Wednesday, March 12, 2008

Future Cars?

An air-powered car: a nifty commuter-mobile, but not much good for long-distance travel.

Electric cars: not bad if they were charged by non-polluting nuclear power, but currently the electricity that charges them is created by burning coal or natural gas--ergo, you're still polluting.

Hybrids: Yahoo contrasts 10 hybrids available this model year.


Oldmath said...

Darren: You are correct about electric cars, but large power plants burn fuel more efficiently than small internal combustion engines so there is a net reduction in pollution.

The "air car" requires a power source (presumably electric) to compress the air in the first place so the question becomes are compressed air tanks a better energy storage device than batteries. I am dubious about this one.

neko said...

I think that it's time to bring back the Stanley Steamer.

(The car... not the rug cleaning machine.)

Step Back said...


As a math teacher it shouldn't be too hard to learn some physics and pass the lessons on to your readers.

Air car: Each time you compress a gas (e.g. air), part of the compression energy is lost as heat. PV=nRT, the gas law. Temperature goes up as pressure increases.

Electric car in place of gas guzzler: Coal powered plants are not "efficient". 60% of more of energy goes up as waste heat. Then there is transmission loss (about 10%) over electric lines, conversion losses in the battery for converting from electrical energy to chemical and back again.

It all sounds good until you start doing the math.

Darren said...

And as a host it shouldn't be too hard for me to identify some lessons about gratuitous swipes at people and pass those lessons onto my readers--which is why I posted your comment, jacquesasse.

David said...

Large power plants are in fact considerably more efficient than automotive gasoline engines, even when transmission-line losses are taken into account. This is especially true of new combined-cycle technology like the GE "H" series turbines, which offer 60% efficiency (not 60% waste.)

You can buy them here.

Step Back said...

To bash is human. I'm human. (So are you.} :-)

Since we both read Robert Rapier and The Energy Blog, you kind of know what my next comment is going to be: Where do I buy the transoceanic pipeline to feed the natural gas (methane) into my H series given that the gas is over "there" and not over here in the United Saudi Arabia (USA) of Coal? :-)

p.s. Aside from I2R and Energy Blog, are you also an Oil Drum reader?

David said...

sb...only occasionally an Oil Drum reader.

You can of course gasify coal before feeding it into your brand new "H" series. The other option is LNG tankers, assuming that various interests do not totally succeed in suppressing the building of port facilities. (The practical solution will probably be that the LNG tankers will dock in Mexico and the gas will flow to the U.S. by pipeline)

But I think that even for pure coal plants, whose efficiency is of course lower than the combined-cycle stuff, the overall efficiency of electric vehicles is going to come out better...IIRC, Rapier has posted some analysis about this. Also, remember the cost per BTU is lower for coal than for oil, so economics could be favorable ***if*** the battery problems could be solved at reasonable cost.