[OT] Engine braking

[H. S. Teoh]

On Thu, Aug 01, 2013 at 01:17:51PM -0700, Walter Bright wrote:
[...]
> There's an inherent efficiency in gas cars in that the energy is
> generated on site. For electric cars, the energy is generated
> elsewhere (at the power plant), and then you're faced with all the
> losses from transmitting the energy, storing it, and recovering it.
> It's a tough hill to climb. Gasoline is pretty remarkable in its
> energy density and portability.
[...]

Your comparison isn't totally accurate. Gasoline stores energy in the
form of chemical bonds, and batteries store energy in the form of
electrical charge.  Both release the energy on site.

The advantage of gasoline is that chemical bonds in gasoline are far
more persistent than the electrical charge in batteries, and they are
also denser in terms of units of energy per volume than batteries made
with current technology. That's why gasoline is so much easier to store,
transport, and have very high efficiency.

The disadvantage of gasoline is that in a sense we're "cheating",
because the energy stored in it was built up over millions of years by
ancient organisms that have long decayed, and we're only now discharging
all that build-up. We didn't pay anything to put that energy there,
that's why it's so economical. If we had to live on synthetic gasoline,
it'd be a totally different story (it *is* possible to synthesize this
stuff, y'know, and attain the same efficiency, if not better; the
problem is that this costs far too much to compete with the stuff we
"stole" from ancient organisms).


T

-- 
People tell me that I'm skeptical, but I don't believe it.