[SGVLUG] [OT] Especially for Tom & his Prius.... [my rebuttal, then I'll shut up]

[David Lawyer]

Dustin Laurence wrote:
> > > And advanced diesel hybrid is probably the most efficient city vehicle
> > > we actually know how to build.
> > 
> On Tue, Jul 11, 2006 at 12:34:57PM -0700, Christopher Smith wrote:
> > Nah, purely electric and fuel cell vehicles beat it. While we can build
> > them, there are problems with usability outside of city commuting.

I don't agree.  The efficiency of electricity generation (after
transmission losses) is still only about 30% (Transportation Energy
Data Book, Ed. 24, footnote to table B.6 uses 29%).  Now in 1956 (50
years ago I learned that the best gasoline engines were nearly 30%
efficient, and this number is still being used today 50 years later.
In fact, test data on our 1968 Ford V-8 showed only 25%.  I got this
test data due to a very unusual set of coincidences which would be
grossly off-topic to explain (serendipity).

So it's just that simple, the gasoline auto engine is about the same
efficiency as electric power generation.  But due to the way people drive
autos at off-peak efficiency, the average efficiency is often less
than 15% and then there may be air conditioning losses too, etc.  With
straight electric, there's also the high battery charge-discharge
losses plus the efficiency of the electric motor which varies say
between 0% and 90%.  The 0% is at high speed and zero torque, like
when you run a motor fast with no load connected.

The result is that the electric car is generally less efficient than
the gasoline car unless you drive your car at very low efficiency
operating points (as many people do).

Fuel cells?  I understand that they can be very efficient, but where
does the hydrogen come from?  If you generate it by electricity, you
are only about 30% or so efficient starting out the energy chain.
Then if the fuel cell were 50% efficient you're now at only 15%
efficiency.  Then if the electric motor is...

Now for electric energy, you need to use the marginal cost, which is
the cost for fossil fuel generation.  The hydro and wind generated
electricity is going to be used anyway and if you change the amount of
electricity used a little it will all come from fossil fuel
generation.  So that's why electricity efficiency is calculated
assuming fossil fuel generation.

The bottom line is that neither the electric or fuel-cell auto is as
inherently efficient as the gasoline or diesel auto.

On Tue, Jul 11, 2006 at 03:38:56PM -0700, Dustin Laurence wrote:
> Hmm, well, "we know how to build" means (to me) it actually works with
> the same sort of price, performance, and reliability as gasoline
> passenger cars.  I didn't make that clear, but it *was* in the context
> of "actually doing something" and to do that you need to get them in the
> hands of 50,000,000 people or so.  People expect and demand the
> convenience and value of gasburners, which is a very mature technology.
> 
> By that criterion, we *really* don't know how to do that for either of
> those.  Performance is fine on electric 
No.  See above.
> but range sucks, and the price is crazy.  Don't know about
> reliability, but I might if GM hadn't decided to send all the EV1's
> to the crusher.  Fuel cells--price again is fantastic, and unless
> they've fixed it recently the cells are still finicky and not very
> durable.  Performance should be fine, though.
Absolutely not.  See above.
> Range--hah.  Hydrogen storage is just as problematic as durable
> cheap fuel cells, maybe worse.  Bill Gates might be able to afford a
> palladium sponge based tank, but the rest of us...I was hoping
> they'd find a cheap easily manufacturable material that had similar
> properties, still do, but I haven't heard of any signs of success.
> 
[snip]
			David Lawyer

PS: If you're interested in transportation energy, especially rail and
mass transit, visit my website www.lafn.org/~dave.