EcoModder Forum H2 equivalent to 1 liter of gasoline

Register Now
 Remember

 07-13-2017, 04:37 AM #1 (permalink) EcoModding Lurker   Join Date: Jul 2017 Location: Planet Earth Posts: 43 Thanks: 3 Thanked 0 Times in 0 Posts H2 equivalent to 1 liter of gasoline A question I had was how much hydrogen gas (and at what pressure !) equals 1 liter of gasoline. Wikipedia mentions gasoline has 33,41 kWh per gallon (or hence 125 kWh per liter) and (idealhy.eu mentions that) hydrogen gas contains 0,003 kWh per liter (at a pressure of 1 bar). I would thus assume that to attain a same amount of energy (125 kWh per liter), I'd need to use a 41666 bar compression on that 1 liter tank. Is this actually correct ? I don't see where I made a mistake, yet such kind of pressures are not used in everyday life (the biggest compression rate used is some 700 bar). Can anyone verify whether my calculation is correct or not ?
 Today Popular topics Other popular topics in this forum...
 07-13-2017, 08:16 AM #2 (permalink) Master EcoModder     Join Date: Jun 2017 Location: Scotland Posts: 654 All That Jazz - '06 Honda Jazz i-DSI S Team Honda 90 day: 48.72 mpg (US) Thanks: 36 Thanked 128 Times in 95 Posts I think you will find that the hydrogen is stored at 350 or 700 bar, therefore to hold 1 litre petrol equivalent you require a far greater volume than 1 litre. __________________ People Think They Are Thinking When They Are Merely Rearranging Their Prejudices
 07-13-2017, 08:37 AM #3 (permalink) EV convert     Join Date: Jul 2011 Location: NewMexico (USA) Posts: 5,605 Sub - '84 Chevy Diesel Suburban C10 SUV 90 day: 19.5 mpg (US) camaro - '85 Chevy Camaro Z28 Riot - '03 Kia Rio POS Team Hyundai 90 day: 30.21 mpg (US) Bug - '01 VW Beetle GLSturbo 90 day: 26.43 mpg (US) Sub2500 - '86 GMC Suburban C2500 90 day: 11.95 mpg (US) Shocker - '11 Nissan Leaf SL 90 day: 130.28 mpg (US) Thanks: 127 Thanked 1,371 Times in 1,014 Posts I gallon of gas equivalent is about 2kg. So a liter would be about half a Kg. Forget volume, do calculations in mass any time possible. I think that is correct. What are you trying to do with hydrogen exactly? __________________ 1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost. 1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end. 2011 leaf SL, white 240v evse mod, trailer hitch, new batt as of 2014.
Thalmaturge

Join Date: Mar 2011
Location: The edge of nowhere
Posts: 580

Eeyore - '04 Honda Civic Hybrid

Go Pod - '00 Honda Insight AC

The Tinyvan - '07 Honda Fit Sport
Thanks: 233
Thanked 246 Times in 178 Posts
Quote:
 Wikipedia mentions gasoline has 33,41 kWh per gallon (or hence 125 kWh per liter)
Your conversion is backward. 33.41kWh/gal / 3.78541 L/gal = 8.83 kWh/L

So your calculations following that point are off by a factor of about 14x.

