Also, Li is rare, making us dependent on the few countries where this can be found. There is also the question of from which source electricity is generated: coal-fired are an immediate nuisance, atomic-powered a long-term nuisance.
__Fuel Cells run on Hydrogen. I know nothing of the materials used and production methods for Fuel Cells. But Hydrogen can be created from renewable energy sources, including tidal power. The latter is environment-friendly.
I would appreciate some learned(!) comments/information on these two issues.
Thank you.

[atalanta]

Hydrogen if used as fuel has to be transported. In Germany it has to be transported under pressure, and by the time it reaches its destination, ten percent of it has leaked away. The "waste" product of using hydrogen as fuel is water, which sound wonderful, but when you consider the amount of water which would be produced by millions of vehicles travelling billions of miles, you have to realise that the air would be so full of moisture that we should end up changing the climate for the worse. Rain would increase hugely, the atmosphere would be so full of clouds that might never see the sun again. And, of course, the very production of this hydrogen energy/fuel takes energy itself. Quite a lot of energy, too.

[TheChair]

Most of the hydrogen used today comes from natural gas. In other words from fossil fuels - so it's not exactly a renewable resource. What's more, when Hydrogen is extracted from natural gas, there are a number of by-products, one of which is Carbon Dioxide - a greenhouse gas. On top of that, although the energy used for its extraction could theoretically come from renewables, in practice, it doesn't. Then, of course, there is the carbon footprint involved in its transportation.

[gl556tr]

Oh, lawd! In spite of the CO2 threat, "alternative energy for transport" seems to be little better, if at all.
H: Why does Hydrogen have to be pressurised? To squeeze more in? If I had a choice between clouds of Carbon Dioxide and clouds of H2O, I would be inclined to take an umbrella and breathe fresher air, rather than (diesel-causing) carcinogenic stuff. (Wouldn't be returning whence we came ...?!)
TC: But we have to have an alternative to fossil fuels. So, sooner or later, we will have to turn to eBattery or fuel-cell cars. With the former being heavy, but readily-available alternatives to Li promising, what are fuel cells made of and are they just as heavy?
Thank you.

[Karolina82]

Fuel cells normally use hydrogen as the "fuel" and air as the oxygen supply. In addition there is an electrolyte and a catalyst, usually platinum.
The problem with the hydrogen supply in a car is maximising its energy density. Compressing it to say 3000psi requires bulky and heavy steel cylinders. Liquid hydrogen at atmospheric pressure would have to be cooled to temperatures only a dozen or so degrees above absolute zero. Also as little as 5% hydrogen in air forms an explosive mixture.
An old method of producing hydrogen gas is to blast steam through white hot coke. This also produces carbon monoxide, a calorific fuel which oxidises to our old enemy carbon dioxide.
I fail to see how the steam produced in the exhaust of fuel cell-powered cars could cause any measurable climatic change. However, the vast amount of water vapour released from cooling towers such as those at Drax Power Station do cause localised weather anomalies.

[EDDIE51]

Hydrogen is a Element it can not be 'Created' . Hydrogen is however very abundant , in fact it is the most common Element in the Universe . Water consists of Two parts Hydrogen to 1 part Oxygen H2O . All we have to do to get Hydrogen is separate water into its two components Hydrogen and Oxygen.This can be done by 'electrolysis' using electricity. The electricity can be obtained from solar power or any other source.
When Hydrogen is burned in an engine the only byproduct is water, it recombines to the same amount of water that was used to produce it in the first place. So there is no pollution of any sort , nor is there any extra water produced , water used = water produced.
There are problems however, Hydrogen is explosive and it has a very low density ( the lightest of all Elements) so it has to be very highly compressed to be of any use as fuel.

[EDDIE51]

Details of how Hydrogen and Oxygen are produced from Water here
http://www1.lsbu.ac.uk/water/electrolysis.html

[EDDIE51]

In working electrolysis systems there has to be a catalyst, normally Platinum to speed up the reaction. But the catalyst is not consumed in the reaction and can be recycled so only small amounts are needed.