CAFE Electric Aircraft Symposium Set For May 1

On 5/8/2015 2:30 PM, Larry Dighera wrote:

Personally, I find the whole argument on hydrogen as a replacement
for gasoline a joke.
The limited research I conducted years ago seemed to suggest that there wasn't
much else that approached the energy density of gasoline/kerosene. So, while
perhaps not ideal, hydrogen is a somewhat viable alternative to petroleum, that
has the potential to provide efficiencies several times better than the ~30%
efficiency obtained with internal combustion power plants. If you consider
that only one third the fuel will be required to achieve the current
performance, the numbers begin to make more sense.

With 70% of the energy blowing out the exhaust as heat, internal combustion
engine efficiency is comparable to an incandescent lamp that consumes ~90% of
its energy usage to produce heat, and only ~10% to produce light. LEDs, on the
other hand, can be 90% more efficient than tungsten filament lamps, and they
last many times longer too.

Simply put, the problem with using hydrogen as a fuel is that we have no
natural source of it in unattached gaseous form. So we have to MAKE
hydrogen by reforming it from natural gas, or by some even more
energy-hungry method such as electrolysis of water.

So while hydrogen can be used as a fuel, it is not a SOURCE of energy
such as natural gas or gasoline is. Hydrogen is only a CARRIER of
energy (much like our electrical utilities are a carrier of energy, not
a source of energy). In the process of converting "something" to
hydrogen, you never have 100% efficiency, so on a whole-cycle macro
scale the efficiency picture of hydrogen can look pretty dismal.

Also, an article might extol the clean burning properties of hydrogen in
an engine or fuel cell, while failing the mention the pollution produced
by the manufacture of hydrogen.