 The Following User Says Thank You to samwichse For This Useful Post: 14'ecocruze (07-13-2017)
 07-13-2017, 11:29 AM #5 (permalink) CruzeMTgrind   Join Date: Mar 2017 Location: Wisconsin Posts: 139 BlueBawls - '14 Chevrolet Cruze Eco 90 day: 41.67 mpg (US) Eddie - '02 Ford Explorer Eddie Bauer 90 day: 23.07 mpg (US) Thanks: 56 Thanked 9 Times in 9 Posts I knew something looked wrong in there but I just couldn't figure it out. Thanks for pointing it out for me and we'll the OP I guess. 3 1/2 hours of sleep got me a little fuzzy.
 07-13-2017, 12:14 PM #6 (permalink) EcoModding Lurker   Join Date: Jul 2017 Location: Planet Earth Posts: 43 Thanks: 3 Thanked 0 Times in 0 Posts Re: thanks for noticing this samwichse; updated the calculation: 1 liter of gasoline= 33,41 kWh per gallon (or hence 8,83 kWh per liter) hydrogen gas contains 0,003 kWh per liter (at a pressure of 1 bar). I would thus assume that to attain a same amount of energy (8,83 kWh per liter), I'd need to use a 2943 bar compression on that 1 liter tank. This still seems huge (the biggest compression rate used is some 700 bar). I guess it's doable if I am to use a 10 liter tank pressured at 294,3 bar but still that's a relatively large tank for just 1 liter of gasoline equivalent. The other thing I've been wondering about: does this take into account the size the gas still takes in after compression (I would assume that 1 liter of hydrogen, after compression to say 294 bar only takes in about 1/294th of the space (so 0,003397 liter). Or well, about that amount of space ... ---------------------- The other calculation I did actually used weight rather than volume (as oil pan 4 suggested). It went as follows: 1 liter of gasoline = 0,26 gallon of gasoline 14 liter of hydrogen = 1 kg of hydrogen @ 1 bar (see uigi.com/h2_conv.html ) 1 kg of hydrogen = energy in 1 gallon of gasoline (see heshydrogen.com/hydrogen-fuel-cost-vs-gasoline ) 0,26 kg hydrogen = 3,64 liter of hydrogen (compressed at 1 bar) -0,26 X 14- So in this latter calculation, it looks as if a mere 3,64 liter tank with hydrogen, without any compression at all would do This obviously doesn't seem correct, but I don't see the mistake here either.
 07-13-2017, 02:33 PM #7 (permalink) Master EcoModder     Join Date: May 2008 Location: Maynard, MA Eaarth Posts: 6,991 Mica Blue - '05 Scion xA RS 2.0 Team Toyota 90 day: 42.48 mpg (US) Forest - '15 Nissan Leaf S Team Nissan 90 day: 156.46 mpg (US) Number 7 - '15 VW e-Golf SEL TEAM VW AUDI Group 90 day: 155.81 mpg (US) Thanks: 2,081 Thanked 2,036 Times in 1,228 Posts I think 1kg hydrogen is equivalent to a gallon of gasoline. And 1 gallon of gas = 33.7kWh. __________________ Sincerely, Neil http://neilblanchard.blogspot.com/
 07-14-2017, 12:50 PM #8 (permalink) Master EcoModder   Join Date: Jun 2008 Location: Earth Posts: 5,008 Thanks: 215 Thanked 741 Times in 541 Posts The real problem with compressed H2 is the tank. From a quick search, the air in a typical scuba tank weighs about 6.5 lbs. Firgure H2 is about 1/14 as dense as air, and you get about 1/2 lb of H2 in a tank that weighs 30 libs or so. Then there's the energy needed to compress it to 3000 psi...
 07-14-2017, 02:03 PM #9 (permalink) Master EcoModder     Join Date: May 2008 Location: Maynard, MA Eaarth Posts: 6,991 Mica Blue - '05 Scion xA RS 2.0 Team Toyota 90 day: 42.48 mpg (US) Forest - '15 Nissan Leaf S Team Nissan 90 day: 156.46 mpg (US) Number 7 - '15 VW e-Golf SEL TEAM VW AUDI Group 90 day: 155.81 mpg (US) Thanks: 2,081 Thanked 2,036 Times in 1,228 Posts 3,000? How about 10,000PSI? __________________ Sincerely, Neil http://neilblanchard.blogspot.com/
EcoModding Lurker

Join Date: Jul 2017
Location: Planet Earth
Posts: 43
Thanks: 3
Thanked 0 Times in 0 Posts
Quote:
 Originally Posted by jamesqf The real problem with compressed H2 is the tank. From a quick search, the air in a typical scuba tank weighs about 6.5 lbs. H2 is about 1/14 as dense as air, and you get about 1/2 lb of H2 in a tank that weighs 30 libs or so.
Have you read my other post ?

I calculated out you could get about 6,95 kWh in a SCUBA.
Haven't tried it in practice though, so if you have, let me know.

I got the SCUBA tank idea from USH2. If it won't work, I guess I could always change it for a CNG tank, but I don't see any structural difference between the 2, so I assume both should work.

As for the energy needed and the compression used (3000 instead of 10 000 psi): using less compression means less energy needed (and less energy loss as well). Obviously it still remains inefficient from this standpoint, but on the other hand it has no (polluting) exhaust gases and you could use renewable electricity to make the hydrogen.

 Tags gasoline, hydrogen