On 17/10/2012 20:56, The Natural Philosopher wrote:
John Rumm wrote:
On 17/10/2012 13:56, The Natural Philosopher wrote:
Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
But 80% of the energy in that tank is wasted. So go back and do some
sums.

Why don't you give us some realistic realisable sums instead?..

Dribble do sums? He thinks a battery car 100% efficient. Bit like his
brain...

In actual fact a battery car with regeneration added in is sort of
about 100% compared to a fuel car without which is probably in the
25%-35% range.

He's a bit out, but not by much.

Even with regen, you are going to lose heat from the motor, and each
time you convert to and from chemical energy for battery storage
(there is where a capacitor for collecting regen would be better).

However its worth mentioning that most cars peak braking power tends
to exceed their motive power by several times.

True

Hence the motors won't have the power to capture all the regen energy
on heavy braking,

False

How do you figure that if the motor can't generate the required current?

and you will need to rely on the normal brakes thus wasting that energy.


No.

This of course glosses over the big picture stuff such as the
inefficiency of the power station and the national grid in getting
power to your charger in the first place.

Indeed.

The actual grid and battery turnaround efficiency and motor efficiency
will be somewhere in the 80%-90% level

Couple that with a 60% CCGT power statin and you have around 50%
gas-to-wheel which is better than any IC engine will achieve.

Indeed - but given the lack of energy density of the best batteries,
still well short of liquid fuels.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/