Hydrogen cars at the Royal Society
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Couple of things to set kirby mohr’s mind at rest.
Although he is right that the Joule-Thompson coefficient for hydrogen is positive, in any practical scenario it would never get anywhere close to the 500+ degrees C required to auto ignite.
Although hydrogen fuel is produced using hydrocarbons now most of the latest fuel cell vehicles will have a better well to wheel efficiency that the petrol equivalents. They are also comparable with power station electricity production/transmission efficiencies also. Remember electric vehicles are also getting their power primarily from hydrocarbons in most countries. The aim in the future would be to use alternative sources such as electrolysis turning fuel cell vehicles into instant recharge electric vehicles.
With regards to creation of h2 and infrastructure.
Currently a lot of H2 is a waste product in many chemical industries and gets burned off after usage so this could be reused at filling stations. You can also mix a percentage into the current natural gas network making gas “cleaner” and Germany is investing heavily in the infrastructure to support the future of H2 cars.
Hydrogen is a low density fuel however stored. If combined with CO2 by catalytic reaction, we get Methanol which is a capable and proven motor fuel, albeit 16 Mpg instead of the norm,.i
Believe it or not, some fuels are more dangerous than others. Petrol is more dangerous than Deisel and any kind of gas is more dangerous than either.
There is no net benefit to the environment from using electricity generated in ways that are common in current use. The additional processes involved and storage methods just decrease the efficiency of energy use.
The only use of electricity in transport that does seem to have an overall benefit is regenerative braking
Here in southern Germany there are some
BMW hydrogen cars running. But as long the oil industry not agrees to act as an H2 reseller, there is little hope for this kind of cars.
It appears to me that the proponents of hydrogen fuels are ignoring two things:
hydrogen has a negative Joule-Thompson coefficient. This means that as the pressure is decreased, the temperature increases. In a high-temperature hydrogen leak, the temperature can increase enough to set the gas on fire. I have seen this in the oil refinery. I think this would be very dangerous in an automobile, and I do not see how it would be possible to always be sure to not have any leaks.
In general, hydrogen is made by reforming hydrocarbons, so unless it is made by electrolysis I do not see how it is a net benefit to the environment.
If nothing else it would be absolutely wonderful to see some REAL competition to break the monopoly and stranglehold that oil companies and oil producing nations have on the rest of the world.
kirby posted –
“hydrogen has a negative Joule-Thompson coefficient. This means that as the pressure is decreased, the temperature increases.”
Eh?…..???!!
Are you sure? I thought it was a general property of all gasses that they cool as they expand and pressure drops (energy out) , or as you compress them (energy in) heat is given off. ?
At last, a bit of good news, as for Hydrogen comeing from Hydrocarbons, well electrolysis would be better, ideally excess power from all these new wind turbines the national grid is paying to turn off, as for Hydrogen being dangerous, no more so than any other fuel that burns afterall it is Hydrogen in these fuels that allows them to burn, anyway cars will oneday have v electrolysers on board to produce Hydrogen from H20 thus eliminating the need for Hydrogen tanks, keep an open mind, this technology exists NOW.
Not really green overall. Clean at the tailpipe yes, which makes the local air and our health better. I firmly believe battery electric is the way to go though, and especially with renewable energy source will always be more energy efficient overall. Hydrogen is one way to keep the system (government and oil companies) in control and stealing from our wallets, and I cant help thinking thats the only reason the technology is pushed so hard. I always see hydrogen linked to big oil. i think they should be using the new Tesla model S!
In re the Joule-Thompson effect: the original poster was correct. It is always true that if an expanding gas does useful work as it expands (such as running a turbine) it will cool, but if all the potential work is wasted (say in turbulence), that is a Joule-Thompson expansion; some gases get colder, others warmer, though it is normally a small effect and I doubt that it is high enough to cause ignition starting from room temperature.
What a great story presented. In the short term the production cost would outway the sale price however the long term benifits will be terriffic. In relation to Oil companies strangle hold would be as strong as the weak salesmarket on these cars. The quicker the Governments around the world look at this seriously the better the propects will be.
Great News.
Why are people commenting on the possibility of the cars and setting fire – electrical shorting can also do this – please review the Honda Hydrogen car currently running successfully in USA
The reliability of hydrogen fuel cell vehicles was demonstrated in several major cities around the world (2004-5) I have worked on design and material for liquid hydrogen refuelling and also on a project to set up refuelling stations in America with an Italian who had Russian funding. The financial crissis stopped or slowed much of the work It looked as though it would be financiaally viable when oil goes through the $250-300 barrier .Biggest problem with the busses was that they were too quiet
10 years ago in 2002 the Cabinet Office PIU Energy Review estimated that to produce enough hydrogen to supply its use in transport we would have to double our present electricity generation of about 375 Twh a year
(In a)”…..a Joule-Thompson expansion; some gases get colder, others warmer”.
Thanks for that, my education stopped before I got to that point! Another safety point not mentioned so far is the volatility of Hydrogen – it is lighter than air so any gas released floats away quickly unlike petrol or diesel.