Vaughn wrote:
On 9/8/2014 6:43 AM, Larry Dighera wrote:
She told me that their
fuel cell was 60% efficient in producing electricity from oxygen in the air and
compressed hydrogen; this is in contrast to ~30% efficiency of internal
combustion engines. If true, that will enable this technology to surpass
current propulsion technology.

Fuel cells have been the ultimate "vaporware". Starting about in the
1990's and continuing thru the first decade of the 2000's, fuel cells
were always "next year's technology. Several companies actually
announced consumer products, only to see them never actually materialize
on the marketplace.

Now we seem to hear a lot less about them.

It turns out that fuel cells are delicate things that have trouble
lasting in the real world. Feed them tainted fuel just once, and they
are junk. There are major problems obtaining a huge supply of hydrogen
and making the infrastructure to distribute it. It seems that we have
lots of oil wells and lots of natural gas wells, but no hydrogen wells.
To produce hydrogen takes prodigious amounts of energy, so it will
never be cheap.

The vast majority of commercial hydrogen is produced by steam reforming
of natural gas.

A fuel cell that runs directly on natural gas would make a lot more
sense for many reasons, but primarily because you can skip the reforming
stage and natural gas is a LOT easier and safer to store in a tank.

Still, when Honda actually introduced a few fuel cell cars starting in
the early 2000's, I thought that fuel cells were finally on the way.
History seems to be proving otherwise. The Honda fuel cell cars
remained a pilot program, producing only a few hundred units over a
decade or so. Not one unit was actually sold. Honda leased them to
carefully vetted customers. Now the word is that they will end
production with the 2015 model.

Over all this time, battery technology has continued to improve and has
actually led to real products in the consumer market. We now have a
choice of several practical battery cars that are on the mass market,
although most of us choose not to buy them for solid economic and
practical reasons.

Like the 2 to 3 times greater cost for an electric car versus a gas
car and the fact that batteries have a limited life span and are not
cheap to replace.

Another issue that is significant for aviation is the self discharge
rate of those high-tech batteries.

If you let them sit without charging for a month or two they go dead
and won't recharge.

Now we are seeing the beginnings of the same thing happening in
aviation. There will be eventually be a few practical battery airplanes
available. They will be around, but few of us will actually buy them.

Unless you fly a motor glider which is the only aviation application
where electric power is practical and likely to be for a very long
time.

Fuel cells? Don't hold your breath! But if we ever get them, they will
be expensive to operate because hydrogen will never be cheap.

Again, only natural gas fuel cells make any sense.


--
Jim Pennino