The Anonymous Widower

How Much Energy Can Extracted From a Kilogram Of Hydrogen?

This article on EnergyH, is entitled About Hydrogen Energy.

This is said.

Hydrogen has an energy density of 39 kWh/kg, which means that 1 kg of hydrogen contains 130 times more energy than 1kg of batteries. So lots of energy can be stored with hydrogen in only a small volume.

But as in most things in life, you can’t have it all as fuel cells are not 100 %  efficient.

Wikipedia has a sub-section which gives the in-practice efficiency of a fuel cell, where this is said.

In a fuel-cell vehicle the tank-to-wheel efficiency is greater than 45% at low loads and shows average values of about 36% when a driving cycle like the NEDC (New European Driving Cycle) is used as test procedure. The comparable NEDC value for a Diesel vehicle is 22%. In 2008 Honda released a demonstration fuel cell electric vehicle (the Honda FCX Clarity) with fuel stack claiming a 60% tank-to-wheel efficiency.

For the purpose of this exercise, I’ll assume a conservative forty percent.

This means that a kilogram of hydrogen would generate 16 kWh

Raise that efficiency to fifty percent and 19 kWh would be generated.

Conclusion

Fuel cell efficiency will be key.

May 9, 2019 - Posted by | Transport, World | ,

1 Comment »

  1. Hydrogen is light, but at STP bulky – 1kg occupies 11,200l (over 11 cubic metres) and won’t liquify by pressure alone (unlike LPG).
    Older readers may have seen vehicles using gas as fuel: –
    https://www.build-a-gasifier.com/gas-bag-buses/
    https://www.lowtechmagazine.com/2011/11/gas-bag-vehicles.html
    or even
    https://www.reddit.com/r/OldSchoolCool/comments/2mgkj3/female_taxi_driver_with_a_gas_bag_vehicle_using/
    Hydrogen can also be stored in palladium (~ 200 volumes), but the metal costs ~$5 per gram

    Comment by R. Mark Clayton | May 9, 2019 | Reply


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