On Apr 24, 2015, at 6:03 AM, Russ Sciville via EV <ev@lists.evdl.org> wrote:
> Who would wish to drive around with a hydrogen tank in the back pressurised > to 10,000 psi? There's lots of insanity associated with FCVs, but fuel safety isn't part of it. Hydrogen is much safer than gasoline in that regards. Not that gasoline is especially safe, of course, but it's a well-accepted and well-managed risk, and hydrogen is a lesser risk than that. Gasoline vapors are heavier than air and tend to pool. Liquid gasoline wicks very easily into fabric. Gasoline fires stay close to the ground and in your clothes. Hydrogen is the most buoyant gas there is. An hydrogen leak is going straight up and isn't going to collect anywhere in enough volume to sustain combustion. If you started an hydrogen fire, the flames are going to shoot right up rather than spread laterally. And, unlike gasoline fires which are excellent at sustaining themselves, the slightest interruption of an hydrogen flame is going to extinguish it. Indeed, even creating a sustaining flame in the first place is going to be a bit of a challenge -- think of how careful you have to be to light a propane torch; hydrogen will be even more challenging. Pressurized tanks can be scary, yes, but, in practice, it takes either malicious intent or something spectacularly catastrophic to set off one built to automotive specs. Where hydrogen falls flat is first in terms of pollution. Hydrogen is commercially sourced from mined hydrocarbons and thus is as much of a CO2 pollutant as the coal, oil, or gas it's produced from. Because it's the lightest and most highly possibly refined form of those hydrocarbons, it next loses out on efficiency (for the same reason gasoline loses to diesel) -- especially compared with electric vehicles. It loses out in a really big way in terms of the distribution network which doesn't exist for hydrogen but does for everything else -- and which would be much more challenging and expensive and less efficient to build than anything else we've already built. And it loses out to gasoline and diesel in terms of practicality because...well, while hydrogen has far and away the greatest energy density per unit of _mass,_ it's also got the _least_ energy density per unit of _volume._ A fifteen gallon tank of hydrogen gas, under any form of compression you'd want to be anywhere n ear, contains _far_ fewer hydrogen atoms than a fifteen gallon tank of gasoline. Hydrogen is a great fuel...for rocket ships in space. Here on Earth? Forget it. Cheers, b& -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: Message signed with OpenPGP using GPGMail URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150424/390663a7/attachment.pgp> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
