Originally Posted by cuban335i
LMAO... Please do you're own research before trying to debunk my ideas. My professor is the head scientist for exxon-mobil in their quest for an efficient and cheap fuel cell that can be used by the general population. I've had tons of conversations with him about this.
Hydrogen in gas form DOES have an energy density of 120 MJ/kg. BUT that is in the gas form, do you know how much volume one 1kg of the least dense element on the planet is? ALOT! So, in order to be able to hold enough hydrogen in a car, it needs to be compressed into a liquid form (compressed=explosive when there's an accident).
When hydrogen is liquified it only has a energy density of 9 MJ/L which is nothing compared to gasoline at 31 MJ/L (translation= you need more than 3 times as much liquid hydrogen to get the same amount of usable energy out as gasoline to power a car). Other energy densities for example are: methanol 16 MJ/L and ethanol 21 MJ/L. FINALLY, when hydrogen is compressed, it's energy density is further reduced to 4.7 MJ/L (or ~7 times less energy per liter of gasoline).
SO, in summary, hydrogen won't work for cars. It may work for a power source for much bigger things, but cars are way too small.
BMW scrapped their hydrogen project, it was just a marketing strategy to show how BMW is really technologically advanced. They don't think hydrogen is the future
wow it is so funny that people think they know what they are talking about on this forum. This is you now:
Hydrogen may be a fuel of distant future, once we find a way to very efficiently harness solar power or miraculously come up with viable fusion technology... then we can hydrolyze water to our heart's content without having to worry about the relatively pitiful efficiency of it.
There are many researchers working on metal hydrides and other storage systems that are not pure hydrogen. However, the penalty you pay with these types are in weight because a large portion of the storage medium is not hydrogen. However, these material can theoretically give a higher energy density.
Also, if we get to point where we have a lot of excess energy (pipe dream), we can generate hydrogen and then use it to hydrogenate CO2 to create methane and other hydrocarbons. We can actually do this now, it just horribly inefficient because hydrogen is expensive to make and you have to force things in an energetically unfavorable direction.
Hydrogen from fossil fuels is reasonable, but then you still have the fossil fuel issues to deal with.
Originally Posted by ENINTY
And jet fuel is where the rub is. Millions of people a day depend on jet aircraft for travel. Jets are highly efficient in moving goods and people far distances at a low cost. Jets are able to fly because they use a fuel type that has a very high energy storage to weight ratio. There is no alternative fuel source for jets that will come on line in the near future to replace jet fuel as there is for cars such as electricity. Electricity is only viable for cars because the limit of its energy storage for drive range (of 80 - 100 miles per fill up) is somewhat acceptable in most cases. Because there is no alternative fuel source for jets, aviation transportation will rely on petrol-based fuel for the next several decades.
Although governments can try to dictate the use of alternate fuels for automobiles (such as electricity), however because there are jets flying that have to rely on petrol-based fuels, the infrastructure that makes aviation fuel will remain in place and will provide the least-expensive, highest density fuel source for cars, which will continue to be the best economical choice for automobile companies to design their products around.
That's partially true, but you can generate renewable biofuels for using as jet fuel. Lufthansa has been flying biofuel on a dedicated route and plane for about 6 months and 500+ flights.
So even though you need a high energy fuel, it can be relatively green.