The car that runs on air....

Jonnycoupe · 14 Feb 2008 at 16:15

One would have hoped the word 'recovery' rather than creation would give a clue as to what it does.

Simon · 14 Feb 2008 at 16:16

Jonnycoupe said:
One would have hoped the word 'recovery' rather than creation would give a clue as to what it does.

Quite

Fourstar · 14 Feb 2008 at 16:52

DingleBerry said:
I'm not sure what the efficiency of these engines is but I've heard 30% mentioned when talking about charging then discharging batteries (although that was for bog standard car batteries). If this is true then 60% for a multistage compressor is actually very attractive (lets face it you'd never use a single stage for these pressures). The weak link then is how the pressure to kinetic conversion compares to electric to kinetic.

Don't forget compressing the air is only one stage.

1) extracting energy source ??
2) Generating electricity, lets say ~50%
Coal and Nuclear 40-50%, Natural gas 50-60%
3) Transmission over nation grid 92.6%
4) Air compression 60%
5) Engine efficiency ??
I can't find any references

(figures mostly taken from wiki)

Ignoring the parts I don't know about we come out at 28% efficiency. Call it 20% assuming the air engine is 70% efficient.

Petrol is ~30%, diesel 40%

It would produce a net benefit in urban areas where pollution reduction would improve the health of many.

This is talking about thermodynamic efficiency so any improvements on power generation/renewables will improve the air car from a pollution point of view.

Dogbreath · 14 Feb 2008 at 17:48

DingleBerry said:
I'm not sure what the efficiency of these engines is but I've heard 30% mentioned when talking about charging then discharging batteries (although that was for bog standard car batteries).

The charging efficiency for Lithium Ion batteries can be very high indeed (over 95%), if they are not "fast" charged (which lowers the charging efficiency of any battery technology). No serious electric car is going to use lead acid batteries these days, the energy density of Li-ion is so much better.

That said charge efficiency of lead acid batteries can be very good, but drops off significantly as the battery gets close to 100% charge, i.e. charging to 80% capacity may be over 90% efficient, but putting the extra 20% charge in requires proportionally more energy input and lowers overall efficiency. However, the figures I have seen suggest at least 70% is achievable.

BigglesPiP · 14 Feb 2008 at 17:59

Trouble is recovery systems are be no means perfect. In a few driving styles/conditions, lugging around all the extra battery (Prius I'm talking about here) wastes fuel.

Simon · 14 Feb 2008 at 18:13

BigglesPiP said:
Trouble is recovery systems are be no means perfect. In a few driving styles/conditions, lugging around all the extra battery (Prius I'm talking about here) wastes fuel.

That's not a recovery system as such. That is a normal hybrid.

What i described is known as 'micro-hybrids'

DingleBerry · 16 Feb 2008 at 11:04

Fourstar said:
Don't forget compressing the air is only one stage.

1) extracting energy source ??
2) Generating electricity, lets say ~50%
Coal and Nuclear 40-50%, Natural gas 50-60%
3) Transmission over nation grid 92.6%

Don't forget these stages are required for most of the new car power sources. As someone said previously the hydrogen powered car is a bit of a red herring as at the moment its just a fancy battery.

Dogbreath said:
The charging efficiency for Lithium Ion batteries can be very high indeed (over 95%)

I suspected Lithium Ion might be a bit better. I'm surprised its that much better though! And your right they would never use lead acid.